const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://mongo:27017';
const dbName = 'workshopDatabase';
const COLLECTION_NAME = "workshops"
let db;

function init() {
    return new Promise((resolve, reject) => {
        MongoClient.connect(url, function(err, client) {
            if (err) {
                return reject(err)
            }
            console.log("Connected successfully to server");           
            db = client.db(dbName);
            resolve();
          });
    })
}

function getWorkshopList() {
    return new Promise((resolve, reject) => {
        const collection = db.collection(COLLECTION_NAME);
        collection.find({}).toArray(function(err, workshops) {
            if (err) {
                return reject(err);
            }
            return resolve(workshops)
        })
    })
}

function getWorkshopByName(name) {
    return new Promise((resolve, reject) => {
        if (!name) {
            reject(new Error("name parameter is required"))
        }
        const collection = db.collection(COLLECTION_NAME);
        collection.find({
            name
        }).toArray(function(err, workshops) {
            if (err) {
                return reject(err);
            }
            if (workshops.length > 0) {
                return resolve(workshops[0])
            } else {
                return resolve(null)
            }
        })
    })
}

function addWorkshop(name, description) {
    if (!name) {
        return Promise.reject(new Error("Workshop name required"));
    }
    if (!description) {
        return Promise.reject(new Error("Workshop description required"));
    }
    const collection = db.collection(COLLECTION_NAME);
    return collection.insert({
        name, description
    }).then(() => {return})
}

function removeWorkshopByName(name) {
    const collection = db.collection(COLLECTION_NAME);
    return collection.deleteMany({
        name
    }).then(() => {return})
}

function updateWorkshop(name, description) {
    const collection = db.collection(COLLECTION_NAME);
    return collection.updateMany({
        name
    }, {
        description
    }).then(() => {return})
}

module.exports = {
    init,
    getWorkshopList,
    getWorkshopByName,
    addWorkshop,
    removeWorkshopByName,
    updateWorkshop
}