/*
 * file: RemoveTextAction.js
 *
 * @BEGINLICENSE
 * Copyright 2010 Brook Novak  (email : brooknovak@seaweed-editor.com) 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 * @ENDLICENSE
 */

// @DEPENDS: UndoMan
bootstrap.provides("actions.RemoveTextAction");

_registerAction("RemoveText", {
    
    /**
     * Removes text within a single text node.
     * 
     * @param {Node} textNode    The text node to remove text from
     * 
     * @param {Number} index     The index at which to begin removing text from.
     *                           Ranges from 0 - textlength - 1
     * 
     * @param {Number} length    The amount of charactors to remove start from the given index. Must be at least 1
     */
    exec : function(textNode, index, length) {
        
    	debug.assert(index >= 0);
        debug.assert(length > 0);
    	debug.assert(textNode.nodeType == Node.TEXT_NODE);
        debug.assert((index + length) <= textNode.nodeValue.length);

        // Avoid removing text from placeholders            
        if (de.doc.isESPlaceHolder(textNode, false) || de.doc.isMNPlaceHolder(textNode, false)) {
            // Keep current cursor position
            if (this.flags & de.UndoMan.ExecFlag.UPDATE_SELECTION) {
                var cDesc = de.cursor.getCurrentCursorDesc();
                if (cDesc)
                    this.selAfter = {startNode : cDesc.domNode, startIndex : cDesc.relIndex + (cDesc.domNode.nodeType == Node.TEXT_NODE && cDesc.isRightOf ? 1 : 0)};
            }
            return;
        }
        

        // Check for surrounding whitespace
        var convertLeftCA, convertRightCA;
        if (index == 0) {
            
            // Look for preceeding whitespace
            _visitAllNodes(docBody, textNode, false, function(domNode) {
                
                if (domNode == textNode) return;
                
                var ca = _getCommonAncestor(textNode, domNode);
                
                if (_findAncestor(domNode, ca, _isBlockLevel, true))
                    return false;
                    
                if (domNode.nodeType == Node.TEXT_NODE && _nodeLength(domNode) > 0) {
                    if (_isAllWhiteSpace(domNode.nodeValue.charAt(_nodeLength(domNode)-1))) {
                        convertLeftCA = ca;
                        return false;
                    }
                }
            });
            
        } else {
            if(_isAllWhiteSpace(textNode.nodeValue.charAt(index-1)))
                convertLeftCA = textNode;
        }
        
        if ((index + length) == _nodeLength(textNode)) {
            
            // Look for proceeding whitespace
            _visitAllNodes(docBody, textNode, true, function(domNode) {
                
                if (domNode == textNode) return;
                
                var ca = _getCommonAncestor(textNode, domNode);
                
                if (_isBlockLevel(domNode) || _findAncestor(textNode, ca, _isBlockLevel, true))
                    return false;
                    
                if (_nodeLength(domNode, 0) > 0) {
                    if (_isAllWhiteSpace(domNode.nodeValue.charAt(0))) {
                        convertRightCA = ca;
                        return false;
                    }
                }
            });
        } else {
            if (_isAllWhiteSpace(textNode.nodeValue.charAt(index + length)))
                convertRightCA = textNode;
        }
        
        var convertTarget = (convertLeftCA && convertRightCA && convertLeftCA != convertRightCA) ?
                            _getCommonAncestor(convertLeftCA, convertRightCA, true) : convertLeftCA || convertRightCA;

        if (convertTarget)
            _convertWSToNBSP(convertTarget);
        
        // Remove the text
        _execOp(_Operation.REMOVE_TEXT, textNode, index, length);
        
        // Normalize converted white space
        if (convertTarget) 
            _normalizeNBSP(convertTarget);
        
        // See if need to add a placeholder
        var ph, phParent = de.doc.getEditSectionContainer(textNode);

        if (phParent && _doesNeedESPlaceholder(phParent)) 
			ph = de.doc.createESPlaceholder(phParent);
		else {
			phParent = _findAncestor(textNode, docBody, _isBlockLevel, true) || docBody;
			if (_doesNeedMNPlaceholder(phParent))
				ph = de.doc.createMNPlaceholder();
		}

        // Add the needed placeholder
        if (ph)
            _execOp(_Operation.INSERT_NODE, ph, phParent);

        // Update the selection if requested
        if (this.flags & de.UndoMan.ExecFlag.UPDATE_SELECTION) {
            var cDesc = ph ? de.cursor.createCursorDesc(ph, 0, false) : 
                                   de.cursor.getNearestCursorDesc(textNode, index == 0 ? 0 : index-1, index > 0, false);
            if (cDesc)
                this.selAfter = {startNode : cDesc.domNode, startIndex : cDesc.relIndex + (cDesc.domNode.nodeType == Node.TEXT_NODE && cDesc.isRightOf ? 1 : 0)};
        }
        
        // If the text node is left without text then get rid of it
        if (_nodeLength(textNode) == 0)
            _execOp(_Operation.REMOVE_NODE, textNode);

    }
});