/**
 * This plugin provides a method to animate a sigma instance by interpolating
 * some node properties. Check the sigma.plugins.animate function doc or the
 * examples/animate.html code sample to know more.
 */
(function() {
  'use strict';

  if (typeof sigma === 'undefined')
    throw 'sigma is not declared';

  sigma.utils.pkg('sigma.plugins');

  var _id = 0,
      _cache = {};

  // TOOLING FUNCTIONS:
  // ******************
  function parseColor(val) {
    if (_cache[val])
      return _cache[val];

    var result = [0, 0, 0];

    if (val.match(/^#/)) {
      val = (val || '').replace(/^#/, '');
      result = (val.length === 3) ?
        [
          parseInt(val.charAt(0) + val.charAt(0), 16),
          parseInt(val.charAt(1) + val.charAt(1), 16),
          parseInt(val.charAt(2) + val.charAt(2), 16)
        ] :
        [
          parseInt(val.charAt(0) + val.charAt(1), 16),
          parseInt(val.charAt(2) + val.charAt(3), 16),
          parseInt(val.charAt(4) + val.charAt(5), 16)
        ];
    } else if (val.match(/^ *rgba? *\(/)) {
      val = val.match(
        /^ *rgba? *\( *([0-9]*) *, *([0-9]*) *, *([0-9]*) *(,.*)?\) *$/
      );
      result = [
        +val[1],
        +val[2],
        +val[3]
      ];
    }

    _cache[val] = {
      r: result[0],
      g: result[1],
      b: result[2]
    };

    return _cache[val];
  }

  function interpolateColors(c1, c2, p) {
    c1 = parseColor(c1);
    c2 = parseColor(c2);

    var c = {
      r: c1.r * (1 - p) + c2.r * p,
      g: c1.g * (1 - p) + c2.g * p,
      b: c1.b * (1 - p) + c2.b * p
    };

    return 'rgb(' + [c.r | 0, c.g | 0, c.b | 0].join(',') + ')';
  }

  /**
   * This function will animate some specified node properties. It will
   * basically call requestAnimationFrame, interpolate the values and call the
   * refresh method during a specified duration.
   *
   * Events fired though sigma instance:
   * *************
   * animate.start  Fired at the beginning of the animation.
   * animate.end    Fired at the end of the animation.
   *
   * Recognized parameters:
   * **********************
   * Here is the exhaustive list of every accepted parameters in the settings
   * object:
   *
   *   {?array}             nodes      An array of node objects or node ids. If
   *                                   not specified, all nodes of the graph
   *                                   will be animated.
   *   {?(function|string)} easing     Either the name of an easing in the
   *                                   sigma.utils.easings package or a
   *                                   function. If not specified, the
   *                                   quadraticInOut easing from this package
   *                                   will be used instead.
   *   {?number}            duration   The duration of the animation. If not
   *                                   specified, the "animationsTime" setting
   *                                   value of the sigma instance will be used
   *                                   instead.
   *   {?function}          onComplete Eventually a function to call when the
   *                                   animation is ended.
   *
   * @param  {sigma}   s       The related sigma instance.
   * @param  {object}  animate An hash with the keys being the node properties
   *                           to interpolate, and the values being the related
   *                           target values.
   * @param  {?object} options Eventually an object with options.
   */
  sigma.plugins.animate = function(s, animate, options) {
    var o = options || {},
        id = ++_id,
        duration = o.duration || s.settings('animationsTime'),
        easing = typeof o.easing === 'string' ?
          sigma.utils.easings[o.easing] :
          typeof o.easing === 'function' ?
          o.easing :
          sigma.utils.easings.quadraticInOut,
        start = sigma.utils.dateNow(),
        nodes,
        startPositions;

    if (o.nodes && o.nodes.length) {
      if (typeof o.nodes[0] === 'object')
        nodes = o.nodes;
      else
        nodes = s.graph.nodes(o.nodes); // argument is an array of IDs
    }
    else
      nodes = s.graph.nodes();

    // Store initial positions:
    startPositions = nodes.reduce(function(res, node) {
      var k;
      res[node.id] = {};
      for (k in animate)
        if (k in node)
          res[node.id][k] = node[k];
      return res;
    }, {});

    s.animations = s.animations || Object.create({});
    sigma.plugins.killAnimate(s);

    s.dispatchEvent('animate.start'); // send a sigma event

    function step() {
      var p = (sigma.utils.dateNow() - start) / duration;

      if (p >= 1) {
        nodes.forEach(function(node) {
          for (var k in animate)
            if (k in animate && animate[k] in node)
              node[k] = node[animate[k]];
        });

        s.refresh({skipIndexation: true});
        if (typeof o.onComplete === 'function') {
          o.onComplete();
        }
        s.dispatchEvent('animate.end'); // send a sigma event
      }
      else {
        p = easing(p);
        nodes.forEach(function(node) {
          for (var k in animate)
            if (k in animate && animate[k] in node) {
              if (k.match(/color$/))
                node[k] = interpolateColors(
                  startPositions[node.id][k],
                  node[animate[k]],
                  p
                );
              else
                node[k] =
                  node[animate[k]] * p +
                  startPositions[node.id][k] * (1 - p);
            }
        });

        s.refresh({skipIndexation: true});
        s.animations[id] = requestAnimationFrame(step);
      }
    }

    step();
  };

  sigma.plugins.killAnimate = function(s) {
    for (var k in (s.animations || {}))
      cancelAnimationFrame(s.animations[k]);
  };
}).call(window);