"""SQLite schema creation and migrations."""

from __future__ import annotations

import sqlite3

SCHEMA_VERSION = 4


def table_exists(conn: sqlite3.Connection, name: str) -> bool:
    row = conn.execute(
        "SELECT 1 FROM sqlite_master WHERE type='table' AND name=?",
        (name,),
    ).fetchone()
    return row is not None


def column_exists(conn: sqlite3.Connection, table: str, column: str) -> bool:
    if not table_exists(conn, table):
        return False
    cols = conn.execute(f"PRAGMA table_info({table})").fetchall()
    return any(c[1] == column for c in cols)


def ensure_column(
    conn: sqlite3.Connection, table: str, column: str, ddl: str, log: list[str]
) -> None:
    if not column_exists(conn, table, column):
        conn.execute(f"ALTER TABLE {table} ADD COLUMN {column} {ddl}")
        log.append(f"ALTER {table} ADD {column}")


def get_schema_version(conn: sqlite3.Connection) -> int:
    if not table_exists(conn, "schema_version"):
        return 0
    row = conn.execute("SELECT version FROM schema_version LIMIT 1").fetchone()
    return int(row[0]) if row else 0


def set_schema_version(conn: sqlite3.Connection, version: int) -> None:
    conn.execute(
        """
        CREATE TABLE IF NOT EXISTS schema_version (version INTEGER NOT NULL);
        """
    )
    conn.execute("DELETE FROM schema_version")
    conn.execute("INSERT INTO schema_version (version) VALUES (?)", (version,))


def apply_migrations(conn: sqlite3.Connection) -> list[str]:
    log: list[str] = []

    conn.executescript(
        """
        CREATE TABLE IF NOT EXISTS devices (
            device_id TEXT PRIMARY KEY,
            label TEXT,
            last_seen REAL NOT NULL
        );
        CREATE TABLE IF NOT EXISTS telemetry (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            device_id TEXT NOT NULL,
            lat REAL,
            lon REAL,
            rssi REAL,
            range_m REAL,
            raw_frame TEXT,
            ts REAL NOT NULL
        );
        CREATE INDEX IF NOT EXISTS idx_telemetry_device_ts
            ON telemetry(device_id, ts DESC);
        CREATE TABLE IF NOT EXISTS chat (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            device_id TEXT NOT NULL,
            text TEXT NOT NULL,
            ts REAL NOT NULL
        );
        CREATE INDEX IF NOT EXISTS idx_chat_ts ON chat(ts);
        """
    )
    log.append("ensure base tables")

    ensure_column(conn, "telemetry", "source", "TEXT", log)
    ensure_column(conn, "telemetry", "meta", "TEXT", log)
    ensure_column(conn, "telemetry", "role", "TEXT", log)

    if not table_exists(conn, "tracks"):
        conn.executescript(
            """
            CREATE TABLE tracks (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                device_id TEXT NOT NULL,
                started_at REAL NOT NULL,
                ended_at REAL,
                label TEXT
            );
            CREATE INDEX IF NOT EXISTS idx_tracks_device ON tracks(device_id, started_at DESC);
            """
        )
        log.append("CREATE tracks")

    if not table_exists(conn, "track_points"):
        conn.executescript(
            """
            CREATE TABLE track_points (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                track_id INTEGER NOT NULL,
                ts REAL NOT NULL,
                lat REAL NOT NULL,
                lon REAL NOT NULL,
                altitude_gps REAL,
                elevation_m REAL,
                rssi REAL,
                role TEXT,
                meta TEXT,
                FOREIGN KEY (track_id) REFERENCES tracks(id)
            );
            CREATE INDEX IF NOT EXISTS idx_track_points_track_ts
                ON track_points(track_id, ts);
            """
        )
        log.append("CREATE track_points")

    if not table_exists(conn, "device_commands"):
        conn.executescript(
            """
            CREATE TABLE device_commands (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                from_device_id TEXT NOT NULL,
                to_device_id TEXT NOT NULL,
                kind TEXT NOT NULL,
                payload TEXT,
                created_at REAL NOT NULL,
                delivered_at REAL
            );
            CREATE INDEX IF NOT EXISTS idx_commands_to_pending
                ON device_commands(to_device_id, delivered_at, created_at);
            """
        )
        log.append("CREATE device_commands")

    if not table_exists(conn, "paired_track_sessions"):
        conn.executescript(
            """
            CREATE TABLE paired_track_sessions (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                device_a TEXT NOT NULL,
                device_b TEXT NOT NULL,
                initiator TEXT NOT NULL,
                status TEXT NOT NULL,
                start_at REAL NOT NULL,
                track_id_a INTEGER,
                track_id_b INTEGER,
                created_at REAL NOT NULL
            );
            CREATE INDEX IF NOT EXISTS idx_paired_status
                ON paired_track_sessions(status, created_at DESC);
            """
        )
        log.append("CREATE paired_track_sessions")

    set_schema_version(conn, SCHEMA_VERSION)
    log.append(f"schema_version={SCHEMA_VERSION}")
    return log


def check_db_ok(conn: sqlite3.Connection) -> bool:
    required = [
        ("devices", None),
        ("telemetry", "meta"),
        ("tracks", None),
        ("track_points", "elevation_m"),
        ("device_commands", None),
        ("paired_track_sessions", None),
    ]
    for table, col in required:
        if not table_exists(conn, table):
            return False
        if col and not column_exists(conn, table, col):
            return False
    return True