dm-database-sqllog2db 1.16.0

//! 统计聚合层：慢 SQL 最小堆 + 高频 SQL `HashMap`，支持单次扫描双侧聚合。

use std::cmp::{Ordering, Reverse};
use std::collections::{BinaryHeap, HashMap};

/// 慢 SQL 输出行（写入 CSV 或 `SQLite`）
#[derive(Debug, Clone)]
pub struct SlowSqlRow {
    pub sql_text: String,
    pub elapsed_ms: i64,
    pub timestamp: String,
}

/// 高频 SQL 输出行（写入 CSV 或 `SQLite`）
#[derive(Debug, Clone)]
pub struct FrequentSqlRow {
    pub normalized_sql: String,
    pub call_count: u64,
    pub avg_elapsed_ms: i64,
    pub max_elapsed_ms: i64,
}

/// 慢 SQL 堆条目（内部使用，`f32` 保留精度，写出时用 `f32_ms_to_i64` 转换）
#[derive(Debug)]
struct SlowSqlEntry {
    sql_text: String,
    elapsed_ms: f32,
    timestamp: String,
}

impl PartialEq for SlowSqlEntry {
    fn eq(&self, other: &Self) -> bool {
        self.elapsed_ms.total_cmp(&other.elapsed_ms) == Ordering::Equal
    }
}

impl Eq for SlowSqlEntry {}

impl PartialOrd for SlowSqlEntry {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for SlowSqlEntry {
    fn cmp(&self, other: &Self) -> Ordering {
        self.elapsed_ms.total_cmp(&other.elapsed_ms)
    }
}

/// 高频 SQL 聚合状态（`HashMap` value）
#[derive(Debug)]
struct AggState {
    call_count: u64,
    total_elapsed: f64,
    max_elapsed: f32,
}

/// 统计聚合器：单次扫描同时聚合慢 SQL（最小堆）与高频 SQL（`HashMap`）。
#[derive(Debug)]
pub struct StatsAccumulator {
    slow_heap: BinaryHeap<Reverse<SlowSqlEntry>>,
    freq_map: HashMap<String, AggState>,
    top_n: usize,
    from: Option<String>,
    to: Option<String>,
}

impl StatsAccumulator {
    /// 创建新的聚合器，`top_n` 为输出行数上限（≥ 1），`from`/`to` 为时间段过滤范围（均 None 时不过滤）。
    ///
    /// # Panics
    ///
    /// 当 `top_n` 为 0 时 panic。
    #[must_use]
    pub fn new(top_n: u32, from: Option<String>, to: Option<String>) -> Self {
        assert!(top_n >= 1, "top_n must be >= 1");
        Self {
            slow_heap: BinaryHeap::new(),
            freq_map: HashMap::new(),
            top_n: top_n as usize,
            from,
            to,
        }
    }

    /// 处理单条日志记录，同时更新慢 SQL 堆与高频 SQL 映射。
    pub fn update(&mut self, record: &dm_database_parser_sqllog::Sqllog) {
        if !self.in_range(&record.ts) {
            return;
        }
        let slow_entry = SlowSqlEntry {
            sql_text: record.sql.clone(),
            elapsed_ms: record.exectime,
            timestamp: record.ts.clone(),
        };
        self.push_slow(slow_entry);

        let normalized_key = crate::stats::normalize::normalize_sql(&record.sql);
        let freq_state = self.freq_map.entry(normalized_key).or_insert(AggState {
            call_count: 0,
            total_elapsed: 0.0,
            max_elapsed: f32::NEG_INFINITY,
        });
        freq_state.call_count += 1;
        freq_state.total_elapsed += f64::from(record.exectime);
        if record.exectime > freq_state.max_elapsed {
            freq_state.max_elapsed = record.exectime;
        }
    }

    /// 检查 `ts` 是否在 `[from, to]` 时间范围内（字符串前缀截取比较，零分配）。
    fn in_range(&self, ts: &str) -> bool {
        if let Some(from) = &self.from {
            if ts.len() < from.len() {
                return false;
            }
            if &ts[..from.len()] < from.as_str() {
                return false;
            }
        }
        if let Some(to) = &self.to {
            if ts.len() < to.len() {
                return false;
            }
            if &ts[..to.len()] > to.as_str() {
                return false;
            }
        }
        true
    }

    /// 推入慢 SQL 条目到最小堆，维护堆大小 ≤ `top_n`。
    fn push_slow(&mut self, entry: SlowSqlEntry) {
        if self.slow_heap.len() < self.top_n {
            self.slow_heap.push(Reverse(entry));
            return;
        }
        if let Some(Reverse(heap_top)) = self.slow_heap.peek() {
            if entry.elapsed_ms.total_cmp(&heap_top.elapsed_ms) == Ordering::Greater {
                self.slow_heap.pop();
                self.slow_heap.push(Reverse(entry));
            }
        }
    }

