jpx_core/extensions/

array.rs

//! Array manipulation functions.

use std::collections::HashSet;

use serde_json::{Number, Value};

use crate::ast::Ast;
use crate::functions::{Function, custom_error};
use crate::interpreter::{SearchResult, interpret};
use crate::registry::register_if_enabled;
use crate::{Context, Runtime, arg, defn, get_expref_id};

/// Helper to extract an expref AST from a function argument.
fn get_expref_ast<'a>(value: &Value, ctx: &'a Context<'_>) -> Option<&'a Ast> {
    get_expref_id(value).and_then(|id| ctx.get_expref(id))
}

/// Convert a Value to a string key for grouping/indexing.
fn value_to_key(value: &Value) -> String {
    match value {
        Value::String(s) => s.clone(),
        Value::Number(n) => n.to_string(),
        Value::Bool(b) => b.to_string(),
        Value::Null => "null".to_string(),
        _ => serde_json::to_string(value).unwrap_or_default(),
    }
}

/// Extract a key from an item using either an expref or a string field name.
/// Returns `None` if the item is not an object (for string field mode) or the
/// field is missing and we should skip the item.
fn extract_key(
    item: &Value,
    second_arg: &Value,
    ctx: &mut Context<'_>,
) -> Result<Option<String>, crate::error::JmespathError> {
    if let Some(ast) = get_expref_ast(second_arg, ctx) {
        let ast = ast.clone();
        let key_val = interpret(item, &ast, ctx)?;
        Ok(Some(value_to_key(&key_val)))
    } else if let Some(field_name) = second_arg.as_str() {
        if let Some(obj) = item.as_object() {
            if let Some(field_value) = obj.get(field_name) {
                Ok(Some(value_to_key(field_value)))
            } else {
                Ok(None) // field missing
            }
        } else {
            Ok(None) // not an object
        }
    } else {
        Err(custom_error(ctx, "Expected expref or string field name"))
    }
}

/// Register only the array functions that are in the enabled set.
pub fn register_filtered(runtime: &mut Runtime, enabled: &HashSet<&str>) {
    register_if_enabled(runtime, "unique", enabled, Box::new(UniqueFn::new()));
    register_if_enabled(runtime, "zip", enabled, Box::new(ZipFn::new()));
    register_if_enabled(runtime, "chunk", enabled, Box::new(ChunkFn::new()));
    register_if_enabled(runtime, "take", enabled, Box::new(TakeFn::new()));
    register_if_enabled(runtime, "drop", enabled, Box::new(DropFn::new()));
    register_if_enabled(
        runtime,
        "flatten_deep",
        enabled,
        Box::new(FlattenDeepFn::new()),
    );
    register_if_enabled(runtime, "flatten", enabled, Box::new(FlattenFn::new()));
    register_if_enabled(runtime, "compact", enabled, Box::new(CompactFn::new()));
    register_if_enabled(runtime, "range", enabled, Box::new(RangeFn::new()));
    register_if_enabled(runtime, "index_at", enabled, Box::new(IndexAtFn::new()));
    register_if_enabled(runtime, "includes", enabled, Box::new(IncludesFn::new()));
    register_if_enabled(runtime, "find_index", enabled, Box::new(FindIndexFn::new()));
    register_if_enabled(runtime, "first", enabled, Box::new(FirstFn::new()));
    register_if_enabled(runtime, "last", enabled, Box::new(LastFn::new()));
    register_if_enabled(runtime, "group_by", enabled, Box::new(GroupByFn::new()));
    register_if_enabled(runtime, "index_by", enabled, Box::new(IndexByFn::new()));
    register_if_enabled(runtime, "nth", enabled, Box::new(NthFn::new()));
    register_if_enabled(
        runtime,
        "interleave",
        enabled,
        Box::new(InterleaveFn::new()),
    );
    register_if_enabled(runtime, "rotate", enabled, Box::new(RotateFn::new()));
    register_if_enabled(runtime, "partition", enabled, Box::new(PartitionFn::new()));
    register_if_enabled(
        runtime,
        "difference",
        enabled,
        Box::new(DifferenceFn::new()),
    );
    register_if_enabled(
        runtime,
        "intersection",
        enabled,
        Box::new(IntersectionFn::new()),
    );
    register_if_enabled(runtime, "union", enabled, Box::new(UnionFn::new()));
    register_if_enabled(
        runtime,
        "frequencies",
        enabled,
        Box::new(FrequenciesFn::new()),
    );
    register_if_enabled(runtime, "cartesian", enabled, Box::new(CartesianFn::new()));
    register_if_enabled(runtime, "initial", enabled, Box::new(InitialFn::new()));
    // Alias for initial (Clojure-style name)
    register_if_enabled(runtime, "butlast", enabled, Box::new(InitialFn::new()));
    // Clojure-inspired functions
    register_if_enabled(runtime, "interpose", enabled, Box::new(InterposeFn::new()));
    register_if_enabled(runtime, "zipmap", enabled, Box::new(ZipmapFn::new()));
    register_if_enabled(
        runtime,
        "partition_by",
        enabled,
        Box::new(PartitionByFn::new()),
    );
    register_if_enabled(runtime, "dedupe", enabled, Box::new(DedupeFn::new()));
    register_if_enabled(runtime, "tail", enabled, Box::new(TailFn::new()));
    register_if_enabled(runtime, "without", enabled, Box::new(WithoutFn::new()));
    register_if_enabled(runtime, "xor", enabled, Box::new(XorFn::new()));
    register_if_enabled(runtime, "fill", enabled, Box::new(FillFn::new()));
    register_if_enabled(runtime, "pull_at", enabled, Box::new(PullAtFn::new()));
    register_if_enabled(runtime, "window", enabled, Box::new(WindowFn::new()));
    register_if_enabled(
        runtime,
        "combinations",
        enabled,
        Box::new(CombinationsFn::new()),
    );
    register_if_enabled(runtime, "transpose", enabled, Box::new(TransposeFn::new()));
    register_if_enabled(runtime, "pairwise", enabled, Box::new(PairwiseFn::new()));
    // Alias for window (sliding_window is a common name)
    register_if_enabled(
        runtime,
        "sliding_window",
        enabled,
        Box::new(WindowFn::new()),
    );
    // jq-parity functions
    register_if_enabled(
        runtime,
        "indices_array",
        enabled,
        Box::new(IndicesArrayFn::new()),
    );
    register_if_enabled(
        runtime,
        "inside_array",
        enabled,
        Box::new(InsideArrayFn::new()),
    );
    register_if_enabled(runtime, "bsearch", enabled, Box::new(BsearchFn::new()));
    // Clojure-inspired functions (Phase 3)
    register_if_enabled(
        runtime,
        "repeat_array",
        enabled,
        Box::new(RepeatArrayFn::new()),
    );
    register_if_enabled(runtime, "cycle", enabled, Box::new(CycleFn::new()));
    register_if_enabled(runtime, "lag", enabled, Box::new(LagFn::new()));
    register_if_enabled(runtime, "lead", enabled, Box::new(LeadFn::new()));
}

// =============================================================================
// unique(array) -> array
// =============================================================================

defn!(UniqueFn, vec![arg!(array)], None);

impl Function for UniqueFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut seen = HashSet::new();
        let mut result = Vec::new();

        for item in arr {
            let key = serde_json::to_string(item).unwrap_or_default();
            if seen.insert(key) {
                result.push(item.clone());
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// zip(array1, array2) -> array of pairs
// =============================================================================

defn!(ZipFn, vec![arg!(array), arg!(array)], None);

impl Function for ZipFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr1 = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let arr2 = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let result: Vec<Value> = arr1
            .iter()
            .zip(arr2.iter())
            .map(|(a, b)| Value::Array(vec![a.clone(), b.clone()]))
            .collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// chunk(array, size) -> array of arrays
// =============================================================================

defn!(ChunkFn, vec![arg!(array), arg!(number)], None);

impl Function for ChunkFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let size = args[1]
            .as_f64()
            .map(|n| n as usize)
            .ok_or_else(|| custom_error(ctx, "Expected positive number for size"))?;

        if size == 0 {
            return Ok(Value::Array(vec![]));
        }

        let chunks: Vec<Value> = arr
            .chunks(size)
            .map(|chunk| Value::Array(chunk.to_vec()))
            .collect();

        Ok(Value::Array(chunks))
    }
}

// =============================================================================
// take(array, n) -> array (first n elements)
// =============================================================================

defn!(TakeFn, vec![arg!(array), arg!(number)], None);

impl Function for TakeFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let n = args[1]
            .as_f64()
            .map(|n| n as usize)
            .ok_or_else(|| custom_error(ctx, "Expected positive number"))?;

        let result: Vec<Value> = arr.iter().take(n).cloned().collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// drop(array, n) -> array (skip first n elements)
// =============================================================================

defn!(DropFn, vec![arg!(array), arg!(number)], None);

impl Function for DropFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let n = args[1]
            .as_f64()
            .map(|n| n as usize)
            .ok_or_else(|| custom_error(ctx, "Expected positive number"))?;

        let result: Vec<Value> = arr.iter().skip(n).cloned().collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// flatten_deep(array) -> array (recursively flatten)
// =============================================================================

defn!(FlattenDeepFn, vec![arg!(array)], None);

fn flatten_recursive(arr: &[Value]) -> Vec<Value> {
    let mut result = Vec::new();
    for item in arr {
        if let Some(inner) = item.as_array() {
            result.extend(flatten_recursive(inner));
        } else {
            result.push(item.clone());
        }
    }
    result
}

impl Function for FlattenDeepFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        Ok(Value::Array(flatten_recursive(arr)))
    }
}

