/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.catalina.core;

import java.io.IOException;
import java.io.Serial;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;

import javax.naming.NamingException;

import jakarta.servlet.AsyncContext;
import jakarta.servlet.AsyncEvent;
import jakarta.servlet.AsyncListener;
import jakarta.servlet.RequestDispatcher;
import jakarta.servlet.ServletContext;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletResponse;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import org.apache.catalina.AsyncDispatcher;
import org.apache.catalina.Context;
import org.apache.catalina.Host;
import org.apache.catalina.Valve;
import org.apache.catalina.connector.Request;
import org.apache.coyote.ActionCode;
import org.apache.coyote.AsyncContextCallback;
import org.apache.coyote.RequestInfo;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.buf.UDecoder;
import org.apache.tomcat.util.res.StringManager;

public class AsyncContextImpl implements AsyncContext, AsyncContextCallback {

    private static final Log log = LogFactory.getLog(AsyncContextImpl.class);

    protected static final StringManager sm = StringManager.getManager(AsyncContextImpl.class);

    /*
     * When a request uses a sequence of multiple start(); dispatch() with non-container threads it is possible for a
     * previous dispatch() to interfere with a following start(). This lock prevents that from happening. It is a
     * dedicated object as user code may lock on the AsyncContext so if container code also locks on that object
     * deadlocks may occur.
     */
    private final Object asyncContextLock = new Object();

    private volatile ServletRequest servletRequest = null;
    private volatile ServletResponse servletResponse = null;
    private final List<AsyncListenerWrapper> listeners = new ArrayList<>();
    private boolean hasOriginalRequestAndResponse = true;
    private volatile Runnable dispatch = null;
    private Context context = null;
    // Default of 30000 (30s) is set by the connector
    private long timeout = -1;
    private AsyncEvent event = null;
    private volatile Request request;
    private final AtomicBoolean hasErrorProcessingStarted = new AtomicBoolean(false);
    private final AtomicBoolean hasOnErrorReturned = new AtomicBoolean(false);

    public AsyncContextImpl(Request request) {
        this.request = request;
        if (log.isTraceEnabled()) {
            logDebug("Constructor");
        }
    }

    @Override
    public void complete() {
        if (log.isTraceEnabled()) {
            logDebug("complete   ");
        }
        check();
        request.getCoyoteRequest().action(ActionCode.ASYNC_COMPLETE, null);
    }

    @Override
    public void fireOnComplete() {
        if (log.isTraceEnabled()) {
            log.trace(sm.getString("asyncContextImpl.fireOnComplete"));
        }
        List<AsyncListenerWrapper> listenersCopy = new ArrayList<>(listeners);

        ClassLoader oldCL = context.bind(null);
        try {
            for (AsyncListenerWrapper listener : listenersCopy) {
                try {
                    listener.fireOnComplete(event);
                } catch (Throwable t) {
                    ExceptionUtils.handleThrowable(t);
                    log.warn(sm.getString("asyncContextImpl.onCompleteError", listener.getClass().getName()), t);
                }
            }
        } finally {
            context.fireRequestDestroyEvent(request.getRequest());
            clearServletRequestResponse();
            context.unbind(oldCL);
        }
    }


    public boolean timeout() {
        AtomicBoolean result = new AtomicBoolean();
        request.getCoyoteRequest().action(ActionCode.ASYNC_TIMEOUT, result);
        // Avoids NPEs during shutdown. A call to recycle will null this field.
        Context context = this.context;

        if (result.get()) {
            if (log.isTraceEnabled()) {
                log.trace(sm.getString("asyncContextImpl.fireOnTimeout"));
            }
            ClassLoader oldCL = context.bind(null);
            try {
                List<AsyncListenerWrapper> listenersCopy = new ArrayList<>(listeners);
                for (AsyncListenerWrapper listener : listenersCopy) {
                    try {
                        listener.fireOnTimeout(event);
                    } catch (Throwable t) {
                        ExceptionUtils.handleThrowable(t);
                        log.warn(sm.getString("asyncContextImpl.onTimeoutError", listener.getClass().getName()), t);
                    }
                }
                request.getCoyoteRequest().action(ActionCode.ASYNC_IS_TIMINGOUT, result);
            } finally {
                context.unbind(oldCL);
            }
        }
        return !result.get();
    }

    @Override
    public void dispatch() {
        check();
        String path;
        String cpath;
        ServletRequest servletRequest = getRequest();
        if (servletRequest instanceof HttpServletRequest sr) {
            path = sr.getRequestURI();
            cpath = sr.getContextPath();
        } else {
            path = request.getRequestURI();
            cpath = request.getContextPath();
        }
        if (cpath.length() > 1) {
            path = path.substring(cpath.length());
        }
        if (!context.getDispatchersUseEncodedPaths()) {
            path = UDecoder.URLDecode(path, StandardCharsets.UTF_8);
        }
        dispatch(path);
    }

