import * as plugins from './mongodump.plugins.js';

/**
 * a MongoDump Target is a pointer to a database
 * + exposes functions to interact with the dump target
 */
export class MongoDumpTarget {
  public static async createAndInit(
    mongoDescriptorArg: plugins.tsclass.database.IMongoDescriptor
  ) {
    const mongoDumpTarget = new MongoDumpTarget(mongoDescriptorArg);
    await mongoDumpTarget.init();
    return mongoDumpTarget;
  }

  public readyDeferred = plugins.smartpromise.defer();
  public mongoDescriptor: plugins.tsclass.database.IMongoDescriptor;
  public mongoDbClient: plugins.mongodb.MongoClient;
  public mongoDb: plugins.mongodb.Db;
  constructor(mongoDescriptorArg: plugins.tsclass.database.IMongoDescriptor) {
    this.mongoDescriptor = mongoDescriptorArg;
  }

  /**
   * connects to the database that was specified during instance creation
   */
  public async init(): Promise<any> {
    const finalConnectionUrl = this.mongoDescriptor.mongoDbUrl
      .replace('<USERNAME>', this.mongoDescriptor.mongoDbUser)
      .replace('<username>', this.mongoDescriptor.mongoDbUser)
      .replace('<USER>', this.mongoDescriptor.mongoDbUser)
      .replace('<user>', this.mongoDescriptor.mongoDbUser)
      .replace('<PASSWORD>', this.mongoDescriptor.mongoDbPass)
      .replace('<password>', this.mongoDescriptor.mongoDbPass)
      .replace('<DBNAME>', this.mongoDescriptor.mongoDbName)
      .replace('<dbname>', this.mongoDescriptor.mongoDbName);

    this.mongoDbClient = await plugins.mongodb.MongoClient.connect(finalConnectionUrl, {
      maxPoolSize: 100,
      maxIdleTimeMS: 10,
    });
    this.mongoDb = this.mongoDbClient.db(this.mongoDescriptor.mongoDbName);
    console.log(`Connected to database ${this.mongoDescriptor.mongoDbName}`);
    this.readyDeferred.resolve();
  }

  /**
   * gets all collections
   */
  public async getCollections() {
    await this.readyDeferred.promise;
    const collections = await this.mongoDb.collections();
    console.log(`The follwing collections have been found:`);
    for (const collection of collections) {
      console.log(collection.collectionName);
    }

    return collections;
  }

  /**
   * dumps a collection to a directory
   */
  public async dumpCollectionToDir(collectionArg: plugins.mongodb.Collection, dirArg: string, nameTransformFunction = (doc: any) => doc._id) {
    const dirPath = plugins.smartpath.transform.makeAbsolute(dirArg);
    const collectionDir = plugins.path.join(dirPath, collectionArg.collectionName);
    await plugins.smartfile.fs.ensureDir(collectionDir);
    const cursor = collectionArg.find();
    let value = await cursor.next();
    while(value) {
      await plugins.smartfile.memory.toFs(JSON.stringify(value, null, 2), plugins.path.join(collectionDir, `${nameTransformFunction(value)}.json`));
      value = await cursor.next();
    }
  }

  public async dumpCollectionToTarArchive(collectionArg: plugins.mongodb.Collection) {}

  public async dumpAllCollectionsToDir() {}
}