//     Emerson Sink
//
//     "sink - a body or process that acts to absorb or remove energy or a
//     particular component from a system."
//
//     Adds...

(function(ns) {

  // Emerson Extension
  // --------------------------------------------------------------------------

  // ### Emerson.sink module
  var define = ns.sink = function(view) {};

  // ### Module API
  //   * `ns` is a reference to the namespace.
  //   * `init` is a hook for initializing the module.
  _.extend(define, {
    ns     : ns,
    init   : function init() {}
  });


  // "Base" Libary Extension
  // --------------------------------------------------------------------------

  // Make a local copy of Emerson.base. e.g., one of jQuery, Zepto or Ender.
  var $ = ns.base;

  // ### $.fn.sink
  //
  //     $(target).sink()
  //
  // Given "replacement" content and for each "sink" (existing content):
  //
  //   1. fire "sink:before" with the sink as the target.
  //   2. replace the sink with a "prepared" replacement.
  //   3. fire "sink:after" with the replacement as the target.
  //
  // Note that, while this method will handle multiple sinks, it does so by
  // cloning the source, thereby breaking the chain.  It's probably a good idea
  // to have one-to-one matches, but the multiple match option could be good
  // for doing something along the lines of updating an avatar that is rendered
  // many times on the page.  The `sink:after` event may be used to manipulate
  // the resultant nodes.
  //
  // Pass an `override` argument to target a specific sink, say:
  //
  //     data-sink="modal"
  //
  // Strategies:
  //
  //   * `replace` (default)
  //   * `inner`
  //   * `prepend`
  //   * `append`
  //   * `before`
  //   * `after`
  //
  //     data-sink"modal:inner"
  //
  $.fn.sink = function(override) {
    _.each(this, function(e) {
      var element = $(e);
      var key     = override || element.data('sink');
      var selector, matches, count;

      if(key) {
        selector = '[data-sink^="' + key + '"]';
        matches  = $(selector);
        count    = matches.length;

        if(count) {
          process(element, matches);
        }
      }
    });

    return this;
  };


  // Internal Implementation
  // --------------------------------------------------------------------------

  var strategies = {
    replace : $.fn.replaceAll,
    inner   : function(target) {
      target.empty();
      return this.appendTo(target);
    },
    prepend : $.fn.prependTo,
    append  : $.fn.appendTo,
    before  : $.fn.insertBefore,
    after   : $.fn.insertAfter
  };

  // ### prepare
  // Clone the replacement source and, if Emerson.view is defined, apply that.
  function prepare(source) {
    var result = source;

    if(Emerson.view) {
      result.view();
    }

    return result;
  }

  // ### process
  // ...
  // TODO: DRY-up the update code.
  function process(element, matches) {
    var parts, strategy, clone;

    if(matches.length > 1) {
      matches.each(function(current) {
        current  = $(this);
        clone    = prepare(element.clone(true));
        parts    = current.data('sink').split(':');
        strategy = parts[1] || 'replace';

        current.trigger('sink:before');
        strategies[strategy]
          .call(clone, current)
          .each(forceCalculateStyle)
          .trigger('sink:after');

        clone.trigger('sink:after');
      });
    }
    else {
      parts    = matches.data('sink').split(':');
      strategy = parts[1] || 'replace';

      matches.trigger('sink:before');
      strategies[strategy]
        .call(prepare(element), matches)
        .each(forceCalculateStyle)
        .trigger('sink:after');
    }
  }

  // ### forceCalculateStyle
  //
  //     forceCalculateStyle.call(node)
  //
  // Given a DOM node, force style calculation. e.g., this might be useful for
  // establishing a render baseline to enable CSS animations. Note that the
  // particular property accessed is arbitrary.
  //
  // TODO: Add spec coverage (needs pre-/post-render and some CSS transition).
  //
  // Credits:
  //
  //     * Doug Rohrer & Rachel Heaton for the bug fix:
  //       <https://github.com/coreyti/emerson/pull/9>
  function forceCalculateStyle() {
    if(this.jquery) {
      window.getComputedStyle(this[0]).opacity;
    }
    else {
      window.getComputedStyle(this).opacity;
    }

    return this;
  }
})(Emerson);