/**
 * Module dependencies.
 */

var EventEmitter = require('events').EventEmitter
  , debug = require('debug')('runner')
  , Test = require('./test')
  , utils = require('./utils')
  , noop = function(){};

/**
 * Expose `Runner`.
 */

module.exports = Runner;

/**
 * Initialize a `Runner` for the given `suite`.
 *
 * Events:
 *
 *   - `start`  execution started
 *   - `end`  execution complete
 *   - `suite`  (suite) test suite execution started
 *   - `suite end`  (suite) all tests (and sub-suites) have finished
 *   - `test`  (test) test execution started
 *   - `test end`  (test) test completed
 *   - `hook`  (hook) hook execution started
 *   - `hook end`  (hook) hook complete
 *   - `pass`  (test) test passed
 *   - `fail`  (test, err) test failed
 *
 * @api public
 */

function Runner(suite) {
  var self = this;
  this._globals = [];
  this.suite = suite;
  this.total = suite.total();
  this.failures = 0;
  this.on('test end', function(test){ self.checkGlobals(test); });
  this.on('hook end', function(hook){ self.checkGlobals(hook); });
  this.grep(/.*/);
  this.globals(utils.keys(global).concat(['errno']));
}

/**
 * Inherit from `EventEmitter.prototype`.
 */

Runner.prototype.__proto__ = EventEmitter.prototype;

/**
 * Run tests with full titles matching `re`.
 *
 * @param {RegExp} re
 * @return {Runner} for chaining
 * @api public
 */

Runner.prototype.grep = function(re){
  debug('grep %s', re);
  this._grep = re;
  return this;
};

/**
 * Allow the given `arr` of globals.
 *
 * @param {Array} arr
 * @return {Runner} for chaining
 * @api public
 */

Runner.prototype.globals = function(arr){
  if (0 == arguments.length) return this._globals;
  debug('globals %j', arr);
  utils.forEach(arr, function(arr){
    this._globals.push(arr);
  }, this);
  return this;
};

/**
 * Check for global variable leaks.
 *
 * @api private
 */

Runner.prototype.checkGlobals = function(test){
  if (this.ignoreLeaks) return;

  var leaks = utils.filter(utils.keys(global), function(key){
    return !~utils.indexOf(this._globals, key) && (!global.navigator || 'onerror' !== key);
  }, this);

  this._globals = this._globals.concat(leaks);

  if (leaks.length > 1) {
    this.fail(test, new Error('global leaks detected: ' + leaks.join(', ') + ''));
  } else if (leaks.length) {
    this.fail(test, new Error('global leak detected: ' + leaks[0]));
  }
};

/**
 * Fail the given `test`.
 *
 * @param {Test} test
 * @param {Error} err
 * @api private
 */

Runner.prototype.fail = function(test, err){
  ++this.failures;
  test.failed = true;
  this.emit('fail', test, err);
};

/**
 * Fail the given `hook` with `err`.
 *
 * Hook failures (currently) hard-end due
 * to that fact that a failing hook will
 * surely cause subsequent tests to fail,
 * causing jumbled reporting.
 *
 * @param {Hook} hook
 * @param {Error} err
 * @api private
 */

Runner.prototype.failHook = function(hook, err){
  this.fail(hook, err);
  this.emit('end');
};

/**
 * Run hook `name` callbacks and then invoke `fn()`.
 *
 * @param {String} name
 * @param {Function} function
 * @api private
 */

Runner.prototype.hook = function(name, fn){
  var suite = this.suite
    , hooks = suite['_' + name]
    , ms = suite._timeout
    , self = this
    , timer;

  function next(i) {
    var hook = hooks[i];
    if (!hook) return fn();
    self.currentRunnable = hook;
    hook.context = self.test;

    self.emit('hook', hook);

    hook.on('error', function(err){
      self.failHook(hook, err);
    });

    hook.run(function(err){
      hook.removeAllListeners('error');
      if (err) return self.failHook(hook, err);
      self.emit('hook end', hook);
      next(++i);
    });
  }

  process.nextTick(function(){
    next(0);
  });
};

/**
 * Run hook `name` for the given array of `suites`
 * in order, and callback `fn(err)`.
 *
 * @param {String} name
 * @param {Array} suites
 * @param {Function} fn
 * @api private
 */

