// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0

#include "terminalprocess_p.h"

#include "commandline.h"
#include "environment.h"
#include "hostosinfo.h"
#include "qtcassert.h"
#include "qtcprocess.h"
#include "terminalcommand.h"

#include <QCoreApplication>
#include <QLocalServer>
#include <QLocalSocket>
#include <QRegularExpression>
#include <QTemporaryFile>
#include <QTextCodec>
#include <QTimer>
#include <QWinEventNotifier>

#ifdef Q_OS_WIN

#include "winutils.h"

#include <cstring>
#include <stdlib.h>
#include <windows.h>

#else

#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

#endif

namespace Utils {
namespace Internal {

static QString modeOption(TerminalMode m)
{
    switch (m) {
        case TerminalMode::Run:
        return QLatin1String("run");
        case TerminalMode::Debug:
        return QLatin1String("debug");
        case TerminalMode::Suspend:
        return QLatin1String("suspend");
        case TerminalMode::Off:
        QTC_CHECK(false);
        break;
    }
    return {};
}

static QString msgCommChannelFailed(const QString &error)
{
    return QtcProcess::tr("Cannot set up communication channel: %1").arg(error);
}

static QString msgPromptToClose()
{
    // Shown in a terminal which might have a different character set on Windows.
    return QtcProcess::tr("Press <RETURN> to close this window...");
}

static QString msgCannotCreateTempFile(const QString &why)
{
    return QtcProcess::tr("Cannot create temporary file: %1").arg(why);
}

static QString msgCannotWriteTempFile()
{
    return QtcProcess::tr("Cannot write temporary file. Disk full?");
}

static QString msgCannotCreateTempDir(const QString & dir, const QString &why)
{
    return QtcProcess::tr("Cannot create temporary directory \"%1\": %2").arg(dir, why);
}

static QString msgUnexpectedOutput(const QByteArray &what)
{
    return QtcProcess::tr("Unexpected output from helper program (%1).")
        .arg(QString::fromLatin1(what));
}

static QString msgCannotChangeToWorkDir(const FilePath &dir, const QString &why)
{
    return QtcProcess::tr("Cannot change to working directory \"%1\": %2").arg(dir.toString(), why);
}

static QString msgCannotExecute(const QString & p, const QString &why)
{
    return QtcProcess::tr("Cannot execute \"%1\": %2").arg(p, why);
}

class TerminalProcessPrivate
{
public:
    TerminalProcessPrivate(QObject *parent)
        : m_stubServer(parent)
        , m_process(parent) {}

    qint64 m_processId = 0;
    ProcessResultData m_result;
    QLocalServer m_stubServer;
    QLocalSocket *m_stubSocket = nullptr;
    QTemporaryFile *m_tempFile = nullptr;

    // Used on Unix only
    QtcProcess m_process;
    QTimer *m_stubConnectTimer = nullptr;
    QByteArray m_stubServerDir;

    // Used on Windows only
    qint64 m_appMainThreadId = 0;

#ifdef Q_OS_WIN
    PROCESS_INFORMATION *m_pid = nullptr;
    HANDLE m_hInferior = NULL;
    QWinEventNotifier *inferiorFinishedNotifier = nullptr;
    QWinEventNotifier *processFinishedNotifier = nullptr;
#endif
};

TerminalImpl::TerminalImpl()
    : d(new TerminalProcessPrivate(this))
{
    connect(&d->m_stubServer, &QLocalServer::newConnection,
            this, &TerminalImpl::stubConnectionAvailable);

    d->m_process.setProcessChannelMode(QProcess::ForwardedChannels);
}

TerminalImpl::~TerminalImpl()
{
    stopProcess();
    delete d;
}

void TerminalImpl::start()
{
    if (isRunning())
        return;

    d->m_result = {};

#ifdef Q_OS_WIN

    QString pcmd;
    QString pargs;
    if (m_setup.m_terminalMode != TerminalMode::Run) { // The debugger engines already pre-process the arguments.
        pcmd = m_setup.m_commandLine.executable().toString();
        pargs = m_setup.m_commandLine.arguments();
    } else {
        ProcessArgs outArgs;
        ProcessArgs::prepareCommand(m_setup.m_commandLine, &pcmd, &outArgs,
                                    &m_setup.m_environment, &m_setup.m_workingDirectory);
        pargs = outArgs.toWindowsArgs();
    }

    const QString err = stubServerListen();
    if (!err.isEmpty()) {
        emitError(QProcess::FailedToStart, msgCommChannelFailed(err));
        return;
    }

