prax_query/

filter.rs

//! Filter types for building WHERE clauses.
//!
//! This module provides the building blocks for constructing type-safe query filters.
//!
//! # Performance
//!
//! Field names use `Cow<'static, str>` for optimal performance:
//! - Static strings (`&'static str`) are borrowed with zero allocation
//! - Dynamic strings are stored as owned `String`
//! - Use `.into()` from static strings for best performance
//!
//! # Examples
//!
//! ## Basic Filters
//!
//! ```rust
//! use prax_query::filter::{Filter, FilterValue};
//!
//! // Equality filter - zero allocation with static str
//! let filter = Filter::Equals("id".into(), FilterValue::Int(42));
//!
//! // String contains
//! let filter = Filter::Contains("email".into(), FilterValue::String("@example.com".into()));
//!
//! // Greater than
//! let filter = Filter::Gt("age".into(), FilterValue::Int(18));
//! ```
//!
//! ## Combining Filters
//!
//! ```rust
//! use prax_query::filter::{Filter, FilterValue};
//!
//! // AND combination - use Filter::and() for convenience
//! let filter = Filter::and([
//!     Filter::Equals("active".into(), FilterValue::Bool(true)),
//!     Filter::Gt("score".into(), FilterValue::Int(100)),
//! ]);
//!
//! // OR combination - use Filter::or() for convenience
//! let filter = Filter::or([
//!     Filter::Equals("status".into(), FilterValue::String("pending".into())),
//!     Filter::Equals("status".into(), FilterValue::String("processing".into())),
//! ]);
//!
//! // NOT
//! let filter = Filter::Not(Box::new(
//!     Filter::Equals("deleted".into(), FilterValue::Bool(true))
//! ));
//! ```
//!
//! ## Null Checks
//!
//! ```rust
//! use prax_query::filter::{Filter, FilterValue};
//!
//! // Is null
//! let filter = Filter::IsNull("deleted_at".into());
//!
//! // Is not null
//! let filter = Filter::IsNotNull("verified_at".into());
//! ```

use serde::{Deserialize, Serialize};
use smallvec::SmallVec;
use std::borrow::Cow;
use tracing::debug;

/// A list of filter values for IN/NOT IN clauses.
///
/// Uses `Vec<FilterValue>` for minimal Filter enum size (~64 bytes).
/// This prioritizes cache efficiency over avoiding small allocations.
///
/// # Performance
///
/// While this does allocate for IN clauses, the benefits are:
/// - Filter enum fits in a single cache line (64 bytes)
/// - Better memory locality for filter iteration
/// - Smaller stack usage for complex queries
///
/// For truly allocation-free IN filters, use `Filter::in_static()` with
/// a static slice reference.
pub type ValueList = Vec<FilterValue>;

/// SmallVec-based value list for hot paths where small IN clauses are common.
/// Use this explicitly when you know IN clauses are small (≤8 elements).
pub type SmallValueList = SmallVec<[FilterValue; 8]>;

/// Large value list type with 32 elements inline.
/// Use this for known large IN clauses (e.g., batch operations).
pub type LargeValueList = SmallVec<[FilterValue; 32]>;

/// A field name that can be either a static string (zero allocation) or an owned string.
///
/// Uses `Cow<'static, str>` for optimal performance:
/// - Static strings are borrowed without allocation
/// - Dynamic strings are stored as owned `String`
///
/// # Examples
///
/// ```rust
/// use prax_query::FieldName;
///
/// // Static strings - zero allocation (Cow::Borrowed)
/// let name: FieldName = "id".into();
/// let name: FieldName = "email".into();
/// let name: FieldName = "user_id".into();
/// let name: FieldName = "created_at".into();
///
/// // Dynamic strings work too (Cow::Owned)
/// let name: FieldName = format!("field_{}", 1).into();
/// ```
pub type FieldName = Cow<'static, str>;

/// A filter value that can be used in comparisons.
///
/// # Examples
///
/// ```rust
/// use prax_query::FilterValue;
///
/// // From integers
/// let val: FilterValue = 42.into();
/// let val: FilterValue = 42i64.into();
///
/// // From strings
/// let val: FilterValue = "hello".into();
/// let val: FilterValue = String::from("world").into();
///
/// // From booleans
/// let val: FilterValue = true.into();
///
/// // From floats
/// let val: FilterValue = 3.14f64.into();
///
/// // Null value
/// let val = FilterValue::Null;
///
/// // From vectors
/// let val: FilterValue = vec![1, 2, 3].into();
///
/// // From Option (Some becomes value, None becomes Null)
/// let val: FilterValue = Some(42).into();
/// let val: FilterValue = Option::<i32>::None.into();
/// assert!(val.is_null());
/// ```
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(untagged)]
pub enum FilterValue {
    /// Null value.
    Null,
    /// Boolean value.
    Bool(bool),
    /// Integer value.
    Int(i64),
    /// Float value.
    Float(f64),
    /// String value.
    String(String),
    /// JSON value.
    Json(serde_json::Value),
    /// List of values.
    List(Vec<FilterValue>),
}

impl FilterValue {
    /// Check if this is a null value.
    pub fn is_null(&self) -> bool {
        matches!(self, Self::Null)
    }

    /// Convert to SQL parameter placeholder.
    pub fn to_sql_placeholder(&self, param_index: usize) -> String {
        format!("${}", param_index)
    }
}

impl From<bool> for FilterValue {
    fn from(v: bool) -> Self {
        Self::Bool(v)
    }
}

impl From<i32> for FilterValue {
    fn from(v: i32) -> Self {
        Self::Int(v as i64)
    }
}

impl From<i64> for FilterValue {
    fn from(v: i64) -> Self {
        Self::Int(v)
    }
}

impl From<f64> for FilterValue {
    fn from(v: f64) -> Self {
        Self::Float(v)
    }
}

impl From<String> for FilterValue {
    fn from(v: String) -> Self {
        Self::String(v)
    }
}

impl From<&str> for FilterValue {
    fn from(v: &str) -> Self {
        Self::String(v.to_string())
    }
}

impl<T: Into<FilterValue>> From<Vec<T>> for FilterValue {
    fn from(v: Vec<T>) -> Self {
        Self::List(v.into_iter().map(Into::into).collect())
    }
}

impl<T: Into<FilterValue>> From<Option<T>> for FilterValue {
    fn from(v: Option<T>) -> Self {
        match v {
            Some(v) => v.into(),
            None => Self::Null,
        }
    }
}

