lucisearch 0.8.0

//! Aggregation JSON parser.
//!
//! See [[aggregations]] and [[feature-aggregations-v010#Step 4]].
//!
//! Every per-agg-type parser routes its body through [`validate_keys`]
//! so typos (``missing_value`` on an avg, ``percission`` on
//! geohash_grid, ``calendar_unit`` on date_histogram) surface as parse
//! errors listing the valid keys — see [[fix-strict-search-parsing]].

use crate::core::{LuciError, Result};
use serde_json::Value;

use super::{AggregationExpression, RangeDef};
use crate::query::parser::{opt_f64, opt_str, opt_u64, parse_query};

/// Reject keys outside the expected set. See [[fix-strict-search-parsing]].
fn validate_keys<'a>(
    val: &'a Value,
    expected: &[&str],
    ctx: &str,
) -> Result<&'a serde_json::Map<String, Value>> {
    let obj = val
        .as_object()
        .ok_or_else(|| LuciError::InvalidQuery(format!("{ctx}: must be an object")))?;
    for key in obj.keys() {
        if !expected.contains(&key.as_str()) {
            let expected_list = expected
                .iter()
                .map(|k| format!("`{k}`"))
                .collect::<Vec<_>>()
                .join(", ");
            return Err(LuciError::InvalidQuery(format!(
                "{ctx}: unknown field `{key}`, expected one of {expected_list}"
            )));
        }
    }
    Ok(obj)
}

// ---------------------------------------------------------------------------
// Parser
// ---------------------------------------------------------------------------

/// Parse the `"aggs"` section of a search request.
pub fn parse_aggs(json: &Value) -> Result<Vec<(String, AggregationExpression)>> {
    let obj = match json.as_object() {
        Some(o) => o,
        None => return Err(LuciError::InvalidQuery("aggs must be an object".into())),
    };

    let mut aggs = Vec::new();
    for (name, agg_val) in obj {
        aggs.push(parse_single_agg(name, agg_val)?);
    }
    Ok(aggs)
}

fn parse_single_agg(name: &str, val: &Value) -> Result<(String, AggregationExpression)> {
    let obj = val.as_object().ok_or_else(|| {
        LuciError::InvalidQuery(format!("aggregation '{name}' must be an object"))
    })?;

    // Find the agg type key (not "aggs" / "aggregations").
    let mut agg_type = None;
    let mut sub_aggs_val = None;

    for (key, v) in obj {
        match key.as_str() {
            "aggs" | "aggregations" => sub_aggs_val = Some(v),
            _ => {
                if agg_type.is_some() {
                    return Err(LuciError::InvalidQuery(format!(
                        "aggregation '{name}' has multiple type keys"
                    )));
                }
                agg_type = Some((key.as_str(), v));
            }
        }
    }

    let (type_key, type_val) = agg_type
        .ok_or_else(|| LuciError::InvalidQuery(format!("aggregation '{name}' has no type")))?;

    let sub_aggs = match sub_aggs_val {
        Some(v) => parse_aggs(v)?,
        None => Vec::new(),
    };

    // Only bucket aggregations nest sub-aggregations. Metric/leaf aggs
    // (avg, sum, cardinality, percentiles, top_hits, geo_bounds, …) have no
    // `sub_agg_factories` and would silently drop `sub_aggs` in their
    // `parse_agg_expr` arm. Reject the combination here, before the drop —
    // matching Elasticsearch, which rejects metric+sub-aggs outright. This
    // is the parse-time half of the sub_aggs honest-refusal; the deferred
    // bucket arms (range/histogram/…) pass this check and honest-refuse at
    // bind. See [[code-must-not-lie]], [[bucket-agg-sub-aggs-silent-drop]].
    if !sub_aggs.is_empty() && !agg_type_accepts_sub_aggs(type_key) {
        return Err(LuciError::InvalidQuery(format!(
            "aggregation '{name}' of type [{type_key}] cannot have sub-aggregations"
        )));
    }

    let expr = parse_agg_expr(name, type_key, type_val, sub_aggs)?;
    Ok((name.to_string(), expr))
}

