/*
 * Copyright (c) 2012, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (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.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.dart.tools.ui.web.html;

import com.google.dart.tools.core.html.HtmlKeywords;
import com.google.dart.tools.ui.web.utils.WebEditorAutoIndentStrategy;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentCommand;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;

/**
 * An indent strategy for html.
 */
class HtmlAutoIndentStrategy extends WebEditorAutoIndentStrategy {

  public HtmlAutoIndentStrategy() {

  }

  @Override
  protected void doAutoIndentAfterNewLine(IDocument document, DocumentCommand command) {
    if (command.offset == -1 || document.getLength() == 0) {
      return;
    }

    try {
      // find start of line
      int location = (command.offset == document.getLength() ? command.offset - 1 : command.offset);
      IRegion lineInfo = document.getLineInformationOfOffset(location);
      int start = lineInfo.getOffset();

      boolean endsInBracket = (document.getChar(command.offset - 1) == '>');
      String startStr = document.get(start, command.offset - start);

      // find white spaces
      int end = findEndOfWhiteSpace(document, start, command.offset);

      StringBuffer buf = new StringBuffer(command.text);
      String wsStart = "";

      if (end > start) {
        wsStart = document.get(start, end - start);

        // append to input
        buf.append(wsStart);
      }

      if (endsInBracket) {
        // handle self-closing tags
        String startTagName = getStartTagName(startStr);

        boolean selfClosing = (startTagName != null && HtmlKeywords.isSelfClosing(startTagName.toLowerCase()));

        if (!selfClosing) {
          if (startStr.indexOf('<') != -1) {
            startStr = startStr.substring(startStr.lastIndexOf('<'));
          }

          // Indent after an ">", but not if we're closing an element tag.
          if (!(startStr.startsWith("</") || startStr.endsWith("/>"))) {
            buf.append("  ");

            // TODO(devoncarew): check to make sure the tag is not already completed before we
            // insert </foo>
//            // Insert </foo> and back up the caret position.
//            String eol = getEol(document, command.offset);
//
//            String closingTag = eol + wsStart + "</" + startTagName + ">";
//
//            buf.append(closingTag);
//
//            command.shiftsCaret = false;
//            command.caretOffset = command.offset + buf.length() - closingTag.length();
          }
        }
      }

      command.text = buf.toString();
    } catch (BadLocationException excp) {

    }
  }

  @SuppressWarnings("unused")
  private String getEol(IDocument document, int offset) throws BadLocationException {
    String eol = document.getLineDelimiter(document.getLineOfOffset(offset));

    if (eol == null) {
      eol = document.getLineDelimiter(0);
    }

    if (eol == null) {
      eol = "\n";
    }

    return eol;
  }

  private String getStartTagName(String line) {
    String tag = line;

    if (tag.indexOf('<') != -1) {
      tag = tag.substring(tag.lastIndexOf('<'));
    }

    if (tag.startsWith("<")) {
      StringBuilder builder = new StringBuilder();

      for (int i = 1; i < tag.length(); i++) {
        if (!Character.isJavaIdentifierPart(tag.charAt(i))) {
          return builder.toString();
        } else {
          builder.append(tag.charAt(i));
        }
      }

      return builder.toString();
    } else {
      return null;
    }
  }

}