var MongoClient = require("mongodb").MongoClient
var Winston = require("winston")

class MongoDocumentStore {

  constructor(options) {
    this.connectionURL = `mongodb+srv://${options.username}:${options.password}@cluster0-vycgu.mongodb.net/${options.dbName}?retryWrites=true&w=majority`;
    this.dbName = options.dbName;
    this.collectionName = options.collectionName;
  }

  set(key, data, callback) {
    var _this = this;
    const client = new MongoClient(this.connectionURL, { useUnifiedTopology: true, useNewUrlParser: true });
    client.connect(err => {
      if (err) {
        callback(false);
        Winston.error("Error connecting to MongoDB database.", { error: err });
        return;
      }
      const db = client.db(_this.dbName);
      const collection = db.collection(_this.collectionName);

      collection.insertOne({key: key, data: data}, (err, result) => {
        if (err) {
          callback(false);
          Winston.error("Error inserting data into MongoDB database.", { error: error });
          return;
        }
        Winston.info("Inserted data into MongoDB database.");
        callback(true);
      });
    });
  }

  get(key, callback) {
    var _this = this;
    MongoClient.connect(this.connectionURL, { useUnifiedTopology: true }, function(err, client) {
      if (err) {
        callback(false);
        Winston.error("Error connecting to MongoDB database.", { error: err });
        return;
      }
      const db = client.db(_this.dbName);
      const collection = db.collection(_this.collectionName);
      
      collection.findOne({key: key}, (err, result) => {
        if (err || !result) {
          callback(false);
          if (err) {
            Winston.error("Error getting data from MongoDB database.", { error: error });
          }
          return;
        }
        Winston.info("Retrieved data from MongoDB database.");
        callback(result.data);
      });
    });
  }
}

module.exports = MongoDocumentStore;