/*
 * Copyright (C) by Olivier Goffart <ogoffart@owncloud.com>
 * Copyright (C) by Klaas Freitag <freitag@owncloud.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 */

#include "owncloudpropagator.h"
#include "account.h"
#include "common/asserts.h"
#include "common/syncjournaldb.h"
#include "common/syncjournalfilerecord.h"
#include "common/utility.h"
#include "discoveryphase.h"
#include "filesystem.h"
#include "propagatedownload.h"
#include "propagateremotedelete.h"
#include "propagateremotemkdir.h"
#include "propagateremotemove.h"
#include "propagateupload.h"
#include "propagateuploadtus.h"
#include "propagatorjobs.h"

#ifdef Q_OS_WIN
#include "common/utility_win.h"
#endif

#include <QApplication>
#include <QFileInfo>
#include <QLoggingCategory>
#include <QObject>
#include <QStack>
#include <QTimer>
#include <qmath.h>

using namespace std::chrono_literals;

namespace OCC {

Q_LOGGING_CATEGORY(lcPropagator, "sync.propagator", QtInfoMsg)
Q_LOGGING_CATEGORY(lcDirectory, "sync.propagator.directory", QtInfoMsg)

namespace {
    std::chrono::seconds getMinBlacklistTime = 5s;

    std::chrono::seconds getMaxBlacklistTime = 24h;
}

qint64 criticalFreeSpaceLimit()
{
    return qBound(0LL, 50 * 1000 * 1000LL, freeSpaceLimit());
}

qint64 freeSpaceLimit()
{
    return 250 * 1000 * 1000LL;
}

OwncloudPropagator::~OwncloudPropagator()
{
}


int OwncloudPropagator::maximumActiveTransferJob()
{
    if (_bandwidthManager || !_syncOptions._parallelNetworkJobs()) {
        // disable parallelism when there is a network limit.
        return 1;
    }
    return std::max(3, qCeil(_syncOptions._parallelNetworkJobs() / 2.));
}

/* The maximum number of active jobs in parallel  */
int OwncloudPropagator::hardMaximumActiveJob()
{
    if (!_syncOptions._parallelNetworkJobs())
        return 1;
    return _syncOptions._parallelNetworkJobs();
}

PropagateItemJob::~PropagateItemJob()
{
    if (auto p = propagator()) {
        // Normally, every job should clean itself from the _activeJobList. So this should not be
        // needed. But if a job has a bug or is deleted before the network jobs signal get received,
        // we might risk end up with dangling pointer in the list which may cause crashes.
        p->_activeJobList.removeAll(this);
    }
}

bool PropagateItemJob::scheduleSelfOrChild()
{
    if (state() != NotYetStarted) {
        return false;
    }
    qCInfo(lcPropagator) << u"Starting propagation of" << _item << u"by" << this;

    setState(Running);
    if (thread() != QApplication::instance()->thread()) {
        QMetaObject::invokeMethod(this, &PropagateItemJob::start); // We could be in a different thread (neon jobs)
    } else {
        start();
    }
    return true;
}

/** Creates a blacklist entry, possibly taking into account an old one.
 *
 * The old entry may be invalid, then a fresh entry is created.
 */
static SyncJournalErrorBlacklistRecord createBlacklistEntry(
    const SyncJournalErrorBlacklistRecord &old, const SyncFileItem &item)
{
    SyncJournalErrorBlacklistRecord entry;
    entry._file = item.localName();
    entry._errorString = item._errorString;
    entry._lastTryModtime = item._modtime;
    entry._lastTryEtag = item._etag.toUtf8();
    entry._lastTryTime = Utility::qDateTimeToTime_t(QDateTime::currentDateTimeUtc());
    entry._renameTarget = item._renameTarget;
    entry._retryCount = old._retryCount + 1;
    entry._requestId = item._requestId;

    static qint64 minBlacklistTime(getMinBlacklistTime.count());
    static qint64 maxBlacklistTime(qMax(getMaxBlacklistTime.count(), minBlacklistTime));

    // The factor of 5 feels natural: 5s, 25s, 2 min, 10 min, ~1h, ~5h, ~24h
    // we start with 0 the actual value will be adjusted by qBound
    entry._ignoreDuration = old._ignoreDuration * 5;

    if (item._httpErrorCode == 403) {
        qCWarning(lcPropagator) << u"Probably firewall error: " << item._httpErrorCode << u", blacklisting up to 1h only";
        entry._ignoreDuration = qMin(entry._ignoreDuration, qint64(60 * 60));

    } else if (item._httpErrorCode == 413 || item._httpErrorCode == 415) {
        qCWarning(lcPropagator) << u"Fatal Error condition" << item._httpErrorCode << u", maximum blacklist ignore time!";
        entry._ignoreDuration = maxBlacklistTime;
    }

    entry._ignoreDuration = qBound(minBlacklistTime, entry._ignoreDuration, maxBlacklistTime);

    if (item._httpErrorCode == 507) {
        entry._errorCategory = SyncJournalErrorBlacklistRecord::Category::InsufficientRemoteStorage;
    } else if (item._httpErrorCode == 0 && item._status == SyncFileItem::SoftError) {
        // assume a local error
        entry._errorCategory = SyncJournalErrorBlacklistRecord::Category::LocalSoftError;
    }

    return entry;
}

/** Updates, creates or removes a blacklist entry for the given item.
 *
 * May adjust the status or item._errorString.
 */
static void blacklistUpdate(SyncJournalDb *journal, SyncFileItem &item)
{
    SyncJournalErrorBlacklistRecord oldEntry = journal->errorBlacklistEntry(item.localName());

    const bool mayBlacklist = item._status == SyncFileItem::NormalError
        || item._status == SyncFileItem::SoftError
        || item._status == SyncFileItem::DetailError;

    // No new entry? Possibly remove the old one, then done.
    if (!mayBlacklist) {
        if (oldEntry.isValid()) {
            journal->wipeErrorBlacklistEntry(item.localName());
        }
        return;
    }

    auto newEntry = createBlacklistEntry(oldEntry, item);
    journal->setErrorBlacklistEntry(newEntry);

