const Mongoose = require(`mongoose`);
const DBManagement = require(`./management`).DBManagement;
const URLs = require(`../utilities/URLs`).URLs;
const CustomErrors = require(`../utilities/errors`).CustomErrors;
const HashTools = require(`../utilities/hash`).HashTools;

class URLManage extends DBManagement {
	/*
		Begin the URL management and connection. 
	*/
	constructor () {
		super(`localhost:27017`);

		this.schema = new Mongoose.Schema({
			"original": {"type": String, "required": true}, 
			"shortened": {"type": String, "required": true}
		});

		this[`state`].then(() => {this.model = this[`connection`].model(`URL`, this[`schema`]);})
	};

	/*
		Open the original URL given an identifier. 
		
		@param {string} ID the ID
		@param {function} done the callback function when successful
		@return {string} the original URL
	*/
	open (ID, done) {
		this.state.then(() => {
			this.model.findOne({"shortened": ID}).then((DATA) => {
				console.log((DATA) ? `Lengthened shortened URL with ID ${ID} to ${DATA[`original`]}.` : `No shortened URL with ID ${ID}.`);
				return done((DATA) ? DATA[`original`] : null);
			}).catch((ERR) => {
				throw ERR;
			})
		}).catch((ERROR) => {throw new CustomErrors.DBProblem(ERROR.message)});
	};

	/*
		Search for a short link given a URL. 

		@param {string} URL the URL to shorten
		@param {function} done the callback function when successful
		@return {string} ID the ID
	*/
	search(URL, done) {
		// Throw an error for an incorrect URL. 
		if (!URLs.test(URL)) {
			throw new CustomErrors.URL(null, URL);
		};

		this.state.then(() => {
			this.model.findOne({"original": URL}).then((DATA) => {
				console.log((DATA) ? `The ID ${DATA[`shortened`]} refers to ${URL}.` : `No ID pertains to ${URL}.`);
				return done((DATA) ? DATA[`shortened`] : null);
			}).catch((ERR) => {
				throw ERR;
			});
		}).catch((ERROR) => {throw new CustomErrors.DBProblem(ERROR.message)})
	};

	/*
		Shorten the URL. 

		@param {string} URL the URL to shorten
		@param {function} done the callback function
		@return {string} ID the ID
	*/
	create(URL, done) {
		// Throw an error for an incorrect URL. 
		if (!URLs.test(URL)) {
			throw new CustomErrors.URL(null, URL);
		};
		
		let ENTRY = {"original": URL};
		const save = (ID) => {
			(ID)
				? done(ID)
				: HashTools.digest(URL, {"output": "Number"}).then((HASH) => {
					ENTRY[`shortened`] = HASH;
		
					let DOCUMENT = new this.model(ENTRY);
		
					this.state.then(() => {
						DOCUMENT.save().then((DATA) => {done(HASH)}).catch((ERR) => {throw ERR;})
					}).catch((ERROR) => {throw new CustomErrors.DBProblem(ERROR.message)});
				});
		}

		this.search((ENTRY[`original`]), save);

	}

}

module.exports = {URLManage};