    /// 消费聚合器，返回慢 SQL 行（按 elapsed 降序）与高频 SQL 行（按 `call_count` 降序）。
    #[must_use]
    pub fn into_results(self) -> (Vec<SlowSqlRow>, Vec<FrequentSqlRow>) {
        let slow_rows = build_slow_rows(self.slow_heap);
        let freq_rows = build_freq_rows(self.freq_map, self.top_n);
        (slow_rows, freq_rows)
    }
}

/// 从堆中提取并排序慢 SQL 行（降序）。
fn build_slow_rows(heap: BinaryHeap<Reverse<SlowSqlEntry>>) -> Vec<SlowSqlRow> {
    let mut rows: Vec<SlowSqlRow> = heap
        .into_iter()
        .map(|Reverse(entry)| SlowSqlRow {
            sql_text: entry.sql_text,
            elapsed_ms: crate::exporter::f32_ms_to_i64(entry.elapsed_ms),
            timestamp: entry.timestamp,
        })
        .collect();
    rows.sort_by_key(|row| std::cmp::Reverse(row.elapsed_ms));
    rows
}

/// 从 `HashMap` 构建高频 SQL 行，排序并截断到 `top_n`。
fn build_freq_rows(freq_map: HashMap<String, AggState>, top_n: usize) -> Vec<FrequentSqlRow> {
    let mut rows: Vec<FrequentSqlRow> = freq_map
        .into_iter()
        .map(|(normalized_sql, state)| {
            // f64 -> f32 精度在此为有意舍入（ms 级精度已足够），抑制 clippy 截断警告
            #[expect(
                clippy::cast_precision_loss,
                reason = "call_count as f64 may lose precision for large counts; acceptable for stats use"
            )]
            #[expect(
                clippy::cast_possible_truncation,
                reason = "avg in ms fits f32 range for typical SQL elapsed times"
            )]
            let avg_f32 = (state.total_elapsed / state.call_count as f64) as f32;
            FrequentSqlRow {
                normalized_sql,
                call_count: state.call_count,
                avg_elapsed_ms: crate::exporter::f32_ms_to_i64(avg_f32),
                max_elapsed_ms: crate::exporter::f32_ms_to_i64(state.max_elapsed),
            }
        })
        .collect();
    rows.sort_by_key(|row| std::cmp::Reverse(row.call_count));
    rows.truncate(top_n);
    rows
}

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

    fn make_record(sql: &str, exectime: f32, ts: &str) -> Sqllog {
        Sqllog {
            sql: sql.to_string(),
            exectime,
            ts: ts.to_string(),
            ..Sqllog::default()
        }
    }

    #[test]
    fn test_slow_sql_top_n_limit() {
        let mut acc = StatsAccumulator::new(3, None, None);
        acc.update(&make_record("SELECT 1", 10.0, "2025-01-01"));
        acc.update(&make_record("SELECT 2", 50.0, "2025-01-02"));
        acc.update(&make_record("SELECT 3", 30.0, "2025-01-03"));
        acc.update(&make_record("SELECT 4", 20.0, "2025-01-04"));
        acc.update(&make_record("SELECT 5", 40.0, "2025-01-05"));

        let (slow, _) = acc.into_results();
        assert_eq!(slow.len(), 3);
        // 降序：50, 40, 30
        assert_eq!(slow[0].elapsed_ms, 50);
        assert_eq!(slow[1].elapsed_ms, 40);
        assert_eq!(slow[2].elapsed_ms, 30);
    }

    #[test]
    fn test_slow_sql_includes_zero_and_negative_elapsed() {
        let mut acc = StatsAccumulator::new(5, None, None);
        acc.update(&make_record("SELECT A", 0.0, "2025-01-01"));
        acc.update(&make_record("SELECT B", -1.0, "2025-01-02"));
        acc.update(&make_record("SELECT C", 5.0, "2025-01-03"));

        let (slow, _) = acc.into_results();
        assert_eq!(slow.len(), 3, "all 3 records should be included (D-12)");
    }

    #[test]
    fn test_frequent_sql_aggregation() {
        let mut acc = StatsAccumulator::new(10, None, None);
        // 同一模板 3 条
        acc.update(&make_record(
            "SELECT id FROM t WHERE id = 1",
            1.0,
            "2025-01-01",
        ));
        acc.update(&make_record(
            "SELECT id FROM t WHERE id = 2",
            2.0,
            "2025-01-02",
        ));
        acc.update(&make_record(
            "SELECT id FROM t WHERE id = 3",
            3.0,
            "2025-01-03",
        ));
        // 不同模板 1 条
        acc.update(&make_record("INSERT INTO t VALUES (1)", 5.0, "2025-01-04"));

        let (_, frequent) = acc.into_results();
        // 找到 call_count == 3 的那条
        let target = frequent.iter().find(|r| r.call_count == 3);
        assert!(target.is_some(), "should find 3-call entry");
        let target = target.unwrap();
        assert_eq!(target.avg_elapsed_ms, 2, "avg of 1+2+3 = 2ms");
        assert_eq!(target.max_elapsed_ms, 3, "max of 1,2,3 = 3ms");
    }