// =============================================================================
// flatten(array) -> array (single-level flatten)
// =============================================================================

defn!(FlattenFn, vec![arg!(array)], None);

impl Function for FlattenFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut result = Vec::new();
        for item in arr {
            if let Some(inner) = item.as_array() {
                result.extend(inner.iter().cloned());
            } else {
                result.push(item.clone());
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// compact(array) -> array (remove null/false values)
// =============================================================================

defn!(CompactFn, vec![arg!(array)], None);

impl Function for CompactFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let result: Vec<Value> = arr
            .iter()
            .filter(|v| !v.is_null() && !matches!(v, Value::Bool(false)))
            .cloned()
            .collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// range(start, end, step?) -> array
// =============================================================================

defn!(
    RangeFn,
    vec![arg!(number), arg!(number)],
    Some(arg!(number))
);

impl Function for RangeFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let start = args[0]
            .as_f64()
            .map(|n| n as i64)
            .ok_or_else(|| custom_error(ctx, "Expected start number"))?;

        let end = args[1]
            .as_f64()
            .map(|n| n as i64)
            .ok_or_else(|| custom_error(ctx, "Expected end number"))?;

        let step = if args.len() > 2 {
            args[2]
                .as_f64()
                .map(|n| n as i64)
                .ok_or_else(|| custom_error(ctx, "Expected step number"))?
        } else {
            1
        };

        if step == 0 {
            return Err(custom_error(ctx, "Step cannot be zero"));
        }

        let mut result = Vec::new();
        let mut current = start;

        const MAX_RANGE: usize = 10000;

        if step > 0 {
            while current < end && result.len() < MAX_RANGE {
                result.push(Value::Number(Number::from(current)));
                current += step;
            }
        } else {
            while current > end && result.len() < MAX_RANGE {
                result.push(Value::Number(Number::from(current)));
                current += step;
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// index_at(array, index) -> element (supports negative index)
// =============================================================================

defn!(IndexAtFn, vec![arg!(array), arg!(number)], None);

impl Function for IndexAtFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let index = args[1]
            .as_f64()
            .map(|n| n as i64)
            .ok_or_else(|| custom_error(ctx, "Expected number for index"))?;

        let len = arr.len() as i64;
        let actual_index = if index < 0 {
            (len + index) as usize
        } else {
            index as usize
        };

        if actual_index < arr.len() {
            Ok(arr[actual_index].clone())
        } else {
            Ok(Value::Null)
        }
    }
}

// =============================================================================
// includes(array, value) -> boolean
// =============================================================================

defn!(IncludesFn, vec![arg!(array), arg!(any)], None);

impl Function for IncludesFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let search_key = serde_json::to_string(&args[1]).unwrap_or_default();

        let found = arr.iter().any(|item| {
            let item_key = serde_json::to_string(item).unwrap_or_default();
            item_key == search_key
        });

        Ok(Value::Bool(found))
    }
}

// =============================================================================
// find_index(array, value) -> number (-1 if not found)
// =============================================================================

defn!(FindIndexFn, vec![arg!(array), arg!(any)], None);

impl Function for FindIndexFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let search_key = serde_json::to_string(&args[1]).unwrap_or_default();

        let index = arr
            .iter()
            .position(|item| {
                let item_key = serde_json::to_string(item).unwrap_or_default();
                item_key == search_key
            })
            .map(|i| i as i64)
            .unwrap_or(-1);

        Ok(Value::Number(Number::from(index)))
    }
}

// =============================================================================
// first(array) -> any (first element or null)
// =============================================================================

defn!(FirstFn, vec![arg!(array)], None);

impl Function for FirstFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        Ok(arr.first().cloned().unwrap_or(Value::Null))
    }
}

// =============================================================================
// last(array) -> any (last element or null)
// =============================================================================

defn!(LastFn, vec![arg!(array)], None);

impl Function for LastFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        Ok(arr.last().cloned().unwrap_or(Value::Null))
    }
}

// =============================================================================
// group_by(array, &expr | field_name) -> object
// =============================================================================

defn!(GroupByFn, vec![arg!(array), arg!(expref | string)], None);

impl Function for GroupByFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut group_keys: Vec<String> = Vec::new();
        let mut group_map: std::collections::HashMap<String, Vec<Value>> =
            std::collections::HashMap::new();

        for item in arr {
            let key = match extract_key(item, &args[1], ctx)? {
                Some(k) => k,
                None => "null".to_string(),
            };
            if !group_map.contains_key(&key) {
                group_keys.push(key.clone());
            }
            group_map.entry(key).or_default().push(item.clone());
        }

        let mut result = serde_json::Map::new();
        for key in group_keys {
            if let Some(items) = group_map.remove(&key) {
                result.insert(key, Value::Array(items));
            }
        }

        Ok(Value::Object(result))
    }
}

// =============================================================================
// index_by(array, &expr | field_name) -> object (last value wins for duplicates)
// =============================================================================

defn!(IndexByFn, vec![arg!(array), arg!(expref | string)], None);

impl Function for IndexByFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut result = serde_json::Map::new();

        for item in arr {
            let key = match extract_key(item, &args[1], ctx)? {
                Some(k) => k,
                None => continue, // skip items without the key
            };
            // Last value wins for duplicate keys
            result.insert(key, item.clone());
        }

        Ok(Value::Object(result))
    }
}

// =============================================================================
// nth(array, n) -> array (every nth element)
// =============================================================================

defn!(NthFn, vec![arg!(array), arg!(number)], None);

impl Function for NthFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let n = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number argument"))? as usize;

        if n == 0 {
            return Ok(Value::Null);
        }

        let result: Vec<Value> = arr.iter().step_by(n).cloned().collect();
        Ok(Value::Array(result))
    }
}

// =============================================================================
// interleave(array1, array2) -> array (alternate elements)
// =============================================================================

defn!(InterleaveFn, vec![arg!(array), arg!(array)], None);

impl Function for InterleaveFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr1 = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let arr2 = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut result = Vec::with_capacity(arr1.len() + arr2.len());
        let mut iter1 = arr1.iter();
        let mut iter2 = arr2.iter();

        loop {
            match (iter1.next(), iter2.next()) {
                (Some(a), Some(b)) => {
                    result.push(a.clone());
                    result.push(b.clone());
                }
                (Some(a), None) => {
                    result.push(a.clone());
                    result.extend(iter1.cloned());
                    break;
                }
                (None, Some(b)) => {
                    result.push(b.clone());
                    result.extend(iter2.cloned());
                    break;
                }
                (None, None) => break,
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// rotate(array, n) -> array (rotate elements by n positions)
// =============================================================================

defn!(RotateFn, vec![arg!(array), arg!(number)], None);

impl Function for RotateFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        let n = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number argument"))? as i64;

        let len = arr.len() as i64;
        let rotation = ((n % len) + len) % len;
        let rotation = rotation as usize;

        let mut result = Vec::with_capacity(arr.len());
        result.extend(arr[rotation..].iter().cloned());
        result.extend(arr[..rotation].iter().cloned());

