/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.html;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.spi.IThrowableProxy;
import ch.qos.logback.classic.spi.StackTraceElementProxy;
import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.helpers.Transform;
import ch.qos.logback.core.html.IThrowableRenderer;

public class DefaultThrowableRenderer implements
    IThrowableRenderer<ILoggingEvent> {

  static final String TRACE_PREFIX = "<br />&nbsp;&nbsp;&nbsp;&nbsp;";

  public void render(StringBuilder sbuf, ILoggingEvent event) {
    IThrowableProxy tp = event.getThrowableProxy();
    sbuf.append("<tr><td class=\"Exception\" colspan=\"6\">");
    while (tp != null) {
      render(sbuf, tp);
      tp = tp.getCause();
    }
    sbuf.append("</td></tr>");
  }

  void render(StringBuilder sbuf, IThrowableProxy tp) {
    printFirstLine(sbuf, tp);
    
    int commonFrames = tp.getCommonFrames();
    StackTraceElementProxy[] stepArray = tp.getStackTraceElementProxyArray();
    
    for (int i = 0; i < stepArray.length - commonFrames; i++) {
      StackTraceElementProxy step = stepArray[i];
      sbuf.append(TRACE_PREFIX);
      sbuf.append(Transform.escapeTags(step.toString()));
      sbuf.append(CoreConstants.LINE_SEPARATOR);
    }
    
    if (commonFrames > 0) {
      sbuf.append(TRACE_PREFIX);
      sbuf.append("\t... " + commonFrames).append(" common frames omitted")
          .append(CoreConstants.LINE_SEPARATOR);
    }
  }

  public void printFirstLine(StringBuilder sb, IThrowableProxy tp) {
    int commonFrames = tp.getCommonFrames();
    if (commonFrames > 0) {
      sb.append("<br />").append(CoreConstants.CAUSED_BY);
    }
    sb.append(tp.getClassName()).append(": ").append(
        Transform.escapeTags(tp.getMessage()));
    sb.append(CoreConstants.LINE_SEPARATOR);
  }

}