/// Whether an aggregation type nests sub-aggregations. Only bucket
/// aggregations do; metric/leaf aggregations (avg, sum, stats, cardinality,
/// percentiles, top_hits, geo_bounds, geo_centroid, …) reject them like
/// Elasticsearch. The currently-deferred bucket arms (range, date_range,
/// histogram, date_histogram, geohash_grid) still appear here: they accept
/// `sub_aggs` at parse and honest-refuse at bind, so the error names the
/// agg with "not yet supported" rather than the harder "cannot have"
/// boundary that applies to metric aggs. See [[bucket-agg-sub-aggs-silent-drop]].
fn agg_type_accepts_sub_aggs(type_key: &str) -> bool {
    matches!(
        type_key,
        "terms"
            | "range"
            | "date_range"
            | "histogram"
            | "date_histogram"
            | "filter"
            | "filters"
            | "nested"
            | "reverse_nested"
            | "geohash_grid"
    )
}

fn parse_agg_expr(
    name: &str,
    key: &str,
    val: &Value,
    sub_aggs: Vec<(String, AggregationExpression)>,
) -> Result<AggregationExpression> {
    let ctx = format!("{name}.{key}");
    match key {
        "avg" => Ok(AggregationExpression::Avg {
            field: parse_field_only(val, &ctx)?,
        }),
        "sum" => Ok(AggregationExpression::Sum {
            field: parse_field_only(val, &ctx)?,
        }),
        "min" => Ok(AggregationExpression::Min {
            field: parse_field_only(val, &ctx)?,
        }),
        "max" => Ok(AggregationExpression::Max {
            field: parse_field_only(val, &ctx)?,
        }),
        "value_count" => Ok(AggregationExpression::ValueCount {
            field: parse_field_only(val, &ctx)?,
        }),
        "stats" => Ok(AggregationExpression::Stats {
            field: parse_field_only(val, &ctx)?,
        }),
        "extended_stats" => Ok(AggregationExpression::ExtendedStats {
            field: parse_field_only(val, &ctx)?,
        }),
        "terms" => {
            let obj = validate_keys(val, &["field", "size"], &ctx)?;
            Ok(AggregationExpression::Terms {
                field: require_field(obj, &ctx)?,
                size: opt_u64(obj, "size", &ctx)?.unwrap_or(10) as usize,
                sub_aggs,
            })
        }
        "range" => {
            let obj = validate_keys(val, &["field", "ranges"], &ctx)?;
            let field = require_field(obj, &ctx)?;
            let ranges = parse_range_defs(obj, &ctx, false)?;
            Ok(AggregationExpression::Range {
                field,
                ranges,
                sub_aggs,
            })
        }
        "histogram" => {
            let obj = validate_keys(val, &["field", "interval"], &ctx)?;
            let field = require_field(obj, &ctx)?;
            let interval = obj
                .get("interval")
                .and_then(|v| v.as_f64())
                .ok_or_else(|| LuciError::InvalidQuery("histogram requires 'interval'".into()))?;
            Ok(AggregationExpression::Histogram {
                field,
                interval,
                sub_aggs,
            })
        }
        "filter" => {
            // `val` is the raw filter query body (e.g. `{"term": {...}}`);
            // the query parser enforces its own strictness.
            let query = parse_query(val)?;
            Ok(AggregationExpression::Filter { query, sub_aggs })
        }
        "cardinality" => {
            let obj = validate_keys(val, &["field", "precision_threshold"], &ctx)?;
            Ok(AggregationExpression::Cardinality {
                field: require_field(obj, &ctx)?,
                precision_threshold: opt_u64(obj, "precision_threshold", &ctx)?.unwrap_or(3000)
                    as u32,
            })
        }
        "percentiles" => {
            let obj = validate_keys(val, &["field", "percents", "tdigest"], &ctx)?;
            let field = require_field(obj, &ctx)?;
            let percents = match obj.get("percents") {
                Some(v) => {
                    let arr = v.as_array().ok_or_else(|| {
                        LuciError::InvalidQuery(
                            "percentiles: \"percents\" must be an array of numbers".into(),
                        )
                    })?;
                    arr.iter()
                        .map(|p| {
                            p.as_f64().ok_or_else(|| {
                                LuciError::InvalidQuery(format!(
                                    "percentiles: percents[] entries must be numbers, got {p}"
                                ))
                            })
                        })
                        .collect::<Result<Vec<f64>>>()?
                }
                None => vec![1.0, 5.0, 25.0, 50.0, 75.0, 95.0, 99.0],
            };
            let compression = match obj.get("tdigest") {
                Some(t) => {
                    let tdigest_obj = validate_keys(t, &["compression"], "percentiles.tdigest")?;