    @Override
    public void dispatch(String path) {
        check();
        dispatch(getRequest().getServletContext(), path);
    }

    @Override
    public void dispatch(ServletContext servletContext, String path) {
        synchronized (asyncContextLock) {
            if (log.isTraceEnabled()) {
                logDebug("dispatch   ");
            }
            check();
            if (dispatch != null) {
                throw new IllegalStateException(sm.getString("asyncContextImpl.dispatchingStarted"));
            }
            if (request.getAttribute(ASYNC_REQUEST_URI) == null) {
                request.setAttribute(ASYNC_REQUEST_URI, request.getRequestURI());
                request.setAttribute(ASYNC_CONTEXT_PATH, request.getContextPath());
                request.setAttribute(ASYNC_SERVLET_PATH, request.getServletPath());
                request.setAttribute(ASYNC_PATH_INFO, request.getPathInfo());
                request.setAttribute(ASYNC_QUERY_STRING, request.getQueryString());
            }
            final RequestDispatcher requestDispatcher = servletContext.getRequestDispatcher(path);
            if (!(requestDispatcher instanceof AsyncDispatcher applicationDispatcher)) {
                throw new UnsupportedOperationException(sm.getString("asyncContextImpl.noAsyncDispatcher"));
            }
            final ServletRequest servletRequest = getRequest();
            final ServletResponse servletResponse = getResponse();
            this.dispatch = new AsyncRunnable(request, applicationDispatcher, servletRequest, servletResponse);
            this.request.getCoyoteRequest().action(ActionCode.ASYNC_DISPATCH, null);
            clearServletRequestResponse();
        }
    }

    @Override
    public ServletRequest getRequest() {
        check();
        if (servletRequest == null) {
            throw new IllegalStateException(sm.getString("asyncContextImpl.request.ise"));
        }
        return servletRequest;
    }

    @Override
    public ServletResponse getResponse() {
        check();
        if (servletResponse == null) {
            throw new IllegalStateException(sm.getString("asyncContextImpl.response.ise"));
        }
        return servletResponse;
    }

    @Override
    public void start(final Runnable run) {
        if (log.isTraceEnabled()) {
            logDebug("start      ");
        }
        check();
        Runnable wrapper = new RunnableWrapper(run, context, this.request.getCoyoteRequest());
        this.request.getCoyoteRequest().action(ActionCode.ASYNC_RUN, wrapper);
    }

    @Override
    public void addListener(AsyncListener listener) {
        check();
        AsyncListenerWrapper wrapper = new AsyncListenerWrapper();
        wrapper.setListener(listener);
        listeners.add(wrapper);
    }

    @Override
    public void addListener(AsyncListener listener, ServletRequest servletRequest, ServletResponse servletResponse) {
        check();
        AsyncListenerWrapper wrapper = new AsyncListenerWrapper();
        wrapper.setListener(listener);
        wrapper.setServletRequest(servletRequest);
        wrapper.setServletResponse(servletResponse);
        listeners.add(wrapper);
    }

    @SuppressWarnings("unchecked")
    @Override
    public <T extends AsyncListener> T createListener(Class<T> clazz) throws ServletException {
        check();
        T listener;
        try {
            listener = (T) context.getInstanceManager().newInstance(clazz.getName(), clazz.getClassLoader());
        } catch (ReflectiveOperationException | NamingException e) {
            throw new ServletException(e);
        } catch (Exception e) {
            ExceptionUtils.handleThrowable(e.getCause());
            throw new ServletException(e);
        }
        return listener;
    }

    public void recycle() {
        if (log.isTraceEnabled()) {
            logDebug("recycle    ");
        }
        context = null;
        dispatch = null;
        event = null;
        hasOriginalRequestAndResponse = true;
        listeners.clear();
        request = null;
        clearServletRequestResponse();
        timeout = -1;
        hasErrorProcessingStarted.set(false);
        hasOnErrorReturned.set(false);
    }

    private void clearServletRequestResponse() {
        servletRequest = null;
        servletResponse = null;
    }

    public boolean isStarted() {
        AtomicBoolean result = new AtomicBoolean(false);
        Request request = this.request;
        check();
        request.getCoyoteRequest().action(ActionCode.ASYNC_IS_STARTED, result);
        return result.get();
    }

    public void setStarted(Context context, ServletRequest request, ServletResponse response,
            boolean originalRequestResponse) {

        synchronized (asyncContextLock) {
            this.request.getCoyoteRequest().action(ActionCode.ASYNC_START, this);

            this.context = context;
            context.incrementInProgressAsyncCount();
            this.servletRequest = request;
            this.servletResponse = response;
            this.hasOriginalRequestAndResponse = originalRequestResponse;
            this.event = new AsyncEvent(this, request, response);

