//! Database schema migrations for the claudbg cache.

use crate::db::connection::DbHandle;
use crate::error::Result;

/// Run all database migrations to bring the schema up to date.
///
/// Creates all tables if they don't exist. Safe to call on an existing database
/// (all statements use `CREATE TABLE IF NOT EXISTS`).
pub async fn run_migrations(db: &DbHandle) -> Result<()> {
    let conn = db
        .connect()
        .map_err(|e| crate::error::AppError::Db(e.to_string()))?;

    conn.execute_batch(
        "CREATE TABLE IF NOT EXISTS sessions (
            session_id      TEXT PRIMARY KEY,
            project_path    TEXT,
            model           TEXT,
            first_msg_at    TEXT,
            last_msg_at     TEXT,
            message_count   INTEGER NOT NULL DEFAULT 0,
            input_tokens    INTEGER NOT NULL DEFAULT 0,
            output_tokens   INTEGER NOT NULL DEFAULT 0,
            file_path       TEXT NOT NULL
        );
        CREATE INDEX IF NOT EXISTS idx_sessions_last_msg ON sessions(last_msg_at DESC);

        CREATE TABLE IF NOT EXISTS messages (
            id              INTEGER PRIMARY KEY AUTOINCREMENT,
            session_id      TEXT NOT NULL REFERENCES sessions(session_id),
            sequence_num    INTEGER NOT NULL,
            timestamp       TEXT,
            role            TEXT,
            content_preview TEXT,
            entry_type      TEXT,
            UNIQUE(session_id, sequence_num)
        );
        CREATE INDEX IF NOT EXISTS idx_messages_session ON messages(session_id, sequence_num);

        CREATE TABLE IF NOT EXISTS tool_uses (
            id              INTEGER PRIMARY KEY AUTOINCREMENT,
            session_id      TEXT NOT NULL REFERENCES sessions(session_id),
            tool_name       TEXT NOT NULL,
            tool_use_id     TEXT,
            sequence_num    INTEGER,
            timestamp       TEXT
        );
        CREATE INDEX IF NOT EXISTS idx_tool_uses_session ON tool_uses(session_id);

        CREATE TABLE IF NOT EXISTS raw_sessions (
            session_id  TEXT PRIMARY KEY,
            raw_jsonl   TEXT NOT NULL,
            file_mtime  INTEGER NOT NULL,
            file_size   INTEGER NOT NULL
        );",
    )
    .await
    .map_err(|e| crate::error::AppError::Db(e.to_string()))?;

    Ok(())
}

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

    /// `run_migrations` succeeds on a fresh database.
    #[tokio::test]
    async fn migrations_fresh_db() {
        let dir = tempfile::tempdir().expect("tempdir");
        let path = PathBuf::from(dir.path()).join("schema_test.db");
        let db = libsql::Builder::new_local(&path)
            .build()
            .await
            .expect("build db");
        let handle = std::sync::Arc::new(db);
        let result = run_migrations(&handle).await;
        assert!(result.is_ok(), "migration failed: {:?}", result.err());
    }

    /// `run_migrations` is idempotent — calling it twice does not error.
    #[tokio::test]
    async fn migrations_idempotent() {
        let dir = tempfile::tempdir().expect("tempdir");
        let path = PathBuf::from(dir.path()).join("schema_idempotent.db");
        let db = libsql::Builder::new_local(&path)
            .build()
            .await
            .expect("build db");
        let handle = std::sync::Arc::new(db);
        run_migrations(&handle).await.expect("first migration");
        let result = run_migrations(&handle).await;
        assert!(
            result.is_ok(),
            "second migration failed: {:?}",
            result.err()
        );
    }

    /// After migration, inserting and reading a `raw_sessions` row works.
    #[tokio::test]
    async fn raw_sessions_insert_and_read() {
        let dir = tempfile::tempdir().expect("tempdir");
        let path = PathBuf::from(dir.path()).join("raw_sessions_test.db");
        let db = libsql::Builder::new_local(&path)
            .build()
            .await
            .expect("build db");
        let handle = std::sync::Arc::new(db);
        run_migrations(&handle).await.expect("migration");

        let conn = handle.connect().expect("connect");

        // Insert a sessions row first (raw_sessions has no FK to sessions, but
        // let's also ensure the sessions table is accessible).
        conn.execute(
            "INSERT INTO raw_sessions (session_id, raw_jsonl, file_mtime, file_size)
             VALUES (?1, ?2, ?3, ?4)",
            libsql::params![
                "test-session-1",
                "{\"type\":\"user\"}",
                1700000000_i64,
                42_i64
            ],
        )
        .await
        .expect("insert raw_sessions");

        let mut rows = conn
            .query(
                "SELECT session_id, file_mtime, file_size FROM raw_sessions WHERE session_id = ?1",
                libsql::params!["test-session-1"],
            )
            .await
            .expect("query");

        let row = rows.next().await.expect("next").expect("row exists");
        let sid: String = row.get(0).expect("session_id");
        let mtime: i64 = row.get(1).expect("file_mtime");
        let size: i64 = row.get(2).expect("file_size");

        assert_eq!(sid, "test-session-1");
        assert_eq!(mtime, 1700000000);
        assert_eq!(size, 42);
    }

    /// After migration, inserting and reading a `sessions` row works.
    #[tokio::test]
    async fn sessions_table_insert_and_read() {
        let dir = tempfile::tempdir().expect("tempdir");
        let path = PathBuf::from(dir.path()).join("sessions_table_test.db");
        let db = libsql::Builder::new_local(&path)
            .build()
            .await
            .expect("build db");
        let handle = std::sync::Arc::new(db);
        run_migrations(&handle).await.expect("migration");

        let conn = handle.connect().expect("connect");
        conn.execute(
            "INSERT INTO sessions (session_id, file_path) VALUES (?1, ?2)",
            libsql::params!["sess-abc", "/tmp/sess-abc.jsonl"],
        )
        .await
        .expect("insert sessions");

        let mut rows = conn
            .query(
                "SELECT session_id FROM sessions WHERE session_id = ?1",
                libsql::params!["sess-abc"],
            )
            .await
            .expect("query");

        let row = rows.next().await.expect("next").expect("row exists");
        let sid: String = row.get(0).expect("session_id");
        assert_eq!(sid, "sess-abc");
    }
}