/* ***** BEGIN LICENSE BLOCK ***** {{{
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Spatial Navigation.
 *
 * The Initial Developer of the Original Code is Mozilla Corporation
 * Portions created by the Initial Developer are Copyright (C) 2008
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  Doug Turner <dougt@meer.net>  (Original Author)
 *  anekos <anekos@snca.net>  (Vimperator plugin version Author)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** }}} */

/* Original version is "SpatialNavigation.js" of Firefox. */

// PLUGIN_INFO {{{
let PLUGIN_INFO =
<VimperatorPlugin>
  <name>Spatial Navigation</name>
  <name lang="ja">空間ナビゲーション</name>
  <description>Spatial Navigation</description>
  <description lang="ja">空間ナビゲーション</description>
  <version>1.0.0</version>
  <updateURL>https://github.com/vimpr/vimperator-plugins/raw/master/spatial-navigation.js</updateURL>
  <minVersion>2.3</minVersion>
  <maxVersion>2.3</maxVersion>
  <detail><![CDATA[
    Read the help. (:help SpatialNavigation-plugin)
  ]]></detail>
  <detail lang="ja"><![CDATA[
    Read the help. (:help SpatialNavigation-plugin)
  ]]></detail>
</VimperatorPlugin>;
// }}}
// INFO {{{
let INFO =
<>
  <plugin name="SpatialNavigation" version="1.0.0"
          href="http://github.com/vimpr/vimperator-plugins/blob/master/spatial-navigation.js"
          summary="Spatial navigation"
          lang="en-US"
          xmlns="http://vimperator.org/namespaces/liberator">
    <project name="Vimperator" minVersion="2.3"/>
    <item>
      <tags>g:spatial_navigation_mappings</tags>
      <spec>let g:spatial_navigation_mappings=<a>keys</a></spec>
      <description>
        <p>
        </p>
        <code><ex>
let g:spatial_navigation_mappings="&lt;A-h> &lt;A-j> &lt;A-k> &lt;A-l>"
        </ex></code>
      </description>
    </item>
  </plugin>
  <plugin name="SpatialNavigation" version="1.0.0"
          href="http://github.com/vimpr/vimperator-plugins/blob/master/spatial-navigation.js"
          summary="空間ナビゲーション"
          lang="ja"
          xmlns="http://vimperator.org/namespaces/liberator">
    <project name="Vimperator" minVersion="2.3"/>
    <item>
      <tags>g:spatial_navigation_mappings</tags>
      <spec>let g:spatial_navigation_mappings=<a>keys</a></spec>
      <description>
        <p>
        </p>
        <code><ex>
let g:spatial_navigation_mappings="&lt;A-h> &lt;A-j> &lt;A-k> &lt;A-l>"
        </ex></code>
      </description>
    </item>
  </plugin>
</>;
// }}}


(function () {

  // constant {{{

  const DIR = {L: 1, D: 2, U: 3, R: 4};
  const gDirectionalBias = 10;
  const gRectFudge = 1;

  // }}}

  // Functions {{{

  function getFocusedElement ()
    window.document.commandDispatcher.focusedElement;

  function flashFocusedElement () {
    const flasher =
      let (f = Cc['@mozilla.org/inspector/flasher;1'].createInstance(Ci.inIFlasher))
        (f.color = '#FF0000', f.thickness = 2, f);

    let elem = getFocusedElement();
    if (!elem)
      return;

    setTimeout(
      function () {
        flasher.drawElementOutline(elem);
        elem.addEventListener(
          'blur',
          function () {
            elem.removeEventListener(arguments.callee);
            flasher.repaintElement(elem);
          },
          false
        );
      },
      0
    );
  }

  function focusElement (elem) {
    // doc.defaultView.QueryInterface(Ci.nsIInterfaceRequestor).getInterface(Ci.nsIDOMWindowUtils).focus(bestElementToFocus);
    elem.focus();
    flashFocusedElement();
  }

  function defaultMove (dir) {
    if (dir === DIR.R || dir === DIR.D) {
      window.document.commandDispatcher.advanceFocus();
    } else {
      window.document.commandDispatcher.rewindFocus();
    }
    flashFocusedElement();
  }

