package nokogiri;

import static nokogiri.internals.NokogiriHelpers.getNokogiriClass;
import static org.jruby.runtime.Helpers.invoke;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.ThreadFactory;

import org.jruby.Ruby;
import org.jruby.RubyClass;
import org.jruby.RubyObject;
import org.jruby.anno.JRubyClass;
import org.jruby.anno.JRubyMethod;
import org.jruby.exceptions.RaiseException;
import org.jruby.runtime.ThreadContext;
import org.jruby.runtime.builtin.IRubyObject;

import nokogiri.internals.ClosedStreamException;
import nokogiri.internals.NokogiriBlockingQueueInputStream;
import nokogiri.internals.NokogiriHandler;
import nokogiri.internals.NokogiriHelpers;
import nokogiri.internals.ParserContext;

/**
 * Class for Nokogiri::XML::SAX::PushParser
 *
 * @author Patrick Mahoney <pat@polycrystal.org>
 * @author Yoko Harada <yokolet@gmail.com>
 */
@JRubyClass(name = "Nokogiri::XML::SAX::PushParser")
public class XmlSaxPushParser extends RubyObject
{
  ParserContext.Options options;
  IRubyObject saxParser;

  NokogiriBlockingQueueInputStream stream;

  private ParserTask parserTask = null;
  private FutureTask<XmlSaxParserContext> futureTask = null;
  private ExecutorService executor = null;
  RaiseException ex = null;

  public
  XmlSaxPushParser(Ruby ruby, RubyClass rubyClass)
  {
    super(ruby, rubyClass);
  }

  @Override
  public void
  finalize()
  {
    try {
      terminateImpl();
    } catch (Exception e) { /* ignored */ }
  }

  @JRubyMethod
  public IRubyObject
  initialize_native(final ThreadContext context, IRubyObject saxParser, IRubyObject fileName)
  {
    options = new ParserContext.Options(0);
    this.saxParser = saxParser;
    return this;
  }

  private transient IRubyObject parse_options;

  private IRubyObject
  parse_options(final ThreadContext context)
  {
    if (parse_options == null) {
      parse_options = invoke(context, context.runtime.getClassFromPath("Nokogiri::XML::ParseOptions"), "new");
    }
    return parse_options;
  }

  @JRubyMethod(name = "options")
  public IRubyObject
  getOptions(ThreadContext context)
  {
    return invoke(context, parse_options(context), "options");
  }

  @JRubyMethod(name = "options=")
  public IRubyObject
  setOptions(ThreadContext context, IRubyObject opts)
  {
    invoke(context, parse_options(context), "options=", opts);
    options = new ParserContext.Options(opts.convertToInteger().getLongValue());
    return getOptions(context);
  }

  /**
   * Can take a boolean assignment.
   *
   * @param context
   * @param value
   * @return
   */
  @JRubyMethod(name = "replace_entities=")
  public IRubyObject
  setReplaceEntities(ThreadContext context, IRubyObject value)
  {
    // Ignore the value.
    return this;
  }

  @JRubyMethod(name = "replace_entities")
  public IRubyObject
  getReplaceEntities(ThreadContext context)
  {
    // The java parser always replaces entities.
    return context.getRuntime().getTrue();
  }

  @JRubyMethod
  public IRubyObject
  native_write(ThreadContext context, IRubyObject chunk,
               IRubyObject isLast)
  {
    if (ex != null) {
      // parser has already errored, rethrow the exception
      throw ex;
    }

    try {
      initialize_task(context);
    } catch (IOException e) {
      throw context.runtime.newRuntimeError(e.getMessage());
    }
    final ByteArrayInputStream data = NokogiriHelpers.stringBytesToStream(chunk);
    if (data == null) {
      return this;
    }

    int errorCount0 = parserTask.getErrorCount();

    try {
      Future<Void> task = stream.addChunk(data);
      task.get();
    } catch (ClosedStreamException ex) {
      // this means the stream is closed, ignore this exception
    } catch (Exception e) {
      throw context.runtime.newRuntimeError(e.toString());
    }

    if (isLast.isTrue()) {
      parserTask.getNokogiriHandler().endDocument();
      terminateTask(context.runtime);
    }

    if (!options.recover && parserTask.getErrorCount() > errorCount0) {
      terminateTask(context.runtime);
      throw ex = parserTask.getLastError();
    }

    return this;
  }

  private void
  initialize_task(ThreadContext context) throws IOException
  {
    if (futureTask == null || stream == null) {
      stream = new NokogiriBlockingQueueInputStream();

      assert saxParser != null : "saxParser null";
      parserTask = new ParserTask(context, saxParser, stream);
      futureTask = new FutureTask<XmlSaxParserContext>(parserTask);
      executor = Executors.newSingleThreadExecutor(new ThreadFactory() {
        @Override
        public Thread newThread(Runnable r) {
          Thread t = new Thread(r);
          t.setName("XmlSaxPushParser");
          t.setDaemon(true);
          return t;
        }
      });
      executor.submit(futureTask);
    }
  }

  private void
  terminateTask(final Ruby runtime)
  {
    if (executor == null) { return; }

    try {
      terminateImpl();
    } catch (InterruptedException e) {
      throw runtime.newRuntimeError(e.toString());
    } catch (Exception e) {
      throw runtime.newRuntimeError(e.toString());
    }
  }

  private synchronized void
  terminateImpl() throws InterruptedException, ExecutionException
  {
    terminateExecution(executor, stream, futureTask);

    executor = null;
    stream = null;
    futureTask = null;
  }

  // SHARED for Html4SaxPushParser
  static void
  terminateExecution(final ExecutorService executor, final NokogiriBlockingQueueInputStream stream,
                     final FutureTask<?> futureTask)
  throws InterruptedException, ExecutionException
  {

    if (executor == null) { return; }

    try {
      Future<Void> task = stream.addChunk(NokogiriBlockingQueueInputStream.END);
      task.get();
    } catch (ClosedStreamException ex) {
      // ignore this exception, it means the stream was closed
    }
    futureTask.cancel(true);
    executor.shutdown();
  }

  private static XmlSaxParserContext
  parse(final Ruby runtime, final InputStream stream)
  {
    RubyClass klazz = getNokogiriClass(runtime, "Nokogiri::XML::SAX::ParserContext");
    return XmlSaxParserContext.parse_stream(runtime, klazz, stream);
  }

  static class ParserTask extends ParserContext.ParserTask<XmlSaxParserContext>
  {

    final InputStream stream;

    private
    ParserTask(ThreadContext context, IRubyObject handler, InputStream stream)
    {
      this(context, handler, parse(context.runtime, stream), stream);
    }

    // IMPL with Html4SaxPushParser
    protected
    ParserTask(ThreadContext context, IRubyObject handler, XmlSaxParserContext parser, InputStream stream)
    {
      super(context, handler, parser);
      this.stream = stream;
    }

    @Override
    public XmlSaxParserContext
    call() throws Exception
    {
      try {
        parser.parse_with(context, handler);
      } finally { stream.close(); }
      // we have to close the stream before exiting, otherwise someone
      // can add a chunk and block on task.get() forever.
      return parser;
    }

    final NokogiriHandler
    getNokogiriHandler()
    {
      return parser.getNokogiriHandler();
    }

    synchronized final int
    getErrorCount()
    {
      // check for null because thread may not have started yet
      if (parser.getNokogiriHandler() == null) { return 0; }
      return parser.getNokogiriHandler().getErrorCount();
    }

    synchronized final RaiseException
    getLastError()
    {
      return parser.getNokogiriHandler().getLastError();
    }

  }

}