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#include "filemanager.h"

#include "metainfo.h"

#include <QByteArray>

#include <QDir>

#include <QFile>

#include <QTimer>

#include <QTimerEvent>

#include <QCryptographicHash>

FileManager::FileManager(QObject *parent)

    : QThread(parent)

{

    quit = false;

    totalLength = 0;

    readId = 0;

    startVerification = false;

    wokeUp = false;

    newFile = false;

    numPieces = 0;

    verifiedPieces.fill(false);

}

FileManager::~FileManager()

{

    quit = true;

    cond.wakeOne();

    wait();

    foreach (QFile *file, files) {

        file->close();

        delete file;

    }

}

int FileManager::read(int pieceIndex, int offset, int length)

{

    ReadRequest request;

    request.pieceIndex = pieceIndex;

    request.offset = offset;

    request.length = length;

    QMutexLocker locker(&mutex);

    request.id = readId++;

    readRequests << request;

    if (!wokeUp) {

        wokeUp = true;

        QMetaObject::invokeMethod(this, "wakeUp", Qt::QueuedConnection);

    }

    return request.id;

}

void FileManager::write(int pieceIndex, int offset, const QByteArray &data)

{

    WriteRequest request;

    request.pieceIndex = pieceIndex;

    request.offset = offset;

    request.data = data;

    QMutexLocker locker(&mutex);

    writeRequests << request;

    if (!wokeUp) {

        wokeUp = true;

        QMetaObject::invokeMethod(this, "wakeUp", Qt::QueuedConnection);

    }

}

void FileManager::verifyPiece(int pieceIndex)

{

    QMutexLocker locker(&mutex);

    pendingVerificationRequests << pieceIndex;

    startVerification = true;

    if (!wokeUp) {

        wokeUp = true;

        QMetaObject::invokeMethod(this, "wakeUp", Qt::QueuedConnection);

    }

}

int FileManager::pieceLengthAt(int pieceIndex) const

{

    QMutexLocker locker(&mutex);

    return (sha1s.size() == pieceIndex + 1)

        ? (totalLength % pieceLength) : pieceLength;

}

QBitArray FileManager::completedPieces() const

{

    QMutexLocker locker(&mutex);

    return verifiedPieces;

}

void FileManager::setCompletedPieces(const QBitArray &pieces)

{

    QMutexLocker locker(&mutex);

    verifiedPieces = pieces;

}

QString FileManager::errorString() const

{

    return errString;

}

void FileManager::run()

{

    if (!generateFiles())

        return;

    do {

        {

            // Go to sleep if there's nothing to do.

            QMutexLocker locker(&mutex);

            if (!quit && readRequests.isEmpty() && writeRequests.isEmpty() && !startVerification)

                cond.wait(&mutex);

        }

        // Read pending read requests

        mutex.lock();

        QList<ReadRequest> newReadRequests = readRequests;

        readRequests.clear();

        mutex.unlock();

        while (!newReadRequests.isEmpty()) {

            ReadRequest request = newReadRequests.takeFirst();

            QByteArray block = readBlock(request.pieceIndex, request.offset, request.length);

            emit dataRead(request.id, request.pieceIndex, request.offset, block);

        }

        // Write pending write requests

        mutex.lock();

        QList<WriteRequest> newWriteRequests = writeRequests;

        writeRequests.clear();

        while (!quit && !newWriteRequests.isEmpty()) {

            WriteRequest request = newWriteRequests.takeFirst();

            writeBlock(request.pieceIndex, request.offset, request.data);

        }

        // Process pending verification requests

        if (startVerification) {

            newPendingVerificationRequests = pendingVerificationRequests;

            pendingVerificationRequests.clear();

            verifyFileContents();

            startVerification = false;

        }

        mutex.unlock();

        newPendingVerificationRequests.clear();

    } while (!quit);

    // Write pending write requests

    mutex.lock();

    QList<WriteRequest> newWriteRequests = writeRequests;

    writeRequests.clear();

    mutex.unlock();

    while (!newWriteRequests.isEmpty()) {

        WriteRequest request = newWriteRequests.takeFirst();

        writeBlock(request.pieceIndex, request.offset, request.data);

    }

}

void FileManager::startDataVerification()

{

    QMutexLocker locker(&mutex);

    startVerification = true;

    cond.wakeOne();

}

bool FileManager::generateFiles()

{

    numPieces = -1;

    // Set up the thread local data

    if (metaInfo.fileForm() == MetaInfo::SingleFileForm) {

        QMutexLocker locker(&mutex);

        MetaInfoSingleFile singleFile = metaInfo.singleFile();

        QString prefix;

        if (!destinationPath.isEmpty()) {

            prefix = destinationPath;

            if (!prefix.endsWith("/"))

                prefix += "/";

            QDir dir;

            if (!dir.mkpath(prefix)) {

                errString = tr("Failed to create directory %1").arg(prefix);

                emit error();

                return false;

            }

        }

        QFile *file = new QFile(prefix + singleFile.name);

        if (!file->open(QFile::ReadWrite)) {

            errString = tr("Failed to open/create file %1: %2")

                        .arg(file->fileName()).arg(file->errorString());

            emit error();

            return false;

        }

        if (file->size() != singleFile.length) {

            newFile = true;

            if (!file->resize(singleFile.length)) {

                errString = tr("Failed to resize file %1: %2")

                            .arg(file->fileName()).arg(file->errorString());

                emit error();

                return false;

