#!/usr/bin/env node
;(function() {
  'use strict';

  /** Load Node modules */
  var exec = require('child_process').exec,
      fs = require('fs'),
      https = require('https'),
      path = require('path'),
      tar = require('../vendor/tar/tar.js'),
      zlib = require('zlib');

  /** The path of the directory that is the base of the repository */
  var basePath = fs.realpathSync(path.join(__dirname, '..'));

  /** The path of the `vendor` directory */
  var vendorPath = path.join(basePath, 'vendor');

  /** The Git object ID of `closure-compiler.tar.gz` */
  var closureId = 'a2787b470c577cee2404d186c562dd9835f779f5';

  /** The Git object ID of `uglifyjs.tar.gz` */
  var uglifyId = '3390b259e04829538e4d3635d12b317dd6103eca';

  /** The media type for raw blob data */
  var mediaType = 'application/vnd.github.v3.raw';

  /** Used to reference parts of the blob href */
  var location = (function() {
    var host = 'api.github.com',
        origin = 'https://api.github.com',
        pathname = '/repos/bestiejs/lodash/git/blobs';

    return {
      'host': host,
      'href': host + origin + pathname,
      'origin': origin,
      'pathname': pathname
    };
  }());

  /*--------------------------------------------------------------------------*/

  /**
   * Fetches a required `.tar.gz` dependency with the given Git object ID from
   * the Lo-Dash repo on GitHub. The object ID may be obtained by running
   * `git hash-object path/to/dependency.tar.gz`.
   *
   * @private
   * @param {Object} options The options object.
   *  id - The Git object ID of the `.tar.gz` file.
   *  onComplete - The function, invoked with one argument (exception),
   *   called once the extraction has finished.
   *  path - The path of the extraction directory.
   *  title - The dependency's title used in status updates logged to the console.
   */
  function getDependency(options) {
    options || (options = {});

    var id = options.id,
        onComplete = options.onComplete,
        path = options.path,
        title = options.title;

    function callback(exception) {
      if (exception) {
        console.error([
          'There was a problem installing ' + title + '. To manually install, run:',
          '',
          "curl -H 'Accept: " + mediaType + "' " + location.href + '/' + id + " | tar xvz -C '" + path + "'"
        ].join('\n'));
      }
      onComplete(exception);
    }

    console.log('Downloading ' + title + '...');

    https.get({
      'host': location.host,
      'path': location.pathname + '/' + id,
      'headers': {
        // By default, all GitHub blob API endpoints return a JSON document
        // containing Base64-encoded blob data. Overriding the `Accept` header
        // with the GitHub raw media type returns the blob data directly.
        // See http://developer.github.com/v3/media/.
        'Accept': mediaType
      }
    }, function(response) {
      var decompressor = zlib.createUnzip(),
          parser = new tar.Extract({ 'path': path });

      decompressor.on('error', callback)
      parser.on('end', callback).on('error', callback);
      response.pipe(decompressor).pipe(parser);
    })
    .on('error', callback);
  }

  /*--------------------------------------------------------------------------*/

  exec('npm -g root', function(exception, stdout) {
    if (!exception) {
      try {
        var isGlobal = path.resolve(basePath, '..') == fs.realpathSync(stdout.trim());
      } catch(e) {
        exception = e;
      }
    }
    if (exception) {
      console.error([
        'Oops! There was a problem detecting the install mode. If you’re installing the',
        'Lo-Dash command-line executable (via `npm install -g lodash`), you’ll need to',
        'manually install UglifyJS and the Closure Compiler by running:',
        '',
        "curl -H 'Accept: " + mediaType + "' " + location.href + '/' + closureId + " | tar xvz -C '" + vendorPath + "'",
        "curl -H 'Accept: " + mediaType + "' " + location.href + '/' + uglifyId  + " | tar xvz -C '" + vendorPath + "'",
        '',
        'Please submit an issue on the GitHub issue tracker: ' + process.env.npm_package_bugs_url
      ].join('\n'));

      console.error(exception);
    }
    if (!isGlobal) {
      return;
    }
    // download the Closure Compiler
    getDependency({
      'title': 'the Closure Compiler',
      'id': closureId,
      'path': vendorPath,
      'onComplete': function() {
        // download UglifyJS
        getDependency({
          'title': 'UglifyJS',
          'id': uglifyId,
          'path': vendorPath,
          'onComplete': function() {
            process.exit();
          }
        });
      }
    });
  });
}());