/// Scalar filter operations.
#[derive(Debug, Clone, PartialEq)]
pub enum ScalarFilter<T> {
    /// Equals the value.
    Equals(T),
    /// Not equals the value.
    Not(Box<T>),
    /// In a list of values.
    In(Vec<T>),
    /// Not in a list of values.
    NotIn(Vec<T>),
    /// Less than.
    Lt(T),
    /// Less than or equal.
    Lte(T),
    /// Greater than.
    Gt(T),
    /// Greater than or equal.
    Gte(T),
    /// Contains (for strings).
    Contains(T),
    /// Starts with (for strings).
    StartsWith(T),
    /// Ends with (for strings).
    EndsWith(T),
    /// Is null.
    IsNull,
    /// Is not null.
    IsNotNull,
}

impl<T: Into<FilterValue>> ScalarFilter<T> {
    /// Convert to a Filter with the given column name.
    ///
    /// The column name can be a static string (zero allocation) or an owned string.
    /// For IN/NOT IN filters, uses SmallVec to avoid heap allocation for ≤16 values.
    pub fn into_filter(self, column: impl Into<FieldName>) -> Filter {
        let column = column.into();
        match self {
            Self::Equals(v) => Filter::Equals(column, v.into()),
            Self::Not(v) => Filter::NotEquals(column, (*v).into()),
            Self::In(values) => {
                Filter::In(column, values.into_iter().map(Into::into).collect())
            }
            Self::NotIn(values) => {
                Filter::NotIn(column, values.into_iter().map(Into::into).collect())
            }
            Self::Lt(v) => Filter::Lt(column, v.into()),
            Self::Lte(v) => Filter::Lte(column, v.into()),
            Self::Gt(v) => Filter::Gt(column, v.into()),
            Self::Gte(v) => Filter::Gte(column, v.into()),
            Self::Contains(v) => Filter::Contains(column, v.into()),
            Self::StartsWith(v) => Filter::StartsWith(column, v.into()),
            Self::EndsWith(v) => Filter::EndsWith(column, v.into()),
            Self::IsNull => Filter::IsNull(column),
            Self::IsNotNull => Filter::IsNotNull(column),
        }
    }
}

/// A complete filter that can be converted to SQL.
///
/// # Size Optimization
///
/// The Filter enum is designed to fit in a single cache line (~64 bytes):
/// - Field names use `Cow<'static, str>` (24 bytes)
/// - Filter values use `FilterValue` (40 bytes)
/// - IN/NOT IN use `Vec<FilterValue>` (24 bytes) instead of SmallVec
/// - AND/OR use `Box<[Filter]>` (16 bytes)
///
/// This enables efficient iteration and better CPU cache utilization.
///
/// # Zero-Allocation Patterns
///
/// For maximum performance, use static strings:
/// ```rust
/// use prax_query::filter::{Filter, FilterValue};
/// // Zero allocation - static string borrowed
/// let filter = Filter::Equals("id".into(), FilterValue::Int(42));
/// ```
#[derive(Debug, Clone, PartialEq)]
#[repr(C)] // Ensure predictable memory layout
pub enum Filter {
    /// No filter (always true).
    None,

    /// Equals comparison.
    Equals(FieldName, FilterValue),
    /// Not equals comparison.
    NotEquals(FieldName, FilterValue),

    /// Less than comparison.
    Lt(FieldName, FilterValue),
    /// Less than or equal comparison.
    Lte(FieldName, FilterValue),
    /// Greater than comparison.
    Gt(FieldName, FilterValue),
    /// Greater than or equal comparison.
    Gte(FieldName, FilterValue),

    /// In a list of values.
    In(FieldName, ValueList),
    /// Not in a list of values.
    NotIn(FieldName, ValueList),

    /// Contains (LIKE %value%).
    Contains(FieldName, FilterValue),
    /// Starts with (LIKE value%).
    StartsWith(FieldName, FilterValue),
    /// Ends with (LIKE %value).
    EndsWith(FieldName, FilterValue),

    /// Is null check.
    IsNull(FieldName),
    /// Is not null check.
    IsNotNull(FieldName),

    /// Logical AND of multiple filters.
    ///
    /// Uses `Box<[Filter]>` instead of `Vec<Filter>` to save 8 bytes per filter
    /// (no capacity field needed since filters are immutable after construction).
    And(Box<[Filter]>),
    /// Logical OR of multiple filters.
    ///
    /// Uses `Box<[Filter]>` instead of `Vec<Filter>` to save 8 bytes per filter
    /// (no capacity field needed since filters are immutable after construction).
    Or(Box<[Filter]>),
    /// Logical NOT of a filter.
    Not(Box<Filter>),
}

impl Filter {
    /// Create an empty filter (matches everything).
    #[inline(always)]
    pub fn none() -> Self {
        Self::None
    }

    /// Check if this filter is empty.
    #[inline(always)]
    pub fn is_none(&self) -> bool {
        matches!(self, Self::None)
    }

    /// Create an AND filter from an iterator of filters.
    ///
    /// Automatically filters out `None` filters and simplifies single-element combinations.
    ///
    /// For known small counts, prefer `and2`, `and3`, `and5`, or `and_n` for better performance.
    #[inline]
    pub fn and(filters: impl IntoIterator<Item = Filter>) -> Self {
        let filters: Vec<_> = filters.into_iter().filter(|f| !f.is_none()).collect();
        let count = filters.len();
        let result = match count {
            0 => Self::None,
            1 => filters.into_iter().next().unwrap(),
            _ => Self::And(filters.into_boxed_slice()),
        };
        debug!(count, "Filter::and() created");
        result
    }

    /// Create an AND filter from exactly two filters.
    ///
    /// More efficient than `and([a, b])` - avoids Vec allocation.
    #[inline(always)]
    pub fn and2(a: Filter, b: Filter) -> Self {
        match (a.is_none(), b.is_none()) {
            (true, true) => Self::None,
            (true, false) => b,
            (false, true) => a,
            (false, false) => Self::And(Box::new([a, b])),
        }
    }

    /// Create an OR filter from an iterator of filters.
    ///
    /// Automatically filters out `None` filters and simplifies single-element combinations.
    ///
    /// For known small counts, prefer `or2`, `or3`, or `or_n` for better performance.
    #[inline]
    pub fn or(filters: impl IntoIterator<Item = Filter>) -> Self {
        let filters: Vec<_> = filters.into_iter().filter(|f| !f.is_none()).collect();
        let count = filters.len();
        let result = match count {
            0 => Self::None,
            1 => filters.into_iter().next().unwrap(),
            _ => Self::Or(filters.into_boxed_slice()),
        };
        debug!(count, "Filter::or() created");
        result
    }

    /// Create an OR filter from exactly two filters.
    ///
    /// More efficient than `or([a, b])` - avoids Vec allocation.
    #[inline(always)]
    pub fn or2(a: Filter, b: Filter) -> Self {
        match (a.is_none(), b.is_none()) {
            (true, true) => Self::None,
            (true, false) => b,
            (false, true) => a,
            (false, false) => Self::Or(Box::new([a, b])),
        }
    }

    // ========================================================================
    // Const Generic Constructors (Zero Vec Allocation)
    // ========================================================================

    /// Create an AND filter from a fixed-size array (const generic).
    ///
    /// This is the most efficient way to create AND filters when the count is
    /// known at compile time. It avoids Vec allocation entirely.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::{Filter, FilterValue};
    ///
    /// let filter = Filter::and_n([
    ///     Filter::Equals("a".into(), FilterValue::Int(1)),
    ///     Filter::Equals("b".into(), FilterValue::Int(2)),
    ///     Filter::Equals("c".into(), FilterValue::Int(3)),
    /// ]);
    /// ```
    #[inline(always)]
    pub fn and_n<const N: usize>(filters: [Filter; N]) -> Self {
        // Convert array to boxed slice directly (no Vec intermediate)
        Self::And(Box::new(filters))
    }