            List<AsyncListenerWrapper> listenersCopy = new ArrayList<>(listeners);
            listeners.clear();
            if (log.isTraceEnabled()) {
                log.trace(sm.getString("asyncContextImpl.fireOnStartAsync"));
            }
            for (AsyncListenerWrapper listener : listenersCopy) {
                try {
                    listener.fireOnStartAsync(event);
                } catch (Throwable t) {
                    ExceptionUtils.handleThrowable(t);
                    log.warn(sm.getString("asyncContextImpl.onStartAsyncError", listener.getClass().getName()), t);
                }
            }
        }
    }

    @Override
    public boolean hasOriginalRequestAndResponse() {
        check();
        return hasOriginalRequestAndResponse;
    }

    protected void doInternalDispatch() throws ServletException, IOException {
        if (log.isTraceEnabled()) {
            logDebug("intDispatch");
        }
        try {
            Runnable runnable = dispatch;
            dispatch = null;
            runnable.run();
            if (!request.isAsync()) {
                fireOnComplete();
            }
        } catch (RuntimeException x) {
            AtomicBoolean result = new AtomicBoolean();
            request.getCoyoteRequest().action(ActionCode.IS_IO_ALLOWED, result);
            /*
             * If IO is allowed then onComplete() will be called from AbstractProcessorLight.process() when
             * AbstractProcessorLight.postProcess() is called. If IO is not allowed then that call will not happen so
             * call onComplete() here. This can't be handled in AbstractProcessorLight.process() as it does not have the
             * information required to determine that onComplete() needs to be called.
             */
            if (!result.get()) {
                fireOnComplete();
            }
            if (x.getCause() instanceof ServletException) {
                throw (ServletException) x.getCause();
            }
            if (x.getCause() instanceof IOException) {
                throw (IOException) x.getCause();
            }
            throw new ServletException(x);
        }
    }


    @Override
    public long getTimeout() {
        check();
        return timeout;
    }


    @Override
    public void setTimeout(long timeout) {
        check();
        this.timeout = timeout;
        request.getCoyoteRequest().action(ActionCode.ASYNC_SETTIMEOUT, Long.valueOf(timeout));
    }


    @Override
    public boolean isAvailable() {
        Context context = this.context;
        if (context == null) {
            return false;
        }
        return context.getState().isAvailable();
    }


    public void setErrorState(Throwable t, boolean fireOnError) {
        if (!hasErrorProcessingStarted.compareAndSet(false, true)) {
            // Skip duplicate error processing
            return;
        }
        if (t != null) {
            request.setAttribute(RequestDispatcher.ERROR_EXCEPTION, t);
        }
        request.getCoyoteRequest().action(ActionCode.ASYNC_ERROR, null);

        if (fireOnError) {
            if (log.isTraceEnabled()) {
                log.trace(sm.getString("asyncContextImpl.fireOnError"));
            }
            AsyncEvent errorEvent =
                    new AsyncEvent(event.getAsyncContext(), event.getSuppliedRequest(), event.getSuppliedResponse(), t);
            List<AsyncListenerWrapper> listenersCopy = new ArrayList<>(listeners);
            for (AsyncListenerWrapper listener : listenersCopy) {
                try {
                    listener.fireOnError(errorEvent);
                } catch (Throwable t2) {
                    ExceptionUtils.handleThrowable(t2);
                    log.warn(sm.getString("asyncContextImpl.onErrorError", listener.getClass().getName()), t2);
                } finally {
                    hasOnErrorReturned.set(true);
                }
            }
        }


        AtomicBoolean result = new AtomicBoolean();
        request.getCoyoteRequest().action(ActionCode.ASYNC_IS_ERROR, result);
        if (result.get()) {
            // No listener called dispatch() or complete(). This is an error.
            // SRV.2.3.3.3 (search for "error dispatch")
            // Take a local copy to avoid threading issues if another thread
            // clears this (can happen during error handling with non-container
            // threads)
            ServletResponse servletResponse = this.servletResponse;
            if (servletResponse instanceof HttpServletResponse) {
                ((HttpServletResponse) servletResponse).setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            }

            Host host = (Host) context.getParent();
            Valve stdHostValve = host.getPipeline().getBasic();
            if (stdHostValve instanceof StandardHostValve) {
                ((StandardHostValve) stdHostValve).throwable(request, request.getResponse(), t);
            }

            request.getCoyoteRequest().action(ActionCode.ASYNC_IS_ERROR, result);
            if (result.get()) {
                // Still in the error state. The error page did not call
                // complete() or dispatch(). Complete the async processing.
                complete();
            }
        } else if (request.isAsyncDispatching()) {
            /*
             * AsyncListener.onError() called dispatch. Clear the error state on the response else the dispatch will
             * trigger error page handling.
             */
            request.getResponse().resetError();
        }
    }