    QStringList env = m_setup.m_environment.toStringList();
    if (!env.isEmpty()) {
        d->m_tempFile = new QTemporaryFile();
        if (!d->m_tempFile->open()) {
            cleanupAfterStartFailure(msgCannotCreateTempFile(d->m_tempFile->errorString()));
            return;
        }
        QString outString;
        QTextStream out(&outString);
        // Add PATH and SystemRoot environment variables in case they are missing
        const QStringList fixedEnvironment = [env] {
            QStringList envStrings = env;
            // add PATH if necessary (for DLL loading)
            if (envStrings.filter(QRegularExpression("^PATH=.*", QRegularExpression::CaseInsensitiveOption)).isEmpty()) {
                const QString path = qtcEnvironmentVariable("PATH");
                if (!path.isEmpty())
                    envStrings.prepend(QString::fromLatin1("PATH=%1").arg(path));
            }
            // add systemroot if needed
            if (envStrings.filter(QRegularExpression("^SystemRoot=.*", QRegularExpression::CaseInsensitiveOption)).isEmpty()) {
                const QString systemRoot = qtcEnvironmentVariable("SystemRoot");
                if (!systemRoot.isEmpty())
                    envStrings.prepend(QString::fromLatin1("SystemRoot=%1").arg(systemRoot));
            }
            return envStrings;
        }();

        for (const QString &var : fixedEnvironment)
            out << var << QChar(0);
        out << QChar(0);
        const QTextCodec *textCodec = QTextCodec::codecForName("UTF-16LE");
        QTC_CHECK(textCodec);
        const QByteArray outBytes = textCodec ? textCodec->fromUnicode(outString) : QByteArray();
        if (!textCodec || d->m_tempFile->write(outBytes) < 0) {
            cleanupAfterStartFailure(msgCannotWriteTempFile());
            return;
        }
        d->m_tempFile->flush();
    }

    STARTUPINFO si;
    ZeroMemory(&si, sizeof(si));
    si.cb = sizeof(si);

    d->m_pid = new PROCESS_INFORMATION;
    ZeroMemory(d->m_pid, sizeof(PROCESS_INFORMATION));

    QString workDir = m_setup.m_workingDirectory.toUserOutput();
    if (!workDir.isEmpty() && !workDir.endsWith(QLatin1Char('\\')))
        workDir.append(QLatin1Char('\\'));

    // Quote a Windows command line correctly for the "CreateProcess" API
    static const auto quoteWinCommand = [](const QString &program) {
        const QChar doubleQuote = QLatin1Char('"');

        // add the program as the first arg ... it works better
        QString programName = program;
        programName.replace(QLatin1Char('/'), QLatin1Char('\\'));
        if (!programName.startsWith(doubleQuote) && !programName.endsWith(doubleQuote)
                && programName.contains(QLatin1Char(' '))) {
            programName.prepend(doubleQuote);
            programName.append(doubleQuote);
        }
        return programName;
    };
    static const auto quoteWinArgument = [](const QString &arg) {
        if (arg.isEmpty())
            return QString::fromLatin1("\"\"");

        QString ret(arg);
        // Quotes are escaped and their preceding backslashes are doubled.
        ret.replace(QRegularExpression("(\\\\*)\""), "\\1\\1\\\"");
        if (ret.contains(QRegularExpression("\\s"))) {
            // The argument must not end with a \ since this would be interpreted
            // as escaping the quote -- rather put the \ behind the quote: e.g.
            // rather use "foo"\ than "foo\"
            int i = ret.length();
            while (i > 0 && ret.at(i - 1) == QLatin1Char('\\'))
                --i;
            ret.insert(i, QLatin1Char('"'));
            ret.prepend(QLatin1Char('"'));
        }
        return ret;
    };
    static const auto createWinCommandlineMultiArgs = [](const QString &program, const QStringList &args) {
        QString programName = quoteWinCommand(program);
        for (const QString &arg : args) {
            programName += QLatin1Char(' ');
            programName += quoteWinArgument(arg);
        }
        return programName;
    };
    static const auto createWinCommandlineSingleArg = [](const QString &program, const QString &args)
    {
        QString programName = quoteWinCommand(program);
        if (!args.isEmpty()) {
            programName += QLatin1Char(' ');
            programName += args;
        }
        return programName;
    };

