import {QueryResult} from './types.ts'
import {Collection} from "../../../lib/src/collection/Collection.ts";
import {Database} from "../schema/tree/Database.ts";
import AppClass from "../../../lib/src/lifecycle/AppClass.ts";
import {Table} from "../schema/tree/Table.ts";

/**
 * Error thrown when a connection is used before it is ready.
 * @extends Error
 */
export class ConnectionNotReadyError extends Error {
    constructor(name = '') {
        super(`The connection ${name} is not ready and cannot execute queries.`)
    }
}

/**
 * Abstract base class for database connections.
 * @abstract
 */
export abstract class Connection extends AppClass {

    constructor(
        /**
         * The name of this connection
         * @type string
         */
        public readonly name: string,
        /**
         * This connection's config object
         */
        public readonly config: any = {},
    ) { super() }

    /**
     * Open the connection.
     * @return Promise<void>
     */
    public abstract async init(): Promise<void>

    /**
     * Execute an SQL query and get the result.
     * @param {string} query
     * @return Promise<QueryResult>
     */
    public abstract async query(query: string): Promise<QueryResult> // TODO query result

    /**
     * Close the connection.
     * @return Promise<void>
     */
    public abstract async close(): Promise<void>

    public abstract async databases(): Promise<Collection<Database>>

    public abstract async database(name: string): Promise<Database | undefined>

    public abstract async database_as_schema(name: string): Promise<Database>

    public abstract async tables(database_name: string): Promise<Collection<Table>>

    public abstract async table(database_name: string, table_name: string): Promise<Table | undefined>
}