    // Suppress the error if it was and continues to be blacklisted.
    // An ignoreDuration of 0 mean we're tracking the error, but not actively
    // suppressing it.
    // Some soft errors might become louder on repeat occurrence
    if (item._status == SyncFileItem::SoftError
        && newEntry._retryCount > 1
        && item._httpErrorCode != 0) {
        qCWarning(lcPropagator) << u"escalating http soft error on " << item.localName() << u" to normal error, " << item._httpErrorCode;
        item._status = SyncFileItem::NormalError;
    } else if (item._status != SyncFileItem::SoftError && item._hasBlacklistEntry && newEntry._ignoreDuration > 0) {
        item._status = SyncFileItem::BlacklistedError;
    }

    qCInfo(lcPropagator) << u"blacklisting " << item.localName() << u" for " << newEntry._ignoreDuration << u", retry count " << newEntry._retryCount;
}

void PropagateItemJob::done(SyncFileItem::Status statusArg, const QString &errorString)
{
    // Duplicate calls to done() are a logic error
    OC_ENFORCE(state() != Finished);
    setState(Finished);

    _item->_status = statusArg;

    if (_item->_isRestoration) {
        if (_item->_status == SyncFileItem::Success
            || _item->_status == SyncFileItem::Conflict) {
            _item->_status = SyncFileItem::Restoration;
        } else {
            _item->_errorString += tr("; Restoration Failed: %1").arg(errorString);
        }
    } else {
        if (_item->_errorString.isEmpty()) {
            _item->_errorString = errorString;
        }
    }

    if (propagator()->_abortRequested && (_item->_status == SyncFileItem::NormalError
                                          || _item->_status == SyncFileItem::FatalError)) {
        // an abort request is ongoing. Change the status to Soft-Error
        _item->_status = SyncFileItem::SoftError;
    }

    // Blacklist handling
    switch (_item->_status) {
    case SyncFileItem::SoftError:
        [[fallthrough]];
    case SyncFileItem::FatalError:
        [[fallthrough]];
    case SyncFileItem::NormalError:
        [[fallthrough]];
    case SyncFileItem::DetailError:
        [[fallthrough]];
    case SyncFileItem::Message:
        // Check the blacklist, possibly adjusting the item (including its status)
        blacklistUpdate(propagator()->_journal, *_item);
        break;
    case SyncFileItem::Success:
        [[fallthrough]];
    case SyncFileItem::Restoration:
        if (_item->_hasBlacklistEntry) {
            // wipe blacklist entry.
            propagator()->_journal->wipeErrorBlacklistEntry(_item->localName());
            // remove a blacklist entry in case the file was moved.
            if (_item->_originalFile != _item->localName()) {
                propagator()->_journal->wipeErrorBlacklistEntry(_item->_originalFile);
            }
        }
        break;
    case SyncFileItem::Conflict:
        [[fallthrough]];
    case SyncFileItem::FileIgnored:
        [[fallthrough]];
    case SyncFileItem::NoStatus:
        [[fallthrough]];
    case SyncFileItem::BlacklistedError:
        [[fallthrough]];
    case SyncFileItem::Excluded:
        [[fallthrough]];
    case SyncFileItem::FilenameReserved:
        // nothing
        break;
    case SyncFileItem::StatusCount:
        Q_UNREACHABLE();
    }

    if (_item->hasErrorStatus())
        qCWarning(lcPropagator) << u"Could not complete propagation of" << _item->destination() << u"by" << this << u"with status" << _item->_status
                                << u"and error:" << _item->_errorString;
    else
        qCInfo(lcPropagator) << u"Completed propagation of" << _item->destination() << u"by" << this << u"with status" << _item->_status;

    // Will be handled in PropagateDirectory::slotSubJobsFinished at the end
    if (!_item->isDirectory() || _item->_relevantDirectoyInstruction) {
        // we are either not a directory or we are a PropagateDirectory job
        // and an actual instruction was performed for this directory.
        Q_ASSERT(!_item->_relevantDirectoyInstruction || qobject_cast<PropagateDirectory *>(this));
        Q_EMIT propagator()->itemCompleted(_item);
    } else {
        // the directoy needs to call done() in PropagateDirectory::slotSubJobsFinished
        // we don't notify itemCompleted yet as the directory is only complete once its child items are complete.
        _item->_relevantDirectoyInstruction = true;
    }
    Q_EMIT finished(_item->_status);
    if (_item->_status == SyncFileItem::FatalError) {
        // Abort all remaining jobs.
        propagator()->abort();
    }
}

// ================================================================================

PropagateItemJob *OwncloudPropagator::createJob(const SyncFileItemPtr &item)
{
    qCDebug(lcPropagator) << u"Propagating:" << item;
    const bool deleteExisting = item->instruction() == CSYNC_INSTRUCTION_TYPE_CHANGE;
    switch (item->instruction()) {
    case CSYNC_INSTRUCTION_REMOVE:
        if (item->_direction == SyncFileItem::Down) {
            return new PropagateLocalRemove(this, item);
        } else {
            return new PropagateRemoteDelete(this, item);
        }
    case CSYNC_INSTRUCTION_NEW:
    case CSYNC_INSTRUCTION_TYPE_CHANGE:
    case CSYNC_INSTRUCTION_CONFLICT:
        if (item->isDirectory()) {
            // CONFLICT has _direction == None
            if (item->_direction != SyncFileItem::Up) {
                auto job = new PropagateLocalMkdir(this, item);
                job->setDeleteExistingFile(deleteExisting);
                return job;
            } else {
                auto job = new PropagateRemoteMkdir(this, item);
                job->setDeleteExisting(deleteExisting);
                return job;
            }
        } //fall through
    case CSYNC_INSTRUCTION_SYNC:
        if (item->_direction != SyncFileItem::Up) {
            auto job = new PropagateDownloadFile(this, item);
            job->setDeleteExistingFolder(deleteExisting);
            return job;
        } else {
            PropagateUploadFileCommon *job = nullptr;
            if (account()->capabilities().tusSupport().isValid()) {
                job = new PropagateUploadFileTUS(this, item);
            } else {
                job = new PropagateUploadFileV1(this, item);
            }
            job->setDeleteExisting(deleteExisting);
            return job;
        }
    case CSYNC_INSTRUCTION_RENAME:
        if (item->_direction == SyncFileItem::Up) {
            return new PropagateRemoteMove(this, item);
        } else {
            return new PropagateLocalRename(this, item);
        }
    case CSYNC_INSTRUCTION_UPDATE_METADATA:
        // For directories, metadata-only updates will be done after all their files are propagated.
        if (item->isDirectory()) {
            // Will be handled in PropagateDirectory::slotSubJobsFinished at the end
            return nullptr;
        }
        return new PropagateUpdateMetaDataJob(this, item);
    case CSYNC_INSTRUCTION_IGNORE:
    case CSYNC_INSTRUCTION_ERROR:
        return new PropagateIgnoreJob(this, item);
    case CSYNC_INSTRUCTION_NONE:
        return nullptr;
    }
    Q_UNREACHABLE();
}

