// Custom reveal.js integration
(function () {
  var revealElement = document.querySelector('.reveal');
  if (revealElement) {

    revealElement.addEventListener('mousedown', function (event) {
      var defaultModifier = /Linux/.test(window.navigator.platform) ? 'ctrl' : 'alt';

      var modifier = (Reveal.getConfig().zoomKey ? Reveal.getConfig().zoomKey : defaultModifier) + 'Key';
      var zoomLevel = (Reveal.getConfig().zoomLevel ? Reveal.getConfig().zoomLevel : 2);

      if (event[modifier] && !Reveal.isOverview()) {
        event.preventDefault();

        zoom.to({
          x: event.clientX,
          y: event.clientY,
          scale: zoomLevel,
          pan: false
        });
      }
    });

  }
})();

/*!
 * zoom.js 0.3 (modified for use with reveal.js)
 * http://lab.hakim.se/zoom-js
 * MIT licensed
 *
 * Copyright (C) 2011-2014 Hakim El Hattab, http://hakim.se
 */
var zoom = (function () {

  // The current zoom level (scale)
  var level = 1;

  // The current mouse position, used for panning
  var mouseX = 0,
    mouseY = 0;

  // Timeout before pan is activated
  var panEngageTimeout = -1,
    panUpdateInterval = -1;

  // Check for transform support so that we can fallback otherwise
  var supportsTransforms = 'WebkitTransform' in document.body.style ||
    'MozTransform' in document.body.style ||
    'msTransform' in document.body.style ||
    'OTransform' in document.body.style ||
    'transform' in document.body.style;

  if (supportsTransforms) {
    // The easing that will be applied when we zoom in/out
    document.body.style.transition = 'transform 0.8s ease';
    document.body.style.OTransition = '-o-transform 0.8s ease';
    document.body.style.msTransition = '-ms-transform 0.8s ease';
    document.body.style.MozTransition = '-moz-transform 0.8s ease';
    document.body.style.WebkitTransition = '-webkit-transform 0.8s ease';
  }

  // Zoom out if the user hits escape
  document.addEventListener('keyup', function (event) {
    if (level !== 1 && event.keyCode === 27) {
      zoom.out();
    }
  });

  // Monitor mouse movement for panning
  document.addEventListener('mousemove', function (event) {
    if (level !== 1) {
      mouseX = event.clientX;
      mouseY = event.clientY;
    }
  });

  /**
   * Applies the CSS required to zoom in, prefers the use of CSS3
   * transforms but falls back on zoom for IE.
   *
   * @param {Object} rect
   * @param {Number} scale
   */
  function magnify(rect, scale) {

    var scrollOffset = getScrollOffset();

    // Ensure a width/height is set
    rect.width = rect.width || 1;
    rect.height = rect.height || 1;

    // Center the rect within the zoomed viewport
    rect.x -= (window.innerWidth - (rect.width * scale)) / 2;
    rect.y -= (window.innerHeight - (rect.height * scale)) / 2;

    if (supportsTransforms) {
      // Reset
      if (scale === 1) {
        document.body.style.transform = '';
        document.body.style.OTransform = '';
        document.body.style.msTransform = '';
        document.body.style.MozTransform = '';
        document.body.style.WebkitTransform = '';
      }
      // Scale
      else {
        var origin = scrollOffset.x + 'px ' + scrollOffset.y + 'px',
          transform = 'translate(' + -rect.x + 'px,' + -rect.y + 'px) scale(' + scale + ')';

        document.body.style.transformOrigin = origin;
        document.body.style.OTransformOrigin = origin;
        document.body.style.msTransformOrigin = origin;
        document.body.style.MozTransformOrigin = origin;
        document.body.style.WebkitTransformOrigin = origin;

