var _ = require('lodash');
var zlib = require('zlib');
var tar = require('tar');
var request = require('request');
var mkdirp = require('mkdirp');
var fs = require('fs');
var join = require('path').join;
var filesPatern = _.template('node-v<%- version %>-<%- platform %>.tar.gz');
var urlPattern = _.template('http://nodejs.org/dist/v<%- version %>/<%- file %>');
var async = require('async');

module.exports = function (grunt) {
  grunt.registerTask('download_node_binaries', 'Download the node.js binaries', function () {
    var done = this.async();
    var platforms = _.without(grunt.config.get('platforms'), 'windows');
    var rootPath = grunt.config.get('root');
    var version = grunt.config.get('nodeVersion');

    var handle404 = function (response) {
      if (response.statusCode !== 200) {
        throw new Error(response.request.href + ' failed with a ' + response.statusCode);
      }
    };

    var downloadWindows = function (cb) {
      var dest = join(rootPath, '.node_binaries', 'windows');
      fs.stat(dest, function (err) {
        if (!err) return cb(); // skip downloading if we already have them
        var url = urlPattern({ version: version, file: 'node.exe'});
        mkdirp(dest, function (err) {
          if (err) return cb(err);
          var out = fs.createWriteStream(join(dest, 'node.exe'));
          out.on('close', cb).on('error', cb);
          var req = request.get(url);
          req.on('response', handle404);
          req.pipe(out);
        });
      });
    };

    var download = function (platform, cb) {
      var dest = join(rootPath, '.node_binaries', platform);
      fs.stat(dest, function (err) {
        if (!err) return cb(); // skip downloading if we already have them
        var file = filesPatern({ version: version, platform: platform });
        var url = urlPattern({ version: version, file: file });
        mkdirp(dest, function (err) {
          if (err) return cb(err);
          var unzip = zlib.createGunzip();
          var out = tar.Extract({ path: dest, strip: 1 });
          out.on('close', cb).on('error', cb);
          var req = request.get(url);
          req.on('response', handle404);
          req.pipe(unzip).pipe(out);
        });
      });
    };

    async.each(platforms, download, function (err) {
      if (err) return done(err);
      downloadWindows(done);
    });

  });
};