    /// Create an OR filter from a fixed-size array (const generic).
    ///
    /// This is the most efficient way to create OR filters when the count is
    /// known at compile time. It avoids Vec allocation entirely.
    #[inline(always)]
    pub fn or_n<const N: usize>(filters: [Filter; N]) -> Self {
        Self::Or(Box::new(filters))
    }

    /// Create an AND filter from exactly 3 filters.
    #[inline(always)]
    pub fn and3(a: Filter, b: Filter, c: Filter) -> Self {
        Self::And(Box::new([a, b, c]))
    }

    /// Create an AND filter from exactly 4 filters.
    #[inline(always)]
    pub fn and4(a: Filter, b: Filter, c: Filter, d: Filter) -> Self {
        Self::And(Box::new([a, b, c, d]))
    }

    /// Create an AND filter from exactly 5 filters.
    #[inline(always)]
    pub fn and5(a: Filter, b: Filter, c: Filter, d: Filter, e: Filter) -> Self {
        Self::And(Box::new([a, b, c, d, e]))
    }

    /// Create an OR filter from exactly 3 filters.
    #[inline(always)]
    pub fn or3(a: Filter, b: Filter, c: Filter) -> Self {
        Self::Or(Box::new([a, b, c]))
    }

    /// Create an OR filter from exactly 4 filters.
    #[inline(always)]
    pub fn or4(a: Filter, b: Filter, c: Filter, d: Filter) -> Self {
        Self::Or(Box::new([a, b, c, d]))
    }

    /// Create an OR filter from exactly 5 filters.
    #[inline(always)]
    pub fn or5(a: Filter, b: Filter, c: Filter, d: Filter, e: Filter) -> Self {
        Self::Or(Box::new([a, b, c, d, e]))
    }

    // ========================================================================
    // Optimized IN Filter Constructors
    // ========================================================================

    /// Create an IN filter from an iterator of i64 values.
    ///
    /// This is optimized for integer lists, avoiding the generic `Into<FilterValue>`
    /// conversion overhead.
    #[inline]
    pub fn in_i64(field: impl Into<FieldName>, values: impl IntoIterator<Item = i64>) -> Self {
        let list: ValueList = values.into_iter().map(FilterValue::Int).collect();
        Self::In(field.into(), list)
    }

    /// Create an IN filter from an iterator of i32 values.
    #[inline]
    pub fn in_i32(field: impl Into<FieldName>, values: impl IntoIterator<Item = i32>) -> Self {
        let list: ValueList = values.into_iter().map(|v| FilterValue::Int(v as i64)).collect();
        Self::In(field.into(), list)
    }

    /// Create an IN filter from an iterator of string values.
    #[inline]
    pub fn in_strings(field: impl Into<FieldName>, values: impl IntoIterator<Item = String>) -> Self {
        let list: ValueList = values.into_iter().map(FilterValue::String).collect();
        Self::In(field.into(), list)
    }

    /// Create an IN filter from a pre-built ValueList.
    ///
    /// Use this when you've already constructed a ValueList to avoid re-collection.
    #[inline]
    pub fn in_values(field: impl Into<FieldName>, values: ValueList) -> Self {
        Self::In(field.into(), values)
    }

    /// Create an IN filter from a range of i64 values.
    ///
    /// Highly optimized for sequential integer ranges.
    #[inline]
    pub fn in_range(field: impl Into<FieldName>, range: std::ops::Range<i64>) -> Self {
        let list: ValueList = range.map(FilterValue::Int).collect();
        Self::In(field.into(), list)
    }

    /// Create an IN filter from a pre-allocated i64 slice with exact capacity.
    ///
    /// This is the most efficient way to create IN filters for i64 values
    /// when you have a slice available.
    #[inline(always)]
    pub fn in_i64_slice(field: impl Into<FieldName>, values: &[i64]) -> Self {
        let mut list = Vec::with_capacity(values.len());
        for &v in values {
            list.push(FilterValue::Int(v));
        }
        Self::In(field.into(), list)
    }

    /// Create an IN filter for i32 values from a slice.
    #[inline(always)]
    pub fn in_i32_slice(field: impl Into<FieldName>, values: &[i32]) -> Self {
        let mut list = Vec::with_capacity(values.len());
        for &v in values {
            list.push(FilterValue::Int(v as i64));
        }
        Self::In(field.into(), list)
    }

    /// Create an IN filter for string values from a slice.
    #[inline(always)]
    pub fn in_str_slice(field: impl Into<FieldName>, values: &[&str]) -> Self {
        let mut list = Vec::with_capacity(values.len());
        for &v in values {
            list.push(FilterValue::String(v.to_string()));
        }
        Self::In(field.into(), list)
    }

    /// Create a NOT filter.
    #[inline]
    pub fn not(filter: Filter) -> Self {
        if filter.is_none() {
            return Self::None;
        }
        Self::Not(Box::new(filter))
    }

    /// Create an IN filter from a slice of values.
    ///
    /// This is more efficient than `Filter::In(field, values.into())` when you have a slice,
    /// as it avoids intermediate collection.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::Filter;
    ///
    /// let ids: &[i64] = &[1, 2, 3, 4, 5];
    /// let filter = Filter::in_slice("id", ids);
    /// ```
    #[inline]
    pub fn in_slice<T: Into<FilterValue> + Clone>(field: impl Into<FieldName>, values: &[T]) -> Self {
        let list: ValueList = values.iter().map(|v| v.clone().into()).collect();
        Self::In(field.into(), list)
    }

    /// Create a NOT IN filter from a slice of values.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::Filter;
    ///
    /// let ids: &[i64] = &[1, 2, 3, 4, 5];
    /// let filter = Filter::not_in_slice("id", ids);
    /// ```
    #[inline]
    pub fn not_in_slice<T: Into<FilterValue> + Clone>(field: impl Into<FieldName>, values: &[T]) -> Self {
        let list: ValueList = values.iter().map(|v| v.clone().into()).collect();
        Self::NotIn(field.into(), list)
    }

    /// Create an IN filter from an array (const generic).
    ///
    /// This is useful when you know the size at compile time.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::Filter;
    ///
    /// let filter = Filter::in_array("status", ["active", "pending", "processing"]);
    /// ```
    #[inline]
    pub fn in_array<T: Into<FilterValue>, const N: usize>(field: impl Into<FieldName>, values: [T; N]) -> Self {
        let list: ValueList = values.into_iter().map(Into::into).collect();
        Self::In(field.into(), list)
    }

    /// Create a NOT IN filter from an array (const generic).
    #[inline]
    pub fn not_in_array<T: Into<FilterValue>, const N: usize>(field: impl Into<FieldName>, values: [T; N]) -> Self {
        let list: ValueList = values.into_iter().map(Into::into).collect();
        Self::NotIn(field.into(), list)
    }

    /// Combine with another filter using AND.
    pub fn and_then(self, other: Filter) -> Self {
        if self.is_none() {
            return other;
        }
        if other.is_none() {
            return self;
        }
        match self {
            Self::And(filters) => {
                // Convert to Vec, add new filter, convert back to Box<[T]>
                let mut vec: Vec<_> = filters.into_vec();
                vec.push(other);
                Self::And(vec.into_boxed_slice())
            }
            _ => Self::And(Box::new([self, other])),
        }
    }

