/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qfilesystemwatcher.h"
#include "qfilesystemwatcher_win_p.h"

#ifndef QT_NO_FILESYSTEMWATCHER

#include <qdebug.h>
#include <qfileinfo.h>
#include <qstringlist.h>
#include <qset.h>
#include <qdatetime.h>
#include <qdir.h>
#include <qtextstream.h>

#include <qt_windows.h>

QT_BEGIN_NAMESPACE

// #define WINQFSW_DEBUG
#ifdef WINQFSW_DEBUG
#  define DEBUG qDebug
#else
#  define DEBUG if (false) qDebug
#endif

QWindowsFileSystemWatcherEngine::Handle::Handle()
    : handle(INVALID_HANDLE_VALUE), flags(0u)
{
}

QWindowsFileSystemWatcherEngine::~QWindowsFileSystemWatcherEngine()
{
    foreach(QWindowsFileSystemWatcherEngineThread *thread, threads) {
        thread->stop();
        thread->wait();
        delete thread;
    }
}

QStringList QWindowsFileSystemWatcherEngine::addPaths(const QStringList &paths,
                                                       QStringList *files,
                                                       QStringList *directories)
{
    DEBUG() << "Adding" << paths.count() << "to existing" << (files->count() + directories->count()) << "watchers";
    QStringList p = paths;
    QMutableListIterator<QString> it(p);
    while (it.hasNext()) {
        QString path = it.next();
        QString normalPath = path;
        if ((normalPath.endsWith(QLatin1Char('/')) && !normalPath.endsWith(QLatin1String(":/")))
            || (normalPath.endsWith(QLatin1Char('\\')) && !normalPath.endsWith(QLatin1String(":\\")))
#ifdef Q_OS_WINCE
            && normalPath.size() > 1)
#else
            )
#endif
        normalPath.chop(1);
        QFileInfo fileInfo(normalPath);
        if (!fileInfo.exists())
            continue;

        bool isDir = fileInfo.isDir();
        if (isDir) {
            if (directories->contains(path))
                continue;
        } else {
            if (files->contains(path))
                continue;
        }

        DEBUG() << "Looking for a thread/handle for" << normalPath;

        const QString absolutePath = isDir ? fileInfo.absoluteFilePath() : fileInfo.absolutePath();
        const uint flags = isDir
                           ? (FILE_NOTIFY_CHANGE_DIR_NAME
                              | FILE_NOTIFY_CHANGE_FILE_NAME)
                           : (FILE_NOTIFY_CHANGE_DIR_NAME
                              | FILE_NOTIFY_CHANGE_FILE_NAME
                              | FILE_NOTIFY_CHANGE_ATTRIBUTES
                              | FILE_NOTIFY_CHANGE_SIZE
                              | FILE_NOTIFY_CHANGE_LAST_WRITE
                              | FILE_NOTIFY_CHANGE_SECURITY);

        QWindowsFileSystemWatcherEngine::PathInfo pathInfo;
        pathInfo.absolutePath = absolutePath;
        pathInfo.isDir = isDir;
        pathInfo.path = path;
        pathInfo = fileInfo;

        // Look for a thread
        QWindowsFileSystemWatcherEngineThread *thread = 0;
        QWindowsFileSystemWatcherEngine::Handle handle;
        QList<QWindowsFileSystemWatcherEngineThread *>::const_iterator jt, end;
        end = threads.constEnd();
        for(jt = threads.constBegin(); jt != end; ++jt) {
            thread = *jt;
            QMutexLocker locker(&(thread->mutex));

            handle = thread->handleForDir.value(QFileSystemWatcherPathKey(absolutePath));
            if (handle.handle != INVALID_HANDLE_VALUE && handle.flags == flags) {
                // found a thread now insert...
                DEBUG() << "Found a thread" << thread;

