import type { Database as Sqlite3Database } from 'sqlite3';

/**
 * Represents a pool of connections for SQLite databases.
 * The pool is responsible for managing the connections and
 * ensuring that connections are not leaked. Connections can
 * be leased from the pool for use and must be released back.
 */
export interface SqliteConnectionPool {
	runExclusive<T>(
		dbLeaseHolder: DbLeaseHolder,
		callback: (leasedDbConnection: DbLease) => Promise<T>,
	): Promise<T>;
	leaseConnection(dbLeaseHolder: DbLeaseHolder): Promise<DbLease>;
	releaseConnection(leasedDbConnection: DbLease): void;
	close(): Promise<void>;
}

/**
 * Represents a leased database connection. The connection is
 * leased from the owner to the lease holder, and must be
 * released back to the owner when no longer needed.
 */
export interface DbLease {
	readonly connection: Sqlite3Database;
	readonly isInvalid: boolean;

	/**
	 * Marks the connection as invalid. This will cause the
	 * connection to be released and a new connection to be
	 * created when the lease holder requests a new connection.
	 */
	markAsInvalid(): void;
	/**
	 * Releases the connection back to the pool
	 */
	release(): void;
	/**
	 * Signals that the lease holder should release the lease ASAP
	 */
	requestRelease(): void;
}

export interface DbLeaseOwner {
	releaseConnection(leasedDbConnection: DbLease): void;
}

export interface DbLeaseHolder {
	/**
	 * Signals that the lease holder should release the lease ASAP
	 */
	requestRelease(): void;
}