/*
 * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
 * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
 */

package com.intellij.execution.process;

import com.intellij.execution.ExecutionException;
import com.intellij.execution.configurations.GeneralCommandLine;
import com.intellij.openapi.application.Application;
import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.application.ModalityState;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.progress.EmptyProgressIndicator;
import com.intellij.openapi.progress.ProgressManager;
import com.intellij.openapi.progress.Task;
import com.intellij.openapi.util.Key;
import com.intellij.openapi.util.io.FileUtil;
import com.intellij.util.ExceptionUtil;
import com.intellij.util.io.BaseDataReader;
import com.intellij.util.io.BaseOutputReader;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.io.File;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

public class OSProcessHandler extends BaseOSProcessHandler {
    private static final Logger LOG = Logger.getInstance(OSProcessHandler.class);
    private static final Set<String> REPORTED_EXECUTIONS = Collections.newSetFromMap(new ConcurrentHashMap<>());
    private static final long ALLOWED_TIMEOUT_THRESHOLD = 10;

    private static final Key<Set<File>> DELETE_FILES_ON_TERMINATION = Key.create("OSProcessHandler.FileToDelete");

    private final boolean myHasErrorStream;
    @NotNull
    private final ModalityState myModality;
    private boolean myHasPty;
    private final Set<? extends File> myFilesToDelete;

    public OSProcessHandler(@NotNull GeneralCommandLine commandLine) throws ExecutionException {
        super(startProcess(commandLine), commandLine.getCommandLineString(), commandLine.getCharset());

        setHasPty(isPtyProcess(getProcess()));
        myHasErrorStream = !commandLine.isRedirectErrorStream();
        myFilesToDelete = commandLine.getUserData(DELETE_FILES_ON_TERMINATION);
        myModality = getDefaultModality();
    }

    @NotNull
    public static ModalityState getDefaultModality() {
        Application app = ApplicationManager.getApplication();
        return app == null ? ModalityState.NON_MODAL : app.getDefaultModalityState();
    }

    /**
     * {@code commandLine} must not be empty (for correct thread attribution in the stacktrace)
     */
    public OSProcessHandler(@NotNull Process process, /*@NotNull*/ String commandLine, @Nullable Charset charset) {
        this(process, commandLine, charset, null);
    }

    /**
     * {@code commandLine} must not be empty (for correct thread attribution in the stacktrace)
     */
    private OSProcessHandler(
            @NotNull Process process, /*@NotNull*/
            String commandLine,
            @Nullable Charset charset,
            @Nullable Set<? extends File> filesToDelete
    ) {
        super(process, commandLine, charset);
        setHasPty(isPtyProcess(process));
        myFilesToDelete = filesToDelete;
        myHasErrorStream = true;
        myModality = getDefaultModality();
    }

    @NotNull
    private static Process startProcess(@NotNull GeneralCommandLine commandLine) throws ExecutionException {
        try {
            return commandLine.createProcess();
        }
        catch (Throwable e) {
            deleteTempFiles(commandLine.getUserData(DELETE_FILES_ON_TERMINATION));
            throw e;
        }
    }

    @Override
    public boolean waitFor() {
        checkEdtAndReadAction(this);
        return super.waitFor();
    }

    @Override
    public boolean waitFor(long timeoutInMilliseconds) {
        if (timeoutInMilliseconds > ALLOWED_TIMEOUT_THRESHOLD) {
            checkEdtAndReadAction(this);
        }
        return super.waitFor(timeoutInMilliseconds);
    }