    QStringList stubArgs;
    stubArgs << modeOption(m_setup.m_terminalMode)
             << d->m_stubServer.fullServerName()
             << workDir
             << (d->m_tempFile ? d->m_tempFile->fileName() : QString())
             << createWinCommandlineSingleArg(pcmd, pargs)
             << msgPromptToClose();

    const QString cmdLine = createWinCommandlineMultiArgs(
            QCoreApplication::applicationDirPath() + QLatin1String("/qtcreator_process_stub.exe"), stubArgs);

    bool success = CreateProcessW(0, (WCHAR*)cmdLine.utf16(),
                                  0, 0, FALSE, CREATE_NEW_CONSOLE,
                                  0, 0,
                                  &si, d->m_pid);

    if (!success) {
        delete d->m_pid;
        d->m_pid = nullptr;
        const QString msg = QtcProcess::tr("The process \"%1\" could not be started: %2")
                                .arg(cmdLine, winErrorMessage(GetLastError()));
        cleanupAfterStartFailure(msg);
        return;
    }

    d->processFinishedNotifier = new QWinEventNotifier(d->m_pid->hProcess, this);
    connect(d->processFinishedNotifier, &QWinEventNotifier::activated,
            this, &TerminalImpl::stubExited);

#else

    ProcessArgs::SplitError perr;
    ProcessArgs pargs = ProcessArgs::prepareArgs(m_setup.m_commandLine.arguments(),
                                                 &perr,
                                                 HostOsInfo::hostOs(),
                                                 &m_setup.m_environment,
                                                 &m_setup.m_workingDirectory,
                                                 m_setup.m_abortOnMetaChars);

    QString pcmd;
    if (perr == ProcessArgs::SplitOk) {
        pcmd = m_setup.m_commandLine.executable().toString();
    } else {
        if (perr != ProcessArgs::FoundMeta) {
            emitError(QProcess::FailedToStart, QtcProcess::tr("Quoting error in command."));
            return;
        }
        if (m_setup.m_terminalMode == TerminalMode::Debug) {
            // FIXME: QTCREATORBUG-2809
            emitError(QProcess::FailedToStart,
                      QtcProcess::tr("Debugging complex shell commands in a terminal"
                                     " is currently not supported."));
            return;
        }
        pcmd = qtcEnvironmentVariable("SHELL", "/bin/sh");
        pargs = ProcessArgs::createUnixArgs(
                        {"-c", (ProcessArgs::quoteArg(m_setup.m_commandLine.executable().toString())
                         + ' ' + m_setup.m_commandLine.arguments())});
    }

    ProcessArgs::SplitError qerr;
    const TerminalCommand terminal = TerminalCommand::terminalEmulator();
    const ProcessArgs terminalArgs = ProcessArgs::prepareArgs(terminal.executeArgs,
                                                              &qerr,
                                                              HostOsInfo::hostOs(),
                                                              &m_setup.m_environment,
                                                              &m_setup.m_workingDirectory);
    if (qerr != ProcessArgs::SplitOk) {
        emitError(QProcess::FailedToStart,
                  qerr == ProcessArgs::BadQuoting
                      ? QtcProcess::tr("Quoting error in terminal command.")
                      : QtcProcess::tr("Terminal command may not be a shell command."));
        return;
    }

    const QString err = stubServerListen();
    if (!err.isEmpty()) {
        emitError(QProcess::FailedToStart, msgCommChannelFailed(err));
        return;
    }

    m_setup.m_environment.unset(QLatin1String("TERM"));

    const QStringList env = m_setup.m_environment.toStringList();
    if (!env.isEmpty()) {
        d->m_tempFile = new QTemporaryFile(this);
        if (!d->m_tempFile->open()) {
            cleanupAfterStartFailure(msgCannotCreateTempFile(d->m_tempFile->errorString()));
            return;
        }
        QByteArray contents;
        for (const QString &var : env) {
            const QByteArray l8b = var.toLocal8Bit();
            contents.append(l8b.constData(), l8b.size() + 1);
        }
        if (d->m_tempFile->write(contents) != contents.size() || !d->m_tempFile->flush()) {
            cleanupAfterStartFailure(msgCannotWriteTempFile());
            return;
        }
    }

    const QString stubPath = QCoreApplication::applicationDirPath()
            + QLatin1String("/" RELATIVE_LIBEXEC_PATH "/qtcreator_process_stub");