Runner.prototype.hooks = function(name, suites, fn){
  var self = this
    , orig = this.suite;

  function next(suite) {
    self.suite = suite;

    if (!suite) {
      self.suite = orig;
      return fn();
    }

    self.hook(name, function(err){
      if (err) {
        self.suite = orig;
        return fn(err);
      }

      next(suites.pop());
    });
  }

  next(suites.pop());
};

/**
 * Run hooks from the top level down.
 *
 * @param {String} name
 * @param {Function} fn
 * @api private
 */

Runner.prototype.hookUp = function(name, fn){
  var suites = [this.suite].concat(this.parents()).reverse();
  this.hooks(name, suites, fn);
};

/**
 * Run hooks from the bottom up.
 *
 * @param {String} name
 * @param {Function} fn
 * @api private
 */

Runner.prototype.hookDown = function(name, fn){
  var suites = [this.suite].concat(this.parents());
  this.hooks(name, suites, fn);
};

/**
 * Return an array of parent Suites from
 * closest to furthest.
 *
 * @return {Array}
 * @api private
 */

Runner.prototype.parents = function(){
  var suite = this.suite
    , suites = [];
  while (suite = suite.parent) suites.push(suite);
  return suites;
};

/**
 * Run the current test and callback `fn(err)`.
 *
 * @param {Function} fn
 * @api private
 */

Runner.prototype.runTest = function(fn){
  var test = this.test
    , self = this;

  try {
    test.on('error', function(err){
      self.fail(test, err);
    });
    test.run(fn);
  } catch (err) {
    fn(err);
  }
};

/**
 * Run tests in the given `suite` and invoke
 * the callback `fn()` when complete.
 *
 * @param {Suite} suite
 * @param {Function} fn
 * @api private
 */

Runner.prototype.runTests = function(suite, fn){
  var self = this
    , tests = suite.tests
    , test;

  function next(err) {
    // if we bail after first err
    if (self.failures && suite._bail) return fn();

    // next test
    test = tests.shift();

    // all done
    if (!test) return fn();

    // grep
    if (!self._grep.test(test.fullTitle())) return next();

    // pending
    if (test.pending) {
      self.emit('pending', test);
      self.emit('test end', test);
      return next();
    }

    // execute test and hook(s)
    self.emit('test', self.test = test);
    self.hookDown('beforeEach', function(){
      self.currentRunnable = self.test;
      self.runTest(function(err){
        test = self.test;

        if (err) {
          self.fail(test, err);
          self.emit('test end', test);
          return self.hookUp('afterEach', next);
        }

        test.passed = true;
        self.emit('pass', test);
        self.emit('test end', test);
        self.hookUp('afterEach', next);
      });
    });
  }

  this.next = next;
  next();
};

/**
 * Run the given `suite` and invoke the
 * callback `fn()` when complete.
 *
 * @param {Suite} suite
 * @param {Function} fn
 * @api private
 */

Runner.prototype.runSuite = function(suite, fn){
  var self = this
    , i = 0;

  debug('run suite %s', suite.fullTitle());
  this.emit('suite', this.suite = suite);

  function next() {
    var curr = suite.suites[i++];
    if (!curr) return done();
    self.runSuite(curr, next);
  }

  function done() {
    self.suite = suite;
    self.hook('afterAll', function(){
      self.emit('suite end', suite);
      fn();
    });
  }

  this.hook('beforeAll', function(){
    self.runTests(suite, next);
  });
};

/**
 * Handle uncaught exceptions.
 *
 * @param {Error} err
 * @api private
 */

Runner.prototype.uncaught = function(err){
  debug('uncaught exception');
  var runnable = this.currentRunnable;
  if (runnable.failed) return;
  runnable.clearTimeout();
  err.uncaught = true;
  this.fail(runnable, err);

  // recover from test
  if ('test' == runnable.type) {
    this.emit('test end', runnable);
    this.hookUp('afterEach', this.next);
    return;
  }

  // bail on hooks
  this.emit('end');
};

/**
 * Run the root suite and invoke `fn(failures)`
 * on completion.
 *
 * @param {Function} fn
 * @return {Runner} for chaining
 * @api public
 */

Runner.prototype.run = function(fn){
  var self = this
    , fn = fn || function(){};

  debug('start');

  // callback
  this.on('end', function(){
    debug('end');
    process.removeListener('uncaughtException', this.uncaught);
    fn(self.failures);
  });

  // run suites
  this.emit('start');
  this.runSuite(this.suite, function(){
    debug('finished running');
    self.emit('end');
  });

  // uncaught exception
  process.on('uncaughtException', function(err){
    self.uncaught(err);
  });

  return this;
};