    /// Combine with another filter using OR.
    pub fn or_else(self, other: Filter) -> Self {
        if self.is_none() {
            return other;
        }
        if other.is_none() {
            return self;
        }
        match self {
            Self::Or(filters) => {
                // Convert to Vec, add new filter, convert back to Box<[T]>
                let mut vec: Vec<_> = filters.into_vec();
                vec.push(other);
                Self::Or(vec.into_boxed_slice())
            }
            _ => Self::Or(Box::new([self, other])),
        }
    }

    /// Generate SQL for this filter with parameter placeholders.
    /// Returns (sql, params) where params are the values to bind.
    pub fn to_sql(&self, param_offset: usize) -> (String, Vec<FilterValue>) {
        let mut params = Vec::new();
        let sql = self.to_sql_with_params(param_offset, &mut params);
        (sql, params)
    }

    fn to_sql_with_params(&self, mut param_idx: usize, params: &mut Vec<FilterValue>) -> String {
        match self {
            Self::None => "TRUE".to_string(),

            Self::Equals(col, val) => {
                if val.is_null() {
                    format!("{} IS NULL", col)
                } else {
                    params.push(val.clone());
                    param_idx += params.len();
                    format!("{} = ${}", col, param_idx)
                }
            }
            Self::NotEquals(col, val) => {
                if val.is_null() {
                    format!("{} IS NOT NULL", col)
                } else {
                    params.push(val.clone());
                    param_idx += params.len();
                    format!("{} != ${}", col, param_idx)
                }
            }

            Self::Lt(col, val) => {
                params.push(val.clone());
                param_idx += params.len();
                format!("{} < ${}", col, param_idx)
            }
            Self::Lte(col, val) => {
                params.push(val.clone());
                param_idx += params.len();
                format!("{} <= ${}", col, param_idx)
            }
            Self::Gt(col, val) => {
                params.push(val.clone());
                param_idx += params.len();
                format!("{} > ${}", col, param_idx)
            }
            Self::Gte(col, val) => {
                params.push(val.clone());
                param_idx += params.len();
                format!("{} >= ${}", col, param_idx)
            }

            Self::In(col, values) => {
                if values.is_empty() {
                    return "FALSE".to_string();
                }
                let placeholders: Vec<_> = values
                    .iter()
                    .map(|v| {
                        params.push(v.clone());
                        param_idx += params.len();
                        format!("${}", param_idx)
                    })
                    .collect();
                format!("{} IN ({})", col, placeholders.join(", "))
            }
            Self::NotIn(col, values) => {
                if values.is_empty() {
                    return "TRUE".to_string();
                }
                let placeholders: Vec<_> = values
                    .iter()
                    .map(|v| {
                        params.push(v.clone());
                        param_idx += params.len();
                        format!("${}", param_idx)
                    })
                    .collect();
                format!("{} NOT IN ({})", col, placeholders.join(", "))
            }

            Self::Contains(col, val) => {
                if let FilterValue::String(s) = val {
                    params.push(FilterValue::String(format!("%{}%", s)));
                } else {
                    params.push(val.clone());
                }
                param_idx += params.len();
                format!("{} LIKE ${}", col, param_idx)
            }
            Self::StartsWith(col, val) => {
                if let FilterValue::String(s) = val {
                    params.push(FilterValue::String(format!("{}%", s)));
                } else {
                    params.push(val.clone());
                }
                param_idx += params.len();
                format!("{} LIKE ${}", col, param_idx)
            }
            Self::EndsWith(col, val) => {
                if let FilterValue::String(s) = val {
                    params.push(FilterValue::String(format!("%{}", s)));
                } else {
                    params.push(val.clone());
                }
                param_idx += params.len();
                format!("{} LIKE ${}", col, param_idx)
            }

            Self::IsNull(col) => format!("{} IS NULL", col),
            Self::IsNotNull(col) => format!("{} IS NOT NULL", col),

            Self::And(filters) => {
                if filters.is_empty() {
                    return "TRUE".to_string();
                }
                let parts: Vec<_> = filters
                    .iter()
                    .map(|f| f.to_sql_with_params(param_idx + params.len(), params))
                    .collect();
                format!("({})", parts.join(" AND "))
            }
            Self::Or(filters) => {
                if filters.is_empty() {
                    return "FALSE".to_string();
                }
                let parts: Vec<_> = filters
                    .iter()
                    .map(|f| f.to_sql_with_params(param_idx + params.len(), params))
                    .collect();
                format!("({})", parts.join(" OR "))
            }
            Self::Not(filter) => {
                let inner = filter.to_sql_with_params(param_idx, params);
                format!("NOT ({})", inner)
            }
        }
    }

    /// Create a builder for constructing AND filters with pre-allocated capacity.
    ///
    /// This is more efficient than using `Filter::and()` when you know the
    /// approximate number of conditions upfront.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::{Filter, FilterValue};
    ///
    /// // Build an AND filter with pre-allocated capacity for 3 conditions
    /// let filter = Filter::and_builder(3)
    ///     .push(Filter::Equals("active".into(), FilterValue::Bool(true)))
    ///     .push(Filter::Gt("score".into(), FilterValue::Int(100)))
    ///     .push(Filter::IsNotNull("email".into()))
    ///     .build();
    /// ```
    #[inline]
    pub fn and_builder(capacity: usize) -> AndFilterBuilder {
        AndFilterBuilder::with_capacity(capacity)
    }

    /// Create a builder for constructing OR filters with pre-allocated capacity.
    ///
    /// This is more efficient than using `Filter::or()` when you know the
    /// approximate number of conditions upfront.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::{Filter, FilterValue};
    ///
    /// // Build an OR filter with pre-allocated capacity for 2 conditions
    /// let filter = Filter::or_builder(2)
    ///     .push(Filter::Equals("role".into(), FilterValue::String("admin".into())))
    ///     .push(Filter::Equals("role".into(), FilterValue::String("moderator".into())))
    ///     .build();
    /// ```
    #[inline]
    pub fn or_builder(capacity: usize) -> OrFilterBuilder {
        OrFilterBuilder::with_capacity(capacity)
    }

    /// Create a general-purpose filter builder.
    ///
    /// Use this for building complex filter trees with a fluent API.
    ///
    /// # Examples
    ///
    /// ```rust
    /// use prax_query::filter::Filter;
    ///
    /// let filter = Filter::builder()
    ///     .eq("status", "active")
    ///     .gt("age", 18)
    ///     .is_not_null("email")
    ///     .build_and();
    /// ```
    #[inline]
    pub fn builder() -> FluentFilterBuilder {
        FluentFilterBuilder::new()
    }
}

/// Builder for constructing AND filters with pre-allocated capacity.
///
/// This avoids vector reallocations when the number of conditions is known upfront.
#[derive(Debug, Clone)]
pub struct AndFilterBuilder {
    filters: Vec<Filter>,
}

impl AndFilterBuilder {
    /// Create a new builder with default capacity.
    #[inline]
    pub fn new() -> Self {
        Self {
            filters: Vec::new(),
        }
    }

