// Copyright (C) 2018 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0

#include "qmlpreviewapplication.h"

#include <QtCore/QStringList>
#include <QtCore/QTextStream>
#include <QtCore/QProcess>
#include <QtCore/QTimer>
#include <QtCore/QDateTime>
#include <QtCore/QFileInfo>
#include <QtCore/QDebug>
#include <QtCore/QDir>
#include <QtCore/QCommandLineParser>
#include <QtCore/QTemporaryFile>
#include <QtCore/QUrl>
#include <QtCore/QLibraryInfo>

QmlPreviewApplication::QmlPreviewApplication(int &argc, char **argv) :
    QCoreApplication(argc, argv),
    m_verbose(false),
    m_connectionAttempts(0)
{
    m_connection.reset(new QQmlDebugConnection);
    m_qmlPreviewClient.reset(new QQmlPreviewClient(m_connection.data()));
    m_connectTimer.setInterval(1000);

    m_loadTimer.setInterval(100);
    m_loadTimer.setSingleShot(true);
    connect(&m_loadTimer, &QTimer::timeout, this, [this]() {
        m_qmlPreviewClient->triggerLoad(QUrl());
    });

    connect(&m_connectTimer, &QTimer::timeout, this, &QmlPreviewApplication::tryToConnect);
    connect(m_connection.data(), &QQmlDebugConnection::connected, &m_connectTimer, &QTimer::stop);

    connect(m_qmlPreviewClient.data(), &QQmlPreviewClient::error,
            this, &QmlPreviewApplication::logError);
    connect(m_qmlPreviewClient.data(), &QQmlPreviewClient::request,
            this, &QmlPreviewApplication::serveRequest);

    connect(&m_watcher, &QmlPreviewFileSystemWatcher::fileChanged,
            this, &QmlPreviewApplication::sendFile);
    connect(&m_watcher, &QmlPreviewFileSystemWatcher::directoryChanged,
            this, &QmlPreviewApplication::sendDirectory);
}

QmlPreviewApplication::~QmlPreviewApplication()
{
    if (m_process && m_process->state() != QProcess::NotRunning) {
        logStatus("Terminating process ...");
        m_process->disconnect();
        m_process->terminate();
        if (!m_process->waitForFinished(1000)) {
            logStatus("Killing process ...");
            m_process->kill();
        }
    }
}

void QmlPreviewApplication::parseArguments()
{
    setApplicationName(QLatin1String("qmlpreview"));
    setApplicationVersion(QLatin1String(qVersion()));

    QCommandLineParser parser;
    parser.setSingleDashWordOptionMode(QCommandLineParser::ParseAsLongOptions);
    parser.setOptionsAfterPositionalArgumentsMode(QCommandLineParser::ParseAsPositionalArguments);

    parser.setApplicationDescription(QChar::LineFeed + tr(
        "The QML Preview tool watches QML and JavaScript files on disk and updates\n"
        "the application live with any changes. The application to be previewed\n"
        "has to enable QML debugging. See the Qt Creator documentation on how to do\n"
        "this for different Qt versions."));

    QCommandLineOption verbose(QStringList() << QLatin1String("verbose"),
                               tr("Print debugging output."));
    parser.addOption(verbose);

    parser.addHelpOption();
    parser.addVersionOption();

    parser.addPositionalArgument(QLatin1String("executable"),
                                 tr("The executable to be started and previewed."),
                                 QLatin1String("[executable]"));
    parser.addPositionalArgument(QLatin1String("parameters"),
                                 tr("Parameters for the executable to be started."),
                                 QLatin1String("[parameters...]"));

    parser.process(*this);