qint64 OwncloudPropagator::smallFileSize()
{
    const qint64 smallFileSize = 100 * 1024; //default to 1 MB. Not dynamic right now.
    return smallFileSize;
}

/**
 * This builds all the jobs needed for the propagation.
 * Each directory is a PropagateDirectory job, which contains the files in it.
 */
void OwncloudPropagator::start(SyncFileItemSet &&items)
{
    // The items list is sorted in such a way that an item for a directory come before any items
    // inside that directory. For example:
    //  - A       <--- directory
    //  - A/B     <--- directory
    //  - A/B/1   <--- file
    //  - A/2     <--- file
    // This is important, because we rely on the fact that all actions for items inside a directory
    // are grouped together, and that an action on the directory itself preceeds the actions for
    // its child items.

    _rootJob.reset(new PropagateRootDirectory(this));

    // The algorithm could be done recursively, but the implementation is done iteratively in order
    // to prevent us running out of stack space. So the next 3 variables are used to maintain the
    // state.

    // The directories stack below has the current directory on top of the stack. So if we're
    // processing directory `/A/B/C`, then the stack looks like this:
    //  - PropagateDirectory job for A/B/C  <--- top-of-stack
    //  - PropagateDirectory job for A/B
    //  - PropagateDirectory job for A
    //  - PropagateDirectory job for /      <--- bottom-of-stack
    //
    // IMPORTANT: this parent stack is also used when a directory is removed
    // (`CSYNC_INSTRUCTION_REMOVE` in the last step below), in order to suppress updating the etag
    // of the parents of the to-be-removed directory. See the comment in the code for more information.
    QStack<QPair<QString /* directory name */, PropagateDirectory * /* job */>> directories;
    directories.push({QString(), _rootJob.data()});

    // Due to the ordering of the items, it can happen that we have the following list:
    //  - remove directory A
    //  - remove file A/a
    //  - etc
    // So when we find a have a sync instruction to remove a directory, we remember it in the
    // `currentRemoveDirectoryJob` variable, so we know/see it when processing the next item
    // in the list.
    PropagatorJob *currentRemoveDirectoryJob = nullptr;

    // We skip items inside conflict directories. So, when we see an item that's marked as such,
    // remember its name to see if in the next iteration, we will hit an item for that directory.
    // See the `else` statment in the second step.
    QString maybeConflictDirectory;

    for (const auto &item : std::as_const(items)) {
        // First check if this is an item in a directory which is going to be removed.
        if (currentRemoveDirectoryJob && FileSystem::isChildPathOf(item->localName(), currentRemoveDirectoryJob->path())) {
            // Check the sync instruction for the item:
            if (item->instruction() == CSYNC_INSTRUCTION_REMOVE) {
                // already taken care of. (by the removal of the parent directory)

                if (auto delDirJob = qobject_cast<PropagateDirectory *>(currentRemoveDirectoryJob)) {
                    // increase the number of subjobs that would be there.
                    delDirJob->increaseAffectedCount();
                }
                continue;
            } else if (item->isDirectory() && (item->instruction() & (CSYNC_INSTRUCTION_NEW | CSYNC_INSTRUCTION_TYPE_CHANGE))) {
                // Create a new directory within a deleted directory? That can happen if the directory
                // etag was not fetched properly on the previous sync because the sync was aborted
                // while uploading this directory (which is now removed).  We can ignore it.
                if (auto delDirJob = qobject_cast<PropagateDirectory *>(currentRemoveDirectoryJob)) {
                    // increase the number of subjobs that would be there.
                    delDirJob->increaseAffectedCount();
                }
                continue;
            } else if (item->instruction() & (CSYNC_INSTRUCTION_IGNORE | CSYNC_INSTRUCTION_NONE)) {
                continue;
            } else if (item->instruction() != CSYNC_INSTRUCTION_RENAME) {
                // all is good, the rename will be executed before the directory deletion
                qCWarning(lcPropagator) << u"WARNING:  Job within a removed directory?  This should not happen!" << item;
                Q_ASSERT(false); // we shouldn't land here, but assert for debug purposes
            }
        }

        // Second step: if a CONFLICT item contains files, these files can't be processed because
        // the conflict handling is likely to rename the directory. This can happen
        // when there's a new local directory at the same time as a remote file.
        if (!maybeConflictDirectory.isEmpty()) {
            if (FileSystem::isChildPathOf(item->destination(), maybeConflictDirectory)) {
                // We're processing an item in a CONFLICT directory.
                qCInfo(lcPropagator) << u"Skipping job inside CONFLICT directory" << item->localName() << item->instruction();
                item->setInstruction(CSYNC_INSTRUCTION_NONE);
                continue;
            } else {
                // This is not an item inside the conflict directory, which means we're done
                // processing the conflict directory in the previous iteration, so clear the string.
                maybeConflictDirectory.clear();
            }
        }

        // Thirth step: pop the directory stack when we're finished there.
        // For example, we were processing directory `A/B`, which means that the
        // `PropagateDirectory` job for `B` is on top of the stack. If we now have
        // an item `A/c`, then we're back to processing directory `A`, so we have
        // to pop the `B` job off of the stack.
        while (!FileSystem::isChildPathOf(item->destination(), directories.top().first)) {
            directories.pop();
        }