    /// Create a new builder with the specified capacity.
    #[inline]
    pub fn with_capacity(capacity: usize) -> Self {
        Self {
            filters: Vec::with_capacity(capacity),
        }
    }

    /// Add a filter to the AND condition.
    #[inline]
    pub fn push(mut self, filter: Filter) -> Self {
        if !filter.is_none() {
            self.filters.push(filter);
        }
        self
    }

    /// Add multiple filters to the AND condition.
    #[inline]
    pub fn extend(mut self, filters: impl IntoIterator<Item = Filter>) -> Self {
        self.filters.extend(filters.into_iter().filter(|f| !f.is_none()));
        self
    }

    /// Add a filter conditionally.
    #[inline]
    pub fn push_if(self, condition: bool, filter: Filter) -> Self {
        if condition {
            self.push(filter)
        } else {
            self
        }
    }

    /// Add a filter conditionally, evaluating the closure only if condition is true.
    #[inline]
    pub fn push_if_some<F>(self, opt: Option<F>) -> Self
    where
        F: Into<Filter>,
    {
        match opt {
            Some(f) => self.push(f.into()),
            None => self,
        }
    }

    /// Build the final AND filter.
    #[inline]
    pub fn build(self) -> Filter {
        match self.filters.len() {
            0 => Filter::None,
            1 => self.filters.into_iter().next().unwrap(),
            _ => Filter::And(self.filters.into_boxed_slice()),
        }
    }

    /// Get the current number of filters.
    #[inline]
    pub fn len(&self) -> usize {
        self.filters.len()
    }

    /// Check if the builder is empty.
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.filters.is_empty()
    }
}

impl Default for AndFilterBuilder {
    fn default() -> Self {
        Self::new()
    }
}

/// Builder for constructing OR filters with pre-allocated capacity.
///
/// This avoids vector reallocations when the number of conditions is known upfront.
#[derive(Debug, Clone)]
pub struct OrFilterBuilder {
    filters: Vec<Filter>,
}

impl OrFilterBuilder {
    /// Create a new builder with default capacity.
    #[inline]
    pub fn new() -> Self {
        Self {
            filters: Vec::new(),
        }
    }

    /// Create a new builder with the specified capacity.
    #[inline]
    pub fn with_capacity(capacity: usize) -> Self {
        Self {
            filters: Vec::with_capacity(capacity),
        }
    }

    /// Add a filter to the OR condition.
    #[inline]
    pub fn push(mut self, filter: Filter) -> Self {
        if !filter.is_none() {
            self.filters.push(filter);
        }
        self
    }

    /// Add multiple filters to the OR condition.
    #[inline]
    pub fn extend(mut self, filters: impl IntoIterator<Item = Filter>) -> Self {
        self.filters.extend(filters.into_iter().filter(|f| !f.is_none()));
        self
    }

    /// Add a filter conditionally.
    #[inline]
    pub fn push_if(self, condition: bool, filter: Filter) -> Self {
        if condition {
            self.push(filter)
        } else {
            self
        }
    }

    /// Add a filter conditionally, evaluating the closure only if condition is true.
    #[inline]
    pub fn push_if_some<F>(self, opt: Option<F>) -> Self
    where
        F: Into<Filter>,
    {
        match opt {
            Some(f) => self.push(f.into()),
            None => self,
        }
    }

    /// Build the final OR filter.
    #[inline]
    pub fn build(self) -> Filter {
        match self.filters.len() {
            0 => Filter::None,
            1 => self.filters.into_iter().next().unwrap(),
            _ => Filter::Or(self.filters.into_boxed_slice()),
        }
    }

    /// Get the current number of filters.
    #[inline]
    pub fn len(&self) -> usize {
        self.filters.len()
    }

    /// Check if the builder is empty.
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.filters.is_empty()
    }
}

impl Default for OrFilterBuilder {
    fn default() -> Self {
        Self::new()
    }
}

/// A fluent builder for constructing filters with a convenient API.
///
/// This builder collects conditions and can produce either an AND or OR filter.
///
/// # Examples
///
/// ```rust
/// use prax_query::filter::Filter;
///
/// // Build an AND filter
/// let filter = Filter::builder()
///     .eq("active", true)
///     .gt("score", 100)
///     .contains("email", "@example.com")
///     .build_and();
///
/// // Build an OR filter with capacity hint
/// let filter = Filter::builder()
///     .with_capacity(3)
///     .eq("role", "admin")
///     .eq("role", "moderator")
///     .eq("role", "owner")
///     .build_or();
/// ```
#[derive(Debug, Clone)]
pub struct FluentFilterBuilder {
    filters: Vec<Filter>,
}

impl FluentFilterBuilder {
    /// Create a new fluent builder.
    #[inline]
    pub fn new() -> Self {
        Self {
            filters: Vec::new(),
        }
    }

    /// Set the capacity hint for the internal vector.
    #[inline]
    pub fn with_capacity(mut self, capacity: usize) -> Self {
        self.filters.reserve(capacity);
        self
    }

    /// Add an equals filter.
    #[inline]
    pub fn eq<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::Equals(field.into(), value.into()));
        self
    }

    /// Add a not equals filter.
    #[inline]
    pub fn ne<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::NotEquals(field.into(), value.into()));
        self
    }

    /// Add a less than filter.
    #[inline]
    pub fn lt<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::Lt(field.into(), value.into()));
        self
    }

    /// Add a less than or equal filter.
    #[inline]
    pub fn lte<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::Lte(field.into(), value.into()));
        self
    }

    /// Add a greater than filter.
    #[inline]
    pub fn gt<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::Gt(field.into(), value.into()));
        self
    }

    /// Add a greater than or equal filter.
    #[inline]
    pub fn gte<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::Gte(field.into(), value.into()));
        self
    }

    /// Add an IN filter.
    #[inline]
    pub fn is_in<F, I, V>(mut self, field: F, values: I) -> Self
    where
        F: Into<FieldName>,
        I: IntoIterator<Item = V>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::In(
            field.into(),
            values.into_iter().map(Into::into).collect(),
        ));
        self
    }

    /// Add a NOT IN filter.
    #[inline]
    pub fn not_in<F, I, V>(mut self, field: F, values: I) -> Self
    where
        F: Into<FieldName>,
        I: IntoIterator<Item = V>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::NotIn(
            field.into(),
            values.into_iter().map(Into::into).collect(),
        ));
        self
    }

    /// Add a contains filter (LIKE %value%).
    #[inline]
    pub fn contains<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::Contains(field.into(), value.into()));
        self
    }

    /// Add a starts with filter (LIKE value%).
    #[inline]
    pub fn starts_with<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::StartsWith(field.into(), value.into()));
        self
    }

    /// Add an ends with filter (LIKE %value).
    #[inline]
    pub fn ends_with<F, V>(mut self, field: F, value: V) -> Self
    where
        F: Into<FieldName>,
        V: Into<FilterValue>,
    {
        self.filters.push(Filter::EndsWith(field.into(), value.into()));
        self
    }

    /// Add an IS NULL filter.
    #[inline]
    pub fn is_null<F>(mut self, field: F) -> Self
    where
        F: Into<FieldName>,
    {
        self.filters.push(Filter::IsNull(field.into()));
        self
    }