        Ok(Value::Array(result))
    }
}

// =============================================================================
// partition(array, n) -> array (split into n equal parts)
// =============================================================================

defn!(PartitionFn, vec![arg!(array), arg!(number)], None);

impl Function for PartitionFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let n = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number argument"))? as usize;

        if n == 0 {
            return Ok(Value::Null);
        }

        let len = arr.len();
        let base_size = len / n;
        let remainder = len % n;

        let mut result = Vec::with_capacity(n);
        let mut start = 0;

        for i in 0..n {
            let size = base_size + if i < remainder { 1 } else { 0 };
            if size > 0 {
                result.push(Value::Array(arr[start..start + size].to_vec()));
            } else {
                result.push(Value::Array(vec![]));
            }
            start += size;
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// difference(arr1, arr2) -> array (set difference)
// =============================================================================

defn!(DifferenceFn, vec![arg!(array), arg!(array)], None);

impl Function for DifferenceFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr1 = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let arr2 = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let set2: HashSet<String> = arr2
            .iter()
            .map(|v| serde_json::to_string(v).unwrap_or_default())
            .collect();

        let result: Vec<Value> = arr1
            .iter()
            .filter(|v| {
                let key = serde_json::to_string(*v).unwrap_or_default();
                !set2.contains(&key)
            })
            .cloned()
            .collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// intersection(arr1, arr2) -> array (set intersection)
// =============================================================================

defn!(IntersectionFn, vec![arg!(array), arg!(array)], None);

impl Function for IntersectionFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr1 = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let arr2 = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let set2: HashSet<String> = arr2
            .iter()
            .map(|v| serde_json::to_string(v).unwrap_or_default())
            .collect();

        let mut seen: HashSet<String> = HashSet::new();
        let result: Vec<Value> = arr1
            .iter()
            .filter(|v| {
                let key = serde_json::to_string(*v).unwrap_or_default();
                set2.contains(&key) && seen.insert(key)
            })
            .cloned()
            .collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// union(arr1, arr2) -> array (set union)
// =============================================================================

defn!(UnionFn, vec![arg!(array), arg!(array)], None);

impl Function for UnionFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr1 = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let arr2 = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut seen: HashSet<String> = HashSet::new();
        let mut result: Vec<Value> = Vec::new();

        for item in arr1.iter().chain(arr2.iter()) {
            let key = serde_json::to_string(item).unwrap_or_default();
            if seen.insert(key) {
                result.push(item.clone());
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// frequencies(array) -> object (count occurrences)
// =============================================================================

defn!(FrequenciesFn, vec![arg!(array)], None);

impl Function for FrequenciesFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let mut counts: std::collections::HashMap<String, i64> = std::collections::HashMap::new();

        for item in arr {
            let key = match item {
                Value::String(s) => s.clone(),
                Value::Number(n) => n.to_string(),
                Value::Bool(b) => b.to_string(),
                Value::Null => "null".to_string(),
                _ => serde_json::to_string(item).unwrap_or_else(|_| "null".to_string()),
            };
            *counts.entry(key).or_insert(0) += 1;
        }

        let mut result = serde_json::Map::new();
        // Use BTreeMap for sorted output
        let sorted: std::collections::BTreeMap<String, i64> = counts.into_iter().collect();
        for (k, v) in sorted {
            result.insert(k, Value::Number(Number::from(v)));
        }

        Ok(Value::Object(result))
    }
}

// `mode` is owned by the math category (extensions/math.rs); functions.toml
// lists it under `math`.

// =============================================================================
// cartesian(arr1, arr2) -> array (cartesian product of 2 arrays)
// cartesian(array_of_arrays) -> array (cartesian product of N arrays, jq parity)
// =============================================================================

defn!(CartesianFn, vec![arg!(array)], Some(arg!(array)));

impl Function for CartesianFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let first = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        // Two modes:
        // 1. cartesian(arr1, arr2) - two separate arrays (original behavior)
        // 2. cartesian(array_of_arrays) - single array containing arrays (jq-style)

        if args.len() == 2 {
            // Original two-argument mode
            let arr2 = args[1]
                .as_array()
                .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

            let mut result = Vec::with_capacity(first.len() * arr2.len());
            for a in first {
                for b in arr2 {
                    result.push(Value::Array(vec![a.clone(), b.clone()]));
                }
            }
            Ok(Value::Array(result))
        } else {
            // Single argument mode - check if it's an array of arrays
            // If all elements are arrays, do N-way cartesian product
            let arrays: Vec<&Vec<Value>> =
                first.iter().filter_map(|item| item.as_array()).collect();

            if arrays.len() != first.len() || arrays.is_empty() {
                // Not all elements are arrays, or empty - return empty
                return Ok(Value::Array(vec![]));
            }

            // N-way cartesian product
            let result = cartesian_product_n(&arrays);
            Ok(Value::Array(result))
        }
    }
}

/// Compute N-way cartesian product of arrays.
fn cartesian_product_n(arrays: &[&Vec<Value>]) -> Vec<Value> {
    if arrays.is_empty() {
        return vec![];
    }

    if arrays.len() == 1 {
        // Single array - each element becomes a 1-element tuple
        return arrays[0]
            .iter()
            .map(|item| Value::Array(vec![item.clone()]))
            .collect();
    }

    // Calculate total size for pre-allocation
    let total_size: usize = arrays.iter().map(|a| a.len()).product();
    if total_size == 0 {
        return vec![];
    }

    let mut result = Vec::with_capacity(total_size);

    // Iterative cartesian product using indices
    let mut indices = vec![0usize; arrays.len()];

    loop {
        // Build current combination
        let combo: Vec<Value> = indices
            .iter()
            .enumerate()
            .map(|(arr_idx, &elem_idx)| arrays[arr_idx][elem_idx].clone())
            .collect();
        result.push(Value::Array(combo));

        // Increment indices (like counting in mixed radix)
        let mut carry = true;
        for i in (0..arrays.len()).rev() {
            if carry {
                indices[i] += 1;
                if indices[i] >= arrays[i].len() {
                    indices[i] = 0;
                } else {
                    carry = false;
                }
            }
        }

        // If we carried all the way through, we're done
        if carry {
            break;
        }
    }

    result
}

// =============================================================================
// initial(array) -> array (all elements except the last)
// =============================================================================

defn!(InitialFn, vec![arg!(array)], None);

impl Function for InitialFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        let result: Vec<Value> = arr[..arr.len() - 1].to_vec();
        Ok(Value::Array(result))
    }
}

// =============================================================================
// interpose(array, separator) -> array (insert separator between elements)
// =============================================================================

defn!(InterposeFn, vec![arg!(array), arg!(any)], None);

impl Function for InterposeFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let separator = args[1].clone();

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        if arr.len() == 1 {
            return Ok(Value::Array(arr.clone()));
        }

        let mut result = Vec::with_capacity(arr.len() * 2 - 1);
        for (i, item) in arr.iter().enumerate() {
            if i > 0 {
                result.push(separator.clone());
            }
            result.push(item.clone());
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// zipmap(keys, values) -> object (create object from parallel arrays)
// =============================================================================

defn!(ZipmapFn, vec![arg!(array), arg!(array)], None);

impl Function for ZipmapFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let keys = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument for keys"))?;

        let values = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument for values"))?;

        let len = keys.len().min(values.len());
        let mut result = serde_json::Map::new();

        for i in 0..len {
            let key = keys[i]
                .as_str()
                .ok_or_else(|| custom_error(ctx, "Keys must be strings"))?;
            result.insert(key.to_string(), values[i].clone());
        }

        Ok(Value::Object(result))
    }
}

// =============================================================================
// partition_by(array, &expr | field_name) -> array (split when value changes)
// =============================================================================

defn!(
    PartitionByFn,
    vec![arg!(array), arg!(expref | string)],
    None
);

impl Function for PartitionByFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        let is_expref = get_expref_ast(&args[1], ctx).is_some();

        let mut result: Vec<Value> = Vec::new();
        let mut current_partition: Vec<Value> = Vec::new();
        let mut last_key: Option<String> = None;

        for item in arr {
            let key = if is_expref {
                // expref mode: evaluate the expression against each item
                match extract_key(item, &args[1], ctx)? {
                    Some(k) => k,
                    None => "null".to_string(),
                }
            } else if let Some(field_name) = args[1].as_str() {
                // string field mode: extract field, or serialize the item for primitives
                if let Some(obj) = item.as_object() {
                    if let Some(field_value) = obj.get(field_name) {
                        serde_json::to_string(field_value).unwrap_or_default()
                    } else {
                        "null".to_string()
                    }
                } else {
                    serde_json::to_string(item).unwrap_or_default()
                }
            } else {
                return Err(custom_error(ctx, "Expected expref or string field name"));
            };

            match &last_key {
                Some(prev_key) if *prev_key == key => {
                    current_partition.push(item.clone());
                }
                _ => {
                    if !current_partition.is_empty() {
                        result.push(Value::Array(current_partition));
                    }
                    current_partition = vec![item.clone()];
                    last_key = Some(key);
                }
            }
        }

        // Don't forget the last partition
        if !current_partition.is_empty() {
            result.push(Value::Array(current_partition));
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// dedupe(array) -> array (remove consecutive duplicates)
// =============================================================================

defn!(DedupeFn, vec![arg!(array)], None);

impl Function for DedupeFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        let mut result: Vec<Value> = Vec::with_capacity(arr.len());
        let mut last_key: Option<String> = None;

        for item in arr {
            let key = serde_json::to_string(item).unwrap_or_default();
            match &last_key {
                Some(prev_key) if *prev_key == key => {
                    // Skip consecutive duplicate
                }
                _ => {
                    result.push(item.clone());
                    last_key = Some(key);
                }
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// tail(array) -> array (all elements except the first)
// =============================================================================

defn!(TailFn, vec![arg!(array)], None);

impl Function for TailFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        let result: Vec<Value> = arr[1..].to_vec();
        Ok(Value::Array(result))
    }
}

// =============================================================================
// without(array, values_array) -> array (remove specified values)
// =============================================================================

defn!(WithoutFn, vec![arg!(array), arg!(array)], None);

impl Function for WithoutFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let exclude = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument for values to exclude"))?;