    QTemporaryFile file;
    if (file.open())
        m_socketFile = file.fileName();

    if (parser.isSet(verbose))
        m_verbose = true;

    m_arguments = parser.positionalArguments();
    if (!m_arguments.isEmpty())
        m_executablePath = m_arguments.takeFirst();

    if (m_executablePath.isEmpty()) {
        logError(tr("You have to specify an executable to start."));
        parser.showHelp(2);
    }
}

int QmlPreviewApplication::exec()
{
    QTimer::singleShot(0, this, &QmlPreviewApplication::run);
    return QCoreApplication::exec();
}

void QmlPreviewApplication::run()
{
    logStatus(QString("Listening on %1 ...").arg(m_socketFile));
    m_connection->startLocalServer(m_socketFile);
    m_process.reset(new QProcess(this));
    QStringList arguments;
    arguments << QString("-qmljsdebugger=file:%1,block,services:QmlPreview").arg(m_socketFile);
    arguments << m_arguments;

    m_process->setProcessChannelMode(QProcess::MergedChannels);
    connect(m_process.data(), &QIODevice::readyRead,
            this, &QmlPreviewApplication::processHasOutput);
    connect(m_process.data(), QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
            this, [this](int){ processFinished(); });
    logStatus(QString("Starting '%1 %2' ...").arg(m_executablePath, arguments.join(QLatin1Char(' '))));
    m_process->start(m_executablePath, arguments);
    if (!m_process->waitForStarted()) {
        logError(QString("Could not run '%1': %2").arg(m_executablePath, m_process->errorString()));
        exit(1);
    }
    m_connectTimer.start();
}

void QmlPreviewApplication::tryToConnect()
{
    Q_ASSERT(!m_connection->isConnected());
    ++m_connectionAttempts;

    if (m_verbose && !(m_connectionAttempts % 5)) {// print every 5 seconds
        logError(QString("No connection received on %1 for %2 seconds ...")
                 .arg(m_socketFile).arg(m_connectionAttempts));
    }
}

void QmlPreviewApplication::processHasOutput()
{
    Q_ASSERT(m_process);
    while (m_process->bytesAvailable()) {
        QTextStream out(stderr);
        out << m_process->readAll();
    }
}

void QmlPreviewApplication::processFinished()
{
    Q_ASSERT(m_process);
    int exitCode = 0;
    if (m_process->exitStatus() == QProcess::NormalExit) {
        logStatus(QString("Process exited (%1).").arg(m_process->exitCode()));
    } else {
        logError("Process crashed!");
        exitCode = 3;
    }
    exit(exitCode);
}

void QmlPreviewApplication::logError(const QString &error)
{
    QTextStream err(stderr);
    err << "Error: " << error << Qt::endl;
}

void QmlPreviewApplication::logStatus(const QString &status)
{
    if (!m_verbose)
        return;
    QTextStream err(stderr);
    err << status << Qt::endl;
}

void QmlPreviewApplication::serveRequest(const QString &path)
{
    QFileInfo info(path);

    if (info.isDir()) {
        m_qmlPreviewClient->sendDirectory(path, QDir(path).entryList());
        m_watcher.addDirectory(path);
    } else {
        QFile file(path);
        if (file.open(QIODevice::ReadOnly)) {
            m_qmlPreviewClient->sendFile(path, file.readAll());
            m_watcher.addFile(path);
        } else {
            logStatus(QString("Could not open file %1 for reading: %2").arg(path)
                      .arg(file.errorString()));
            m_qmlPreviewClient->sendError(path);
        }
    }
}

bool QmlPreviewApplication::sendFile(const QString &path)
{
    QFile file(path);
    if (file.open(QIODevice::ReadOnly)) {
        m_qmlPreviewClient->sendFile(path, file.readAll());
        // Defer the Load, because files tend to change multiple times in a row.
        m_loadTimer.start();
        return true;
    }
    logStatus(QString("Could not open file %1 for reading: %2").arg(path).arg(file.errorString()));
    return false;
}

void QmlPreviewApplication::sendDirectory(const QString &path)
{
    m_qmlPreviewClient->sendDirectory(path, QDir(path).entryList());
    m_loadTimer.start();
}