    /// Add an IS NOT NULL filter.
    #[inline]
    pub fn is_not_null<F>(mut self, field: F) -> Self
    where
        F: Into<FieldName>,
    {
        self.filters.push(Filter::IsNotNull(field.into()));
        self
    }

    /// Add a raw filter directly.
    #[inline]
    pub fn filter(mut self, filter: Filter) -> Self {
        if !filter.is_none() {
            self.filters.push(filter);
        }
        self
    }

    /// Add a filter conditionally.
    #[inline]
    pub fn filter_if(self, condition: bool, filter: Filter) -> Self {
        if condition {
            self.filter(filter)
        } else {
            self
        }
    }

    /// Add a filter conditionally if the option is Some.
    #[inline]
    pub fn filter_if_some<F>(self, opt: Option<F>) -> Self
    where
        F: Into<Filter>,
    {
        match opt {
            Some(f) => self.filter(f.into()),
            None => self,
        }
    }

    /// Build an AND filter from all collected conditions.
    #[inline]
    pub fn build_and(self) -> Filter {
        let filters: Vec<_> = self.filters.into_iter().filter(|f| !f.is_none()).collect();
        match filters.len() {
            0 => Filter::None,
            1 => filters.into_iter().next().unwrap(),
            _ => Filter::And(filters.into_boxed_slice()),
        }
    }

    /// Build an OR filter from all collected conditions.
    #[inline]
    pub fn build_or(self) -> Filter {
        let filters: Vec<_> = self.filters.into_iter().filter(|f| !f.is_none()).collect();
        match filters.len() {
            0 => Filter::None,
            1 => filters.into_iter().next().unwrap(),
            _ => Filter::Or(filters.into_boxed_slice()),
        }
    }

    /// Get the current number of filters.
    #[inline]
    pub fn len(&self) -> usize {
        self.filters.len()
    }

    /// Check if the builder is empty.
    #[inline]
    pub fn is_empty(&self) -> bool {
        self.filters.is_empty()
    }
}

impl Default for FluentFilterBuilder {
    fn default() -> Self {
        Self::new()
    }
}

impl Default for Filter {
    fn default() -> Self {
        Self::None
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_filter_value_from() {
        assert_eq!(FilterValue::from(42i32), FilterValue::Int(42));
        assert_eq!(FilterValue::from("hello"), FilterValue::String("hello".to_string()));
        assert_eq!(FilterValue::from(true), FilterValue::Bool(true));
    }

    #[test]
    fn test_scalar_filter_equals() {
        let filter = ScalarFilter::Equals("test@example.com".to_string())
            .into_filter("email");

        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "email = $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_and() {
        let f1 = Filter::Equals("name".into(), "Alice".into());
        let f2 = Filter::Gt("age".into(), FilterValue::Int(18));
        let combined = Filter::and([f1, f2]);

        let (sql, params) = combined.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_filter_or() {
        let f1 = Filter::Equals("status".into(), "active".into());
        let f2 = Filter::Equals("status".into(), "pending".into());
        let combined = Filter::or([f1, f2]);

        let (sql, _) = combined.to_sql(0);
        assert!(sql.contains("OR"));
    }

    #[test]
    fn test_filter_not() {
        let filter = Filter::not(Filter::Equals("deleted".into(), FilterValue::Bool(true)));

        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("NOT"));
    }

    #[test]
    fn test_filter_is_null() {
        let filter = Filter::IsNull("deleted_at".into());
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "deleted_at IS NULL");
        assert!(params.is_empty());
    }

    #[test]
    fn test_filter_in() {
        let filter = Filter::In(
            "status".into(),
            vec!["active".into(), "pending".into()],
        );
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("IN"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_filter_contains() {
        let filter = Filter::Contains("email".into(), "example".into());
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("LIKE"));
        assert_eq!(params.len(), 1);
        if let FilterValue::String(s) = &params[0] {
            assert!(s.contains("%example%"));
        }
    }

    // ==================== FilterValue Tests ====================

    #[test]
    fn test_filter_value_is_null() {
        assert!(FilterValue::Null.is_null());
        assert!(!FilterValue::Bool(false).is_null());
        assert!(!FilterValue::Int(0).is_null());
        assert!(!FilterValue::Float(0.0).is_null());
        assert!(!FilterValue::String("".to_string()).is_null());
    }

    #[test]
    fn test_filter_value_to_sql_placeholder() {
        let val = FilterValue::Int(42);
        assert_eq!(val.to_sql_placeholder(1), "$1");
        assert_eq!(val.to_sql_placeholder(10), "$10");
    }

    #[test]
    fn test_filter_value_from_i64() {
        assert_eq!(FilterValue::from(42i64), FilterValue::Int(42));
        assert_eq!(FilterValue::from(-100i64), FilterValue::Int(-100));
    }

    #[test]
    fn test_filter_value_from_f64() {
        assert_eq!(FilterValue::from(3.14f64), FilterValue::Float(3.14));
    }

    #[test]
    fn test_filter_value_from_string() {
        assert_eq!(
            FilterValue::from("hello".to_string()),
            FilterValue::String("hello".to_string())
        );
    }

    #[test]
    fn test_filter_value_from_vec() {
        let values: Vec<i32> = vec![1, 2, 3];
        let filter_val: FilterValue = values.into();
        if let FilterValue::List(list) = filter_val {
            assert_eq!(list.len(), 3);
            assert_eq!(list[0], FilterValue::Int(1));
            assert_eq!(list[1], FilterValue::Int(2));
            assert_eq!(list[2], FilterValue::Int(3));
        } else {
            panic!("Expected List");
        }
    }

    #[test]
    fn test_filter_value_from_option_some() {
        let val: FilterValue = Some(42i32).into();
        assert_eq!(val, FilterValue::Int(42));
    }

    #[test]
    fn test_filter_value_from_option_none() {
        let val: FilterValue = Option::<i32>::None.into();
        assert_eq!(val, FilterValue::Null);
    }

    // ==================== ScalarFilter Tests ====================

    #[test]
    fn test_scalar_filter_not() {
        let filter = ScalarFilter::Not(Box::new("test".to_string())).into_filter("name");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "name != $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_scalar_filter_in() {
        let filter = ScalarFilter::In(vec!["a".to_string(), "b".to_string()]).into_filter("status");
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("IN"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_scalar_filter_not_in() {
        let filter = ScalarFilter::NotIn(vec!["x".to_string()]).into_filter("status");
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("NOT IN"));
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_scalar_filter_lt() {
        let filter = ScalarFilter::Lt(100i32).into_filter("price");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "price < $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_scalar_filter_lte() {
        let filter = ScalarFilter::Lte(100i32).into_filter("price");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "price <= $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_scalar_filter_gt() {
        let filter = ScalarFilter::Gt(0i32).into_filter("quantity");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "quantity > $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_scalar_filter_gte() {
        let filter = ScalarFilter::Gte(0i32).into_filter("quantity");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "quantity >= $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_scalar_filter_starts_with() {
        let filter = ScalarFilter::StartsWith("prefix".to_string()).into_filter("name");
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("LIKE"));
        assert_eq!(params.len(), 1);
        if let FilterValue::String(s) = &params[0] {
            assert!(s.starts_with("prefix"));
            assert!(s.ends_with("%"));
        }
    }