        // Create a set of serialized values to exclude for efficient lookup
        let exclude_set: HashSet<String> = exclude
            .iter()
            .map(|v| serde_json::to_string(v).unwrap_or_default())
            .collect();

        let result: Vec<Value> = arr
            .iter()
            .filter(|item| {
                let key = serde_json::to_string(*item).unwrap_or_default();
                !exclude_set.contains(&key)
            })
            .cloned()
            .collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// xor(array1, array2) -> array (symmetric difference)
// =============================================================================

defn!(XorFn, vec![arg!(array), arg!(array)], None);

impl Function for XorFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr1 = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let arr2 = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        // Create sets of serialized values
        let set1: HashSet<String> = arr1
            .iter()
            .map(|v| serde_json::to_string(v).unwrap_or_default())
            .collect();

        let set2: HashSet<String> = arr2
            .iter()
            .map(|v| serde_json::to_string(v).unwrap_or_default())
            .collect();

        let mut result = Vec::new();

        // Add elements from arr1 that are not in arr2
        for item in arr1 {
            let key = serde_json::to_string(item).unwrap_or_default();
            if !set2.contains(&key) {
                result.push(item.clone());
            }
        }

        // Add elements from arr2 that are not in arr1
        for item in arr2 {
            let key = serde_json::to_string(item).unwrap_or_default();
            if !set1.contains(&key) {
                result.push(item.clone());
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// window(array, size, step?) -> array (sliding window)
// =============================================================================

defn!(
    WindowFn,
    vec![arg!(array), arg!(number)],
    Some(arg!(number))
);

impl Function for WindowFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let size = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number for window size"))?
            as usize;

        if size == 0 {
            return Ok(Value::Array(vec![]));
        }

        // Default step is 1
        let step = if args.len() > 2 {
            args[2]
                .as_f64()
                .ok_or_else(|| custom_error(ctx, "Expected number for step"))? as usize
        } else {
            1
        };

        if step == 0 {
            return Err(custom_error(ctx, "Step cannot be zero"));
        }

        let len = arr.len();
        if len < size {
            return Ok(Value::Array(vec![]));
        }

        let mut result = Vec::new();
        let mut i = 0;

        while i + size <= len {
            let window: Vec<Value> = arr[i..i + size].to_vec();
            result.push(Value::Array(window));
            i += step;
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// combinations(array, k) -> array (k-combinations of array)
// =============================================================================

defn!(CombinationsFn, vec![arg!(array), arg!(number)], None);

fn generate_combinations(arr: &[Value], k: usize) -> Vec<Vec<Value>> {
    if k == 0 {
        return vec![vec![]];
    }
    if arr.len() < k {
        return vec![];
    }

    let mut result = Vec::new();

    // Include first element in combination
    let first = arr[0].clone();
    let rest = &arr[1..];
    for mut combo in generate_combinations(rest, k - 1) {
        let mut new_combo = vec![first.clone()];
        new_combo.append(&mut combo);
        result.push(new_combo);
    }

    // Exclude first element
    result.extend(generate_combinations(rest, k));

    result
}

impl Function for CombinationsFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let k = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number for k"))? as usize;

        // Limit to prevent excessive computation
        const MAX_COMBINATIONS: usize = 10000;

        // Quick check: if C(n, k) would be too large, return error
        let n = arr.len();
        if n > 20 && k > 3 && k < n - 3 {
            return Err(custom_error(ctx, "Combination size too large"));
        }

        let combinations = generate_combinations(arr, k);

        if combinations.len() > MAX_COMBINATIONS {
            return Err(custom_error(ctx, "Too many combinations generated"));
        }

        let result: Vec<Value> = combinations.into_iter().map(Value::Array).collect();

        Ok(Value::Array(result))
    }
}

// =============================================================================
// fill(array, value, start?, end?) -> array (fill range with value)
// =============================================================================

defn!(FillFn, vec![arg!(array), arg!(any)], Some(arg!(number)));

impl Function for FillFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let fill_value = args[1].clone();

        let len = arr.len();
        if len == 0 {
            return Ok(Value::Array(vec![]));
        }

        // Default start is 0, default end is array length
        let start = if args.len() > 2 {
            let s = args[2]
                .as_f64()
                .ok_or_else(|| custom_error(ctx, "Expected number for start index"))?
                as i64;
            // Handle negative indices
            if s < 0 {
                (len as i64 + s).max(0) as usize
            } else {
                (s as usize).min(len)
            }
        } else {
            0
        };

        let end = if args.len() > 3 {
            let e = args[3]
                .as_f64()
                .ok_or_else(|| custom_error(ctx, "Expected number for end index"))?
                as i64;
            // Handle negative indices
            if e < 0 {
                (len as i64 + e).max(0) as usize
            } else {
                (e as usize).min(len)
            }
        } else {
            len
        };

        let mut result: Vec<Value> = arr.clone();

        for item in result.iter_mut().take(end.min(len)).skip(start) {
            *item = fill_value.clone();
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// pull_at(array, indices_array) -> array (get elements at specified indices)
// =============================================================================

defn!(PullAtFn, vec![arg!(array), arg!(array)], None);

impl Function for PullAtFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let indices = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array of indices"))?;

        let len = arr.len();
        let mut result = Vec::new();

        for idx_var in indices {
            let idx = idx_var
                .as_f64()
                .ok_or_else(|| custom_error(ctx, "Expected number in indices array"))?
                as i64;

            // Handle negative indices
            let actual_idx = if idx < 0 {
                (len as i64 + idx).max(0) as usize
            } else {
                idx as usize
            };

            if actual_idx < len {
                result.push(arr[actual_idx].clone());
            }
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// transpose(array) -> array
// =============================================================================

defn!(TransposeFn, vec![arg!(array)], None);

impl Function for TransposeFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.is_empty() {
            return Ok(Value::Array(vec![]));
        }

        // Get all inner arrays and find the minimum length
        let mut inner_arrays: Vec<&Vec<Value>> = Vec::new();
        let mut min_len = usize::MAX;

        for item in arr {
            if let Some(inner) = item.as_array() {
                min_len = min_len.min(inner.len());
                inner_arrays.push(inner);
            } else {
                // If any element is not an array, return empty
                return Ok(Value::Array(vec![]));
            }
        }

        if inner_arrays.is_empty() || min_len == 0 {
            return Ok(Value::Array(vec![]));
        }

        // Transpose: create new arrays where each contains the i-th element from each inner array
        let mut result = Vec::with_capacity(min_len);
        for i in 0..min_len {
            let mut row = Vec::with_capacity(inner_arrays.len());
            for inner in &inner_arrays {
                row.push(inner[i].clone());
            }
            result.push(Value::Array(row));
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// pairwise(array) -> array
// =============================================================================

defn!(PairwiseFn, vec![arg!(array)], None);

impl Function for PairwiseFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        if arr.len() < 2 {
            return Ok(Value::Array(vec![]));
        }

        let mut result = Vec::with_capacity(arr.len() - 1);
        for i in 0..arr.len() - 1 {
            let pair = vec![arr[i].clone(), arr[i + 1].clone()];
            result.push(Value::Array(pair));
        }

        Ok(Value::Array(result))
    }
}

// =============================================================================
// indices_array(array, value) -> array of indices
// =============================================================================

defn!(IndicesArrayFn, vec![arg!(array), arg!(any)], None);

impl Function for IndicesArrayFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let search_key = serde_json::to_string(&args[1]).unwrap_or_default();

        let mut indices: Vec<Value> = Vec::new();
        for (i, item) in arr.iter().enumerate() {
            let item_key = serde_json::to_string(item).unwrap_or_default();
            if item_key == search_key {
                indices.push(Value::Number(Number::from(i as i64)));
            }
        }

        Ok(Value::Array(indices))
    }
}

// =============================================================================
// inside_array(needle, haystack) -> boolean
// =============================================================================

defn!(InsideArrayFn, vec![arg!(array), arg!(array)], None);

impl Function for InsideArrayFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let needle = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let haystack = args[1]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        // Build a set of serialized haystack values for efficient lookup
        let haystack_set: HashSet<String> = haystack
            .iter()
            .map(|item| serde_json::to_string(item).unwrap_or_default())
            .collect();

        // Check if all needle elements are in the haystack
        let result = needle.iter().all(|item| {
            let item_key = serde_json::to_string(item).unwrap_or_default();
            haystack_set.contains(&item_key)
        });

        Ok(Value::Bool(result))
    }
}

// =============================================================================
// bsearch(sorted_array, value) -> number
// =============================================================================

defn!(BsearchFn, vec![arg!(array), arg!(any)], None);

impl Function for BsearchFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let target = &args[1];

        if arr.is_empty() {
            return Ok(Value::Number(Number::from(-1)));
        }

