//! 会话映射存储(IM chat_id ↔ DevFlow conv_id,SQLite + WAL)
//!
//! 建表即带 owner_user_id/platform 列(P0 预留项 ⑤,当前恒默认值,
//! S2 多人场景免迁表)。
//!
//! 表结构:
//! ```sql
//! CREATE TABLE IF NOT EXISTS session_map (
//!   platform      TEXT NOT NULL,           -- feishu/wecom/dingtalk/web
//!   chat_id       TEXT NOT NULL,           -- IM 侧会话(单聊 user_id / 群聊 chat_id)
//!   conv_id       TEXT NOT NULL,           -- DevFlow 会话 ID
//!   owner_user_id TEXT NOT NULL DEFAULT '',-- 预留 S2 多人归属(当前恒 '')
//!   channel_id    TEXT NOT NULL DEFAULT '',-- 路由到的桌面端 channel(预留项 ⑥)
//!   created_at    INTEGER NOT NULL,
//!   updated_at    INTEGER NOT NULL,
//!   PRIMARY KEY (platform, chat_id)
//! );
//! ```

use std::path::Path;
use std::sync::Arc;

use rusqlite::Connection;

/// 单条会话映射(字段预留 S2 多人/多桌面端,当前核心只读 conv_id)
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub struct SessionMap {
    pub platform: String,
    pub chat_id: String,
    pub conv_id: String,
    pub owner_user_id: String,
    pub channel_id: String,
}

#[derive(Clone)]
pub struct SessionStore {
    conn: Arc<std::sync::Mutex<Connection>>,
}

impl SessionStore {
    /// 打开(或创建)库文件并确保表存在。WAL 模式(与桌面端一致)。
    pub fn open(path: &Path) -> anyhow::Result<Self> {
        let conn = Connection::open(path)?;
        conn.pragma_update(None, "journal_mode", "WAL")?;
        conn.execute_batch(
            "CREATE TABLE IF NOT EXISTS session_map (
                platform      TEXT NOT NULL,
                chat_id       TEXT NOT NULL,
                conv_id       TEXT NOT NULL,
                owner_user_id TEXT NOT NULL DEFAULT '',
                channel_id    TEXT NOT NULL DEFAULT '',
                created_at    INTEGER NOT NULL,
                updated_at    INTEGER NOT NULL,
                PRIMARY KEY (platform, chat_id)
            );",
        )?;
        Ok(Self { conn: Arc::new(std::sync::Mutex::new(conn)) })
    }

    /// 内存库(测试/演示)
    #[allow(dead_code)]
    pub fn open_in_memory() -> anyhow::Result<Self> {
        let conn = Connection::open_in_memory()?;
        conn.execute_batch(
            "CREATE TABLE IF NOT EXISTS session_map (
                platform TEXT NOT NULL, chat_id TEXT NOT NULL, conv_id TEXT NOT NULL,
                owner_user_id TEXT NOT NULL DEFAULT '', channel_id TEXT NOT NULL DEFAULT '',
                created_at INTEGER NOT NULL, updated_at INTEGER NOT NULL,
                PRIMARY KEY (platform, chat_id)
            );",
        )?;
        Ok(Self { conn: Arc::new(std::sync::Mutex::new(conn)) })
    }

    /// 查 IM 会话映射的 conv_id(未映射返回 None)
    pub fn get_conv(&self, platform: &str, chat_id: &str) -> Option<SessionMap> {
        let conn = self.conn.lock().ok()?;
        conn.query_row(
            "SELECT platform, chat_id, conv_id, owner_user_id, channel_id FROM session_map \
             WHERE platform = ?1 AND chat_id = ?2",
            [platform, chat_id],
            |row| {
                Ok(SessionMap {
                    platform: row.get(0)?,
                    chat_id: row.get(1)?,
                    conv_id: row.get(2)?,
                    owner_user_id: row.get(3)?,
                    channel_id: row.get(4)?,
                })
            },
        )
        .ok()
    }

    /// 写/更新映射(upsert)
    pub fn set_conv(&self, platform: &str, chat_id: &str, conv_id: &str, channel_id: &str) -> anyhow::Result<()> {
        let conn = self.conn.lock().map_err(|e| anyhow::anyhow!("store 锁中毒: {e}"))?;
        let now = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .map(|d| d.as_millis() as i64)
            .unwrap_or(0);
        conn.execute(
            "INSERT INTO session_map (platform, chat_id, conv_id, owner_user_id, channel_id, created_at, updated_at) \
             VALUES (?1, ?2, ?3, '', ?4, ?5, ?5) \
             ON CONFLICT(platform, chat_id) DO UPDATE SET conv_id = ?3, channel_id = ?4, updated_at = ?5",
            rusqlite::params![platform, chat_id, conv_id, channel_id, now],
        )?;
        Ok(())
    }

    /// 删除映射(桌面端会话已删,悬空清理)
    pub fn remove(&self, platform: &str, chat_id: &str) -> anyhow::Result<()> {
        let conn = self.conn.lock().map_err(|e| anyhow::anyhow!("store 锁中毒: {e}"))?;
        conn.execute("DELETE FROM session_map WHERE platform = ?1 AND chat_id = ?2", [platform, chat_id])?;
        Ok(())
    }
}

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

    #[test]
    fn upsert_and_get() {
        let store = SessionStore::open_in_memory().unwrap();
        store.set_conv("feishu", "oc_123", "conv_abc", "chan-work").unwrap();
        let m = store.get_conv("feishu", "oc_123").unwrap();
        assert_eq!(m.conv_id, "conv_abc");
        assert_eq!(m.channel_id, "chan-work");
        assert_eq!(m.owner_user_id, "");

        // upsert 覆盖
        store.set_conv("feishu", "oc_123", "conv_new", "chan-home").unwrap();
        let m = store.get_conv("feishu", "oc_123").unwrap();
        assert_eq!(m.conv_id, "conv_new");

        // 删除后悬空
        store.remove("feishu", "oc_123").unwrap();
        assert!(store.get_conv("feishu", "oc_123").is_none());
    }

    #[test]
    fn platform_isolated() {
        let store = SessionStore::open_in_memory().unwrap();
        store.set_conv("feishu", "c1", "conv1", "ch").unwrap();
        store.set_conv("wecom", "c1", "conv2", "ch").unwrap();
        assert_eq!(store.get_conv("feishu", "c1").unwrap().conv_id, "conv1");
        assert_eq!(store.get_conv("wecom", "c1").unwrap().conv_id, "conv2");
    }
}