const bodyParser = require(`body-parser`);

const CustomErrors = require(`./utilities/errors.JS`);
const Messaging = require(`./utilities/messaging.JS`);

class DBManagement {};
DBManagement.Activities = require(`./database/management/management_activity.JS`);
DBManagement.Users = require(`./database/management/management_user.JS`);

class ResponseGenerator {};
ResponseGenerator.Activities = require(`./response/activity.JS`);
ResponseGenerator.Users = require(`./response/user.JS`);
ResponseGenerator.Log = require(`./response/log.JS`);

class ExerciseTrackerAPI {
	#paths = {
		"users": ["users"],
		"exercises": ["users/:ID/exercises"],
		"logs": ["users/:ID/logs"]
	}

	constructor(INSTANCE) {
		this[`instance`] = INSTANCE;
		this[`instance`].use(bodyParser.json());
		this[`instance`].use(bodyParser.urlencoded({extended: true}));

		const init_management = () => {
			this[`management`] = {};

			Object.keys(DBManagement).forEach((DATABASE) => {
				this.management[DATABASE] = new DBManagement[DATABASE]();
			});
			this.manageUsers();
			this.manageActivities();
		};

		init_management();
	}

	/*
		Manage the activities. 
	*/
	manageActivities () {
		/*
		Create the new activities. 
		*/
		const activity_creation = async (REQUEST, RESPONSE) => {
			try {
				if (((REQUEST.body) ? Object.keys(REQUEST.body).length : false) ? Object.keys(REQUEST.params).includes(`ID`) : false) {
					let CORRESPONDING_USERS = await this.management[`Users`].search({"ID": REQUEST.params[`ID`]});
					if (!CORRESPONDING_USERS.length || !CORRESPONDING_USERS) {
						throw new CustomErrors.Data.Incorrect(REQUEST.body);
					};

					let RESULT = await this.management[`Activities`].create(Object.assign({}, REQUEST.body, {"username": CORRESPONDING_USERS[0].name}));
					let FORMATTED = new ResponseGenerator.Activities(Object.assign({},RESULT, {"ID": REQUEST.params[`ID`]}));
					FORMATTED[`data`][`date`] = FORMATTED.convert_date();
					FORMATTED = FORMATTED.format();
					RESPONSE.send(FORMATTED);
				} else {
					throw new CustomErrors.Data.Missing(REQUEST.body);
				}
			} catch(ERR) {
				Messaging.exception(RESPONSE, ERR);
			}
		}

		/*
			Display a log of activities. 
		*/
		const activity_log = async (REQUEST, RESPONSE) => {
			const find_users = async () => {
				let USERS = await this.management[`Users`].search({"ID": REQUEST.params[`ID`]});
				if (!USERS.length || !USERS) {
					throw new CustomErrors.Data.Incorrect(REQUEST.params);
				};
				return (USERS)
			}

			const find_activities = async (USERNAME, CRITERIA) => {
				let FILTER = {};
				if (CRITERIA[`from`] || CRITERIA[`to`]) {
					[`from`, `to`].forEach((KEY) => {
						if (CRITERIA[KEY]) {CRITERIA[KEY] = (new Date(CRITERIA[KEY])).getTime();};
					})

					FILTER[`date`] = {};
					if (CRITERIA[`from`]) {FILTER[`date`][`$gte`] = CRITERIA[`from`]};
					if (CRITERIA[`to`]) {FILTER[`date`][`$lte`] = CRITERIA[`to`]};
				}

				let RESULT = await this.management[`Activities`].search_User(USERNAME, FILTER, (CRITERIA[`limit`] ? CRITERIA[`limit`] : 0));
				return (RESULT);
			}

			try {
				let USERS = await find_users();
				let LOG = Object.assign({}, await find_activities(USERS[0].name, (((REQUEST.query) ? Object.keys(REQUEST.query).length : false) || ((REQUEST.body) ? Object.keys(REQUEST.body).length : false)) ? (((REQUEST.body) ? Object.keys(REQUEST.body).length : false) ? REQUEST.body : REQUEST.query) : {}), {"ID": REQUEST.params[`ID`]});
				let FORMATTED = (new ResponseGenerator.Log(LOG)).format();
				RESPONSE.send(FORMATTED);
			} catch(ERR) {
				Messaging.exception(RESPONSE, ERR);
			}
		}

		this.#paths[`exercises`].forEach((PATH) => {
			this[`instance`].post(`/api/${PATH}`, activity_creation)
			console.log(`Activity creation is ready on ${PATH}.`);
		});

		this.#paths[`logs`].forEach((PATH) => {
			this[`instance`].get(`/api/${PATH}`, activity_log);
			console.log(`Activity log generation is ready on ${PATH}.`);
		});
	}

	/*
		Manage the users. 
	*/
	manageUsers () {
		/* 
			Create new users.
		*/
		const users_creation = async (REQUEST, RESPONSE) => {
			try {
				if (((REQUEST.body) ? Object.keys(REQUEST.body).length : false) ? Object.keys(REQUEST.body).includes(`username`) : false) {
					this.management[`Users`].create(REQUEST.body[`username`]).then((RESULT) => {
						let FORMATTED = (new ResponseGenerator.Users(RESULT)).format();
						RESPONSE.send(FORMATTED);	
					})
				} else {
					throw new CustomErrors.Data.Missing(REQUEST.body);
				}
			} catch(ERR) {
				Messaging.exception(RESPONSE, ERR);
			}
		}
		
		/*
			Search for all users. 
		*/
		const users_display = (REQUEST, RESPONSE) => {
			try {
				let CRITERIA = (((REQUEST.query) ? Object.keys(REQUEST.query).length : false) || ((REQUEST.body) ? Object.keys(REQUEST.body).length : false)) ? (((REQUEST.body) ? Object.keys(REQUEST.body).length : false) ? REQUEST.body : REQUEST.query) : {};
				
				this.management[`Users`].search(CRITERIA).then((RESULT) => {
					let FORMATTED = (new ResponseGenerator.Users(RESULT)).format();
					RESPONSE.send(FORMATTED);
				})
			} catch(ERR) {
				Messaging.exception(RESPONSE, ERR);
			}
		}

		this.#paths[`users`].forEach((PATH) => {
			this[`instance`].get(`/api/${PATH}`, users_display)
			console.log(`User search is ready on ${PATH}.`);
		});

		this.#paths[`users`].forEach((PATH) => {
			this[`instance`].post(`/api/${PATH}`, users_creation)
			console.log(`User creation is ready on ${PATH}.`);
		});
	}
} 

module.exports = ExerciseTrackerAPI;