import { CompiledQuery, Kysely } from 'kysely';
import { NodeNativeSqliteDialect } from 'kysely-node-native-sqlite';

import type { DatabaseTables } from './tables.ts';
import type { Logger } from '../../utils/logger.ts';

/** Options required to open a SQLite database connection. */
export type DatabaseOptions = {
    /** Filesystem path to the SQLite database file. */
    path: string;

    /** Logger extended with a database namespace for diagnostics. */
    debug: Logger;
};

/**
 * Thin wrapper around Kysely and NodeNativeSqliteDialect (which uses node:sqlite).
 *
 * Owns connection setup, pragma configuration, and graceful teardown.
 */
export class Database {
    private readonly debug: Logger;
    private readonly dialect: NodeNativeSqliteDialect;
    private readonly kysely: Kysely<DatabaseTables>;

    /**
     * Open a SQLite database and configure it for concurrent writes.
     *
     * @param options - Database file path and debug logger.
     */
    constructor(options: DatabaseOptions) {
        // Extend the debug logger to include the database namespace.
        this.debug = options.debug.extend('database');

        // Create the SQLite database.
        this.dialect = new NodeNativeSqliteDialect(options.path);

        // Create the Kysely database.
        this.kysely = new Kysely<DatabaseTables>({
            dialect: this.dialect,
        });

        // Configure the SQLite pragmas.
        this.configurePragmas();
    }

    /**
     * Gets the Kysely database.
     *
     * @returns The typed Kysely query builder for DatabaseTables.
     */
    get db(): Kysely<DatabaseTables> {
        return this.kysely;
    }

    /**
     * Destroys the database connection.
     */
    async destroy(): Promise<void> {
        this.debug('destroying database connection');
        await this.kysely.destroy();
    }

    /**
     * Configures the SQLite pragmas.
     *
     * WAL improves write concurrency; foreign keys enforce referential integrity.
     */
    private configurePragmas(): void {
        this.debug('configuring SQLite pragmas');

        this.kysely.executeQuery(CompiledQuery.raw('PRAGMA journal_mode = WAL'));
        this.kysely.executeQuery(CompiledQuery.raw('PRAGMA foreign_keys = ON'));
    }
}