// Loaded from https://deno.land/x/denodb@v1.0.18/lib/connectors/mysql-connector.ts


import { MySQLClient, MySQLConnection } from "../../deps.ts";
import type { Connector, ConnectorOptions } from "./connector.ts";
import { SQLTranslator } from "../translators/sql-translator.ts";
import type { QueryDescription } from "../query-builder.ts";

export interface MySQLOptions extends ConnectorOptions {
  database: string;
  host: string;
  username: string;
  password: string;
  port?: number;
}

export class MySQLConnector implements Connector {
  _client: MySQLClient;
  _options: MySQLOptions;
  _translator: SQLTranslator;
  _connected = false;

  /** Create a MySQL connection. */
  constructor(options: MySQLOptions) {
    this._options = options;
    this._client = new MySQLClient();
    this._translator = new SQLTranslator("mysql");
  }

  async _makeConnection() {
    if (this._connected) {
      return;
    }

    await this._client.connect({
      hostname: this._options.host,
      username: this._options.username,
      db: this._options.database,
      password: this._options.password,
      port: this._options.port ?? 3306,
    });

    this._connected = true;
  }

  async ping() {
    await this._makeConnection();

    try {
      const [{ result }] = await this._client.query("SELECT 1 + 1 as result");
      return result === 2;
    } catch (error) {
      return false;
    }
  }

  async query(
    queryDescription: QueryDescription,
    client?: MySQLClient | MySQLConnection,
  ): Promise<any | any[]> {
    await this._makeConnection();

    const queryClient = client ?? this._client;
    const query = this._translator.translateToQuery(queryDescription);
    const subqueries = query.split(";");
    const queryMethod = query.toLowerCase().startsWith("select")
      ? "query"
      : "execute";

    for (let i = 0; i < subqueries.length; i++) {
      const result = await queryClient[queryMethod](subqueries[i]);

      if (i === subqueries.length - 1) {
        return result;
      }
    }
  }

  async transaction(queries: QueryDescription[]): Promise<any | any[]> {
    if (queries.length === 0) {
      return [];
    }

    const results = await this._client.transaction(async (transaction) => {
      const lastQuery = queries.pop()!;

      for (const query of queries) {
        await this.query(query, transaction);
      }

      return this.query(lastQuery, transaction);
    });

    return results as any;
  }

  async close() {
    if (!this._connected) {
      return;
    }

    await this._client.close();
    this._connected = false;
  }
}