                QWindowsFileSystemWatcherEngineThread::PathInfoHash &h =
                    thread->pathInfoForHandle[handle.handle];
                const QFileSystemWatcherPathKey key(fileInfo.absoluteFilePath());
                if (!h.contains(key)) {
                    thread->pathInfoForHandle[handle.handle].insert(key, pathInfo);
                    if (isDir)
                        directories->append(path);
                    else
                        files->append(path);
                }
                it.remove();
                thread->wakeup();
                break;
            }
        }

        // no thread found, first create a handle
        if (handle.handle == INVALID_HANDLE_VALUE || handle.flags != flags) {
            DEBUG() << "No thread found";
            // Volume and folder paths need a trailing slash for proper notification
            // (e.g. "c:" -> "c:/").
            const QString effectiveAbsolutePath =
                    isDir ? (absolutePath + QLatin1Char('/')) : absolutePath;

            handle.handle = FindFirstChangeNotification((wchar_t*) QDir::toNativeSeparators(effectiveAbsolutePath).utf16(), false, flags);
            handle.flags = flags;
            if (handle.handle == INVALID_HANDLE_VALUE)
                continue;

            // now look for a thread to insert
            bool found = false;
            foreach(QWindowsFileSystemWatcherEngineThread *thread, threads) {
                QMutexLocker(&(thread->mutex));
                if (thread->handles.count() < MAXIMUM_WAIT_OBJECTS) {
                    DEBUG() << "Added handle" << handle.handle << "for" << absolutePath << "to watch" << fileInfo.absoluteFilePath()
                            << "to existing thread " << thread;
                    thread->handles.append(handle.handle);
                    thread->handleForDir.insert(QFileSystemWatcherPathKey(absolutePath), handle);

                    thread->pathInfoForHandle[handle.handle].insert(QFileSystemWatcherPathKey(fileInfo.absoluteFilePath()), pathInfo);
                    if (isDir)
                        directories->append(path);
                    else
                        files->append(path);

                    it.remove();
                    found = true;
                    thread->wakeup();
                    break;
                }
            }
            if (!found) {
                QWindowsFileSystemWatcherEngineThread *thread = new QWindowsFileSystemWatcherEngineThread();
                DEBUG() << "  ###Creating new thread" << thread << "(" << (threads.count()+1) << "threads)";
                thread->handles.append(handle.handle);
                thread->handleForDir.insert(QFileSystemWatcherPathKey(absolutePath), handle);

                thread->pathInfoForHandle[handle.handle].insert(QFileSystemWatcherPathKey(fileInfo.absoluteFilePath()), pathInfo);
                if (isDir)
                    directories->append(path);
                else
                    files->append(path);

                connect(thread, SIGNAL(fileChanged(QString,bool)),
                        this, SIGNAL(fileChanged(QString,bool)));
                connect(thread, SIGNAL(directoryChanged(QString,bool)),
                        this, SIGNAL(directoryChanged(QString,bool)));

                thread->msg = '@';
                thread->start();
                threads.append(thread);
                it.remove();
            }
        }
    }
    return p;
}

QStringList QWindowsFileSystemWatcherEngine::removePaths(const QStringList &paths,
                                                          QStringList *files,
                                                          QStringList *directories)
{
    DEBUG() << "removePaths" << paths;
    QStringList p = paths;
    QMutableListIterator<QString> it(p);
    while (it.hasNext()) {
        QString path = it.next();
        QString normalPath = path;
        if (normalPath.endsWith(QLatin1Char('/')) || normalPath.endsWith(QLatin1Char('\\')))
            normalPath.chop(1);
        QFileInfo fileInfo(normalPath);
        DEBUG() << "removing" << normalPath;
        QString absolutePath = fileInfo.absoluteFilePath();
        QList<QWindowsFileSystemWatcherEngineThread *>::iterator jt, end;
        end = threads.end();
        for(jt = threads.begin(); jt!= end; ++jt) {
            QWindowsFileSystemWatcherEngineThread *thread = *jt;
            if (*jt == 0)
                continue;

