'use strict';

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

var chalk   = require('chalk');

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"},

  ],

  run: function(commandOptions, rawArgs) {

    //TODO: check that commandOptions.url is not empty

    var dest = commandOptions.dest || "." + path.sep + commandOptions.type + ".js"

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

    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 = (format==='es6')?'export default ':"module.exports = ";

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

        if(err) {

          return deferred.reject(err);

        }

        deferred.resolve();

      });

      return deferred.promise;

    });

  }

});