// Import external-modules
import * as Mongoose from "mongoose";

// Import peer-modules
import { Logger } from "../logger";
// Import sub-modules
import { MongoCollection } from "./mongo_collection";
import { MongoDbConfig } from "./interfaces/db_config";
import { MongoUltility } from "./mongo_ultility";

// Define gobal variables
const connections: { [cnnSecreteKey: string]: Mongoose.Connection } = {};
const collections: { [colSecreteKey: string]: MongoCollection } = {};

class MongoDb {
  static connect(config: MongoDbConfig): MongoCollection {
    let collection = this.findCollection(config);
    if (!collection) {
      let connection = this.findConnection(config);
      if (!connection) {
        connection = this.initConnection(config);
      }
      collection = this.initCollection(connection, config);
    }
    return collection;
  }

  private static findCollection(config: MongoDbConfig): MongoCollection {
    const secreteKey = `mongodb+srv://${config.username}:${config.password}@${config.hostname}/${config.dbname}/${config.modelname}`;
    return collections[secreteKey];
  }

  private static findConnection(config: MongoDbConfig): Mongoose.Connection {
    const secreteKey = `mongodb+srv://${config.username}:${config.password}@${config.hostname}/${config.dbname}`;
    return connections[secreteKey];
  }

  private static initCollection(
    connection: Mongoose.Connection,
    config: MongoDbConfig
  ): MongoCollection {
    const secreteKey = `mongodb+srv://${config.username}:${config.password}@${config.hostname}/${config.dbname}/${config.modelname}`;
    const collection = new MongoCollection(
      connection,
      config.modelname,
      config.schema
    );
    collections[secreteKey] = collection;
    return collection;
  }

  private static initConnection(config: MongoDbConfig): Mongoose.Connection {
    const secreteKey = `mongodb+srv://${config.username}:${config.password}@${config.hostname}/${config.dbname}`;
    const connection = Mongoose.createConnection(secreteKey, {
      useNewUrlParser: true,
      useCreateIndex: true,
    });
    connection.on("error", (error) => {
      Logger.error(`Mongoose Connection Error!`);
      Logger.error(`Message: ${error.toString()} !`);
    });
    connection.once("open", () => {
      connection[secreteKey] = connection;
      Logger.info(`Mongoose Connection Success, db: ${config.dbname}`);
    });
    return connection;
  }
}

export { MongoDbConfig, MongoCollection, MongoUltility, MongoDb };