    #[test]
    fn test_frequent_sql_top_n_limit_and_sort() {
        let mut acc = StatsAccumulator::new(3, None, None);
        for count in 1..=5u64 {
            let sql = format!("SELECT * FROM t{count}");
            for _ in 0..count {
                acc.update(&make_record(&sql, 1.0, "2025-01-01"));
            }
        }

        let (_, frequent) = acc.into_results();
        assert_eq!(frequent.len(), 3);
        assert_eq!(frequent[0].call_count, 5);
        assert_eq!(frequent[1].call_count, 4);
        assert_eq!(frequent[2].call_count, 3);
    }

    #[test]
    fn test_slow_entry_total_cmp_handles_equal_elapsed() {
        let mut acc = StatsAccumulator::new(1, None, None);
        acc.update(&make_record("SELECT X", 5.0, "2025-01-01"));
        acc.update(&make_record("SELECT Y", 5.0, "2025-01-02"));
        // 不应 panic，结果稳定
        let (slow, _) = acc.into_results();
        assert_eq!(slow.len(), 1);
    }

    #[test]
    fn test_into_results_when_records_fewer_than_top_n() {
        let mut acc = StatsAccumulator::new(5, None, None);
        // 使用结构不同的 SQL，normalize_sql 后 key 不同，保证 frequent 有 2 条
        acc.update(&make_record("SELECT id FROM users", 10.0, "2025-01-01"));
        acc.update(&make_record(
            "INSERT INTO orders VALUES (1)",
            20.0,
            "2025-01-02",
        ));

        let (slow, frequent) = acc.into_results();
        assert_eq!(slow.len(), 2, "D-11: output only actual count");
        assert_eq!(frequent.len(), 2, "D-11: output only actual count");
    }

    #[test]
    fn test_filter_both_from_and_to_excludes_outside_records() {
        let mut acc = StatsAccumulator::new(
            10,
            Some("2024-01-15".to_string()),
            Some("2024-01-15".to_string()),
        );
        acc.update(&make_record("SELECT 1", 1.0, "2024-01-14 10:00:00"));
        acc.update(&make_record("SELECT 2", 2.0, "2024-01-15 00:00:00"));
        acc.update(&make_record("SELECT 3", 3.0, "2024-01-15 23:59:59"));
        acc.update(&make_record("SELECT 4", 4.0, "2024-01-16 10:00:00"));
        let (slow, _) = acc.into_results();
        assert_eq!(
            slow.len(),
            2,
            "only records on 2024-01-15 should be included"
        );
    }

    #[test]
    fn test_filter_from_only_excludes_earlier_records() {
        let mut acc = StatsAccumulator::new(10, Some("2024-01-15".to_string()), None);
        acc.update(&make_record("SELECT A", 1.0, "2024-01-14"));
        acc.update(&make_record("SELECT B", 2.0, "2024-01-15"));
        acc.update(&make_record("SELECT C", 3.0, "2024-01-20"));
        let (slow, _) = acc.into_results();
        assert_eq!(
            slow.len(),
            2,
            "records on/after 2024-01-15 should be included"
        );
    }

    #[test]
    fn test_filter_to_only_excludes_later_records() {
        let mut acc = StatsAccumulator::new(10, None, Some("2024-01-15".to_string()));
        acc.update(&make_record("SELECT A", 1.0, "2024-01-10"));
        acc.update(&make_record("SELECT B", 2.0, "2024-01-15"));
        acc.update(&make_record("SELECT C", 3.0, "2024-01-16"));
        let (slow, _) = acc.into_results();
        assert_eq!(
            slow.len(),
            2,
            "records on/before 2024-01-15 should be included"
        );
    }

    #[test]
    fn test_filter_none_behavior_unchanged() {
        let mut acc = StatsAccumulator::new(3, None, None);
        acc.update(&make_record("SELECT 1", 10.0, "2025-01-01"));
        acc.update(&make_record("SELECT 2", 50.0, "2025-01-02"));
        acc.update(&make_record("SELECT 3", 30.0, "2025-01-03"));
        acc.update(&make_record("SELECT 4", 20.0, "2025-01-04"));
        acc.update(&make_record("SELECT 5", 40.0, "2025-01-05"));
        let (slow, _) = acc.into_results();
        assert_eq!(slow.len(), 3);
        assert_eq!(slow[0].elapsed_ms, 50);
        assert_eq!(slow[1].elapsed_ms, 40);
        assert_eq!(slow[2].elapsed_ms, 30);
    }

    #[test]
    fn test_filter_ts_too_short_treated_as_out_of_range() {
        let mut acc = StatsAccumulator::new(10, Some("2024-01-15 10:00:00".to_string()), None);
        // ts is only 10 bytes, from is 19 bytes — length guard must fire
        acc.update(&make_record("SELECT X", 1.0, "2024-01-15"));
        let (slow, _) = acc.into_results();
        assert_eq!(
            slow.len(),
            0,
            "ts too short should be treated as out of range"
        );
    }
}