package com.jclark.xsl.sax;

import com.jclark.xsl.om.*;
import org.xml.sax.*;
import com.jclark.xsl.tr.OutputMethod;
import java.util.Vector;
import java.util.Enumeration;
import java.io.IOException;

class OutputMethodDefaulter implements DocumentHandler, CommentHandler, RawCharactersHandler {
  private final ResultBase result;
  private final OutputMethod outputMethod;
  private final Vector savedEvents = new Vector();
  private Locator locator;

  static abstract class Event {
    abstract void emit(DocumentHandler handler) throws SAXException;
  }

  static class ProcessingInstructionEvent extends Event {
    private String target;
    private String content;
    ProcessingInstructionEvent(String target, String content) {
      this.target = target;
      this.content = content;
    }
    void emit(DocumentHandler handler) throws SAXException {
      handler.processingInstruction(target, content);
    }
  }

  static class CommentEvent extends Event {
    private String content;
    CommentEvent(String content) {
      this.content = content;
    }
    void emit(DocumentHandler handler) throws SAXException {
      if (handler instanceof CommentHandler)
	((CommentHandler)handler).comment(content);
    }
  }

  static class RawCharactersEvent extends Event {
    private String chars;
    RawCharactersEvent(String chars) {
      this.chars = chars;
    }
    void emit(DocumentHandler handler) throws SAXException {
      if (handler instanceof RawCharactersHandler)
	((RawCharactersHandler)handler).rawCharacters(chars);
      else {
	char[] buf = chars.toCharArray();
	handler.characters(buf, 0, buf.length);
      }
    }
  }

  static class CharactersEvent extends Event {
    private char[] buf;
    CharactersEvent(char[] b, int off, int len) {
      buf = new char[len];
      System.arraycopy(b, off, buf, 0, len);
    }
    void emit(DocumentHandler handler) throws SAXException {
      handler.characters(buf, 0, buf.length);
    }
  }

  static class IgnorableWhitespaceEvent extends Event {
    private char[] buf;
    IgnorableWhitespaceEvent(char[] b, int off, int len) {
      buf = new char[len];
      System.arraycopy(b, off, buf, 0, len);
    }
    void emit(DocumentHandler handler) throws SAXException {
      handler.ignorableWhitespace(buf, 0, buf.length);
    }
  }

  public void startDocument() { }

  public void endDocument() throws SAXException {
    getDocumentHandler(false).endDocument();
  }

  public void startElement(String name, AttributeList atts) throws SAXException {
    getDocumentHandler(name.equalsIgnoreCase("html")
		       && atts.getValue("xmlns") == null)
      .startElement(name, atts);
  }
  
  public void endElement(String name) {
    throw new Error("unbalanced call to endElement");
  }

  public void characters(char[] buf, int off, int len) throws SAXException {
    for (int i = 0; i < len; i++) {
      switch (buf[off + i]) {
      case ' ':
      case '\t':
      case '\r':
      case '\n':
	break;
      default:
	getDocumentHandler(false).characters(buf, off, len);
	return;
      }
    }
    savedEvents.addElement(new CharactersEvent(buf, off, len));
  }

  public void ignorableWhitespace(char[] buf, int off, int len) throws SAXException {
    savedEvents.addElement(new IgnorableWhitespaceEvent(buf, off, len));
  }

  public void comment(String content) {
    savedEvents.addElement(new CommentEvent(content));
  }

  public void processingInstruction(String target, String content) {
    savedEvents.addElement(new ProcessingInstructionEvent(target, content));
  }

  public void rawCharacters(String chars) {
    savedEvents.addElement(new RawCharactersEvent(chars));
  }

  public void setDocumentLocator(Locator loc) {
    this.locator = loc;
  }

  OutputMethodDefaulter(ResultBase result, OutputMethod outputMethod) {
    this.result = result;
    this.outputMethod = outputMethod;
  }

  private DocumentHandler getDocumentHandler(boolean isHtml)
    throws SAXException {
    Name name = outputMethod.getNameTable().createName(isHtml ? "html" : "xml");
    try {
      DocumentHandler handler = result.setOutputMethod(name, outputMethod);
      if (locator != null)
	handler.setDocumentLocator(locator);
      handler.startDocument();
      for (Enumeration iter = savedEvents.elements(); iter.hasMoreElements();)
	((Event)iter.nextElement()).emit(handler);
      return handler;
    }
    catch (IOException e) {
      throw new SAXException(e);
    }
  }
}