        // The last step is to add a subtask for the item. There are 4 cases covered here:
        // a type change vs. a removal, and a file vs. a directory.
        if (item->isDirectory()) {
            PropagateDirectory *dir = new PropagateDirectory(this, item);

            if (item->instruction() == CSYNC_INSTRUCTION_TYPE_CHANGE && item->_direction == SyncFileItem::Up) {
                // Skip all potential uploads to the new folder.
                // Processing them now leads to problems with permissions:
                // checkForPermissions() has already run and used the permissions
                // of the file we're about to delete to decide whether uploading
                // to the new dir is ok...
                for (const auto &item2 : std::as_const(items)) {
                    if (item2 != item && FileSystem::isChildPathOf(item2->destination(), item->destination())) {
                        item2->setInstruction(CSYNC_INSTRUCTION_NONE);
                        _anotherSyncNeeded = true;
                    }
                }
            }

            if (item->instruction() == CSYNC_INSTRUCTION_REMOVE) {
                // We do the removal of directories at the end, because there might be moves from
                // these directories that will happen later.
                currentRemoveDirectoryJob = dir;
                _rootJob->addDeleteJob(currentRemoveDirectoryJob);

                // We should not update the etag of parent directories of the removed directory
                // since it would be done before the actual remove (issue #1845)
                // NOTE: Currently this means that we don't update those etag at all in this sync,
                //       but it should not be a problem, they will be updated in the next sync.
                for (auto &directory : directories) {
                    if (directory.second->item()->instruction() == CSYNC_INSTRUCTION_UPDATE_METADATA) {
                        directory.second->item()->setInstruction(CSYNC_INSTRUCTION_NONE);
                        _anotherSyncNeeded = true;
                    }
                }
            } else {
                directories.top().second->appendJob(dir);
            }

            directories.push(qMakePair(item->destination(), dir));
        } else {
            // The item is not a directory, but a file.
            if (item->instruction() == CSYNC_INSTRUCTION_TYPE_CHANGE) {
                // will delete directories, so defer execution
                currentRemoveDirectoryJob = createJob(item);
                _rootJob->addDeleteJob(currentRemoveDirectoryJob);
            } else {
                directories.top().second->appendTask(item);
            }

            if (item->instruction() == CSYNC_INSTRUCTION_CONFLICT) {
                // This might be a file or a directory on the local side. If it's a
                // directory we want to skip processing items inside it.
                maybeConflictDirectory = item->localName();
            }
        }
    }

    connect(_rootJob.data(), &PropagatorJob::finished, this, &OwncloudPropagator::emitFinished);

    _jobScheduled = false;
    scheduleNextJob();
}

const SyncOptions &OwncloudPropagator::syncOptions() const
{
    return _syncOptions;
}

Result<QString, bool> OwncloudPropagator::localFileNameClash(const QString &relFile)
{
    OC_ASSERT(!relFile.isEmpty());
    if (!relFile.isEmpty() && Utility::fsCasePreserving()) {
        const QFileInfo fileInfo(_localDir + relFile);
#ifdef Q_OS_MAC
        if (!fileInfo.exists()) {
            return false;
        } else {
            // Need to normalize to composited form because of QTBUG-39622/QTBUG-55896
            const QString cName = fileInfo.canonicalFilePath().normalized(QString::NormalizationForm_C);
            if (fileInfo.filePath() != cName && !cName.endsWith(relFile, Qt::CaseSensitive)) {
                qCWarning(lcPropagator) << u"Detected case clash between" << fileInfo.filePath() << u"and" << cName;
                return cName;
            }
        }
#elif defined(Q_OS_WIN)
        WIN32_FIND_DATA FindFileData;
        const Utility::Handle hFind(FindFirstFileW(reinterpret_cast<const wchar_t *>(FileSystem::longWinPath(fileInfo.filePath()).utf16()), &FindFileData),
            [](HANDLE h) { FindClose(h); });
        if (hFind != INVALID_HANDLE_VALUE) {
            const QString realFileName = QString::fromWCharArray(FindFileData.cFileName);

            if (!fileInfo.filePath().endsWith(realFileName, Qt::CaseSensitive)) {
                const QString clashName = fileInfo.path() + QLatin1Char('/') + realFileName;
                qCWarning(lcPropagator) << u"Detected case clash between" << fileInfo.filePath() << u"and" << clashName;
                return clashName;
            }
        }
#else
        // On Linux, the file system is case sensitive, but this code is useful for testing.
        // Just check that there is no other file with the same name and different casing.
        const QString fn = fileInfo.fileName();
        const QStringList list = fileInfo.dir().entryList({ fn });
        if (list.count() > 1 || (list.count() == 1 && list[0] != fn)) {
            return list[0];
        }
#endif
    }
    return false;
}

bool OwncloudPropagator::hasCaseClashAccessibilityProblem(const QString &relfile)
{
#ifdef Q_OS_WIN
    bool result = false;
    const QString file(_localDir + relfile);
    WIN32_FIND_DATA FindFileData;
    HANDLE hFind;

    hFind = FindFirstFileW(reinterpret_cast<const wchar_t *>(FileSystem::longWinPath(file).utf16()), &FindFileData);
    if (hFind != INVALID_HANDLE_VALUE) {
        QString firstFile = QString::fromWCharArray(FindFileData.cFileName);
        if (FindNextFile(hFind, &FindFileData)) {
            QString secondFile = QString::fromWCharArray(FindFileData.cFileName);
            // This extra check shouldn't be necessary, but ensures that there
            // are two different filenames that are identical when case is ignored.
            if (firstFile != secondFile
                && QString::compare(firstFile, secondFile, Qt::CaseInsensitive) == 0) {
                result = true;
                qCWarning(lcPropagator) << u"Found two filepaths that only differ in case: " << firstFile << secondFile;
            }
        }
        FindClose(hFind);
    }
    return result;
#else
    Q_UNUSED(relfile);
    return false;
#endif
}

QString OwncloudPropagator::fullLocalPath(const QString &tmp_file_name) const
{
    return _localDir + tmp_file_name;
}