        // Helper to compare two Value values
        // Returns Ordering based on type-aware comparison
        fn compare_values(a: &Value, b: &Value) -> std::cmp::Ordering {
            match (a, b) {
                // Numbers: compare numerically
                (Value::Number(n1), Value::Number(n2)) => {
                    let f1 = n1.as_f64().unwrap_or(0.0);
                    let f2 = n2.as_f64().unwrap_or(0.0);
                    f1.partial_cmp(&f2).unwrap_or(std::cmp::Ordering::Equal)
                }
                // Strings: compare lexicographically
                (Value::String(s1), Value::String(s2)) => s1.cmp(s2),
                // Booleans: false < true
                (Value::Bool(b1), Value::Bool(b2)) => b1.cmp(b2),
                // Different types or complex types: fall back to JSON string comparison
                _ => {
                    let s1 = serde_json::to_string(a).unwrap_or_default();
                    let s2 = serde_json::to_string(b).unwrap_or_default();
                    s1.cmp(&s2)
                }
            }
        }

        let mut left = 0i64;
        let mut right = arr.len() as i64 - 1;

        while left <= right {
            let mid = left + (right - left) / 2;

            match compare_values(&arr[mid as usize], target) {
                std::cmp::Ordering::Equal => {
                    return Ok(Value::Number(Number::from(mid)));
                }
                std::cmp::Ordering::Less => {
                    left = mid + 1;
                }
                std::cmp::Ordering::Greater => {
                    right = mid - 1;
                }
            }
        }

        // Not found - return -(insertion_point) - 1
        // At this point, left is the insertion point
        let result = -(left) - 1;
        Ok(Value::Number(Number::from(result)))
    }
}

// =============================================================================
// repeat_array(value, n) -> array (create array with value repeated n times)
// =============================================================================

defn!(RepeatArrayFn, vec![arg!(any), arg!(number)], None);

impl Function for RepeatArrayFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let value = &args[0];
        let n = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number for count argument"))?
            as i64;

        if n < 0 {
            return Err(custom_error(ctx, "Count must be non-negative"));
        }

        let result: Vec<Value> = (0..n).map(|_| value.clone()).collect();
        Ok(Value::Array(result))
    }
}

// =============================================================================
// cycle(array, n) -> array (cycle through array n times)
// =============================================================================

defn!(CycleFn, vec![arg!(array), arg!(number)], None);

impl Function for CycleFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;

        let arr = args[0]
            .as_array()
            .ok_or_else(|| custom_error(ctx, "Expected array argument"))?;

        let n = args[1]
            .as_f64()
            .ok_or_else(|| custom_error(ctx, "Expected number for count argument"))?
            as i64;

        if n < 0 {
            return Err(custom_error(ctx, "Count must be non-negative"));
        }

        if arr.is_empty() || n == 0 {
            return Ok(Value::Array(vec![]));
        }

        let mut result: Vec<Value> = Vec::with_capacity(arr.len() * n as usize);
        for _ in 0..n {
            result.extend(arr.iter().cloned());
        }
        Ok(Value::Array(result))
    }
}

// =============================================================================
// lag(array, n) -> array
// =============================================================================

defn!(LagFn, vec![arg!(array), arg!(number)], None);

impl Function for LagFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;
        let arr = args[0].as_array().unwrap();
        let n = args[1].as_f64().unwrap() as usize;
        let len = arr.len();
        let mut result = Vec::with_capacity(len);
        for _ in 0..n.min(len) {
            result.push(Value::Null);
        }
        if n < len {
            result.extend_from_slice(&arr[..len - n]);
        }
        Ok(Value::Array(result))
    }
}

// =============================================================================
// lead(array, n) -> array
// =============================================================================

defn!(LeadFn, vec![arg!(array), arg!(number)], None);

impl Function for LeadFn {
    fn evaluate(&self, args: &[Value], ctx: &mut Context<'_>) -> SearchResult {
        self.signature.validate(args, ctx)?;
        let arr = args[0].as_array().unwrap();
        let n = args[1].as_f64().unwrap() as usize;
        let len = arr.len();
        let mut result = Vec::with_capacity(len);
        if n < len {
            result.extend_from_slice(&arr[n..]);
        }
        let remaining = len.saturating_sub(result.len());
        for _ in 0..remaining {
            result.push(Value::Null);
        }
        Ok(Value::Array(result))
    }
}

#[cfg(test)]
mod tests {
    use crate::Runtime;
    use serde_json::json;

    fn setup_runtime() -> Runtime {
        Runtime::builder()
            .with_standard()
            .with_all_extensions()
            .build()
    }

    #[test]
    fn test_unique() {
        let runtime = setup_runtime();
        let expr = runtime.compile("unique(@)").unwrap();
        let data = json!([1, 2, 1]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
    }

    #[test]
    fn test_first() {
        let runtime = setup_runtime();
        let expr = runtime.compile("first(@)").unwrap();
        let data = json!([1, 2]);
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_last() {
        let runtime = setup_runtime();
        let expr = runtime.compile("last(@)").unwrap();
        let data = json!([1, 2]);
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_range() {
        let runtime = setup_runtime();
        let expr = runtime.compile("range(`0`, `5`)").unwrap();
        let data = json!(null);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 5);
    }

    #[test]
    fn test_butlast() {
        // butlast is an alias for initial
        let runtime = setup_runtime();
        let expr = runtime.compile("butlast(@)").unwrap();
        let data = json!([1, 2, 3]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_interpose() {
        let runtime = setup_runtime();
        let expr = runtime.compile("interpose(@, `0`)").unwrap();
        let data = json!([1, 2, 3]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 5);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 0);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 2);
        assert_eq!(arr[3].as_f64().unwrap() as i64, 0);
        assert_eq!(arr[4].as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_interpose_empty() {
        let runtime = setup_runtime();
        let expr = runtime.compile("interpose(@, `0`)").unwrap();
        let data = json!([]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_interpose_single() {
        let runtime = setup_runtime();
        let expr = runtime.compile("interpose(@, `0`)").unwrap();
        let data = json!([1]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 1);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_interpose_string_separator() {
        let runtime = setup_runtime();
        let expr = runtime.compile("interpose(@, `\"-\"`)").unwrap();
        let data = json!(["a", "b", "c"]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 5);
        assert_eq!(arr[0].as_str().unwrap(), "a");
        assert_eq!(arr[1].as_str().unwrap(), "-");
        assert_eq!(arr[2].as_str().unwrap(), "b");
        assert_eq!(arr[3].as_str().unwrap(), "-");
        assert_eq!(arr[4].as_str().unwrap(), "c");
    }

    #[test]
    fn test_zipmap() {
        let runtime = setup_runtime();
        let expr = runtime
            .compile("zipmap(`[\"a\", \"b\", \"c\"]`, `[1, 2, 3]`)")
            .unwrap();
        let data = json!(null);
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 3);
        assert_eq!(obj.get("a").unwrap().as_f64().unwrap() as i64, 1);
        assert_eq!(obj.get("b").unwrap().as_f64().unwrap() as i64, 2);
        assert_eq!(obj.get("c").unwrap().as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_zipmap_unequal_lengths() {
        let runtime = setup_runtime();
        // Keys shorter than values
        let expr = runtime
            .compile("zipmap(`[\"x\", \"y\"]`, `[10, 20, 30]`)")
            .unwrap();
        let data = json!(null);
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 2);
        assert_eq!(obj.get("x").unwrap().as_f64().unwrap() as i64, 10);
        assert_eq!(obj.get("y").unwrap().as_f64().unwrap() as i64, 20);
    }

    #[test]
    fn test_zipmap_empty() {
        let runtime = setup_runtime();
        let expr = runtime.compile("zipmap(`[]`, `[]`)").unwrap();
        let data = json!(null);
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 0);
    }

    #[test]
    fn test_partition_by() {
        let runtime = setup_runtime();
        // Test with objects - partition by "type" field
        let expr = runtime.compile(r#"partition_by(@, `"type"`)"#).unwrap();
        let data: serde_json::Value = serde_json::from_str(
            r#"[{"type": "a", "v": 1}, {"type": "a", "v": 2}, {"type": "b", "v": 3}, {"type": "a", "v": 4}]"#,
        )
        .unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);

        let partition1 = arr[0].as_array().unwrap();
        assert_eq!(partition1.len(), 2); // Two "a" items

        let partition2 = arr[1].as_array().unwrap();
        assert_eq!(partition2.len(), 1); // One "b" item

        let partition3 = arr[2].as_array().unwrap();
        assert_eq!(partition3.len(), 1); // One more "a" item
    }

    #[test]
    fn test_partition_by_primitives() {
        let runtime = setup_runtime();
        // For primitives, use any field name - it will use the value itself
        let expr = runtime.compile(r#"partition_by(@, `"_"`)"#).unwrap();
        let data = json!([1, 1, 2, 2, 1, 1]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);

        let partition1 = arr[0].as_array().unwrap();
        assert_eq!(partition1.len(), 2);
        assert_eq!(partition1[0].as_f64().unwrap() as i64, 1);

        let partition2 = arr[1].as_array().unwrap();
        assert_eq!(partition2.len(), 2);
        assert_eq!(partition2[0].as_f64().unwrap() as i64, 2);

        let partition3 = arr[2].as_array().unwrap();
        assert_eq!(partition3.len(), 2);
        assert_eq!(partition3[0].as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_partition_by_empty() {
        let runtime = setup_runtime();
        let expr = runtime.compile(r#"partition_by(@, `"type"`)"#).unwrap();
        let data = json!([]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_partition_by_single() {
        let runtime = setup_runtime();
        let expr = runtime.compile(r#"partition_by(@, `"type"`)"#).unwrap();
        let data: serde_json::Value = serde_json::from_str(r#"[{"type": "a"}]"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 1);
        let partition1 = arr[0].as_array().unwrap();
        assert_eq!(partition1.len(), 1);
    }