    #[test]
    fn test_scalar_filter_ends_with() {
        let filter = ScalarFilter::EndsWith("suffix".to_string()).into_filter("name");
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("LIKE"));
        assert_eq!(params.len(), 1);
        if let FilterValue::String(s) = &params[0] {
            assert!(s.starts_with("%"));
            assert!(s.ends_with("suffix"));
        }
    }

    #[test]
    fn test_scalar_filter_is_null() {
        let filter = ScalarFilter::<String>::IsNull.into_filter("deleted_at");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "deleted_at IS NULL");
        assert!(params.is_empty());
    }

    #[test]
    fn test_scalar_filter_is_not_null() {
        let filter = ScalarFilter::<String>::IsNotNull.into_filter("name");
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "name IS NOT NULL");
        assert!(params.is_empty());
    }

    // ==================== Filter Tests ====================

    #[test]
    fn test_filter_none() {
        let filter = Filter::none();
        assert!(filter.is_none());
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "TRUE");  // Filter::None generates TRUE
        assert!(params.is_empty());
    }

    #[test]
    fn test_filter_not_equals() {
        let filter = Filter::NotEquals("status".into(), "deleted".into());
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "status != $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_lte() {
        let filter = Filter::Lte("price".into(), FilterValue::Int(100));
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "price <= $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_gte() {
        let filter = Filter::Gte("quantity".into(), FilterValue::Int(0));
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "quantity >= $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_not_in() {
        let filter = Filter::NotIn(
            "status".into(),
            vec!["deleted".into(), "archived".into()],
        );
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("NOT IN"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_filter_starts_with() {
        let filter = Filter::StartsWith("email".into(), "admin".into());
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("LIKE"));
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_ends_with() {
        let filter = Filter::EndsWith("email".into(), "@example.com".into());
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("LIKE"));
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_is_not_null() {
        let filter = Filter::IsNotNull("name".into());
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "name IS NOT NULL");
        assert!(params.is_empty());
    }

    // ==================== Filter Combination Tests ====================

    #[test]
    fn test_filter_and_empty() {
        let filter = Filter::and([]);
        assert!(filter.is_none());
    }

    #[test]
    fn test_filter_and_single() {
        let f = Filter::Equals("name".into(), "Alice".into());
        let combined = Filter::and([f.clone()]);
        assert_eq!(combined, f);
    }

    #[test]
    fn test_filter_and_with_none() {
        let f1 = Filter::Equals("name".into(), "Alice".into());
        let f2 = Filter::None;
        let combined = Filter::and([f1.clone(), f2]);
        assert_eq!(combined, f1);
    }

    #[test]
    fn test_filter_or_empty() {
        let filter = Filter::or([]);
        assert!(filter.is_none());
    }

    #[test]
    fn test_filter_or_single() {
        let f = Filter::Equals("status".into(), "active".into());
        let combined = Filter::or([f.clone()]);
        assert_eq!(combined, f);
    }

    #[test]
    fn test_filter_or_with_none() {
        let f1 = Filter::Equals("status".into(), "active".into());
        let f2 = Filter::None;
        let combined = Filter::or([f1.clone(), f2]);
        assert_eq!(combined, f1);
    }

    #[test]
    fn test_filter_not_none() {
        let filter = Filter::not(Filter::None);
        assert!(filter.is_none());
    }

    #[test]
    fn test_filter_and_then() {
        let f1 = Filter::Equals("name".into(), "Alice".into());
        let f2 = Filter::Gt("age".into(), FilterValue::Int(18));
        let combined = f1.and_then(f2);

        let (sql, params) = combined.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_filter_and_then_with_none_first() {
        let f1 = Filter::None;
        let f2 = Filter::Equals("name".into(), "Bob".into());
        let combined = f1.and_then(f2.clone());
        assert_eq!(combined, f2);
    }

    #[test]
    fn test_filter_and_then_with_none_second() {
        let f1 = Filter::Equals("name".into(), "Alice".into());
        let f2 = Filter::None;
        let combined = f1.clone().and_then(f2);
        assert_eq!(combined, f1);
    }

    #[test]
    fn test_filter_and_then_chained() {
        let f1 = Filter::Equals("a".into(), "1".into());
        let f2 = Filter::Equals("b".into(), "2".into());
        let f3 = Filter::Equals("c".into(), "3".into());
        let combined = f1.and_then(f2).and_then(f3);

        let (sql, params) = combined.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 3);
    }

    #[test]
    fn test_filter_or_else() {
        let f1 = Filter::Equals("status".into(), "active".into());
        let f2 = Filter::Equals("status".into(), "pending".into());
        let combined = f1.or_else(f2);

        let (sql, _) = combined.to_sql(0);
        assert!(sql.contains("OR"));
    }

    #[test]
    fn test_filter_or_else_with_none_first() {
        let f1 = Filter::None;
        let f2 = Filter::Equals("name".into(), "Bob".into());
        let combined = f1.or_else(f2.clone());
        assert_eq!(combined, f2);
    }

    #[test]
    fn test_filter_or_else_with_none_second() {
        let f1 = Filter::Equals("name".into(), "Alice".into());
        let f2 = Filter::None;
        let combined = f1.clone().or_else(f2);
        assert_eq!(combined, f1);
    }

    // ==================== Complex Filter SQL Generation ====================

    #[test]
    fn test_filter_nested_and_or() {
        let f1 = Filter::Equals("status".into(), "active".into());
        let f2 = Filter::and([
            Filter::Gt("age".into(), FilterValue::Int(18)),
            Filter::Lt("age".into(), FilterValue::Int(65)),
        ]);
        let combined = Filter::and([f1, f2]);

        let (sql, params) = combined.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 3);
    }

    #[test]
    fn test_filter_nested_not() {
        let inner = Filter::and([
            Filter::Equals("status".into(), "deleted".into()),
            Filter::Equals("archived".into(), FilterValue::Bool(true)),
        ]);
        let filter = Filter::not(inner);

        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("NOT"));
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_filter_with_json_value() {
        let json_val = serde_json::json!({"key": "value"});
        let filter = Filter::Equals("metadata".into(), FilterValue::Json(json_val));
        let (sql, params) = filter.to_sql(0);
        assert_eq!(sql, "metadata = $1");
        assert_eq!(params.len(), 1);
    }

    #[test]
    fn test_filter_in_empty_list() {
        let filter = Filter::In("status".into(), vec![]);
        let (sql, params) = filter.to_sql(0);
        // Empty IN generates FALSE (no match possible)
        assert!(sql.contains("FALSE") || sql.contains("1=0") || sql.is_empty() || sql.contains("status"));
        assert!(params.is_empty());
    }

    #[test]
    fn test_filter_with_null_value() {
        // When filtering with Null value, it uses IS NULL instead of = $1
        let filter = Filter::IsNull("deleted_at".into());
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("deleted_at"));
        assert!(sql.contains("IS NULL"));
        assert!(params.is_empty());
    }

    // ==================== Builder Tests ====================

    #[test]
    fn test_and_builder_basic() {
        let filter = Filter::and_builder(3)
            .push(Filter::Equals("active".into(), FilterValue::Bool(true)))
            .push(Filter::Gt("score".into(), FilterValue::Int(100)))
            .push(Filter::IsNotNull("email".into()))
            .build();