                    opt_f64(tdigest_obj, "compression", "percentiles.tdigest")?.unwrap_or(100.0)
                }
                None => 100.0,
            };
            Ok(AggregationExpression::Percentiles {
                field,
                percents,
                compression,
            })
        }
        "geo_bounds" => Ok(AggregationExpression::GeoBounds {
            field: parse_field_only(val, &ctx)?,
        }),
        "geo_centroid" => Ok(AggregationExpression::GeoCentroid {
            field: parse_field_only(val, &ctx)?,
        }),
        "nested" => {
            let obj = validate_keys(val, &["path"], &ctx)?;
            let path = obj
                .get("path")
                .and_then(|v| v.as_str())
                .ok_or_else(|| LuciError::InvalidQuery("nested agg requires 'path'".into()))?
                .to_string();
            Ok(AggregationExpression::Nested { path, sub_aggs })
        }
        "reverse_nested" => {
            validate_keys(val, &[], &ctx)?;
            Ok(AggregationExpression::ReverseNested { sub_aggs })
        }
        "geohash_grid" => {
            let obj = validate_keys(val, &["field", "precision", "size"], &ctx)?;
            Ok(AggregationExpression::GeohashGrid {
                field: require_field(obj, &ctx)?,
                precision: opt_u64(obj, "precision", &ctx)?.unwrap_or(5) as usize,
                size: opt_u64(obj, "size", &ctx)?.unwrap_or(10000) as usize,
                sub_aggs,
            })
        }
        "top_hits" => {
            let obj = validate_keys(val, &["size"], &ctx)?;
            Ok(AggregationExpression::TopHits {
                size: opt_u64(obj, "size", &ctx)?.unwrap_or(3) as usize,
            })
        }
        "date_histogram" => {
            let obj = validate_keys(
                val,
                &["field", "calendar_interval", "fixed_interval", "interval"],
                &ctx,
            )?;
            let field = require_field(obj, &ctx)?;
            let interval = if let Some(cal) = opt_str(obj, "calendar_interval", &ctx)? {
                let cal_int = match cal {
                    "minute" | "1m" => super::CalendarInterval::Minute,
                    "hour" | "1h" => super::CalendarInterval::Hour,
                    "day" | "1d" => super::CalendarInterval::Day,
                    "week" | "1w" => super::CalendarInterval::Week,
                    "month" | "1M" => super::CalendarInterval::Month,
                    "quarter" | "1q" => super::CalendarInterval::Quarter,
                    "year" | "1y" => super::CalendarInterval::Year,
                    other => {
                        return Err(LuciError::InvalidQuery(format!(
                            "date_histogram: unknown calendar_interval '{other}'"
                        )));
                    }
                };
                super::DateInterval::Calendar(cal_int)
            } else if let Some(fixed) = opt_str(obj, "fixed_interval", &ctx)? {
                let ms = parse_fixed_interval(fixed)?;
                super::DateInterval::Fixed(ms)
            } else if let Some(interval_str) = opt_str(obj, "interval", &ctx)? {
                // Legacy "interval" field — try as fixed first.
                if let Ok(ms) = parse_fixed_interval(interval_str) {
                    super::DateInterval::Fixed(ms)
                } else {
                    return Err(LuciError::InvalidQuery(format!(
                        "date_histogram: invalid interval '{interval_str}'"
                    )));
                }
            } else {
                return Err(LuciError::InvalidQuery(
                    "date_histogram requires 'calendar_interval' or 'fixed_interval'".into(),
                ));
            };
            Ok(AggregationExpression::DateHistogram {
                field,
                interval,
                sub_aggs,
            })
        }
        "date_range" => {
            let obj = validate_keys(val, &["field", "ranges"], &ctx)?;
            let field = require_field(obj, &ctx)?;
            let ranges = parse_range_defs(obj, &ctx, true)?;
            Ok(AggregationExpression::DateRange {
                field,
                ranges,
                sub_aggs,
            })
        }
        "filters" => {
            let obj = validate_keys(val, &["filters"], &ctx)?;
            let filters_obj = obj
                .get("filters")
                .and_then(|v| v.as_object())
                .ok_or_else(|| {
                    LuciError::InvalidQuery("filters requires 'filters' object".into())
                })?;
            let mut filters = Vec::new();
            for (name, query_val) in filters_obj {
                let query = parse_query(query_val)?;
                filters.push((name.clone(), query));
            }
            Ok(AggregationExpression::Filters { filters, sub_aggs })
        }
        _ => Err(LuciError::UnsupportedQuery(format!(
            "unknown aggregation type: {key}"
        ))),
    }
}

