import sqlite3
from pathlib import Path
from typing import Callable

from database.connection import get_conn
from util.util import LOGGER

class DatabaseMigrator:
    def __init__(self, db_path: Path, migrations_folder: Path) -> None:
        self.db_path: Path = db_path
        self.migrations_folder: Path = migrations_folder
        self.conn: sqlite3.Connection = get_conn(db_path)
        _ = self.conn.execute("PRAGMA foreign_keys = OFF;")
        self.conn.autocommit = False

    def close(self):
        self.conn.close()

    def get_version(self) -> int:
        cursor = self.conn.cursor()
        _ = cursor.execute("PRAGMA user_version")
        return int(cursor.fetchone()[0])

    def set_version(self, version: int):
        cursor = self.conn.cursor()
        _ = cursor.execute(f"PRAGMA user_version = {version}")
        self.conn.commit()

    def apply_migration(self, version: int, filename: str, migration: Callable[[sqlite3.Connection], None]):
        try:
            _ = migration(self.conn)
            self.set_version(version)
            self.conn.commit()
            LOGGER.info("Applied migration: %s..", filename)
        except sqlite3.Error as e:
            self.conn.rollback()
            raise Exception(f"Error applying migration {filename}: {e}")

    def migrate(self):
        current_version = self.get_version()
        from migrations._registry import load_migrations
        migrations = load_migrations(self.migrations_folder)

        if not migrations:
            LOGGER.warning("No migration files found.")
            return

        pending = [m for m in migrations if m[0] > current_version]
        if not pending:
            LOGGER.info("No pending migrations.")
            return

        for version, filename, migration in pending:
            self.apply_migration(version, filename, migration)