    #[test]
    fn test_dedupe() {
        let runtime = setup_runtime();
        let expr = runtime.compile("dedupe(@)").unwrap();
        let data = json!([1, 1, 2, 2, 1, 1]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 2);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_dedupe_empty() {
        let runtime = setup_runtime();
        let expr = runtime.compile("dedupe(@)").unwrap();
        let data = json!([]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_dedupe_no_consecutive() {
        let runtime = setup_runtime();
        let expr = runtime.compile("dedupe(@)").unwrap();
        let data = json!([1, 2, 3]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
    }

    #[test]
    fn test_dedupe_strings() {
        let runtime = setup_runtime();
        let expr = runtime.compile("dedupe(@)").unwrap();
        let data = json!(["a", "a", "b", "a"]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_str().unwrap(), "a");
        assert_eq!(arr[1].as_str().unwrap(), "b");
        assert_eq!(arr[2].as_str().unwrap(), "a");
    }

    #[test]
    fn test_dedupe_objects() {
        let runtime = setup_runtime();
        let expr = runtime.compile("dedupe(@)").unwrap();
        let data: serde_json::Value =
            serde_json::from_str(r#"[{"x": 1}, {"x": 1}, {"x": 2}, {"x": 1}]"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
    }

    #[test]
    fn test_dedupe_all_same() {
        let runtime = setup_runtime();
        let expr = runtime.compile("dedupe(@)").unwrap();
        let data = json!([1, 1, 1]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 1);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_zipmap_duplicate_keys() {
        // Later key should overwrite earlier one
        let runtime = setup_runtime();
        let expr = runtime
            .compile("zipmap(`[\"a\", \"b\", \"a\"]`, `[1, 2, 3]`)")
            .unwrap();
        let data = json!(null);
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 2);
        assert_eq!(obj.get("a").unwrap().as_f64().unwrap() as i64, 3); // Last value wins
        assert_eq!(obj.get("b").unwrap().as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_zipmap_values_longer() {
        let runtime = setup_runtime();
        let expr = runtime.compile("zipmap(`[\"a\"]`, `[1, 2, 3]`)").unwrap();
        let data = json!(null);
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 1);
        assert_eq!(obj.get("a").unwrap().as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_partition_by_missing_field() {
        let runtime = setup_runtime();
        let expr = runtime.compile(r#"partition_by(@, `"type"`)"#).unwrap();
        // Some objects have type, some don't
        let data: serde_json::Value =
            serde_json::from_str(r#"[{"type": "a"}, {"name": "no-type"}, {"type": "a"}]"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        // Should partition into 3: [type:a], [no type -> null], [type:a]
        assert_eq!(arr.len(), 3);
    }

    #[test]
    fn test_partition_by_all_same() {
        let runtime = setup_runtime();
        let expr = runtime.compile(r#"partition_by(@, `"type"`)"#).unwrap();
        let data: serde_json::Value =
            serde_json::from_str(r#"[{"type": "a"}, {"type": "a"}, {"type": "a"}]"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 1);
        let partition = arr[0].as_array().unwrap();
        assert_eq!(partition.len(), 3);
    }

    #[test]
    fn test_interpose_null_separator() {
        let runtime = setup_runtime();
        let expr = runtime.compile("interpose(@, `null`)").unwrap();
        let data = json!([1, 2]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert!(arr[1].is_null());
        assert_eq!(arr[2].as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_interpose_object_separator() {
        let runtime = setup_runtime();
        let expr = runtime.compile(r#"interpose(@, `{"sep": true}`)"#).unwrap();
        let data = json!([1, 2]);
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert!(arr[1].as_object().is_some());
    }

    // =========================================================================
    // zip tests
    // =========================================================================

    #[test]
    fn test_zip_basic() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2, 3], "b": ["x", "y", "z"]}"#).unwrap();
        let expr = runtime.compile("zip(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_array().unwrap()[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[0].as_array().unwrap()[1].as_str().unwrap(), "x");
    }

    #[test]
    fn test_zip_unequal_lengths() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2], "b": ["x", "y", "z"]}"#).unwrap();
        let expr = runtime.compile("zip(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        // Stops at shorter array
        assert_eq!(arr.len(), 2);
    }

    #[test]
    fn test_zip_empty_array() {
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(r#"{"a": [], "b": [1, 2, 3]}"#).unwrap();
        let expr = runtime.compile("zip(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_zip_with_objects() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"names": ["Alice", "Bob"], "scores": [95, 87]}"#).unwrap();
        let expr = runtime.compile("zip(names, scores)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
        assert_eq!(arr[0].as_array().unwrap()[0].as_str().unwrap(), "Alice");
        assert_eq!(arr[0].as_array().unwrap()[1].as_f64().unwrap() as i64, 95);
    }

    // =========================================================================
    // chunk tests
    // =========================================================================

    #[test]
    fn test_chunk_basic() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5]);
        let expr = runtime.compile("chunk(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3); // [1,2], [3,4], [5]
        assert_eq!(arr[0].as_array().unwrap().len(), 2);
        assert_eq!(arr[2].as_array().unwrap().len(), 1);
    }

    #[test]
    fn test_chunk_exact_fit() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5, 6]);
        let expr = runtime.compile("chunk(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
        assert_eq!(arr[0].as_array().unwrap().len(), 3);
        assert_eq!(arr[1].as_array().unwrap().len(), 3);
    }

    #[test]
    fn test_chunk_size_larger_than_array() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("chunk(@, `10`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 1);
        assert_eq!(arr[0].as_array().unwrap().len(), 3);
    }

    #[test]
    fn test_chunk_size_one() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("chunk(@, `1`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
    }

    #[test]
    fn test_chunk_and_process_pipeline() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
        let expr = runtime.compile("chunk(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        // [1,2,3], [4,5,6], [7,8,9], [10]
        assert_eq!(arr.len(), 4);
    }

    // =========================================================================
    // take tests
    // =========================================================================

    #[test]
    fn test_take_basic() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5]);
        let expr = runtime.compile("take(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_take_more_than_length() {
        let runtime = setup_runtime();
        let data = json!([1, 2]);
        let expr = runtime.compile("take(@, `10`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
    }

    #[test]
    fn test_take_zero() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("take(@, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    // =========================================================================
    // drop tests
    // =========================================================================

    #[test]
    fn test_drop_basic() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5]);
        let expr = runtime.compile("drop(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_drop_more_than_length() {
        let runtime = setup_runtime();
        let data = json!([1, 2]);
        let expr = runtime.compile("drop(@, `10`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_drop_zero() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("drop(@, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
    }

    // =========================================================================
    // flatten_deep tests
    // =========================================================================

    #[test]
    fn test_flatten_deep_basic() {
        let runtime = setup_runtime();
        let data = json!([[1, 2], [3, 4]]);
        let expr = runtime.compile("flatten_deep(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 4);
    }

    #[test]
    fn test_flatten_deep_nested() {
        let runtime = setup_runtime();
        let data = json!([1, [2, [3, [4, [5]]]]]);
        let expr = runtime.compile("flatten_deep(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 5);
        assert_eq!(arr[4].as_f64().unwrap() as i64, 5);
    }

    #[test]
    fn test_flatten_deep_already_flat() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("flatten_deep(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
    }

    #[test]
    fn test_flatten_deep_mixed() {
        let runtime = setup_runtime();
        let data = json!([1, [2, 3], [[4]], [[[5, 6]]]]);
        let expr = runtime.compile("flatten_deep(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 6);
    }

    // =========================================================================
    // compact tests
    // =========================================================================

    #[test]
    fn test_compact_basic() {
        let runtime = setup_runtime();
        let data = json!([1, null, 2, false, 3]);
        let expr = runtime.compile("compact(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
    }

    #[test]
    fn test_compact_keeps_zero_and_empty_string() {
        let runtime = setup_runtime();
        let data = json!([0, "", null, true]);
        let expr = runtime.compile("compact(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3); // 0, "", true
    }

    #[test]
    fn test_compact_all_falsy() {
        let runtime = setup_runtime();
        let data = json!([null, false, null]);
        let expr = runtime.compile("compact(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    // =========================================================================
    // index_at tests
    // =========================================================================

    #[test]
    fn test_index_at_positive() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "c", "d"]);
        let expr = runtime.compile("index_at(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_str().unwrap(), "c");
    }

