(function($) {
  $.fn.connections = function(options) {
    if (options === "update") {
      return processConnections(update, this);
    } else if (options === "remove") {
      return processConnections(destroy, this);
    } else {
      options = $.extend(
        true,
        {
          borderClasses: {},
          class: "connection",
          css: {},
          from: this,
          tag: "connection",
          to: this,
          within: ":root"
        },
        options
      );
      connect(options);
      return this;
    }
  };

  $.event.special.connections = {
    teardown: function(namespaces) {
      processConnections(destroy, $(this));
    }
  };

  var connect = function(options) {
    var borderClasses = options.borderClasses;
    var tag = options.tag;
    var end1 = $(options.from);
    var end2 = $(options.to);
    var within = $(options.within);
    delete options.borderClasses;
    delete options.tag;
    delete options.from;
    delete options.to;
    delete options.within;
    within.each(function() {
      var container = this;
      var done = new Array();
      end1.each(function() {
        var node = this;
        done.push(this);
        end2.not(done).each(function() {
          createConnection(
            container,
            [node, this],
            tag,
            borderClasses,
            options
          );
        });
      });
    });
  };

  var createConnection = function(
    container,
    nodes,
    tag,
    borderClasses,
    options
  ) {
    var css = $.extend({ position: "absolute" }, options.css);
    var connection = $("<" + tag + "/>", options).css(css);
    connection.appendTo(container);

    var border_w = (connection.outerWidth() - connection.innerWidth()) / 2;
    var border_h = (connection.outerHeight() - connection.innerHeight()) / 2;

    if (border_w <= 0 && border_h <= 0) {
      border_w = border_h = 1;
    }

    var data = {
      borderClasses: borderClasses,
      border_h: border_h,
      border_w: border_w,
      node_from: $(nodes[0]),
      node_to: $(nodes[1]),
      nodes_dom: nodes,
      css: css
    };

    if ("none" === connection.css("border-top-style")) {
      data.css.borderStyle = "solid";
    }
    $.data(connection.get(0), "connection", data);
    $.data(connection.get(0), "connections", [connection.get(0)]);
    for (var i = 0; i < 2; i++) {
      var connections = connection.add($.data(nodes[i], "connections")).get();
      $.data(nodes[i], "connections", connections);
      if (connections.length == 1) {
        $(nodes[i]).on("connections.connections", false);
      }
    }
    update(connection.get(0));
  };

  var destroy = function(connection) {
    var nodes = $.data(connection, "connection").nodes_dom;
    for (var i = 0; i < 2; i++) {
      var connections = $($.data(nodes[i], "connections"))
        .not(connection)
        .get();
      $.data(nodes[i], "connections", connections);
    }
    $(connection).remove();
  };

  var getState = function(data) {
    data.rect_from = data.nodes_dom[0].getBoundingClientRect();
    data.rect_to = data.nodes_dom[1].getBoundingClientRect();
    var cached = data.cache;
    data.cache = [
      data.rect_from.top,
      data.rect_from.right,
      data.rect_from.bottom,
      data.rect_from.left,
      data.rect_to.top,
      data.rect_to.right,
      data.rect_to.bottom,
      data.rect_to.left
    ];
    data.hidden =
      0 === (data.cache[0] | data.cache[1] | data.cache[2] | data.cache[3]) ||
      0 === (data.cache[4] | data.cache[5] | data.cache[6] | data.cache[7]);
    data.unmodified = true;
    if (cached === undefined) {
      return (data.unmodified = false);
    }
    for (var i = 0; i < 8; i++) {
      if (cached[i] !== data.cache[i]) {
        return (data.unmodified = false);
      }
    }
  };

  var update = function(connection) {
    var data = $.data(connection, "connection");
    getState(data);
    if (data.unmodified) {
      return;
    }
    var border_h = data.border_h;
    var border_w = data.border_w;
    var from = data.rect_from;
    var to = data.rect_to;
    var b = (from.bottom + from.top) / 2;
    var r = (to.left + to.right) / 2;
    var t = (to.bottom + to.top) / 2;
    var l = (from.left + from.right) / 2;

    var h = ["right", "left"];
    if (l > r) {
      h = ["left", "right"];
      var x = Math.max(r - border_w / 2, Math.min(from.right, to.right));
      r = l + border_w / 2;
      l = x;
    } else {
      l -= border_w / 2;
      r = Math.min(r + border_w / 2, Math.max(from.left, to.left));
    }
    var v = ["bottom", "top"];
    if (t > b) {
      v = ["top", "bottom"];
      var x = Math.max(b - border_h / 2, Math.min(from.bottom, to.bottom));
      b = t + border_h / 2;
      t = x;
    } else {
      b = Math.min(b, Math.max(from.top, to.top));
      t -= border_h / 2;
    }
    var width = r - l;
    var height = b - t;
    if (width < border_w) {
      t = Math.max(t, Math.min(from.bottom, to.bottom));
      b = Math.min(b, Math.max(from.top, to.top));
      l = Math.max(from.left, to.left);
      r = Math.min(from.right, to.right);
      r = l = (l + r - border_w) / 2;
    }
    if (height < border_h) {
      l = Math.max(l, Math.min(from.right, to.right));
      r = Math.min(r, Math.max(from.left, to.left));
      t = Math.max(from.top, to.top);
      b = Math.min(from.bottom, to.bottom);
      b = t = (t + b - border_h) / 2;
    }
    width = r - l;
    height = b - t;
    width <= 0 && (border_h = 0);
    height <= 0 && (border_w = 0);
    var style =
      "border-" +
      v[0] +
      "-" +
      h[0] +
      "-radius: 0;" +
      "border-" +
      v[0] +
      "-" +
      h[1] +
      "-radius: 0;" +
      "border-" +
      v[1] +
      "-" +
      h[0] +
      "-radius: 0;";
    (border_h <= 0 || border_w <= 0) &&
      (style += "border-" + v[1] + "-" + h[1] + "-radius: 0;");
    if (data.hidden) {
      style += "display: none;";
    } else {
      data.css["border-" + v[0] + "-width"] = 0;
      data.css["border-" + h[0] + "-width"] = 0;
      data.css["border-" + v[1] + "-width"] = border_h;
      data.css["border-" + h[1] + "-width"] = border_w;
      var current_rect = connection.getBoundingClientRect();
      data.css.left = connection.offsetLeft + l - current_rect.left;
      data.css.top = connection.offsetTop + t - current_rect.top;
      data.css.width = width - border_w;
      data.css.height = height - border_h;
    }
    var bc = data.borderClasses;
    $(connection)
      .removeClass(bc[v[0]])
      .removeClass(bc[h[0]])
      .addClass(bc[v[1]])
      .addClass(bc[h[1]])
      .attr("style", style)
      .css(data.css);
  };

  var processConnections = function(method, elements) {
    return elements.each(function() {
      var connections = $.data(this, "connections");
      if (connections instanceof Array) {
        for (var i = 0, len = connections.length; i < len; i++) {
          method(connections[i]);
        }
      }
    });
  };
})(jQuery);