const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');

// Connection URL
const url = 'mongodb://thanh:123456@localhost:27017/mydb';

// Database Name
const dbName = 'mydb';

// Use connect method to connect to the server
MongoClient.connect(url, function(err, client) {
  assert.equal(null, err);
  console.log("Connected successfully to server");

  const db = client.db(dbName);

  //insertdocument
  var data = [
    {a : 1}, {a : 2}, {a : 3}
  ];
  //insertDocuments(db, "tbl_setting", data, function callback(result){
	//					console.log(result);
	//				});

  // Find
  findDocuments(db,"tbl_setting", {a:2},{ a: 0}, function callback(result){
						console.log(result);
					});

  //Update
  var new_value = {$set:{text:"Updated by thanhnt."}};
  updateDocuments(db, "tbl_setting", {a: 2}, new_value, function callback(result){
  	//console.log(result);
  });

  //Delete
  deleteDocuments(db, "tbl_setting", {a: 1}, function callback(result){
  	//console.log(result);
  });

	  //Aggregate
	  var lookup =[{
	  	$lookup:{
	  		from: 'documents',
	  		localField: 'a',
	  		foreignField: 'a',
	  		as: "on_document"
	  	}
	  }];
	joinDocuments(db, "tbl_setting", lookup, function callback(result){
		console.log(JSON.stringify(result, 2));
	});

  client.close();
});

const insertDocuments = function(db, table, data, callback) {
  // Get the documents collection
  const collection = db.collection(table);
  // Insert some documents
  collection.insertMany(data, function(err, result) {
    assert.equal(err, null);
    //assert.equal(3, result.result.n);
    //assert.equal(3, result.ops.length);
    console.log("Inserted "+ result.result.n +" documents into the collection");
    callback(result);
  });
}

const findDocuments = function(db, table, condition, projection, callback){
    const collection = db.collection(table);
    // Find  documents
    collection.find(condition, { "projection": projection}).toArray(function abc(err, docs){
    	assert.equal(err, null);
    	console.log("Found the following records");
    	//console.log(docs);
    	callback(docs);
    });
}

const deleteDocuments = function(db, table, condition, callback){
	const collection = db.collection(table);
    // Delete  documents
    collection.deleteMany(condition, function(err, result) {
	    assert.equal(err, null);
	    //assert.equal(3, result.result.n);
	    //assert.equal(3, result.ops.length);
	    console.log("Deleted "+ result.result.n +" documents into the collection");
	    callback(result);
	});
}

const updateDocuments = function(db, table, condition, new_value, callback){
	const collection = db.collection(table);
    // Update  documents
    collection.updateMany(condition, new_value, function(err, result){
    	assert.equal(err, null);

    	console.log("Updated "+ result.result.nModified +" documents into the collection");
    	callback(result);
    });
}

const joinDocuments = function(db, table, join_field, callback ){
	const collection = db.collection(table);
	//Join documents
	collection.aggregate(join_field).toArray(function abc(err, docs){
    	assert.equal(err, null);
    	console.log("Found the following records");
    	//console.log(docs);
    	callback(docs);
    });
}