  function move (dir, target) {
    // Subs {{{
    function isRectInDirection (dir, focusedRect, anotherRect) {
      switch (dir) {
        case DIR.L:
          return anotherRect.left < focusedRect.left;
        case DIR.R:
          return anotherRect.right > focusedRect.right;
        case DIR.U:
          return anotherRect.top < focusedRect.top;
        case DIR.D:
          return anotherRect.bottom > focusedRect.bottom
      }
      return false;
    }

    function inflateRect (rect, value) ({
      left: rect.left - value,
      top: rect.top - value,
      right: rect.right  + value,
      bottom: rect.bottom + value
    });

    function containsRect (a, b)
      ((b.left <= a.right) && (b.right >= a.left) && (b.top <= a.bottom) && (b.bottom >= a.top));

    function spatialDistance (dir, a, b) {
      let inlineNavigation = false;
      let mx, my, nx, ny;

      if (dir === DIR.L) {
        //  |---|
        //  |---|
        //
        //  |---|  |---|
        //  |---|  |---|
        //
        //  |---|
        //  |---|
        if (a.top > b.bottom) {
          // the b rect is above a.
          mx = a.left;
          my = a.top;
          nx = b.right;
          ny = b.bottom;
        } else if (a.bottom < b.top) {
          // the b rect is below a.
          mx = a.left;
          my = a.bottom;
          nx = b.right;
          ny = b.top;
        } else {
          mx = a.left;
          my = 0;
          nx = b.right;
          ny = 0;
        }
      } else if (dir === DIR.R) {
        //         |---|
        //         |---|
        //
        //  |---|  |---|
        //  |---|  |---|
        //
        //         |---|
        //         |---|
        if (a.top > b.bottom) {
          // the b rect is above a.
          mx = a.right;
          my = a.top;
          nx = b.left;
          ny = b.bottom;
        } else if (a.bottom < b.top) {
          // the b rect is below a.
          mx = a.right;
          my = a.bottom;
          nx = b.left;
          ny = b.top;
        } else {
          mx = a.right;
          my = 0;
          nx = b.left;
          ny = 0;
        }
      } else if (dir === DIR.U) {
        //  |---|  |---|  |---|
        //  |---|  |---|  |---|
        //
        //         |---|
        //         |---|
        if (a.left > b.right) {
          // the b rect is to the left of a.
          mx = a.left;
          my = a.top;
          nx = b.right;
          ny = b.bottom;
        } else if (a.right < b.left) {
          // the b rect is to the right of a
          mx = a.right;
          my = a.top;
          nx = b.left;
          ny = b.bottom;
        } else {
          // both b and a share some common x's.
          mx = 0;
          my = a.top;
          nx = 0;
          ny = b.bottom;
        }
      } else if (dir === DIR.D) {
        //         |---|
        //         |---|
        //
        //  |---|  |---|  |---|
        //  |---|  |---|  |---|
        if (a.left > b.right) {
          // the b rect is to the left of a.
          mx = a.left;
          my = a.bottom;
          nx = b.right;
          ny = b.top;
        } else if (a.right < b.left) {
          // the b rect is to the right of a
          mx = a.right;
          my = a.bottom;
          nx = b.left;
          ny = b.top;
        } else {
          // both b and a share some common x's.
          mx = 0;
          my = a.bottom;
          nx = 0;
          ny = b.top;
        }
      }

      let scopedRect = inflateRect(a, gRectFudge);

      if (dir === DIR.L || dir === DIR.R) {
        scopedRect.left = 0;
        scopedRect.right = Infinity;
        inlineNavigation = containsRect(scopedRect, b);
      } else if (dir === DIR.U || dir === DIR.D) {
        scopedRect.top = 0;
        scopedRect.bottom = Infinity;
        inlineNavigation = containsRect(scopedRect, b);
      }

      let d = Math.pow((mx - nx), 2) + Math.pow((my - ny), 2);

      // prefer elements directly aligned with the focused element
      if (inlineNavigation)
        d /= gDirectionalBias;

      return d;
    }
    // }}}

    let doc = target.ownerDocument;

    if (doc instanceof Ci.nsIDOMXULDocument)
      return ;

    // XXX いらないかも
    if (
      (target instanceof Ci.nsIDOMHTMLInputElement && (target.type == "text" || target.type == "password"))
      ||
      target instanceof Ci.nsIDOMHTMLTextAreaElement
    ) {