    /**
     * Checks if we are going to wait for {@code processHandler} to finish on EDT or under ReadAction. Logs error if we do so.
     * <br/><br/>
     * HOW-TO fix an error from this method:
     * <ul>
     * <li>You are on the pooled thread under {@link com.intellij.openapi.application.ReadAction ReadAction}:
     * <ul>
     *     <li>Synchronous (you need to return execution result or derived information to the caller) - get rid the ReadAction or synchronicity.
     *    *     Move execution part out of the code executed under ReadAction, or make your execution asynchronous - execute on
     *    *     {@link Task.Backgroundable other thread} and invoke a callback.</li>
     *     <li>Non-synchronous (you don't need to return something) - execute on another thread. E.g. using {@link Task.Backgroundable}</li>
     * </ul>
     * </li>
     *
     * <li>You are on EDT:
     * <ul>
     *
     * <li>Outside of {@link com.intellij.openapi.application.WriteAction WriteAction}:
     *   <ul>
     *     <li>Synchronous (you need to return execution result or derived information to the caller) - execute under
     *       {@link ProgressManager#runProcessWithProgressSynchronously(Runnable, String, boolean, com.intellij.openapi.project.Project) modal progress}.</li>
     *     <li>Non-synchronous (you don't need to return something) - execute on the pooled thread. E.g. using {@link Task.Backgroundable}</li>
     *   </ul>
     * </li>
     *
     * <li>Under {@link com.intellij.openapi.application.WriteAction WriteAction}
     *   <ul>
     *     <li>Synchronous (you need to return execution result or derived information to the caller) - get rid the WriteAction or synchronicity.
     *       Move execution part out of the code executed under WriteAction, or make your execution asynchronous - execute on
     *      {@link Task.Backgroundable other thread} and invoke a callback.</li>
     *     <li>Non-synchronous (you don't need to return something) - execute on the pooled thread. E.g. using {@link Task.Backgroundable}</li>
     *   </ul>
     * </li>
     * </ul></li></ul>
     *
     * @apiNote works only in the internal non-headless mode. Reports once per running session per stacktrace per cause.
     */
    private static void checkEdtAndReadAction(@NotNull ProcessHandler processHandler) {
        Application application = ApplicationManager.getApplication();
        if (application == null || !application.isInternal() || application.isHeadlessEnvironment()) {
            return;
        }
        @NonNls String message = null;
        if (application.isDispatchThread()) {
            message = "Synchronous execution on EDT: ";
        }
        else if (application.isReadAccessAllowed()) {
            message = "Synchronous execution under ReadAction: ";
        }
        if (message != null && REPORTED_EXECUTIONS.add(ExceptionUtil.currentStackTrace())) {
            LOG.error(message + processHandler + ", see com.intellij.execution.process.OSProcessHandler#checkEdtAndReadAction() Javadoc for resolutions");
        }
    }

    private static void deleteTempFiles(Set<? extends File> tempFiles) {
        if (tempFiles != null) {
            try {
                for (File file : tempFiles) {
                    FileUtil.delete(file);
                }
            }
            catch (Throwable t) {
                LOG.error("failed to delete temp. files", t);
            }
        }
    }

    private static boolean isPtyProcess(Process process) {
        Class<?> c = process.getClass();
        while (c != null) {
            if ("com.pty4j.unix.UnixPtyProcess".equals(c.getName()) || "com.pty4j.windows.WinPtyProcess".equals(c.getName())) {
                return true;
            }
            c = c.getSuperclass();
        }
        return false;
    }

    @Override
    protected void onOSProcessTerminated(int exitCode) {
        if (myModality != ModalityState.NON_MODAL) {
            ProgressManager.getInstance().runProcess(() -> super.onOSProcessTerminated(exitCode), new EmptyProgressIndicator(myModality));
        } else {
            super.onOSProcessTerminated(exitCode);
        }
        deleteTempFiles(myFilesToDelete);
    }

    @Override
    protected boolean processHasSeparateErrorStream() {
        return myHasErrorStream;
    }

    @Override
    protected void doDestroyProcess() {
        getProcess().destroy();
    }

    /**
     * <p>In case of PTY this process handler will use blocking read because {@link InputStream#available()} doesn't work for Pty4j, and there
     * is no reason to "disconnect" leaving PTY alive. See {@link BaseDataReader.SleepingPolicy} for more info.</p>
     *
     * <p>The value should be set before {@link #startNotify()} invocation.
     * It is set by default in case of using GeneralCommandLine based constructor.</p>
     *
     * @param hasPty {@code true} if process is PTY-based.
     */
    private void setHasPty(boolean hasPty) {
        myHasPty = hasPty;
    }

    /**
     * Rule of thumb: use {@link BaseOutputReader.Options#BLOCKING} for short-living process that you never want to "disconnect" from.
     * See {@link BaseDataReader.SleepingPolicy} for the whole story.
     */
    @NotNull
    @Override
    protected BaseOutputReader.Options readerOptions() {
        return myHasPty ? BaseOutputReader.Options.BLOCKING : super.readerOptions();  // blocking read in case of PTY-based process
    }

    /**
     * Registers a file to delete after the given command line finishes.
     * In order to have an effect, the command line has to be executed with {@link #OSProcessHandler(GeneralCommandLine)}.
     */
    public static void deleteFileOnTermination(@NotNull GeneralCommandLine commandLine, @NotNull File fileToDelete) {
        Set<File> set = commandLine.getUserData(DELETE_FILES_ON_TERMINATION);
        if (set == null) {
            set = new HashSet<>();
            commandLine.putUserData(DELETE_FILES_ON_TERMINATION, set);
        }
        set.add(fileToDelete);
    }

    public static class Silent extends OSProcessHandler {
        public Silent(@NotNull GeneralCommandLine commandLine) throws ExecutionException {
            super(commandLine);
        }

        @NotNull
        @Override
        protected BaseOutputReader.Options readerOptions() {
            return BaseOutputReader.Options.forMostlySilentProcess();
        }
    }
}