QString OwncloudPropagator::localPath() const
{
    return _localDir;
}

void OwncloudPropagator::scheduleNextJob()
{
    if (_jobScheduled) return; // don't schedule more than 1
    _jobScheduled = true;
    QTimer::singleShot(0, this, &OwncloudPropagator::scheduleNextJobImpl);
}

void OwncloudPropagator::scheduleNextJobImpl()
{
    // TODO: If we see that the automatic up-scaling has a bad impact we
    // need to check how to avoid this.
    // Down-scaling on slow networks? https://github.com/owncloud/client/issues/3382
    // Making sure we do up/down at same time? https://github.com/owncloud/client/issues/1633

    _jobScheduled = false;

    if (_activeJobList.count() < maximumActiveTransferJob()) {
        if (_rootJob->scheduleSelfOrChild()) {
            scheduleNextJob();
        }
    } else if (_activeJobList.count() < hardMaximumActiveJob()) {
        int likelyFinishedQuicklyCount = 0;
        // NOTE: Only counts the first 3 jobs! Then for each
        // one that is likely finished quickly, we can launch another one.
        // When a job finishes another one will "move up" to be one of the first 3 and then
        // be counted too.
        for (int i = 0; i < maximumActiveTransferJob() && i < _activeJobList.count(); i++) {
            if (_activeJobList.at(i)->isLikelyFinishedQuickly()) {
                likelyFinishedQuicklyCount++;
            }
        }
        if (_activeJobList.count() < maximumActiveTransferJob() + likelyFinishedQuicklyCount) {
            qCDebug(lcPropagator) << u"Can pump in another request! activeJobs =" << _activeJobList.count();
            if (_rootJob->scheduleSelfOrChild()) {
                scheduleNextJob();
            }
        }
    }
}

void OwncloudPropagator::reportFileTotal(const SyncFileItem &item, qint64 newSize)
{
    Q_EMIT updateFileTotal(item, newSize);
}

void OwncloudPropagator::abort()
{
    if (_abortRequested)
        return;
    if (_rootJob) {
        // Connect to abortFinished  which signals that abort has been asynchronously finished
        connect(_rootJob.data(), &PropagateDirectory::abortFinished, this, &OwncloudPropagator::emitFinished);

        // Use Queued Connection because we're possibly already in an item's finished stack
        QMetaObject::invokeMethod(
            _rootJob.data(), [this] {
                _rootJob->abort(PropagatorJob::AbortType::Asynchronous);
            },
            Qt::QueuedConnection);

        // Give asynchronous abort 5 sec to finish on its own
        QTimer::singleShot(5s, this, &OwncloudPropagator::abortTimeout);
    } else {
        // No root job, call emitFinished
        emitFinished(SyncFileItem::NormalError);
    }
}

void OwncloudPropagator::reportProgress(const SyncFileItem &item, qint64 bytes)
{
    Q_EMIT progress(item, bytes);
}

AccountPtr OwncloudPropagator::account() const
{
    return _account;
}

OwncloudPropagator::DiskSpaceResult OwncloudPropagator::diskSpaceCheck() const
{
    const qint64 freeBytes = Utility::freeDiskSpace(_localDir);
    if (freeBytes < 0) {
        return DiskSpaceOk;
    }

    if (freeBytes < criticalFreeSpaceLimit()) {
        return DiskSpaceCritical;
    }

    if (freeBytes - _rootJob->committedDiskSpace() < freeSpaceLimit()) {
        return DiskSpaceFailure;
    }

    return DiskSpaceOk;
}

bool OwncloudPropagator::createConflict(const SyncFileItemPtr &item,
    PropagatorCompositeJob *composite, QString *error)
{
    QString fn = fullLocalPath(item->localName());

    QString renameError;
    auto conflictModTime = FileSystem::getModTime(fn);
    QString conflictUserName;
    if (account()->capabilities().uploadConflictFiles())
        conflictUserName = account()->davDisplayName();
    QString conflictFileName = Utility::makeConflictFileName(item->localName(), Utility::qDateTimeFromTime_t(conflictModTime), conflictUserName);
    QString conflictFilePath = fullLocalPath(conflictFileName);

    // If the file is locked, we want to retry this sync when it
    // becomes available again.
    if (FileSystem::isFileLocked(fn, FileSystem::LockMode::Exclusive)) {
        Q_EMIT seenLockedFile(fn, FileSystem::LockMode::Exclusive);
        if (error)
            *error = tr("The file »%1« is currently in use").arg(fn);
        return false;
    }

    if (!FileSystem::rename(fn, conflictFilePath, &renameError)) {
        // If the rename fails, don't replace it.
        if (error)
            *error = renameError;
        return false;
    }
    qCInfo(lcPropagator) << u"Created conflict file" << fn << u"->" << conflictFileName;

    // Create a new conflict record. To get the base etag, we need to read it from the db.
    ConflictRecord conflictRecord;
    conflictRecord.path = conflictFileName.toUtf8();
    conflictRecord.baseModtime = item->_previousModtime;
    conflictRecord.initialBasePath = item->localName().toUtf8();

    if (const auto baseRecord = _journal->getFileRecord(item->_originalFile); baseRecord.isValid()) {
        conflictRecord.baseEtag = baseRecord.etag().toUtf8();
        conflictRecord.baseFileId = baseRecord.fileId();
    } else {
        // We might very well end up with no fileid/etag for new/new conflicts
    }

    _journal->setConflictRecord(conflictRecord);

    // Create a new upload job if the new conflict file should be uploaded
    if (account()->capabilities().uploadConflictFiles()) {
        if (composite && !QFileInfo(conflictFilePath).isDir()) {
            SyncFileItemPtr conflictItem = SyncFileItemPtr(new SyncFileItem);
            conflictItem->setLocalName(conflictFileName);
            conflictItem->_type = ItemTypeFile;
            conflictItem->_direction = SyncFileItem::Up;
            conflictItem->setInstruction(CSYNC_INSTRUCTION_NEW);
            conflictItem->_modtime = conflictModTime;
            conflictItem->_size = item->_previousSize;
            Q_EMIT newItem(conflictItem);
            composite->appendTask(conflictItem);
        } else {
            // Directories we can't process in one go. The next sync run
            // will take care of uploading the conflict dir contents.
            _anotherSyncNeeded = true;
        }
    }

    return true;
}

QString OwncloudPropagator::adjustRenamedPath(const QString &original) const
{
    return OCC::adjustRenamedPath(_renamedDirectories, original);
}