    #[test]
    fn test_index_at_negative() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "c", "d"]);
        let expr = runtime.compile("index_at(@, `-1`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_str().unwrap(), "d");
    }

    #[test]
    fn test_index_at_negative_second() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "c", "d"]);
        let expr = runtime.compile("index_at(@, `-2`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_str().unwrap(), "c");
    }

    #[test]
    fn test_index_at_out_of_bounds() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "c"]);
        let expr = runtime.compile("index_at(@, `10`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.is_null());
    }

    // =========================================================================
    // includes tests
    // =========================================================================

    #[test]
    fn test_includes_number() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5]);
        let expr = runtime.compile("includes(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.as_bool().unwrap());
    }

    #[test]
    fn test_includes_not_found() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("includes(@, `10`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(!result.as_bool().unwrap());
    }

    #[test]
    fn test_includes_string() {
        let runtime = setup_runtime();
        let data = json!(["apple", "banana", "cherry"]);
        let expr = runtime.compile(r#"includes(@, `"banana"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.as_bool().unwrap());
    }

    #[test]
    fn test_includes_object() {
        let runtime = setup_runtime();
        let data = json!([{"a": 1}, {"b": 2}]);
        let expr = runtime.compile(r#"includes(@, `{"a": 1}`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.as_bool().unwrap());
    }

    // =========================================================================
    // find_index tests
    // =========================================================================

    #[test]
    fn test_find_index_found() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "c", "d"]);
        let expr = runtime.compile(r#"find_index(@, `"c"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_find_index_not_found() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "c"]);
        let expr = runtime.compile(r#"find_index(@, `"z"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, -1);
    }

    // =========================================================================
    // group_by tests
    // =========================================================================

    #[test]
    fn test_group_by_basic() {
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(
            r#"[{"type": "a", "v": 1}, {"type": "b", "v": 2}, {"type": "a", "v": 3}]"#,
        )
        .unwrap();
        let expr = runtime.compile(r#"group_by(@, `"type"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.get("a").unwrap().as_array().unwrap().len(), 2);
        assert_eq!(obj.get("b").unwrap().as_array().unwrap().len(), 1);
    }

    // =========================================================================
    // index_by tests
    // =========================================================================

    #[test]
    fn test_index_by_basic() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"[{"id": 1, "name": "alice"}, {"id": 2, "name": "bob"}]"#)
                .unwrap();
        let expr = runtime.compile(r#"index_by(@, `"id"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 2);
        // Keys are string versions of the id
        let alice = obj.get("1").unwrap().as_object().unwrap();
        assert_eq!(alice.get("name").unwrap().as_str().unwrap(), "alice");
        let bob = obj.get("2").unwrap().as_object().unwrap();
        assert_eq!(bob.get("name").unwrap().as_str().unwrap(), "bob");
    }

    #[test]
    fn test_index_by_string_key() {
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(
            r#"[{"code": "US", "name": "United States"}, {"code": "UK", "name": "United Kingdom"}]"#,
        )
        .unwrap();
        let expr = runtime.compile(r#"index_by(@, `"code"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 2);
        let us = obj.get("US").unwrap().as_object().unwrap();
        assert_eq!(us.get("name").unwrap().as_str().unwrap(), "United States");
    }

    #[test]
    fn test_index_by_duplicate_keys() {
        // Last value wins for duplicate keys
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(
            r#"[{"type": "a", "v": 1}, {"type": "a", "v": 2}, {"type": "a", "v": 3}]"#,
        )
        .unwrap();
        let expr = runtime.compile(r#"index_by(@, `"type"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 1);
        // Last value (v=3) wins
        let a = obj.get("a").unwrap().as_object().unwrap();
        assert_eq!(a.get("v").unwrap().as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_index_by_missing_key() {
        // Items without the key field are skipped
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(
            r#"[{"id": 1, "name": "alice"}, {"name": "bob"}, {"id": 3, "name": "charlie"}]"#,
        )
        .unwrap();
        let expr = runtime.compile(r#"index_by(@, `"id"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.len(), 2);
        assert!(obj.contains_key("1"));
        assert!(obj.contains_key("3"));
        assert!(!obj.contains_key("2")); // bob was skipped
    }

    #[test]
    fn test_index_by_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile(r#"index_by(@, `"id"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert!(obj.is_empty());
    }

    // =========================================================================
    // set operations tests
    // =========================================================================

    #[test]
    fn test_difference() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2, 3, 4], "b": [2, 4]}"#).unwrap();
        let expr = runtime.compile("difference(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2); // 1, 3
    }

    #[test]
    fn test_intersection() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2, 3], "b": [2, 3, 4]}"#).unwrap();
        let expr = runtime.compile("intersection(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2); // 2, 3
    }

    #[test]
    fn test_union() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2], "b": [2, 3]}"#).unwrap();
        let expr = runtime.compile("union(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3); // 1, 2, 3
    }

    // =========================================================================
    // frequencies tests
    // =========================================================================

    #[test]
    fn test_frequencies_basic() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "a", "c", "a", "b"]);
        let expr = runtime.compile("frequencies(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.get("a").unwrap().as_f64().unwrap() as i64, 3);
        assert_eq!(obj.get("b").unwrap().as_f64().unwrap() as i64, 2);
        assert_eq!(obj.get("c").unwrap().as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_frequencies_numbers() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 1, 1, 2, 3]);
        let expr = runtime.compile("frequencies(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let obj = result.as_object().unwrap();
        assert_eq!(obj.get("1").unwrap().as_f64().unwrap() as i64, 3);
        assert_eq!(obj.get("2").unwrap().as_f64().unwrap() as i64, 2);
    }

    // =========================================================================
    // mode tests
    // =========================================================================

    #[test]
    fn test_mode_basic() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 2, 3, 2, 4]);
        let expr = runtime.compile("mode(@)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_mode_empty() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("mode(@)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.is_null());
    }

    // =========================================================================
    // cartesian tests
    // =========================================================================

    #[test]
    fn test_cartesian_basic() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2], "b": ["x", "y"]}"#).unwrap();
        let expr = runtime.compile("cartesian(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 4); // [1,x], [1,y], [2,x], [2,y]
    }

    #[test]
    fn test_cartesian_empty() {
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(r#"{"a": [], "b": [1, 2]}"#).unwrap();
        let expr = runtime.compile("cartesian(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_cartesian_n_way_two_arrays() {
        let runtime = setup_runtime();
        let data = json!([[1, 2], ["a", "b"]]);
        let expr = runtime.compile("cartesian(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 4); // [1,a], [1,b], [2,a], [2,b]
    }

    #[test]
    fn test_cartesian_n_way_three_arrays() {
        let runtime = setup_runtime();
        let data = json!([[1, 2], ["a", "b"], [true, false]]);
        let expr = runtime.compile("cartesian(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 8); // 2 * 2 * 2 = 8 combinations
    }

    #[test]
    fn test_cartesian_n_way_single_array() {
        let runtime = setup_runtime();
        let data = json!([[1, 2, 3]]);
        let expr = runtime.compile("cartesian(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3); // [1], [2], [3]
    }

    #[test]
    fn test_cartesian_n_way_empty() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("cartesian(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    // =========================================================================
    // Edge cases
    // =========================================================================

    #[test]
    fn test_first_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("first(@)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.is_null());
    }

    #[test]
    fn test_last_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("last(@)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.is_null());
    }

    #[test]
    fn test_unique_preserves_order() {
        let runtime = setup_runtime();
        let data = json!(["c", "a", "b", "a", "c"]);
        let expr = runtime.compile("unique(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_str().unwrap(), "c");
        assert_eq!(arr[1].as_str().unwrap(), "a");
        assert_eq!(arr[2].as_str().unwrap(), "b");
    }

    #[test]
    fn test_unique_different_types() {
        let runtime = setup_runtime();
        let data = json!([1, "1", 1, "1"]);
        let expr = runtime.compile("unique(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2); // 1 and "1" are different
    }

    #[test]
    fn test_range_with_step() {
        let runtime = setup_runtime();
        let data = json!(null);
        let expr = runtime.compile("range(`1`, `10`, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 5); // 1, 3, 5, 7, 9
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[4].as_f64().unwrap() as i64, 9);
    }

    #[test]
    fn test_range_descending() {
        let runtime = setup_runtime();
        let data = json!(null);
        let expr = runtime.compile("range(`5`, `0`, `-1`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 5); // 5, 4, 3, 2, 1
        assert_eq!(arr[0].as_f64().unwrap() as i64, 5);
        assert_eq!(arr[4].as_f64().unwrap() as i64, 1);
    }

    // =========================================================================
    // Pipeline patterns with arrays
    // =========================================================================

    #[test]
    fn test_pipeline_unique_sort() {
        let runtime = setup_runtime();
        let data = json!(["redis", "database", "redis", "nosql", "database"]);
        let expr = runtime.compile("unique(@) | sort(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_str().unwrap(), "database");
        assert_eq!(arr[1].as_str().unwrap(), "nosql");
        assert_eq!(arr[2].as_str().unwrap(), "redis");
    }

