const Mongoose = require(`mongoose`);
const CustomErrors = require(`../../utilities/errors.JS`);

class DBManagement {
	/*
		Begin the connection. 

		@param {string} DOMAIN the domain
		@param {string} DBNAME the database name
	*/
	constructor (DOMAIN, DBNAME) {
		const throwError = (ERROR) => {throw ERROR;};

		this[`state`] = Mongoose.connect(`mongodb://${DOMAIN}/${(DBNAME) ? DBNAME : ""}`, { useNewUrlParser: true, useUnifiedTopology: true }).then((CONNECTION) => {
				this[`connection`] = CONNECTION.connection;
				console.log(`Connection successful.`);
		}).catch(throwError);
	};
	
	/*
		Establish the schema and collection. The result is stored in `this.#status`. 

		@param {string} COLLECTION the name of the collection
		@param {object} SCHEMA the scehma
	*/
	configure (COLLECTION, SCHEMA) {
		this[`schema`] = new Mongoose.Schema(SCHEMA);
		this[`collection`] = COLLECTION;
		this.state.then(() => {
			this.model = this[`connection`].model(this[`collection`], this[`schema`]);
		})
	}

	/*
		Find based on corresponding details. 

		@param {object} CRITERIA the search criteria
		@param {number} SIZE the size of the search
		@return {object} the search results
	*/
	async search(CRITERIA = {}, SIZE) {
		await this.state;
		let RESULT = [];

		if ((CRITERIA && CRITERIA instanceof Object) ? !(Object.keys(CRITERIA).length) : true) {
			console.log(`Searching all...`);
			RESULT = await this.model.find();
		} else if (CRITERIA instanceof Object) {
			RESULT = await this.model.find(CRITERIA);
		}

		if (RESULT.length && (SIZE) ? (SIZE > 0 && SIZE < RESULT.length) : false) {
			RESULT = RESULT.slice(0,SIZE);
		}

		return RESULT;
	};
}

module.exports = DBManagement;