Result<Vfs::ConvertToPlaceholderResult, QString> OwncloudPropagator::updatePlaceholder(const SyncFileItem &item, const QString &fileName, const QString &replacesFile)
{
    Q_ASSERT([&] {
        if (item._type == ItemTypeVirtualFileDehydration) {
            // when dehydrating the file must not be pinned
            // don't use destinatio() with suffix placeholder
            const auto pin = syncOptions()._vfs->pinState(item.localName());
            if (pin && pin.get() == PinState::AlwaysLocal) {
                return false;
            }
        }
        return true;
    }());
    return syncOptions()._vfs->updateMetadata(item, fileName, replacesFile);
}

Result<Vfs::ConvertToPlaceholderResult, QString> OwncloudPropagator::updateMetadata(const SyncFileItem &item)
{
    const QString fsPath = fullLocalPath(item.destination());
    if (!QFileInfo::exists(fsPath)) {
        qCWarning(lcPropagator) << u"Skipping updateMetadata on:" << fsPath << u"the file does no longer exist.";
        return Vfs::ConvertToPlaceholderResult::Ok;
    }
    const auto result = updatePlaceholder(item, fsPath, {});
    if (!result) {
        return result;
    }
    auto itemCopy = item;
    if (auto inode = FileSystem::getInode(FileSystem::toFilesystemPath(fsPath))) {
        itemCopy._inode = inode.value();
    } else {
        qCWarning(lcPropagator) << u"Failed to get inode for" << fsPath;
    }
    qCDebug(lcPropagator) << fsPath << u"Retrieved inode " << itemCopy._inode << u"(previous item inode: " << item._inode << u")";
    auto record = SyncJournalFileRecord::fromSyncFileItem(itemCopy);
    if (result.get() == Vfs::ConvertToPlaceholderResult::Locked) {
        record.setDirtyPlaceholder(true);
        Q_EMIT seenLockedFile(fullLocalPath(item.localName()), FileSystem::LockMode::Exclusive);
    }
    const auto dBresult = _journal->setFileRecord(record);
    if (!dBresult) {
        return dBresult.error();
    }
    return Vfs::ConvertToPlaceholderResult::Ok;
}

// ================================================================================

PropagatorJob::PropagatorJob(OwncloudPropagator *propagator, const QString &path)
    : QObject(propagator)
    , _path(path)
    , _jobState(NotYetStarted)
{
}

void PropagatorJob::setState(JobState state)
{
    _jobState = state;
}

OwncloudPropagator *PropagatorJob::propagator() const
{
    return qobject_cast<OwncloudPropagator *>(parent());
}

// ================================================================================

PropagatorJob::JobParallelism PropagatorCompositeJob::parallelism()
{
    // If any of the running sub jobs is not parallel, we have to wait
    for (int i = 0; i < _runningJobs.count(); ++i) {
        if (_runningJobs.at(i)->parallelism() != FullParallelism) {
            return _runningJobs.at(i)->parallelism();
        }
    }
    return FullParallelism;
}

void PropagatorCompositeJob::slotSubJobAbortFinished()
{
    // Count that job has been finished
    _abortsCount--;

    // Emit abort if last job has been aborted
    if (_abortsCount == 0) {
        Q_EMIT abortFinished();
    }
}

void PropagatorCompositeJob::appendJob(PropagatorJob *job)
{
    job->setAssociatedComposite(this);
    _jobsToDo.append(job);
}

bool PropagatorCompositeJob::scheduleSelfOrChild()
{
    if (state() == Finished) {
        return false;
    }

    // Start the composite job
    if (state() == NotYetStarted) {
        setState(Running);
    }

    // Ask all the running composite jobs if they have something new to schedule.
    for (int i = 0; i < _runningJobs.size(); ++i) {
        OC_ASSERT(_runningJobs.at(i)->state() == Running);

        if (possiblyRunNextJob(_runningJobs.at(i))) {
            return true;
        }

        // If any of the running sub jobs is not parallel, we have to cancel the scheduling
        // of the rest of the list and wait for the blocking job to finish and schedule the next one.
        auto paral = _runningJobs.at(i)->parallelism();
        if (paral == WaitForFinished) {
            return false;
        }
    }

    // Now it's our turn, check if we have something left to do.
    // First, convert a task to a job if necessary
    while (_jobsToDo.empty() && !_tasksToDo.empty()) {
        const SyncFileItemPtr nextTask = *_tasksToDo.begin();
        _tasksToDo.erase(_tasksToDo.begin());
        PropagatorJob *job = propagator()->createJob(nextTask);
        if (!job) {
            qCWarning(lcDirectory) << u"Useless task found for file" << nextTask->destination() << u"instruction" << nextTask->instruction();
            continue;
        }
        appendJob(job);
        break;
    }
    // Then run the next job
    if (!_jobsToDo.isEmpty()) {
        PropagatorJob *nextJob = _jobsToDo.first();
        _jobsToDo.remove(0);
        _runningJobs.append(nextJob);
        return possiblyRunNextJob(nextJob);
    }

    // If neither us or our children had stuff left to do we could hang. Make sure
    // we mark this job as finished so that the propagator can schedule a new one.
    if (_jobsToDo.isEmpty() && _tasksToDo.empty() && _runningJobs.isEmpty()) {
        // Our parent jobs are already iterating over their running jobs, post to the event loop
        // to avoid removing ourself from that list while they iterate.
        QMetaObject::invokeMethod(this, &PropagatorCompositeJob::finalize, Qt::QueuedConnection);
    }
    return false;
}

void PropagatorCompositeJob::slotSubJobFinished(SyncFileItem::Status status)
{
    PropagatorJob *subJob = static_cast<PropagatorJob *>(sender());
    OC_ASSERT(subJob);

    // Delete the job and remove it from our list of jobs.
    subJob->deleteLater();
    OC_ENFORCE(_runningJobs.removeAll(subJob) == 1); // we removed exactly one item

