'use strict';

// modules
const express = require('express');
const fs = require('fs');

// HTTP status codes by name
const codes = require('./http-codes');

const apiAuthenticationMiddleware = require('../middleware/auth-middleware');
const checkHl = require('../middleware/permission-check').checkHl;
const checkMT = require('../middleware/permission-check').checkMT;

const offsetlimitMiddleware = require('../middleware/limitoffset-middleware-mongo');
const filterHandlerCreator = require('../middleware/filter-handler-mongo');
const routerHandling = require('../middleware/router-handling');
const idValidator = require('../middleware/validators').idValidator;
const resourceLocation = require('../middleware/resource-location').resourceLocation().concat('/signature/');

// Mongoose Model using mongoDB
const UserModel = require('../models/user');
const SquadModel = require('../models/squad');
const AwardingModel = require('../models/awarding');

const users = new express.Router();

users.get('/', filterHandlerCreator(UserModel.schema.paths));
users.get('/', offsetlimitMiddleware);

// routes **********************
users.route('/')
     .get((req, res, next) => {
       const finishFiltersAndExecute = () => {
         // squad / fraction filter setup
         if (req.query.fractFilter && req.query.fractFilter !== 'UNASSIGNED' && !req.query.squadId) {
           SquadModel.find({'fraction': req.query.fractFilter}, {_id: 1}, (err, squads) => {
             dbFilter['squadId'] = {$in: squads.map((squad) => squad.id)};
             userQuery();
           });
         } else {
           if (req.query.fractFilter === 'UNASSIGNED') {
             dbFilter['squadId'] = {$eq: null};
           }
           userQuery();
         }
       };

       const userQuery = () => {
         UserModel.find(dbFilter, res.locals.filter, res.locals.limitskip)
                  .populate('squadId')
                  .collation({locale: 'en', strength: 2}) // case insensitive order
                  .sort('username')
                  .exec((err, users) => {
                    if (err) return next(err);
                    if (users.length === 0) {
                      res.locals.items = users;
                      res.locals.processed = true;
                      return next();
                    }

                    UserModel.countDocuments(dbFilter, (err, totalCount) => {
                      res.set('x-total-count', totalCount);
                      res.locals.items = users;
                      res.locals.processed = true;
                      return next();
                    });
                  });
       };

       const nameQuery = (!req.query.q) ? '' : req.query.q;

       const dbFilter = {username: {'$regex': nameQuery, '$options': 'i'}};

       if (req.query.squadId) dbFilter['squadId'] = {'$eq': req.query.squadId};

       // decoration filter
       const queryDecoId = req.query.decorationId;
       if (queryDecoId) {
         AwardingModel.find({decorationId: queryDecoId}, (err, awards) => {
           const userIds = [...new Set(awards.map((award) => award.userId))];
           dbFilter._id = {'$in': userIds};
           finishFiltersAndExecute();
         });
       } else {
         finishFiltersAndExecute();
       }
     })

     .post(apiAuthenticationMiddleware, checkHl, (req, res, next) => {
       const user = new UserModel(req.body);
       // timestamp and default are set automatically by Mongoose Schema Validation
       user.save((err) => {
         if (err) {
           err.status = codes.wrongrequest;
           return next(err);
         }
         res.status(codes.created);

         UserModel.populate(user, {path: 'squadId'}, (err, extUser) => {
           res.locals.items = extUser;
           res.locals.processed = true;
           return next();
         });
       });
     })

     .all(routerHandling.httpMethodNotAllowed);


users.route('/:id')
     .get(idValidator, (req, res, next) => {
       UserModel.findById(req.params.id).populate('squadId').exec((err, user) => {
         if (err) {
           err.status = codes.servererror;
           return next(err);
         } else if (!user) {
           err = new Error('item not found');
           err.status = codes.notfound;
           return next(err);
         }
         res.locals.items = user;
         res.locals.processed = true;
         return next();
       });
     })

     .put(apiAuthenticationMiddleware, checkHl, (req, res, next) => {
       // first check that the given element id is the same as the URL id
       if (!req.body || req.body._id !== req.params.id) {
         // the URL does not fit the given element
         let err =
           new Error('id of PUT resource and send JSON body are not equal ' + req.params.id + ' ' + req.body._id);
         err.status = codes.notfound;
         next(err);
         return; // prevent node to process this function further after next() has finished.
       }
       // main difference of PUT and PATCH is that PUT expects all data in request: checked by using the schema
       const user = new UserModel(req.body);
       UserModel.findById(req.params.id, req.body, {new: true}, (err, item) => {
         // with parameter {new: true} the TweetNModel will return the new and changed object
         // from the DB and not the old one.
         if (err) {
           err.status = codes.wrongrequest;
           return next(err);
         } else if (!item) {
           err = new Error('item not found');
           err.status = codes.notfound;
           return next(err);
         } else if (user.__v !== item.__v) {
           //  checked that version is still accurate
           err = new Error('version outdated. Meanwhile update on item happened. Please GET resource again');
           err.status = codes.conflict;
           return next(err);
         }
         // now update all fields in DB item with body data in variable video
         for (let field in UserModel.schema.paths) {
           if ((field !== '_id') && (field !== '__v')) {
             // this includes undefined. is important to reset attributes that are missing in req.body
             item.set(field, user[field]);
           }
         }

         // update updatedAt and increase version
         item.updatedAt = new Date();
         item.increment(); // this sets __v++
         item.save((err) => {
           if (!err) {
             res.locals.items = item;
           } else {
             err.status = codes.wrongrequest;
             err.message += ' in fields: ' + Object.getOwnPropertyNames(err.errors);
           }

           UserModel.populate(item, {path: 'squadId'}, (err, extUser) => {
             res.locals.items = extUser;
             res.locals.processed = true;
             return next();
           });
         });
       });
     })

     .delete(apiAuthenticationMiddleware, checkMT, (req, res, next) => {
       UserModel.findByIdAndRemove(req.params.id, (err, item) => {
         if (err) {
           err.status = codes.wrongrequest;
         } else if (!item) {
           err = new Error('item not found');
           err.status = codes.notfound;
         }

         // deleted all awardings linked to this user
         AwardingModel.find({userId: req.params.id}).deleteOne();

         // check if signature exists and delete compressed and uncompressed file
         const fileMinified = resourceLocation + req.params.id + '.png';
         if (fs.existsSync(fileMinified)) {
           fs.unlink(fileMinified, (err) => {
           });
         }
         const file = resourceLocation + 'big/' + req.params.id + '.png';
         if (fs.existsSync(file)) {
           fs.unlink(file, (err) => {
           });
         }

         // we don't set res.locals.items  and thus it will send a 204 (no content) at the end. see last handler
         // user.use(..)
         res.locals.processed = true;
         next(err); // this works because err is in normal case undefined and that is the same as no parameter
       });
     })

     .all(
       routerHandling.httpMethodNotAllowed
     );

// this middleware function can be used, if you like or remove it
// it looks for object(s) in res.locals.items and if they exist, they are send to the client as json
users.use(routerHandling.emptyResponse);

module.exports = users;