/*
 * jquery.tappable.js version 0.2
 *
 * More responsive (iOS-like) touch behaviour for buttons and other 'tappable' UI
 * elements, instead of Mobile Safari's 300ms delay and ugly grey overlay:
 *
 *  - A 'touched' class is added to the element as soon as it is tapped (or, in
 *    the case of a "long tap" - when the user keeps their finger down for a
 *    moment - after a specified delay).
 *
 *  - The supplied callback is called as soon as the user lifts their finger.
 *
 *  - The class is removed, and firing of the callback cancelled, if the user moves
 *    their finger (though this can be disabled).
 *
 *  - If the browser doesn't support touch events, it falls back to click events.
 *
 * More detailed explanation of behaviour and background:
 * http://aanandprasad.com/articles/jquery-tappable/
 *
 * See it in action here: http://nnnnext.com
 *
 * I recommend that you add a `-webkit-tap-highlight-color: rgba(0,0,0,0)`
 * style rule to any elements you wish to make tappable, to hide the ugly grey
 * click overlay.
 *
 * Tested on iOS 4.3 and some version of Android, I don't know. Leave me alone.
 *
 * Basic usage:
 *
 *   $(element).tappable(function() { console.log("Hello World!") })
 *
 * Advanced usage:
 *
 *   $(element).tappable({
 *     callback:     function() { console.log("Hello World!") },
 *     cancelOnMove: false,
 *     touchDelay:   150,
 *     onlyIf:       function(el) { return $(el).hasClass('enabled') }
 *   })
 *
 * Options:
 *
 *   cancelOnMove: If truthy, then as soon as the user moves their finger, the
 *                 'touched' class is removed from the element. When they lift
 *                 their finger, the callback will *not* be fired. Defaults to
 *                 true.
 *
 *   touchDelay:   Time to wait (ms) before adding the 'touched' class when the
 *                 user performs a "long tap". Best employed on elements that the
 *                 user is likely to touch while scrolling. Around 150 will work
 *                 well. Defaults to 0.
 *   
 *   onlyIf:       Function to run as soon as the user touches the element, to
 *                 determine whether to do anything. If it returns a falsy value,
 *                 the 'touched' class will not be added and the callback will
 *                 not be fired.
 *
 */

;(function($) {
  var touchSupported = ('ontouchstart' in window)

  $.fn.tappable = function(options) {
    var cancelOnMove = true,
        onlyIf = function() { return true },
        touchDelay = 0,
        callback

    switch(typeof options) {
      case 'function':
        callback = options
        break;
      case 'object':
        callback = options.callback

        if (typeof options.cancelOnMove != 'undefined') {
          cancelOnMove = options.cancelOnMove
        }

        if (typeof options.onlyIf != 'undefined') {
          onlyIf = options.onlyIf
        }

        if (typeof options.touchDelay != 'undefined') {
          touchDelay = options.touchDelay
        }

        break;
    }

    var fireCallback = function(el, event) {
      if (typeof callback == 'function' && onlyIf(el)) {
        callback.call(el, event)
      }
    }

    if (touchSupported) {
      this.bind('touchstart', function(event) {
        var el = this

        if (onlyIf(this)) {
          $(el).addClass('touch-started')

          window.setTimeout(function() {
            if ($(el).hasClass('touch-started')) {
              $(el).addClass('touched')
            }
          }, touchDelay)
        }

        return true
      })

      this.bind('touchend', function(event) {
        var el = this

        if ($(el).hasClass('touch-started')) {
          $(el)
            .removeClass('touched')
            .removeClass('touch-started')

          fireCallback(el, event)
        }

        return true
      })

      this.bind('click', function(event) {
        event.preventDefault()
      })

      if (cancelOnMove) {
        this.bind('touchmove', function() {
          $(this)
            .removeClass('touched')
            .removeClass('touch-started')
        })
      }
    } else if (typeof callback == 'function') {
      this.bind('click', function(event) {
        if (onlyIf(this)) {
          callback.call(this, event)
        }
      })
    }

    return this
  }
})(jQuery);