fn parse_field_only(val: &Value, ctx: &str) -> Result<String> {
    let obj = validate_keys(val, &["field"], ctx)?;
    require_field(obj, ctx)
}

fn require_field(obj: &serde_json::Map<String, Value>, ctx: &str) -> Result<String> {
    obj.get("field")
        .and_then(|v| v.as_str())
        .map(String::from)
        .ok_or_else(|| LuciError::InvalidQuery(format!("{ctx} requires 'field'")))
}

fn parse_range_defs(
    obj: &serde_json::Map<String, Value>,
    ctx: &str,
    dates: bool,
) -> Result<Vec<RangeDef>> {
    let ranges_val = obj
        .get("ranges")
        .and_then(|v| v.as_array())
        .ok_or_else(|| LuciError::InvalidQuery(format!("{ctx}: missing 'ranges' array")))?;
    let mut ranges = Vec::with_capacity(ranges_val.len());
    for r in ranges_val {
        let r_obj = validate_keys(r, &["key", "from", "to"], &format!("{ctx}.ranges[]"))?;
        let key = r_obj.get("key").and_then(|v| v.as_str()).map(String::from);
        let (from, to) = if dates {
            (
                r_obj.get("from").and_then(parse_date_value),
                r_obj.get("to").and_then(parse_date_value),
            )
        } else {
            (
                r_obj.get("from").and_then(|v| v.as_f64()),
                r_obj.get("to").and_then(|v| v.as_f64()),
            )
        };
        ranges.push(RangeDef { key, from, to });
    }
    Ok(ranges)
}

/// Parse a fixed interval string (e.g., "1d", "12h", "30m", "1000ms") to milliseconds.
fn parse_fixed_interval(s: &str) -> Result<f64> {
    let s = s.trim();
    if let Some(n) = s.strip_suffix("ms") {
        return n
            .parse::<f64>()
            .map_err(|_| LuciError::InvalidQuery(format!("invalid interval: {s}")));
    }
    if let Some(n) = s.strip_suffix('s') {
        return Ok(n
            .parse::<f64>()
            .map_err(|_| LuciError::InvalidQuery(format!("invalid interval: {s}")))?
            * 1_000.0);
    }
    if let Some(n) = s.strip_suffix('m') {
        return Ok(n
            .parse::<f64>()
            .map_err(|_| LuciError::InvalidQuery(format!("invalid interval: {s}")))?
            * 60_000.0);
    }
    if let Some(n) = s.strip_suffix('h') {
        return Ok(n
            .parse::<f64>()
            .map_err(|_| LuciError::InvalidQuery(format!("invalid interval: {s}")))?
            * 3_600_000.0);
    }
    if let Some(n) = s.strip_suffix('d') {
        return Ok(n
            .parse::<f64>()
            .map_err(|_| LuciError::InvalidQuery(format!("invalid interval: {s}")))?
            * 86_400_000.0);
    }
    Err(LuciError::InvalidQuery(format!(
        "invalid fixed_interval: {s}"
    )))
}

/// Parse a date value to epoch millis (f64).
/// Accepts: epoch millis as number, or ISO 8601 string.
fn parse_date_value(v: &Value) -> Option<f64> {
    match v {
        Value::Number(n) => n.as_f64(),
        Value::String(s) => {
            // Try epoch millis as string
            if let Ok(ms) = s.parse::<f64>() {
                return Some(ms);
            }
            // Try ISO 8601 (basic: "2024-01-15T00:00:00Z")
            if s.len() >= 10 {
                let parts: Vec<&str> = s.split('T').collect();
                let date_parts: Vec<&str> = parts[0].split('-').collect();
                if date_parts.len() == 3 {
                    let y: i64 = date_parts[0].parse().ok()?;
                    let m: i64 = date_parts[1].parse().ok()?;
                    let d: i64 = date_parts[2].parse().ok()?;
                    // Approximate: days since epoch
                    let days = (y - 1970) * 365 + (y - 1969) / 4 + (m - 1) * 30 + d - 1;
                    return Some(days as f64 * 86_400_000.0);
                }
            }
            None
        }
        _ => None,
    }
}

