/**
 * Module dependencies.
 */

var EventEmitter = require('events').EventEmitter
  , debug = require('debug')('runnable');

/**
 * Expose `Runnable`.
 */

module.exports = Runnable;

/**
 * Initialize a new `Runnable` with the given `title` and callback `fn`.
 *
 * @param {String} title
 * @param {Function} fn
 * @api private
 */

function Runnable(title, fn) {
  this.title = title;
  this.fn = fn;
  this.async = fn && fn.length;
  this.sync = ! this.async;
  this._timeout = 2000;
  this.timedOut = false;
  this.context = this;
}

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

Runnable.prototype.__proto__ = EventEmitter.prototype;

/**
 * Set & get timeout `ms`.
 *
 * @param {Number} ms
 * @return {Runnable|Number} ms or self
 * @api private
 */

Runnable.prototype.timeout = function(ms){
  if (0 == arguments.length) return this._timeout;
  debug('timeout %d', ms);
  this._timeout = ms;
  if (this.timer) this.resetTimeout();
  return this;
};

/**
 * Return the full title generated by recursively
 * concatenating the parent's full title.
 *
 * @return {String}
 * @api public
 */

Runnable.prototype.fullTitle = function(){
  return this.parent.fullTitle() + ' ' + this.title;
};

/**
 * Clear the timeout.
 *
 * @api private
 */

Runnable.prototype.clearTimeout = function(){
  clearTimeout(this.timer);
};

/**
 * Reset the timeout.
 *
 * @api private
 */

Runnable.prototype.resetTimeout = function(){
  var self = this
    , ms = this.timeout();

  this.clearTimeout();
  if (ms) {
    this.timer = setTimeout(function(){
      self.callback(new Error('timeout of ' + ms + 'ms exceeded'));
      self.timedOut = true;
    }, ms);
  }
};

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

Runnable.prototype.run = function(fn){
  var self = this
    , ms = this.timeout()
    , start = new Date
    , ctx = this.context
    , finished
    , emitted;

  // timeout
  if (this.async) {
    if (ms) {
      this.timer = setTimeout(function(){
        done(new Error('timeout of ' + ms + 'ms exceeded'));
        self.timedOut = true;
      }, ms);
    }
  }

  // called multiple times
  function multiple() {
    if (emitted) return;
    emitted = true;
    self.emit('error', new Error('done() called multiple times'));
  }

  // finished
  function done(err) {
    if (self.timedOut) return;
    if (finished) return multiple();
    self.clearTimeout();
    self.duration = new Date - start;
    finished = true;
    fn(err);
  }

  // for .resetTimeout()
  this.callback = done;

  // async
  if (this.async) {
    try {
      this.fn.call(ctx, function(err){
        if (err instanceof Error) return done(err);
        if (null != err) return done(new Error('done() invoked with non-Error: ' + err));
        done();
      });
    } catch (err) {
      done(err);
    }
    return;
  }
  
  // sync
  try {
    if (!this.pending) this.fn.call(ctx);
    this.duration = new Date - start;
    fn();
  } catch (err) {
    fn(err);
  }
};