    // Any sub job error will cause the whole composite to fail. This is important
    // for knowing whether to update the etag in PropagateDirectory, for example.
    switch (status) {
    case SyncFileItem::FatalError:
        [[fallthrough]];
    case SyncFileItem::NormalError:
        [[fallthrough]];
    case SyncFileItem::SoftError:
        [[fallthrough]];
    case SyncFileItem::DetailError:
        [[fallthrough]];
    case SyncFileItem::BlacklistedError:
        _errorPaths.insert(subJob->path(), status);
        break;
    default:
        break;
    }

    if (_jobsToDo.isEmpty() && _tasksToDo.empty() && _runningJobs.isEmpty()) {
        finalize();
    } else {
        propagator()->scheduleNextJob();
    }
}

void PropagatorCompositeJob::finalize()
{
    // The propagator will do parallel scheduling and this could be posted
    // multiple times on the event loop, ignore the duplicate calls.
    if (state() == Finished)
        return;

    setState(Finished);
    Q_EMIT finished(_errorPaths.empty() ? SyncFileItem::Success : _errorPaths.last());
}

qint64 PropagatorCompositeJob::committedDiskSpace() const
{
    qint64 needed = 0;
    for (auto *job : _runningJobs) {
        needed += job->committedDiskSpace();
    }
    return needed;
}

PropagatorCompositeJob::PropagatorCompositeJob(OwncloudPropagator *propagator, const QString &path)
    : PropagatorJob(propagator, path)
{
}

// ================================================================================

PropagateDirectory::PropagateDirectory(OwncloudPropagator *propagator, const SyncFileItemPtr &item)
    : PropagateItemJob(propagator, item)
    , _firstJob(propagator->createJob(item))
    , _subJobs(propagator, path())
{
    if (_firstJob) {
        connect(_firstJob.get(), &PropagatorJob::finished, this, &PropagateDirectory::slotFirstJobFinished);
        _firstJob->setAssociatedComposite(&_subJobs);
    }
    connect(&_subJobs, &PropagatorJob::finished, this, &PropagateDirectory::slotSubJobsFinished);
}

PropagatorJob::JobParallelism PropagateDirectory::parallelism()
{
    // If any of the non-finished sub jobs is not parallel, we have to wait
    if (_firstJob && _firstJob->parallelism() != FullParallelism) {
        return WaitForFinished;
    }
    if (_subJobs.parallelism() != FullParallelism) {
        return WaitForFinished;
    }
    return FullParallelism;
}


bool PropagateDirectory::scheduleSelfOrChild()
{
    if (state() == Finished) {
        return false;
    }

    if (state() == NotYetStarted) {
        setState(Running);
    }

    if (_firstJob && _firstJob->state() == NotYetStarted) {
        return _firstJob->scheduleSelfOrChild();
    }

    if (_firstJob && _firstJob->state() == Running) {
        // Don't schedule any more job until this is done.
        return false;
    }

    return _subJobs.scheduleSelfOrChild();
}

void PropagateDirectory::slotFirstJobFinished(SyncFileItem::Status status)
{
    _firstJob.release()->deleteLater();

    switch (status) {
    // non critical states
    case SyncFileItem::Success:
        [[fallthrough]];
    case SyncFileItem::Restoration:
        [[fallthrough]];
    case SyncFileItem::Conflict:
        break;
    // handle all other cases as errors
    default:
        if (state() != Finished) {
            // Synchronously abort
            abort(AbortType::Synchronous);
            done(status);
        }
        return;
    }

    propagator()->scheduleNextJob();
}

void PropagateDirectory::slotSubJobsFinished(const SyncFileItem::Status status)
{
    if (OC_ENSURE(!_item->isEmpty())) {
        // report an error if the acutal action on the folder failed
        if (_item->_relevantDirectoyInstruction && _item->_status != SyncFileItem::Success) {
            Q_ASSERT(_item->_status != SyncFileItem::NoStatus);
            qCWarning(lcDirectory) << u"PropagateDirectory completed with" << status << u"the dirctory job itself is marked as" << _item->_status;
            done(_item->_status);
            return;
        }

        if (status == SyncFileItem::Success) {
            // If a directory is renamed, recursively delete any stale items
            // that may still exist below the old path.
            if (_item->instruction() == CSYNC_INSTRUCTION_RENAME && _item->_originalFile != _item->_renameTarget) {
                // TODO: check result but it breaks TestDatabaseError
                propagator()->_journal->deleteFileRecord(_item->_originalFile, true);
            }

            if (_item->instruction() == CSYNC_INSTRUCTION_NEW && _item->_direction == SyncFileItem::Down) {
                // special case for local MKDIR, set local directory mtime
                // (it's not synced later at all, but can be nice to have it set initially)
                OC_ASSERT(FileSystem::setModTime(propagator()->fullLocalPath(_item->destination()), _item->_modtime));
            }
            // For new directories we always want to update the etag once
            // the directory has been propagated. Otherwise the directory
            // could appear locally without being added to the database.
            // Additionally we need to convert those folders to placeholders with cfapi vfs.
            if (_item->instruction() & (CSYNC_INSTRUCTION_RENAME | CSYNC_INSTRUCTION_NEW | CSYNC_INSTRUCTION_UPDATE_METADATA)) {
                // metatdata changes are relevant
                _item->_relevantDirectoyInstruction = true;
                _item->_status = SyncFileItem::Success;
                const auto result = propagator()->updateMetadata(*_item);
                if (!result) {
                    qCWarning(lcDirectory) << u"Error writing to the database for file" << _item->localName() << u"with" << result.error();
                    done(SyncFileItem::FatalError, tr("Error updating metadata: %1").arg(result.error()));
                    return;
                } else if (result.get() == Vfs::ConvertToPlaceholderResult::Locked) {
                    done(SyncFileItem::SoftError, tr("The folder »%1« is currently in use").arg(_item->destination()));
                    return;
                }
            }
            if (_item->_relevantDirectoyInstruction) {
                done(_item->_status);
                return;
            }
        }
    }

    // don't call done, we only propagate the state of the child items
    // and we don't want error handling for this folder for an error that happened on a child
    Q_ASSERT(state() != Finished);
    setState(Finished);
    Q_EMIT finished(status);
    if (_item->_relevantDirectoyInstruction) {
        Q_EMIT propagator()->itemCompleted(_item);
    }
}