    QStringList allArgs = terminalArgs.toUnixArgs();

    allArgs << stubPath
            << modeOption(m_setup.m_terminalMode)
            << d->m_stubServer.fullServerName()
            << msgPromptToClose()
            << m_setup.m_workingDirectory.path()
            << (d->m_tempFile ? d->m_tempFile->fileName() : QString())
            << QString::number(getpid())
            << pcmd
            << pargs.toUnixArgs();

    if (terminal.needsQuotes)
        allArgs = QStringList { ProcessArgs::joinArgs(allArgs) };

    d->m_process.setEnvironment(m_setup.m_environment);
    d->m_process.setCommand({FilePath::fromString(terminal.command), allArgs});
    d->m_process.setProcessImpl(m_setup.m_processImpl);
    d->m_process.setReaperTimeout(m_setup.m_reaperTimeout);

    d->m_process.start();
    if (!d->m_process.waitForStarted()) {
        const QString msg = QtcProcess::tr("Cannot start the terminal emulator \"%1\", change the "
                                           "setting in the Environment preferences. (%2)")
                                .arg(terminal.command).arg(d->m_process.errorString());
        cleanupAfterStartFailure(msg);
        return;
    }
    d->m_stubConnectTimer = new QTimer(this);
    connect(d->m_stubConnectTimer, &QTimer::timeout, this, &TerminalImpl::stopProcess);
    d->m_stubConnectTimer->setSingleShot(true);
    d->m_stubConnectTimer->start(10000);

#endif
}

void TerminalImpl::cleanupAfterStartFailure(const QString &errorMessage)
{
    stubServerShutdown();
    emitError(QProcess::FailedToStart, errorMessage);
    delete d->m_tempFile;
    d->m_tempFile = nullptr;
}

void TerminalImpl::sendControlSignal(ControlSignal controlSignal)
{
    switch (controlSignal) {
    case ControlSignal::Terminate:
    case ControlSignal::Kill:
        killProcess();
        if (HostOsInfo::isWindowsHost())
            killStub();
        break;
    case ControlSignal::Interrupt:
        sendCommand('i');
        break;
    case ControlSignal::KickOff:
        sendCommand('c');
        break;
    }
}

void TerminalImpl::sendCommand(char c)
{
#ifdef Q_OS_WIN
    Q_UNUSED(c)
#else
    if (d->m_stubSocket && d->m_stubSocket->isWritable()) {
        d->m_stubSocket->write(&c, 1);
        d->m_stubSocket->flush();
    }
#endif
}

void TerminalImpl::killProcess()
{
#ifdef Q_OS_WIN
    if (d->m_hInferior != NULL) {
        TerminateProcess(d->m_hInferior, (unsigned)-1);
        cleanupInferior();
    }
#else
    sendCommand('k');
#endif
    d->m_processId = 0;
}

void TerminalImpl::killStub()
{
    if (!isRunning())
        return;

#ifdef Q_OS_WIN
    TerminateProcess(d->m_pid->hProcess, (unsigned)-1);
    WaitForSingleObject(d->m_pid->hProcess, INFINITE);
    cleanupStub();
    emitFinished(-1, QProcess::CrashExit);
#else
    sendCommand('s');
    stubServerShutdown();
    d->m_process.stop();
    d->m_process.waitForFinished();
#endif
}

void TerminalImpl::stopProcess()
{
    killProcess();
    killStub();
}

bool TerminalImpl::isRunning() const
{
#ifdef Q_OS_WIN
    return d->m_pid != nullptr;
#else
    return d->m_process.state() != QProcess::NotRunning
            || (d->m_stubSocket && d->m_stubSocket->isOpen());
#endif
}