    @Override
    public void incrementInProgressAsyncCount() {
        context.incrementInProgressAsyncCount();
    }


    @Override
    public void decrementInProgressAsyncCount() {
        context.decrementInProgressAsyncCount();
    }


    private void logDebug(String method) {
        String rHashCode;
        String crHashCode;
        String rpHashCode;
        String stage;
        StringBuilder uri = new StringBuilder();
        if (request == null) {
            rHashCode = "null";
            crHashCode = "null";
            rpHashCode = "null";
            stage = "-";
            uri.append("N/A");
        } else {
            rHashCode = Integer.toHexString(request.hashCode());
            org.apache.coyote.Request coyoteRequest = request.getCoyoteRequest();
            if (coyoteRequest == null) {
                crHashCode = "null";
                rpHashCode = "null";
                stage = "-";
            } else {
                crHashCode = Integer.toHexString(coyoteRequest.hashCode());
                RequestInfo rp = coyoteRequest.getRequestProcessor();
                if (rp == null) {
                    rpHashCode = "null";
                    stage = "-";
                } else {
                    rpHashCode = Integer.toHexString(rp.hashCode());
                    stage = Integer.toString(rp.getStage());
                }
            }
            uri.append(request.getRequestURI());
            if (request.getQueryString() != null) {
                uri.append('?');
                uri.append(request.getQueryString());
            }
        }
        String threadName = Thread.currentThread().getName();
        int len = threadName.length();
        if (len > 20) {
            threadName = threadName.substring(len - 20, len);
        }
        String msg = String.format(
                "Req: %1$8s  CReq: %2$8s  RP: %3$8s  Stage: %4$s  " +
                        "Thread: %5$20s  State: %6$20s  Method: %7$11s  URI: %8$s",
                rHashCode, crHashCode, rpHashCode, stage, threadName, "N/A", method, uri);
        if (log.isTraceEnabled()) {
            log.trace(msg, new DebugException());
        } else {
            log.debug(msg);
        }
    }

    private void check() {
        Request request = this.request;
        if (request == null) {
            // AsyncContext has been recycled and should not be being used
            throw new IllegalStateException(sm.getString("asyncContextImpl.requestEnded"));
        }
        if (hasOnErrorReturned.get() && !request.getCoyoteRequest().isRequestThread()) {
            /*
             * Non-container thread is trying to use the AsyncContext after an error has occurred and the call to
             * AsyncListener.onError() has returned. At this point, the non-container thread should not be trying to use
             * the AsyncContext due to possible race conditions.
             */
            throw new IllegalStateException(sm.getString("asyncContextImpl.afterOnError"));
        }
    }

    private static class DebugException extends Exception {
        @Serial
        private static final long serialVersionUID = 1L;
    }

    private static class RunnableWrapper implements Runnable {

        private final Runnable wrapped;
        private final Context context;
        private final org.apache.coyote.Request coyoteRequest;

        RunnableWrapper(Runnable wrapped, Context ctxt, org.apache.coyote.Request coyoteRequest) {
            this.wrapped = wrapped;
            this.context = ctxt;
            this.coyoteRequest = coyoteRequest;
        }

        @Override
        public void run() {
            ClassLoader oldCL = context.bind(null);
            try {
                wrapped.run();
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
                context.getLogger().error(sm.getString("asyncContextImpl.asyncRunnableError"), t);
                coyoteRequest.setAttribute(RequestDispatcher.ERROR_EXCEPTION, t);
                org.apache.coyote.Response coyoteResponse = coyoteRequest.getResponse();
                coyoteResponse.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
                coyoteResponse.setError();
            } finally {
                context.unbind(oldCL);
            }

            // Since this runnable is not executing as a result of a socket
            // event, we need to ensure that any registered dispatches are
            // executed.
            coyoteRequest.action(ActionCode.DISPATCH_EXECUTE, null);
        }
    }


    private record AsyncRunnable(Request request, AsyncDispatcher applicationDispatcher,
                                 ServletRequest servletRequest,
                                 ServletResponse servletResponse) implements Runnable {

        @Override
        public void run() {
            request.getCoyoteRequest().action(ActionCode.ASYNC_DISPATCHED, null);
            try {
                applicationDispatcher.dispatch(servletRequest, servletResponse);
            } catch (Exception e) {
                throw new RuntimeException(sm.getString("asyncContextImpl.asyncDispatchError"), e);
            }
        }

    }
}