PropagateRootDirectory::PropagateRootDirectory(OwncloudPropagator *propagator)
    : PropagateDirectory(propagator, SyncFileItemPtr([] {
        auto f = new SyncFileItem;
        f->setLocalName(QStringLiteral("/"));
        return f;
    }()))
    , _dirDeletionJobs(propagator, path())
{
    connect(&_dirDeletionJobs, &PropagatorJob::finished, this, &PropagateRootDirectory::slotDirDeletionJobsFinished);
}

PropagatorJob::JobParallelism PropagateRootDirectory::parallelism()
{
    // the root directory parallelism isn't important
    return WaitForFinished;
}

void PropagateRootDirectory::abort(PropagatorJob::AbortType abortType)
{
    if (_firstJob) {
        // Force first job to abort synchronously
        // even if caller allows async abort (asyncAbort)
        _firstJob->abort(AbortType::Synchronous);
    }

    if (abortType == AbortType::Asynchronous) {
        struct AbortsFinished {
            bool subJobsFinished = false;
            bool dirDeletionFinished = false;
        };
        auto abortStatus = QSharedPointer<AbortsFinished>(new AbortsFinished);

        connect(&_subJobs, &PropagatorCompositeJob::abortFinished, this, [this, abortStatus]() {
            abortStatus->subJobsFinished = true;
            if (abortStatus->subJobsFinished && abortStatus->dirDeletionFinished)
                Q_EMIT abortFinished();
        });
        connect(&_dirDeletionJobs, &PropagatorCompositeJob::abortFinished, this, [this, abortStatus]() {
            abortStatus->dirDeletionFinished = true;
            if (abortStatus->subJobsFinished && abortStatus->dirDeletionFinished)
                Q_EMIT abortFinished();
        });
    }
    _subJobs.abort(abortType);
    _dirDeletionJobs.abort(abortType);
}

qint64 PropagateRootDirectory::committedDiskSpace() const
{
    return _subJobs.committedDiskSpace() + _dirDeletionJobs.committedDiskSpace();
}

bool PropagateRootDirectory::scheduleSelfOrChild()
{
    if (state() == Finished) {
        return false;
    }

    if (PropagateDirectory::scheduleSelfOrChild()) {
        return true;
    }

    // Important: Finish _subJobs before scheduling any deletes.
    if (_subJobs.state() != Finished) {
        return false;
    }

    return _dirDeletionJobs.scheduleSelfOrChild();
}

void PropagateRootDirectory::slotSubJobsFinished(SyncFileItem::Status status)
{
    switch (status) {
    // non critical states
    case SyncFileItem::Success:
        [[fallthrough]];
    case SyncFileItem::Restoration:
        [[fallthrough]];
    case SyncFileItem::Conflict:
        break;
    // handle all other cases as errors
    default:
        _status = status;
        if (state() != Finished) {
            auto subJob = qobject_cast<PropagatorCompositeJob *>(sender());
            if (OC_ENSURE(subJob)) {
                const QMap<QString, SyncFileItem::Status> errorPaths = subJob->errorPaths();
                auto deleteJobs = _dirDeletionJobs.jobsToDo();
                deleteJobs.erase(std::remove_if(deleteJobs.begin(), deleteJobs.end(),
                                     [&](auto *p) {
                                         for (const auto &[path, error] : Utility::asKeyValueRange(errorPaths)) {
                                             const QFileInfo info(path);
                                             if (FileSystem::isChildPathOf(p->path(), info.isDir() ? info.filePath() : info.path())) {
                                                 return true;
                                             }
                                         }
                                         return false;
                                     }),
                    deleteJobs.end());
                _dirDeletionJobs.setJobsToDo(deleteJobs);
            }
        }
    }
    propagator()->scheduleNextJob();
}

void PropagateRootDirectory::slotDirDeletionJobsFinished(SyncFileItem::Status status)
{
    setState(Finished);
    Q_EMIT finished(_status != SyncFileItem::NoStatus ? _status : status);
}

void PropagateRootDirectory::addDeleteJob(PropagatorJob *job)
{
    _dirDeletionJobs.appendJob(job);
}

// ================================================================================

QString OwncloudPropagator::fullRemotePath(const QString &tmp_file_name) const
{
    // TODO: should this be part of the _item (SyncFileItemPtr)?
    return _remoteFolder + tmp_file_name;
}

QString OwncloudPropagator::remotePath() const
{
    return _remoteFolder;
}

PropagateUpdateMetaDataJob::PropagateUpdateMetaDataJob(OwncloudPropagator *propagator, const SyncFileItemPtr &item)
    : PropagateItemJob(propagator, item)
{
}

void OCC::PropagateUpdateMetaDataJob::start()
{
    // Update the database:  New remote fileid or Etag or RemotePerm
    // Or for files that were detected as "resolved conflict".
    // Or a local inode/mtime change

    // In case of "resolved conflict": there should have been a conflict because they
    // both were new, or both had their local mtime or remote etag modified, but the
    // size and mtime is the same on the server.  This typically happens when the
    // database is removed. Nothing will be done for those files, but we still need
    // to update the database.

    const QString filePath = propagator()->fullLocalPath(_item->destination());
    if (_item->_direction == SyncFileItem::Down) {
        const SyncJournalFileRecord prev = propagator()->_journal->getFileRecord(_item->localName());
        if (prev.isValid()) {
            if (_item->_checksumHeader.isEmpty()) {
                _item->_checksumHeader = prev.checksumHeader();
            }
            _item->_serverHasIgnoredFiles |= prev.serverHasIgnoredFiles();
        }
    }
    const auto result = propagator()->updateMetadata(*_item);
    if (!result) {
        done(SyncFileItem::FatalError, tr("Could not update file: %1").arg(result.error()));
        return;
    } else if (result.get() == Vfs::ConvertToPlaceholderResult::Locked) {
        done(SyncFileItem::SoftError, tr("The file »%1« is currently in use").arg(_item->localName()));
        return;
    }
    done(SyncFileItem::Success);
}
}