QString TerminalImpl::stubServerListen()
{
#ifdef Q_OS_WIN
    if (d->m_stubServer.listen(QString::fromLatin1("creator-%1-%2")
                            .arg(QCoreApplication::applicationPid())
                            .arg(rand())))
        return QString();
    return d->m_stubServer.errorString();
#else
    // We need to put the socket in a private directory, as some systems simply do not
    // check the file permissions of sockets.
    QString stubFifoDir;
    while (true) {
        {
            QTemporaryFile tf;
            if (!tf.open())
                return msgCannotCreateTempFile(tf.errorString());
            stubFifoDir = tf.fileName();
        }
        // By now the temp file was deleted again
        d->m_stubServerDir = QFile::encodeName(stubFifoDir);
        if (!::mkdir(d->m_stubServerDir.constData(), 0700))
            break;
        if (errno != EEXIST)
            return msgCannotCreateTempDir(stubFifoDir, QString::fromLocal8Bit(strerror(errno)));
    }
    const QString stubServer = stubFifoDir + QLatin1String("/stub-socket");
    if (!d->m_stubServer.listen(stubServer)) {
        ::rmdir(d->m_stubServerDir.constData());
        return QtcProcess::tr("Cannot create socket \"%1\": %2")
            .arg(stubServer, d->m_stubServer.errorString());
    }
    return {};
#endif
}

void TerminalImpl::stubServerShutdown()
{
#ifdef Q_OS_WIN
    delete d->m_stubSocket;
    d->m_stubSocket = nullptr;
    if (d->m_stubServer.isListening())
        d->m_stubServer.close();
#else
    if (d->m_stubSocket) {
        readStubOutput(); // we could get the shutdown signal before emptying the buffer
        d->m_stubSocket->disconnect(); // avoid getting queued readyRead signals
        d->m_stubSocket->deleteLater(); // we might be called from the disconnected signal of m_stubSocket
    }
    d->m_stubSocket = nullptr;
    if (d->m_stubServer.isListening()) {
        d->m_stubServer.close();
        ::rmdir(d->m_stubServerDir.constData());
    }
#endif
}

void TerminalImpl::stubConnectionAvailable()
{
    if (d->m_stubConnectTimer) {
        delete d->m_stubConnectTimer;
        d->m_stubConnectTimer = nullptr;
    }

    d->m_stubSocket = d->m_stubServer.nextPendingConnection();
    connect(d->m_stubSocket, &QIODevice::readyRead, this, &TerminalImpl::readStubOutput);

    if (HostOsInfo::isAnyUnixHost())
        connect(d->m_stubSocket, &QLocalSocket::disconnected, this, &TerminalImpl::stubExited);
}

static QString errorMsg(int code)
{
    return QString::fromLocal8Bit(strerror(code));
}

void TerminalImpl::readStubOutput()
{
    while (d->m_stubSocket->canReadLine()) {
        QByteArray out = d->m_stubSocket->readLine();
#ifdef Q_OS_WIN
        out.chop(2); // \r\n
        if (out.startsWith("err:chdir ")) {
            emitError(QProcess::FailedToStart,
                      msgCannotChangeToWorkDir(m_setup.m_workingDirectory, winErrorMessage(out.mid(10).toInt())));
        } else if (out.startsWith("err:exec ")) {
            emitError(QProcess::FailedToStart,
                      msgCannotExecute(m_setup.m_commandLine.executable().toUserOutput(), winErrorMessage(out.mid(9).toInt())));
        } else if (out.startsWith("thread ")) { // Windows only
            // TODO: ensure that it comes before "pid " comes
            d->m_appMainThreadId = out.mid(7).toLongLong();
        } else if (out.startsWith("pid ")) {
            // Will not need it any more
            delete d->m_tempFile;
            d->m_tempFile = nullptr;
            d->m_processId = out.mid(4).toLongLong();