      // if there is any selection at all, just ignore
      if (target.selectionEnd - target.selectionStart > 0)
        return;

      // if there is no text, there is nothing special to do.
      if (target.textLength > 0) {
        if (dir === DIR.R || dir === DIR.D) {
          // we are moving forward into the document
          if (target.textLength != target.selectionEnd)
            return;
        } else {
          // we are at the start of the text, okay to move
          if (target.selectionStart != 0)
            return;
        }
      }
    }

    // Check to see if we are in a select
    if (target instanceof Ci.nsIDOMHTMLSelectElement) {
      if (dir === DIR.D) {
        if (target.selectedIndex + 1 < target.length)
          return;
      }

      if (dir === DIR.U) {
        if (target.selectedIndex > 0)
          return;
      }
    }

    function snavfilter (node) {
      if (node instanceof Ci.nsIDOMHTMLLinkElement || node instanceof Ci.nsIDOMHTMLAnchorElement) {
        // if a anchor doesn't have a href, don't target it.
        if (node.href == "")
          return Ci.nsIDOMNodeFilter.FILTER_SKIP;
        return  Ci.nsIDOMNodeFilter.FILTER_ACCEPT;
      }
      if (
        (node instanceof Ci.nsIDOMHTMLButtonElement ||
         node instanceof Ci.nsIDOMHTMLLinkElement ||
         node instanceof Ci.nsIDOMHTMLOptGroupElement ||
         node instanceof Ci.nsIDOMHTMLSelectElement)
        &&
        !node.disabled
      )
        return Ci.nsIDOMNodeFilter.FILTER_ACCEPT;
      return Ci.nsIDOMNodeFilter.FILTER_SKIP;
    }

    let bestElementToFocus = null;
    let distanceToBestElement = Infinity;
    let focusedRect = inflateRect(target.getBoundingClientRect(), -gRectFudge);

    let treeWalker = doc.createTreeWalker(doc, Ci.nsIDOMNodeFilter.SHOW_ELEMENT, snavfilter, false);
    let nextNode;

    while (nextNode = treeWalker.nextNode()) {
      if (nextNode == target)
        continue;

      let nextRect = inflateRect(nextNode.getBoundingClientRect(), -gRectFudge);
      if (!isRectInDirection(dir, focusedRect, nextRect))
        continue;

      let distance = spatialDistance(dir, focusedRect, nextRect);
      if (distance <= distanceToBestElement && distance > 0) {
        distanceToBestElement = distance;
        bestElementToFocus = nextNode;
      }
    }

    if (bestElementToFocus != null) {
      // Wishing we could do element.focus()
      focusElement(bestElementToFocus);

      // if it is a text element, select all.
      if (
        (bestElementToFocus instanceof Ci.nsIDOMHTMLInputElement &&
         (bestElementToFocus.type == "text" || bestElementToFocus.type == "password"))
        ||
        bestElementToFocus instanceof Ci.nsIDOMHTMLTextAreaElement
      ) {
        bestElementToFocus.selectionStart = 0;
        bestElementToFocus.selectionEnd = bestElementToFocus.textLength;
      }

    } else {
      // couldn't find anything.  just advance and hope.
      // XXX XUL をフォーカスしてしまう場合があるので、とりあえずコメントアウト
      // defaultMove(dir);
    }

  }

  // }}}

  // Export API {{{

  __context__.API = {
    DIR: DIR,
    move: function (dir, target) {
      if (!target)
        target = getFocusedElement();
      if (typeof dir === 'string')
        dir = DIR[dir.slice(0, 1).toUpperCase()];
      return (target ? move : defaultMove)(dir, target);
    }
  };

  // }}}

  // Define mappings {{{

  {
    let ms =
      (
        liberator.globalVariables.spatial_navigation_mappings
        ||
        '<A-h> <A-j> <A-k> <A-l>'
      ).split(/\s+/);

    [
      DIR.L,
      DIR.D,
      DIR.U,
      DIR.R
    ].forEach(
      function (dir, index) {
        mappings.addUserMap(
          [modes.NORMAL],
          [ms[index]],
          'Spatial Navigation',
          function () {
            let (target = getFocusedElement())
              (target ? move : defaultMove)(dir, target);
          },
          {}
        )
      }
    );
  }

  // }}}

})();

// vim:sw=2 ts=2 et si fdm=marker: