var q = require('q');

/**
 * Execute the Runner's test cases through Mocha.
 *
 * @param {Runner} runner The current Protractor Runner.
 * @param {Array} specs Array of Directory Path Strings.
 * @return {q.Promise} Promise resolved with the test results
 */
exports.run = function(runner, specs) {
  var Mocha = require('mocha'),
      mocha = new Mocha(runner.getConfig().mochaOpts);

  var deferred = q.defer();

  // Mocha doesn't set up the ui until the pre-require event, so
  // wait until then to load mocha-webdriver adapters as well.
  mocha.suite.on('pre-require', function() {
    try {
      // We need to re-wrap all of the global functions, which selenium-webdriver/
      // testing only does when it is required. So first we must remove it from
      // the cache.
      delete require.cache[require.resolve('selenium-webdriver/testing')];
      var mochaAdapters = require('selenium-webdriver/testing');
      global.after = mochaAdapters.after;
      global.afterEach = mochaAdapters.afterEach;
      global.before = mochaAdapters.before;
      global.beforeEach = mochaAdapters.beforeEach;

      global.it = mochaAdapters.it;
      global.it.only = global.iit = mochaAdapters.iit;
      global.it.skip = global.xit = mochaAdapters.xit;
    } catch (err) {
      deferred.reject(err);
    }
  });

  mocha.loadFiles();

  runner.runTestPreparer().then(function() {

    specs.forEach(function(file) {
      mocha.addFile(file);
    });

    var testResult = [];

    var mochaRunner = mocha.run(function(failures) {
      try {
        var completed = q();
        if (runner.getConfig().onComplete) {
          completed = q(runner.getConfig().onComplete());
        }
        completed.then(function() {
          deferred.resolve({
            failedCount: failures,
            specResults: testResult
          });
        });
      } catch (err) {
        deferred.reject(err);
      }
    });

    mochaRunner.on('pass', function(test) {
      var testInfo = {
        name: test.title,
        category: test.fullTitle().slice(0, -test.title.length).trim()
      };
      runner.emit('testPass', testInfo);
      testResult.push({
        description: test.title,
        assertions: [{
          passed: true
        }],
        duration: test.duration
      });
    });

    mochaRunner.on('fail', function(test) {
      var testInfo = {
        name: test.title,
        category: test.fullTitle().slice(0, -test.title.length).trim()
      };
      runner.emit('testFail', testInfo);
      testResult.push({
        description: test.title,
        assertions: [{
          passed: false,
          errorMsg: test.err.message,
          stackTrace: test.err.stack
        }],
        duration: test.duration
      });
    });
  }).catch (function(reason) {
      deferred.reject(reason);
  });

  return deferred.promise;
};