            d->m_hInferior = OpenProcess(
                    SYNCHRONIZE | PROCESS_QUERY_INFORMATION | PROCESS_TERMINATE,
                    FALSE, d->m_processId);
            if (d->m_hInferior == NULL) {
                emitError(QProcess::FailedToStart,
                          QtcProcess::tr("Cannot obtain a handle to the inferior: %1")
                              .arg(winErrorMessage(GetLastError())));
                // Uhm, and now what?
                continue;
            }
            d->inferiorFinishedNotifier = new QWinEventNotifier(d->m_hInferior, this);
            connect(d->inferiorFinishedNotifier, &QWinEventNotifier::activated, this, [this] {
                DWORD chldStatus;

                if (!GetExitCodeProcess(d->m_hInferior, &chldStatus))
                    emitError(QProcess::UnknownError,
                              QtcProcess::tr("Cannot obtain exit status from inferior: %1")
                                  .arg(winErrorMessage(GetLastError())));
                cleanupInferior();
                emitFinished(chldStatus, QProcess::NormalExit);
            });

            emit started(d->m_processId, d->m_appMainThreadId);
        } else {
            emitError(QProcess::UnknownError, msgUnexpectedOutput(out));
            TerminateProcess(d->m_pid->hProcess, (unsigned)-1);
            break;
        }
#else
        out.chop(1); // \n
        if (out.startsWith("err:chdir ")) {
            emitError(QProcess::FailedToStart,
                      msgCannotChangeToWorkDir(m_setup.m_workingDirectory, errorMsg(out.mid(10).toInt())));
        } else if (out.startsWith("err:exec ")) {
            emitError(QProcess::FailedToStart,
                      msgCannotExecute(m_setup.m_commandLine.executable().toString(), errorMsg(out.mid(9).toInt())));
        } else if (out.startsWith("spid ")) {
            delete d->m_tempFile;
            d->m_tempFile = nullptr;
        } else if (out.startsWith("pid ")) {
            d->m_processId = out.mid(4).toInt();
            emit started(d->m_processId);
        } else if (out.startsWith("exit ")) {
            emitFinished(out.mid(5).toInt(), QProcess::NormalExit);
        } else if (out.startsWith("crash ")) {
            emitFinished(out.mid(6).toInt(), QProcess::CrashExit);
        } else {
            emitError(QProcess::UnknownError, msgUnexpectedOutput(out));
            d->m_process.terminate();
            break;
        }
#endif
    } // while
}

void TerminalImpl::stubExited()
{
    // The stub exit might get noticed before we read the pid for the kill on Windows
    // or the error status elsewhere.
    if (d->m_stubSocket && d->m_stubSocket->state() == QLocalSocket::ConnectedState)
        d->m_stubSocket->waitForDisconnected();

#ifdef Q_OS_WIN
    cleanupStub();
    if (d->m_hInferior != NULL) {
        TerminateProcess(d->m_hInferior, (unsigned)-1);
        cleanupInferior();
        emitFinished(-1, QProcess::CrashExit);
    }
#else
    stubServerShutdown();
    delete d->m_tempFile;
    d->m_tempFile = nullptr;
    if (d->m_processId)
        emitFinished(-1, QProcess::CrashExit);
#endif
}

void TerminalImpl::cleanupInferior()
{
#ifdef Q_OS_WIN
    delete d->inferiorFinishedNotifier;
    d->inferiorFinishedNotifier = nullptr;
    CloseHandle(d->m_hInferior);
    d->m_hInferior = NULL;
#endif
}

void TerminalImpl::cleanupStub()
{
#ifdef Q_OS_WIN
    stubServerShutdown();
    delete d->processFinishedNotifier;
    d->processFinishedNotifier = nullptr;
    CloseHandle(d->m_pid->hThread);
    CloseHandle(d->m_pid->hProcess);
    delete d->m_pid;
    d->m_pid = nullptr;
    delete d->m_tempFile;
    d->m_tempFile = nullptr;
#endif
}

void TerminalImpl::emitError(QProcess::ProcessError error, const QString &errorString)
{
    d->m_result.m_error = error;
    d->m_result.m_errorString = errorString;
    if (error == QProcess::FailedToStart)
        emit done(d->m_result);
}

void TerminalImpl::emitFinished(int exitCode, QProcess::ExitStatus exitStatus)
{
    d->m_processId = 0;
    d->m_result.m_exitCode = exitCode;
    d->m_result.m_exitStatus = exitStatus;
    emit done(d->m_result);
}


} // Internal
} // Utils