            QMutexLocker locker(&(thread->mutex));

            QWindowsFileSystemWatcherEngine::Handle handle = thread->handleForDir.value(QFileSystemWatcherPathKey(absolutePath));
            if (handle.handle == INVALID_HANDLE_VALUE) {
                // perhaps path is a file?
                absolutePath = fileInfo.absolutePath();
                handle = thread->handleForDir.value(QFileSystemWatcherPathKey(absolutePath));
            }
            if (handle.handle != INVALID_HANDLE_VALUE) {
                QWindowsFileSystemWatcherEngineThread::PathInfoHash &h =
                        thread->pathInfoForHandle[handle.handle];
                if (h.remove(QFileSystemWatcherPathKey(fileInfo.absoluteFilePath()))) {
                    // ###
                    files->removeAll(path);
                    directories->removeAll(path);

                    if (h.isEmpty()) {
                        DEBUG() << "Closing handle" << handle.handle;
                        FindCloseChangeNotification(handle.handle);    // This one might generate a notification

                        int indexOfHandle = thread->handles.indexOf(handle.handle);
                        Q_ASSERT(indexOfHandle != -1);
                        thread->handles.remove(indexOfHandle);

                        thread->handleForDir.remove(QFileSystemWatcherPathKey(absolutePath));
                        // h is now invalid

                        it.remove();

                        if (thread->handleForDir.isEmpty()) {
                            DEBUG() << "Stopping thread " << thread;
                            locker.unlock();
                            thread->stop();
                            thread->wait();
                            locker.relock();
                            // We can't delete the thread until the mutex locker is
                            // out of scope
                        }
                    }
                }
                // Found the file, go to next one
                break;
            }
        }
    }

    // Remove all threads that we stopped
    QList<QWindowsFileSystemWatcherEngineThread *>::iterator jt, end;
    end = threads.end();
    for(jt = threads.begin(); jt != end; ++jt) {
        if (!(*jt)->isRunning()) {
            delete *jt;
            *jt = 0;
        }
    }

    threads.removeAll(0);
    return p;
}

///////////
// QWindowsFileSystemWatcherEngineThread
///////////

QWindowsFileSystemWatcherEngineThread::QWindowsFileSystemWatcherEngineThread()
        : msg(0)
{
    if (HANDLE h = CreateEvent(0, false, false, 0)) {
        handles.reserve(MAXIMUM_WAIT_OBJECTS);
        handles.append(h);
    }
}


QWindowsFileSystemWatcherEngineThread::~QWindowsFileSystemWatcherEngineThread()
{
    CloseHandle(handles.at(0));
    handles[0] = INVALID_HANDLE_VALUE;

    foreach (HANDLE h, handles) {
        if (h == INVALID_HANDLE_VALUE)
            continue;
        FindCloseChangeNotification(h);
    }
}

static inline QString msgFindNextFailed(const QWindowsFileSystemWatcherEngineThread::PathInfoHash &pathInfos)
{
    QString result;
    QTextStream str(&result);
    str << "QFileSystemWatcher: FindNextChangeNotification failed for";
    foreach (const QWindowsFileSystemWatcherEngine::PathInfo &pathInfo, pathInfos)
        str << " \"" << QDir::toNativeSeparators(pathInfo.absolutePath) << '"';
    str << ' ';
    return result;
}

void QWindowsFileSystemWatcherEngineThread::run()
{
    QMutexLocker locker(&mutex);
    forever {
        QVector<HANDLE> handlesCopy = handles;
        locker.unlock();
        DEBUG() << "QWindowsFileSystemWatcherThread" << this << "waiting on" << handlesCopy.count() << "handles";
        DWORD r = WaitForMultipleObjects(handlesCopy.count(), handlesCopy.constData(), false, INFINITE);
        locker.relock();
        do {
            if (r == WAIT_OBJECT_0) {
                int m = msg;
                msg = 0;
                if (m == 'q') {
                    DEBUG() << "thread" << this << "told to quit";
                    return;
                }
                if (m != '@')
                    DEBUG() << "QWindowsFileSystemWatcherEngine: unknown message sent to thread: " << char(m);
                break;
            } else if (r > WAIT_OBJECT_0 && r < WAIT_OBJECT_0 + uint(handlesCopy.count())) {
                int at = r - WAIT_OBJECT_0;
                Q_ASSERT(at < handlesCopy.count());
                HANDLE handle = handlesCopy.at(at);