    #[test]
    fn test_pipeline_filter_take() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
        let expr = runtime.compile("[?@ > `3`] | take(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 4);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 5);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 6);
    }

    #[test]
    fn test_pipeline_flatten_unique() {
        let runtime = setup_runtime();
        let data = json!([[1, 2], [2, 3], [3, 4]]);
        let expr = runtime.compile("flatten_deep(@) | unique(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 4); // 1, 2, 3, 4
    }

    #[test]
    fn test_large_array_processing() {
        let runtime = setup_runtime();
        // Create array with 1000 elements
        let items: Vec<i32> = (1..=1000).collect();
        let json_str = serde_json::to_string(&items).unwrap();
        let data: serde_json::Value = serde_json::from_str(&json_str).unwrap();

        let expr = runtime.compile("length(@)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, 1000);
    }

    #[test]
    fn test_transpose_basic() {
        let runtime = setup_runtime();
        let data = json!([[1, 2, 3], [4, 5, 6]]);
        let expr = runtime.compile("transpose(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        // First column: [1, 4]
        let col0 = arr[0].as_array().unwrap();
        assert_eq!(col0[0].as_f64().unwrap() as i64, 1);
        assert_eq!(col0[1].as_f64().unwrap() as i64, 4);
        // Second column: [2, 5]
        let col1 = arr[1].as_array().unwrap();
        assert_eq!(col1[0].as_f64().unwrap() as i64, 2);
        assert_eq!(col1[1].as_f64().unwrap() as i64, 5);
    }

    #[test]
    fn test_transpose_empty() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("transpose(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_transpose_unequal_rows() {
        let runtime = setup_runtime();
        let data = json!([[1, 2], [3, 4, 5], [6, 7]]);
        let expr = runtime.compile("transpose(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        // Should use minimum length (2)
        assert_eq!(arr.len(), 2);
    }

    #[test]
    fn test_pairwise_basic() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4]);
        let expr = runtime.compile("pairwise(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        // First pair: [1, 2]
        let pair0 = arr[0].as_array().unwrap();
        assert_eq!(pair0[0].as_f64().unwrap() as i64, 1);
        assert_eq!(pair0[1].as_f64().unwrap() as i64, 2);
        // Second pair: [2, 3]
        let pair1 = arr[1].as_array().unwrap();
        assert_eq!(pair1[0].as_f64().unwrap() as i64, 2);
        assert_eq!(pair1[1].as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_pairwise_short_array() {
        let runtime = setup_runtime();
        let data = json!([1]);
        let expr = runtime.compile("pairwise(@)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_sliding_window_alias() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 4, 5]);
        let expr = runtime.compile("sliding_window(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        // First window: [1, 2, 3]
        let win0 = arr[0].as_array().unwrap();
        assert_eq!(win0.len(), 3);
        assert_eq!(win0[0].as_f64().unwrap() as i64, 1);
    }

    // indices_array tests
    #[test]
    fn test_indices_array_found() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3, 2, 4, 2]);
        let expr = runtime.compile("indices_array(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 3);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 5);
    }

    #[test]
    fn test_indices_array_not_found() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("indices_array(@, `5`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_indices_array_strings() {
        let runtime = setup_runtime();
        let data = json!(["a", "b", "a", "c", "a"]);
        let expr = runtime.compile(r#"indices_array(@, `"a"`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 0);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 2);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 4);
    }

    // inside_array tests
    #[test]
    fn test_inside_array_true() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 2], "b": [1, 2, 3, 4]}"#).unwrap();
        let expr = runtime.compile("inside_array(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.as_bool().unwrap());
    }

    #[test]
    fn test_inside_array_false() {
        let runtime = setup_runtime();
        let data: serde_json::Value =
            serde_json::from_str(r#"{"a": [1, 5], "b": [1, 2, 3, 4]}"#).unwrap();
        let expr = runtime.compile("inside_array(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(!result.as_bool().unwrap());
    }

    #[test]
    fn test_inside_array_empty() {
        let runtime = setup_runtime();
        let data: serde_json::Value = serde_json::from_str(r#"{"a": [], "b": [1, 2, 3]}"#).unwrap();
        let expr = runtime.compile("inside_array(a, b)").unwrap();
        let result = expr.search(&data).unwrap();
        assert!(result.as_bool().unwrap());
    }

    // bsearch tests
    #[test]
    fn test_bsearch_found() {
        let runtime = setup_runtime();
        let data = json!([1, 3, 5, 7, 9]);
        let expr = runtime.compile("bsearch(@, `5`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_bsearch_not_found_middle() {
        let runtime = setup_runtime();
        let data = json!([1, 3, 5, 7, 9]);
        let expr = runtime.compile("bsearch(@, `4`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, -3);
    }

    #[test]
    fn test_bsearch_not_found_start() {
        let runtime = setup_runtime();
        let data = json!([1, 3, 5, 7, 9]);
        let expr = runtime.compile("bsearch(@, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, -1);
    }

    #[test]
    fn test_bsearch_not_found_end() {
        let runtime = setup_runtime();
        let data = json!([1, 3, 5, 7, 9]);
        let expr = runtime.compile("bsearch(@, `10`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, -6);
    }

    #[test]
    fn test_bsearch_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("bsearch(@, `5`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result.as_f64().unwrap() as i64, -1);
    }

    // repeat_array tests
    #[test]
    fn test_repeat_array_basic() {
        let runtime = setup_runtime();
        let data = json!(null);
        let expr = runtime.compile("repeat_array(`1`, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 3);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 1);
    }

    #[test]
    fn test_repeat_array_string() {
        let runtime = setup_runtime();
        let data = json!(null);
        let expr = runtime.compile(r#"repeat_array(`"x"`, `4`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 4);
        assert_eq!(arr[0].as_str().unwrap(), "x");
        assert_eq!(arr[3].as_str().unwrap(), "x");
    }

    #[test]
    fn test_repeat_array_zero() {
        let runtime = setup_runtime();
        let data = json!(null);
        let expr = runtime.compile("repeat_array(`1`, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_repeat_array_object() {
        let runtime = setup_runtime();
        let data = json!(null);
        let expr = runtime.compile(r#"repeat_array(`{"a": 1}`, `2`)"#).unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
        assert_eq!(
            arr[0]
                .as_object()
                .unwrap()
                .get("a")
                .unwrap()
                .as_f64()
                .unwrap() as i64,
            1
        );
    }

    // cycle tests
    #[test]
    fn test_cycle_basic() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("cycle(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 6);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 2);
        assert_eq!(arr[2].as_f64().unwrap() as i64, 3);
        assert_eq!(arr[3].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[4].as_f64().unwrap() as i64, 2);
        assert_eq!(arr[5].as_f64().unwrap() as i64, 3);
    }

    #[test]
    fn test_cycle_strings() {
        let runtime = setup_runtime();
        let data = json!(["a", "b"]);
        let expr = runtime.compile("cycle(@, `3`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 6);
        assert_eq!(arr[0].as_str().unwrap(), "a");
        assert_eq!(arr[1].as_str().unwrap(), "b");
        assert_eq!(arr[2].as_str().unwrap(), "a");
    }

    #[test]
    fn test_cycle_zero() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("cycle(@, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_cycle_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("cycle(@, `5`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 0);
    }

    #[test]
    fn test_cycle_once() {
        let runtime = setup_runtime();
        let data = json!([1, 2]);
        let expr = runtime.compile("cycle(@, `1`)").unwrap();
        let result = expr.search(&data).unwrap();
        let arr = result.as_array().unwrap();
        assert_eq!(arr.len(), 2);
        assert_eq!(arr[0].as_f64().unwrap() as i64, 1);
        assert_eq!(arr[1].as_f64().unwrap() as i64, 2);
    }

    #[test]
    fn test_lag_by_one() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lag(@, `1`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([null, 1, 2]));
    }

    #[test]
    fn test_lag_by_two() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lag(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([null, null, 1]));
    }

    #[test]
    fn test_lag_by_zero() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lag(@, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([1, 2, 3]));
    }

    #[test]
    fn test_lag_exceeds_length() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lag(@, `5`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([null, null, null]));
    }

    #[test]
    fn test_lag_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("lag(@, `1`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([]));
    }

    #[test]
    fn test_lead_by_one() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lead(@, `1`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([2, 3, null]));
    }

    #[test]
    fn test_lead_by_two() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lead(@, `2`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([3, null, null]));
    }

    #[test]
    fn test_lead_by_zero() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lead(@, `0`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([1, 2, 3]));
    }

    #[test]
    fn test_lead_exceeds_length() {
        let runtime = setup_runtime();
        let data = json!([1, 2, 3]);
        let expr = runtime.compile("lead(@, `5`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([null, null, null]));
    }

    #[test]
    fn test_lead_empty_array() {
        let runtime = setup_runtime();
        let data = json!([]);
        let expr = runtime.compile("lead(@, `1`)").unwrap();
        let result = expr.search(&data).unwrap();
        assert_eq!(result, json!([]));
    }
}