/*
 * Copyright (c) 2008, 2020 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 * 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 org.glassfish.grizzly.servlet;

import java.io.IOException;

import org.glassfish.grizzly.WriteHandler;
import org.glassfish.grizzly.http.io.NIOOutputStream;
import org.glassfish.grizzly.localization.LogMessages;

import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.WriteListener;

Author:
Jeanfrancois Arcand/**
 *
 * @author Jeanfrancois Arcand
 */
public class ServletOutputStreamImpl extends ServletOutputStream {

    private final HttpServletResponseImpl servletResponse;
    private NIOOutputStream outputStream;

    private WriteHandler writeHandler = null;
    private boolean hasSetWriteListener = false;
    private boolean prevIsReady = true;

    private static final ThreadLocal<Boolean> CAN_WRITE_SCOPE = new ThreadLocal<>();

    protected ServletOutputStreamImpl(final HttpServletResponseImpl servletResponse) {
        this.servletResponse = servletResponse;
    }

    protected void initialize() throws IOException {
        this.outputStream = servletResponse.getResponse().createOutputStream();
    }

    @Override
    public void write(int i) throws IOException {
        if (!prevIsReady) {
            throw new IllegalStateException(LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_NON_BLOCKING_ERROR());
        }

        outputStream.write(i);
    }

    @Override
    public void write(byte[] b) throws IOException {
        write(b, 0, b.length);
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        if (!prevIsReady) {
            throw new IllegalStateException(LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_NON_BLOCKING_ERROR());
        }

        outputStream.write(b, off, len);
    }

    
Will send the buffer to the client.
/**
     * Will send the buffer to the client.
     */
    @Override
    public void flush() throws IOException {
        if (!prevIsReady) {
            throw new IllegalStateException(LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_NON_BLOCKING_ERROR());
        }

        outputStream.flush();
    }

    @Override
    public void close() throws IOException {
        if (!prevIsReady) {
            throw new IllegalStateException(LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_NON_BLOCKING_ERROR());
        }

        outputStream.close();
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public boolean isReady() {
        if (!hasSetWriteListener) {
            throw new IllegalStateException(LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_OUTPUTSTREAM_ISREADY_ERROR());
        }

        if (!prevIsReady) {
            return false;
        }

        boolean result = outputStream.canWrite();
        if (!result) {
            if (hasSetWriteListener) {
                prevIsReady = false; // Not data available
                CAN_WRITE_SCOPE.set(Boolean.TRUE);
                try {
                    outputStream.notifyCanWrite(writeHandler);
                } finally {
                    CAN_WRITE_SCOPE.remove();
                }

            } else {
                prevIsReady = true; // Allow next .isReady() call to check underlying inputStream
            }
        }

        return result;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void setWriteListener(WriteListener writeListener) {
        if (hasSetWriteListener) {
            throw new IllegalStateException("The WriteListener has already been set.");
        }

        final HttpServletRequestImpl req = servletResponse.servletRequest;
        if (!(req.isAsyncStarted() || req.isUpgrade())) {
            throw new IllegalStateException(LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_OUTPUTSTREAM_SETWRITELISTENER_ERROR());
        }

        writeHandler = new WriteHandlerImpl(writeListener);
        hasSetWriteListener = true;
    }

    void recycle() {
        outputStream = null;

        writeHandler = null;
        prevIsReady = true;
        hasSetWriteListener = false;
    }

    class WriteHandlerImpl implements WriteHandler {
        private WriteListener writeListener = null;

        private WriteHandlerImpl(WriteListener listener) {
            writeListener = listener;
        }

        @Override
        public void onWritePossible() throws Exception {
            if (!Boolean.TRUE.equals(CAN_WRITE_SCOPE.get())) {
                invokeWriteCallback();
            } else {
                AsyncContextImpl.pool.execute(new Runnable() {
                    @Override
                    public void run() {
                        invokeWriteCallback();
                    }
                });
            }
        }

        @Override
        public void onError(final Throwable t) {
            if (!Boolean.TRUE.equals(CAN_WRITE_SCOPE.get())) {
                writeListener.onError(t);
            } else {
                AsyncContextImpl.pool.execute(new Runnable() {
                    @Override
                    public void run() {
                        writeListener.onError(t);
                    }
                });
            }
        }

        private void invokeWriteCallback() {
            prevIsReady = true;
            try {
                writeListener.onWritePossible();
            } catch (Throwable t) {
                writeListener.onError(t);
            }
        }

    }
}