/*eslint-env node */

/*global require:true*/

'use strict';

var Command = require('ember-cli/lib/models/command');

var path    = require('path');

var Q       = require('q');

var request = require('request');

var _       = require('lodash');

var fs      = require('fs');

// taken from http://stackoverflow.com/a/17238793

// `condition` is a function that returns a boolean

// `body` is a function that returns a promise

// returns a promise for the completion of the loop

function promiseWhile(condition, body) {

    var done = Q.defer();

    function loop() {

        // When the result of calling `condition` is no longer true, we are

        // done.

        if (!condition()) return done.resolve();

        // Use `when`, in case `body` does not return a promise.

        // When it completes loop again otherwise, if it fails, reject the

        // done promise

        Q.when(body(), loop, done.reject);

    }

    // Start running the loop in the next tick so that this function is

    // completely async. It would be unexpected if `body` was called

    // synchronously the first time.

    Q.nextTick(loop);

    // The promise

    return done.promise;

}

module.exports = Command.extend({

    name: 'dl-fixtures',

    description: 'Download fixtures',

    works: 'everywhere',

    availableOptions: [

        { name: 'type', type: String, default: 'documents', aliases: ['t'], description: 'type of obejcts to downloads' },

        { name: 'url',  type: String, aliases: ['u'], description: 'Source url' },

        { name: 'dest', type: String, aliases: ['d'], description: 'File destination'  },

        { name: 'page', type: Number, default: 1 , aliases: ['p'], description: 'number of page to download'},

        { name: 'format', type: String, default: 'es6' , aliases: ['f'], description: 'Format for module export, es6 or require'}

    ],

    dl_themes: function(commandOptions) {

        var done = Q.defer();

        var that = this;

        request.get({url: commandOptions.url, json: true}, function (err, res, body) {

            var objectList = _.reduce(

                _.keys(body.themes),

                function(res, themeKey) {

                    var themeValue = body.themes[themeKey];

                    res.push({id: themeKey, count: themeValue.count, label: themeValue.label});

                    return res;

                },

                []

            );

            var prefix = (that.format==='es6')?'export default ':'module.exports = ';

            console.log(that.dest);

            fs.writeFile(that.dest, prefix + JSON.stringify(objectList,null,2) + ';', function(err) {

                if(err) {

                    return done.reject(err);

                }

                done.resolve();

            });

        });

        return done.promise;

    },

    dl_documents: function(commandOptions, rawArgs) { // eslint-disable-line no-unused-vars

        var ids = [];

        var pageIndex = 1;

        var nextPageUrl = commandOptions.url;

        return promiseWhile(

            function() { return pageIndex <= commandOptions.page && nextPageUrl; },

            function() {

                var deferred = Q.defer();

                request.get({url: nextPageUrl, json: true}, function (err, res, body) {

                    if (err) {

                        return deferred.reject(err);

                    } else if (res.statusCode !== 200) {

                        err = new Error('Unexpected status code: ' + res.statusCode);

                        err.res = res;

                        return deferred.reject(err);

                    }

                    nextPageUrl = body.next_page_url;

                    pageIndex++;

                    ids = _.reduce(

                        body.documents,

                        function(res, doc) {

                            res.push(doc.id);

                            return res;

                        },

                        ids

                    );

                    deferred.resolve(ids);

                });

                return deferred.promise;

            }

        ).then(function() {

            return Q.all(_.map(ids, function(id) {

                var deferred = Q.defer();

                request.get({url: commandOptions.url + id, json: true}, function (err, res, body) {

                    if (err) {

                        return deferred.reject(err);

                    } else if (res.statusCode !== 200) {

                        err = new Error('Unexpected status code: ' + res.statusCode);

                        err.res = res;

                        return deferred.reject(err);

                    }

                    deferred.resolve(body.document);

                });

                return deferred.promise;

            }));

        }).then(function(res) {

            var deferred = Q.defer();

            var prefix = (this.format==='es6')?'export default ':'module.exports = ';

            fs.writeFile(this.dest, prefix + JSON.stringify(res,null,2) + ';', function(err) {

                if(err) {

                    return deferred.reject(err);

                }

                deferred.resolve();

            });

            return deferred.promise;

    },

    run: function(commandOptions, rawArgs) { // eslint-disable-line no-unused-vars

        var type = commandOptions.type || 'documents';

        this.dest = commandOptions.dest || '.' + path.sep + type + '.js';

        this.format = commandOptions.format || 'es6';

        return this['dl_' + type](commandOptions, rawArgs);

    }

});