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

    #[test]
    fn parse_avg() {
        let aggs = parse_aggs(&json!({"my_avg": {"avg": {"field": "price"}}})).unwrap();
        assert_eq!(aggs.len(), 1);
        assert_eq!(aggs[0].0, "my_avg");
        assert!(matches!(&aggs[0].1, AggregationExpression::Avg { field } if field == "price"));
    }

    #[test]
    fn parse_terms_with_size() {
        let aggs = parse_aggs(&json!({"by_tag": {"terms": {"field": "tag", "size": 5}}})).unwrap();
        if let AggregationExpression::Terms { field, size, .. } = &aggs[0].1 {
            assert_eq!(field, "tag");
            assert_eq!(*size, 5);
        } else {
            panic!();
        }
    }

    #[test]
    fn parse_terms_default_size() {
        let aggs = parse_aggs(&json!({"by_tag": {"terms": {"field": "tag"}}})).unwrap();
        if let AggregationExpression::Terms { size, .. } = &aggs[0].1 {
            assert_eq!(*size, 10);
        } else {
            panic!();
        }
    }

    // --- E10: strict value types on known agg fields. ES coerces "5"→5;
    // Luci is strict because it receives typed values, not untyped JSON
    // over HTTP. See [[code-must-not-lie]]. ---

    #[test]
    fn parse_terms_string_size_rejected() {
        let err =
            parse_aggs(&json!({"by_tag": {"terms": {"field": "tag", "size": "5"}}})).unwrap_err();
        assert!(format!("{err}").contains("size"), "{err}");
    }

    #[test]
    fn parse_percentiles_non_number_percent_rejected() {
        let err =
            parse_aggs(&json!({"p": {"percentiles": {"field": "price", "percents": [50, "99"]}}}))
                .unwrap_err();
        assert!(format!("{err}").contains("percents"), "{err}");
    }

    #[test]
    fn parse_range() {
        let aggs = parse_aggs(&json!({
            "price_ranges": {"range": {"field": "price", "ranges": [
                {"to": 50.0},
                {"from": 50.0, "to": 100.0},
                {"from": 100.0}
            ]}}
        }))
        .unwrap();
        if let AggregationExpression::Range { ranges, .. } = &aggs[0].1 {
            assert_eq!(ranges.len(), 3);
        } else {
            panic!();
        }
    }

    #[test]
    fn parse_histogram() {
        let aggs = parse_aggs(&json!({
            "prices": {"histogram": {"field": "price", "interval": 10.0}}
        }))
        .unwrap();
        if let AggregationExpression::Histogram { interval, .. } = &aggs[0].1 {
            assert_eq!(*interval, 10.0);
        } else {
            panic!();
        }
    }

    #[test]
    fn parse_nested_sub_aggs() {
        let aggs = parse_aggs(&json!({
            "by_tag": {
                "terms": {"field": "tag"},
                "aggs": {
                    "avg_price": {"avg": {"field": "price"}}
                }
            }
        }))
        .unwrap();
        if let AggregationExpression::Terms { sub_aggs, .. } = &aggs[0].1 {
            assert_eq!(sub_aggs.len(), 1);
            assert_eq!(sub_aggs[0].0, "avg_price");
        } else {
            panic!();
        }
    }

    #[test]
    fn parse_multiple_aggs() {
        let aggs = parse_aggs(&json!({
            "total": {"sum": {"field": "amount"}},
            "average": {"avg": {"field": "amount"}}
        }))
        .unwrap();
        assert_eq!(aggs.len(), 2);
    }

    #[test]
    fn parse_filter_agg() {
        let aggs = parse_aggs(&json!({
            "active": {"filter": {"term": {"status": "active"}}}
        }))
        .unwrap();
        assert!(matches!(&aggs[0].1, AggregationExpression::Filter { .. }));
    }

    #[test]
    fn unknown_agg_type_error() {
        let r = parse_aggs(&json!({"x": {"unknown_type": {"field": "f"}}}));
        assert!(r.is_err());
    }

    #[test]
    fn missing_field_error() {
        let r = parse_aggs(&json!({"x": {"avg": {}}}));
        assert!(r.is_err());
    }

    #[test]
    fn unknown_agg_body_key_error() {
        let r = parse_aggs(&json!({
            "x": {"avg": {"field": "price", "missing_value": 0}}
        }));
        assert!(r.is_err(), "missing_value is not a valid avg key");
        let msg = r.unwrap_err().to_string();
        assert!(msg.contains("missing_value"));
    }
}