        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 2); // score and active, IS NOT NULL has no param
    }

    #[test]
    fn test_and_builder_empty() {
        let filter = Filter::and_builder(0).build();
        assert!(filter.is_none());
    }

    #[test]
    fn test_and_builder_single() {
        let filter = Filter::and_builder(1)
            .push(Filter::Equals("id".into(), FilterValue::Int(42)))
            .build();

        // Single filter should not be wrapped in AND
        assert!(matches!(filter, Filter::Equals(_, _)));
    }

    #[test]
    fn test_and_builder_filters_none() {
        let filter = Filter::and_builder(3)
            .push(Filter::None)
            .push(Filter::Equals("id".into(), FilterValue::Int(1)))
            .push(Filter::None)
            .build();

        // None filters should be filtered out, leaving single filter
        assert!(matches!(filter, Filter::Equals(_, _)));
    }

    #[test]
    fn test_and_builder_push_if() {
        let include_deleted = false;
        let filter = Filter::and_builder(2)
            .push(Filter::Equals("active".into(), FilterValue::Bool(true)))
            .push_if(include_deleted, Filter::IsNull("deleted_at".into()))
            .build();

        // Should only have active filter since include_deleted is false
        assert!(matches!(filter, Filter::Equals(_, _)));
    }

    #[test]
    fn test_or_builder_basic() {
        let filter = Filter::or_builder(2)
            .push(Filter::Equals("role".into(), FilterValue::String("admin".into())))
            .push(Filter::Equals("role".into(), FilterValue::String("moderator".into())))
            .build();

        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("OR"));
    }

    #[test]
    fn test_or_builder_empty() {
        let filter = Filter::or_builder(0).build();
        assert!(filter.is_none());
    }

    #[test]
    fn test_or_builder_single() {
        let filter = Filter::or_builder(1)
            .push(Filter::Equals("id".into(), FilterValue::Int(42)))
            .build();

        // Single filter should not be wrapped in OR
        assert!(matches!(filter, Filter::Equals(_, _)));
    }

    #[test]
    fn test_fluent_builder_and() {
        let filter = Filter::builder()
            .eq("status", "active")
            .gt("age", 18)
            .is_not_null("email")
            .build_and();

        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_fluent_builder_or() {
        let filter = Filter::builder()
            .eq("role", "admin")
            .eq("role", "moderator")
            .build_or();

        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("OR"));
    }

    #[test]
    fn test_fluent_builder_with_capacity() {
        let filter = Filter::builder()
            .with_capacity(5)
            .eq("a", 1)
            .ne("b", 2)
            .lt("c", 3)
            .lte("d", 4)
            .gte("e", 5)
            .build_and();

        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 5);
    }

    #[test]
    fn test_fluent_builder_string_operations() {
        let filter = Filter::builder()
            .contains("name", "john")
            .starts_with("email", "admin")
            .ends_with("domain", ".com")
            .build_and();

        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("LIKE"));
    }

    #[test]
    fn test_fluent_builder_null_operations() {
        let filter = Filter::builder()
            .is_null("deleted_at")
            .is_not_null("created_at")
            .build_and();

        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("IS NULL"));
        assert!(sql.contains("IS NOT NULL"));
    }

    #[test]
    fn test_fluent_builder_in_operations() {
        let filter = Filter::builder()
            .is_in("status", vec!["pending", "processing"])
            .not_in("role", vec!["banned", "suspended"])
            .build_and();

        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("IN"));
        assert!(sql.contains("NOT IN"));
    }

    #[test]
    fn test_fluent_builder_filter_if() {
        let include_archived = false;
        let filter = Filter::builder()
            .eq("active", true)
            .filter_if(include_archived, Filter::Equals("archived".into(), FilterValue::Bool(true)))
            .build_and();

        // Should only have active filter
        assert!(matches!(filter, Filter::Equals(_, _)));
    }

    #[test]
    fn test_fluent_builder_filter_if_some() {
        let maybe_status: Option<Filter> = Some(Filter::Equals("status".into(), "active".into()));
        let filter = Filter::builder()
            .eq("id", 1)
            .filter_if_some(maybe_status)
            .build_and();

        assert!(matches!(filter, Filter::And(_)));
    }

    #[test]
    fn test_and_builder_extend() {
        let extra_filters = vec![
            Filter::Gt("score".into(), FilterValue::Int(100)),
            Filter::Lt("score".into(), FilterValue::Int(1000)),
        ];

        let filter = Filter::and_builder(3)
            .push(Filter::Equals("active".into(), FilterValue::Bool(true)))
            .extend(extra_filters)
            .build();

        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 3);
    }

    #[test]
    fn test_builder_len_and_is_empty() {
        let mut builder = AndFilterBuilder::new();
        assert!(builder.is_empty());
        assert_eq!(builder.len(), 0);

        builder = builder.push(Filter::Equals("id".into(), FilterValue::Int(1)));
        assert!(!builder.is_empty());
        assert_eq!(builder.len(), 1);
    }

    // ==================== and2/or2 Tests ====================

    #[test]
    fn test_and2_both_valid() {
        let a = Filter::Equals("id".into(), FilterValue::Int(1));
        let b = Filter::Equals("active".into(), FilterValue::Bool(true));
        let filter = Filter::and2(a, b);

        assert!(matches!(filter, Filter::And(_)));
        let (sql, params) = filter.to_sql(0);
        assert!(sql.contains("AND"));
        assert_eq!(params.len(), 2);
    }

    #[test]
    fn test_and2_first_none() {
        let a = Filter::None;
        let b = Filter::Equals("active".into(), FilterValue::Bool(true));
        let filter = Filter::and2(a, b.clone());

        assert_eq!(filter, b);
    }

    #[test]
    fn test_and2_second_none() {
        let a = Filter::Equals("id".into(), FilterValue::Int(1));
        let b = Filter::None;
        let filter = Filter::and2(a.clone(), b);

        assert_eq!(filter, a);
    }

    #[test]
    fn test_and2_both_none() {
        let filter = Filter::and2(Filter::None, Filter::None);
        assert!(filter.is_none());
    }

    #[test]
    fn test_or2_both_valid() {
        let a = Filter::Equals("role".into(), FilterValue::String("admin".into()));
        let b = Filter::Equals("role".into(), FilterValue::String("mod".into()));
        let filter = Filter::or2(a, b);

        assert!(matches!(filter, Filter::Or(_)));
        let (sql, _) = filter.to_sql(0);
        assert!(sql.contains("OR"));
    }

    #[test]
    fn test_or2_first_none() {
        let a = Filter::None;
        let b = Filter::Equals("active".into(), FilterValue::Bool(true));
        let filter = Filter::or2(a, b.clone());

        assert_eq!(filter, b);
    }

    #[test]
    fn test_or2_second_none() {
        let a = Filter::Equals("id".into(), FilterValue::Int(1));
        let b = Filter::None;
        let filter = Filter::or2(a.clone(), b);

        assert_eq!(filter, a);
    }

    #[test]
    fn test_or2_both_none() {
        let filter = Filter::or2(Filter::None, Filter::None);
        assert!(filter.is_none());
    }
}