        document.body.style.transform = transform;
        document.body.style.OTransform = transform;
        document.body.style.msTransform = transform;
        document.body.style.MozTransform = transform;
        document.body.style.WebkitTransform = transform;
      }
    } else {
      // Reset
      if (scale === 1) {
        document.body.style.position = '';
        document.body.style.left = '';
        document.body.style.top = '';
        document.body.style.width = '';
        document.body.style.height = '';
        document.body.style.zoom = '';
      }
      // Scale
      else {
        document.body.style.position = 'relative';
        document.body.style.left = (-(scrollOffset.x + rect.x) / scale) + 'px';
        document.body.style.top = (-(scrollOffset.y + rect.y) / scale) + 'px';
        document.body.style.width = (scale * 100) + '%';
        document.body.style.height = (scale * 100) + '%';
        document.body.style.zoom = scale;
      }
    }

    level = scale;

    if (document.documentElement.classList) {
      if (level !== 1) {
        document.documentElement.classList.add('zoomed');
      } else {
        document.documentElement.classList.remove('zoomed');
      }
    }
  }

  /**
   * Pan the document when the mosue cursor approaches the edges
   * of the window.
   */
  function pan() {
    var range = 0.12,
      rangeX = window.innerWidth * range,
      rangeY = window.innerHeight * range,
      scrollOffset = getScrollOffset();

    // Up
    if (mouseY < rangeY) {
      window.scroll(scrollOffset.x, scrollOffset.y - (1 - (mouseY / rangeY)) * (14 / level));
    }
    // Down
    else if (mouseY > window.innerHeight - rangeY) {
      window.scroll(scrollOffset.x, scrollOffset.y + (1 - (window.innerHeight - mouseY) / rangeY) * (14 / level));
    }

    // Left
    if (mouseX < rangeX) {
      window.scroll(scrollOffset.x - (1 - (mouseX / rangeX)) * (14 / level), scrollOffset.y);
    }
    // Right
    else if (mouseX > window.innerWidth - rangeX) {
      window.scroll(scrollOffset.x + (1 - (window.innerWidth - mouseX) / rangeX) * (14 / level), scrollOffset.y);
    }
  }

  function getScrollOffset() {
    return {
      x: window.scrollX !== undefined ? window.scrollX : window.pageXOffset,
      y: window.scrollY !== undefined ? window.scrollY : window.pageYOffset
    }
  }

  return {
    /**
     * Zooms in on either a rectangle or HTML element.
     *
     * @param {Object} options
     *   - element: HTML element to zoom in on
     *   OR
     *   - x/y: coordinates in non-transformed space to zoom in on
     *   - width/height: the portion of the screen to zoom in on
     *   - scale: can be used instead of width/height to explicitly set scale
     */
    to: function (options) {

      // Due to an implementation limitation we can't zoom in
      // to another element without zooming out first
      if (level !== 1) {
        zoom.out();
      } else {
        options.x = options.x || 0;
        options.y = options.y || 0;

        // If an element is set, that takes precedence
        if (!!options.element) {
          // Space around the zoomed in element to leave on screen
          var padding = 20;
          var bounds = options.element.getBoundingClientRect();

          options.x = bounds.left - padding;
          options.y = bounds.top - padding;
          options.width = bounds.width + (padding * 2);
          options.height = bounds.height + (padding * 2);
        }

        // If width/height values are set, calculate scale from those values
        if (options.width !== undefined && options.height !== undefined) {
          options.scale = Math.max(Math.min(window.innerWidth / options.width, window.innerHeight / options.height), 1);
        }

        if (options.scale > 1) {
          options.x *= options.scale;
          options.y *= options.scale;

          magnify(options, options.scale);

          if (options.pan !== false) {

            // Wait with engaging panning as it may conflict with the
            // zoom transition
            panEngageTimeout = setTimeout(function () {
              panUpdateInterval = setInterval(pan, 1000 / 60);
            }, 800);

          }
        }
      }
    },

    /**
     * Resets the document zoom state to its default.
     */
    out: function () {
      clearTimeout(panEngageTimeout);
      clearInterval(panUpdateInterval);

      magnify({x: 0, y: 0}, 1);

      level = 1;
    },

    // Alias
    magnify: function (options) {
      this.to(options)
    },
    reset: function () {
      this.out()
    },

    zoomLevel: function () {
      return level;
    }
  }

})();