                // When removing a path, FindCloseChangeNotification might actually fire a notification
                // for some reason, so we must check if the handle exist in the handles vector
                if (handles.contains(handle)) {
                    DEBUG() << "thread" << this << "Acknowledged handle:" << at << handle;
                    QWindowsFileSystemWatcherEngineThread::PathInfoHash &h = pathInfoForHandle[handle];
                    bool fakeRemove = false;

                    if (!FindNextChangeNotification(handle)) {
                        const DWORD error = GetLastError();

                        if (error == ERROR_ACCESS_DENIED) {
                            // for directories, our object's handle appears to be woken up when the target of a
                            // watch is deleted, before the watched thing is actually deleted...
                            // anyway.. we're given an error code of ERROR_ACCESS_DENIED in that case.
                            fakeRemove = true;
                        }

                        qErrnoWarning(error, "%s", qPrintable(msgFindNextFailed(h)));
                    }
                    QMutableHashIterator<QFileSystemWatcherPathKey, QWindowsFileSystemWatcherEngine::PathInfo> it(h);
                    while (it.hasNext()) {
                        QWindowsFileSystemWatcherEngineThread::PathInfoHash::iterator x = it.next();
                        QString absolutePath = x.value().absolutePath;
                        QFileInfo fileInfo(x.value().path);
                        DEBUG() << "checking" << x.key();

                        // i'm not completely sure the fileInfo.exist() check will ever work... see QTBUG-2331
                        // ..however, I'm not completely sure enough to remove it.
                        if (fakeRemove || !fileInfo.exists()) {
                            DEBUG() << x.key() << "removed!";
                            if (x.value().isDir)
                                emit directoryChanged(x.value().path, true);
                            else
                                emit fileChanged(x.value().path, true);
                            h.erase(x);

                            // close the notification handle if the directory has been removed
                            if (h.isEmpty()) {
                                DEBUG() << "Thread closing handle" << handle;
                                FindCloseChangeNotification(handle);    // This one might generate a notification

                                int indexOfHandle = handles.indexOf(handle);
                                Q_ASSERT(indexOfHandle != -1);
                                handles.remove(indexOfHandle);

                                handleForDir.remove(QFileSystemWatcherPathKey(absolutePath));
                                // h is now invalid
                            }
                        } else if (x.value().isDir) {
                            DEBUG() << x.key() << "directory changed!";
                            emit directoryChanged(x.value().path, false);
                            x.value() = fileInfo;
                        } else if (x.value() != fileInfo) {
                            DEBUG() << x.key() << "file changed!";
                            emit fileChanged(x.value().path, false);
                            x.value() = fileInfo;
                        }
                    }
                }
            } else {
                // qErrnoWarning("QFileSystemWatcher: error while waiting for change notification");
                break;  // avoid endless loop
            }
            handlesCopy = handles;
            r = WaitForMultipleObjects(handlesCopy.count(), handlesCopy.constData(), false, 0);
        } while (r != WAIT_TIMEOUT);
    }
}


void QWindowsFileSystemWatcherEngineThread::stop()
{
    msg = 'q';
    SetEvent(handles.at(0));
}

void QWindowsFileSystemWatcherEngineThread::wakeup()
{
    msg = '@';
    SetEvent(handles.at(0));
}

QT_END_NAMESPACE
#endif // QT_NO_FILESYSTEMWATCHER