/*
 * A Java Script containing methods to manipulate a MongoDB
 * Biney Kingsley - 07-04-2019
 *
 * */

package com.mongo;

import org.bson.Document;

import com.mongodb.BasicDBObject;
import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;

import java.util.*;

public class MongoServices {
	// make some variables global for general access
	private MongoClient mongoClient;
	private MongoCredential credential;
	private MongoCollection<Document> collection;
	private MongoDatabase db;

	// create a MongoClient and start server on a port with a host
	protected void connectServer(String host, int port) {
		/*
		 * host: host of server
		 * port: port to connect to
		 * */
		try {
			mongoClient = new MongoClient(host, port);
			System.out.println("Connected successfully");
		}catch(Exception e) {
			System.out.print("Unable to connect to server");
		}
	}

	// return the client server after creation
	protected MongoClient getClient() {
		return mongoClient;
	}

	// create a database with user credentials
	protected void createCredentials(String username, String password, String dbName) {
		/*
		 * username: database protection credentials
		 * password: database protection credentials
		 * dbName: name  of database to be created
		 * */
		try {
			credential = MongoCredential.createCredential(username, dbName, password.toCharArray());
			// print status
			System.out.println("Database Created successfully");
		}catch(Exception e) {
			System.out.println("Unable to create database");
		}
	}

	// get the database credentials
	protected MongoCredential getCredential() {
		return credential;
	}

	// access the created database
	protected void setDb(String dbName) {
		/*
		 * dbName: access the database created and view credentials set to it
		 * */
		try {
			mongoClient = getClient();
			db = mongoClient.getDatabase(dbName);
			System.out.println("Database Credentials::" + credential);
		}catch(Exception e) {
			System.out.println("Cannot access Database with name " + dbName);
		}
	}

	// get the created database
	protected MongoDatabase getDb() {
		return db;
	}

    // create a collection
	protected void createCollection(MongoDatabase db, String collectionName) {
		/*
		 * db: Database to hold collection
		 * collectionName: Name of the collection to be created
		 * */
		try {
			db.createCollection(collectionName);
			System.out.println("Collection " + collectionName + " created successfully");
		}catch(Exception e) {
			System.out.println("Collection " + collectionName + " creation failed");
		}
	}

	// select a collection to perform operations on
	protected MongoCollection<Document> getCollection(String collectionName){
		/*
		 * collectionName: select a collection to perform operations on it
		 * */
		MongoDatabase db = getDb();
		MongoCollection<Document> collection = db.getCollection(collectionName);
		System.out.println("Collection " + collectionName + " has been selected");
		return collection;
	}

	// insert documents into a collection
	protected void insert(MongoCollection<Document> collection, Document doc) {
		/*
		 * collection: the collection to insert documents in it
		 * doc: the document to insert into the database
		 * */
		try {
			collection.insertOne(doc);
			System.out.println("Document has been inserted into collection");
		}catch(Exception e) {
			System.out.println("Could not insert document into collection");
		}
	}

	// view all documents in a collection
	protected void printDocs(MongoCollection<Document> collection) {
		/*
		 * collection: collection to view all documents within
		 * */
		try {
			FindIterable<Document> iterDoc = collection.find();
			Iterator it = iterDoc.iterator();
			while(it.hasNext()) {
				System.out.println(it.next());
			}
		}catch(Exception e) {
			System.out.println("Failed to print documents in the collection");
		}
	}

	// update a document
	protected void updateDocument(MongoCollection<Document> collection, String key, String value, BasicDBObject newDocument) {
		/*
		 * collection: the collection containing the document to update
		 * key: the unique key (ideally id field) of the document to update
		 * value: the value of the key (ideally the id value) of the document to update
		 * newDocument: data to update the current data in the document with
		 * */
		try {
			BasicDBObject searchquery = new BasicDBObject().append(key, value);
			collection.updateOne(searchquery, newDocument);
			System.out.println("Updated the Document successfully");
		}catch(Exception e) {
			System.out.println("Could not update the document with " + key + ":" + value + " pairs");
		}
	}

	// delete a document
	protected void deleteDocument(MongoCollection<Document> collection, String key, String value) {
		/*
		 * collection: the collection containing the document to delete
		 * key: the unique key field of the document to delete
		 * value: the value of the unique key field of the document to delete
		 * */
		try {
			collection.deleteOne(Filters.eq(key, value));
			System.out.print("Document with field " + key + ":" + value + " has been deleted");
		}catch(Exception e) {
			System.out.println("Document deletion failed");
		}
	}

	// list collections in a db
	protected void listCollection(MongoDatabase db) {
		/*
		 * db: database in focus
		 * */
		try {
			for (String collNames: db.listCollectionNames()) {
			System.out.println(collNames);
			}
		}catch(Exception e) {
			System.out.println("Could not list collections");
		}
	}

	// drop a collection in a db
	protected void dropCollection(MongoDatabase db, String collectionName) {
		/*
		 * db: database in focus
		 * collectionName: collection to drop
		 * */
		try {
			MongoCollection<Document> collection = db.getCollection(collectionName);
			collection.drop();
			System.out.println("Collection " + collectionName + " dropped successfully");
		}catch(Exception e) {
			System.out.println("Could not drop collection " + collectionName);
		}
	}
}