            }

        }

        fileSizes << file->size();

        files << file;

        file->close();

        pieceLength = singleFile.pieceLength;

        totalLength = singleFile.length;

        sha1s = singleFile.sha1Sums;

    } else {

        QMutexLocker locker(&mutex);

        QDir dir;

        QString prefix;

        if (!destinationPath.isEmpty()) {

            prefix = destinationPath;

            if (!prefix.endsWith("/"))

                prefix += "/";

        }

        if (!metaInfo.name().isEmpty()) {

            prefix += metaInfo.name();

            if (!prefix.endsWith("/"))

                prefix += "/";

        }

        if (!dir.mkpath(prefix)) {

            errString = tr("Failed to create directory %1").arg(prefix);

            emit error();

            return false;

        }

        foreach (const MetaInfoMultiFile &entry, metaInfo.multiFiles()) {

            QString filePath = QFileInfo(prefix + entry.path).path();

            if (!QFile::exists(filePath)) {

                if (!dir.mkpath(filePath)) {

                    errString = tr("Failed to create directory %1").arg(filePath);

                    emit error();

                    return false;

                }

            }

            QFile *file = new QFile(prefix + entry.path);

            if (!file->open(QFile::ReadWrite)) {

                errString = tr("Failed to open/create file %1: %2")

                            .arg(file->fileName()).arg(file->errorString());

                emit error();

                return false;

            }

            if (file->size() != entry.length) {

                newFile = true;

                if (!file->resize(entry.length)) {

                    errString = tr("Failed to resize file %1: %2")

                                .arg(file->fileName()).arg(file->errorString());

                    emit error();

                    return false;

                }

            }

            fileSizes << file->size();

            files << file;

            file->close();

            totalLength += entry.length;

        }

        sha1s = metaInfo.sha1Sums();

        pieceLength = metaInfo.pieceLength();

    }

    numPieces = sha1s.size();

    return true;

}

QByteArray FileManager::readBlock(int pieceIndex, int offset, int length)

{

    QByteArray block;

    qint64 startReadIndex = (quint64(pieceIndex) * pieceLength) + offset;

    qint64 currentIndex = 0;

    for (int i = 0; !quit && i < files.size() && length > 0; ++i) {

        QFile *file = files[i];

        qint64 currentFileSize = fileSizes.at(i);

        if ((currentIndex + currentFileSize) > startReadIndex) {

            if (!file->isOpen()) {

                if (!file->open(QFile::ReadWrite)) {

                    errString = tr("Failed to read from file %1: %2")

                        .arg(file->fileName()).arg(file->errorString());

                    emit error();

                    break;

                }

            }

            file->seek(startReadIndex - currentIndex);

            QByteArray chunk = file->read(qMin<qint64>(length, currentFileSize - file->pos()));

            file->close();

            block += chunk;

            length -= chunk.size();

            startReadIndex += chunk.size();

            if (length < 0) {

                errString = tr("Failed to read from file %1 (read %3 bytes): %2")

                            .arg(file->fileName()).arg(file->errorString()).arg(length);

                emit error();

                break;

            }

        }

        currentIndex += currentFileSize;

    }

    return block;

}

bool FileManager::writeBlock(int pieceIndex, int offset, const QByteArray &data)

{

    qint64 startWriteIndex = (qint64(pieceIndex) * pieceLength) + offset;

    qint64 currentIndex = 0;

    int bytesToWrite = data.size();

    int written = 0;

    for (int i = 0; !quit && i < files.size(); ++i) {

        QFile *file = files[i];

        qint64 currentFileSize = fileSizes.at(i);

        if ((currentIndex + currentFileSize) > startWriteIndex) {

            if (!file->isOpen()) {

                if (!file->open(QFile::ReadWrite)) {

                    errString = tr("Failed to write to file %1: %2")

                        .arg(file->fileName()).arg(file->errorString());

                    emit error();

                    break;

                }

            }

            file->seek(startWriteIndex - currentIndex);

            qint64 bytesWritten = file->write(data.constData() + written,

                                              qMin<qint64>(bytesToWrite, currentFileSize - file->pos()));

            file->close();

            if (bytesWritten <= 0) {

                errString = tr("Failed to write to file %1: %2")

                            .arg(file->fileName()).arg(file->errorString());

                emit error();

                return false;

            }

            written += bytesWritten;

            startWriteIndex += bytesWritten;

            bytesToWrite -= bytesWritten;

            if (bytesToWrite == 0)

                break;

        }

        currentIndex += currentFileSize;

    }

    return true;

}

void FileManager::verifyFileContents()

{

    // Verify all pieces the first time

    if (newPendingVerificationRequests.isEmpty()) {

        if (verifiedPieces.count(true) == 0) {

            verifiedPieces.resize(sha1s.size());

            int oldPercent = 0;

            if (!newFile) {

                int numPieces = sha1s.size();

                for (int index = 0; index < numPieces; ++index) {

                    verifySinglePiece(index);

                    int percent = ((index + 1) * 100) / numPieces;

                    if (oldPercent != percent) {

                        emit verificationProgress(percent);

                        oldPercent = percent;

                    }

                }

            }

        }

        emit verificationDone();

        return;

    }

    // Verify all pending pieces

    foreach (int index, newPendingVerificationRequests)

        emit pieceVerified(index, verifySinglePiece(index));

}

bool FileManager::verifySinglePiece(int pieceIndex)

{

    QByteArray block = readBlock(pieceIndex, 0, pieceLength);

    QByteArray sha1Sum = QCryptographicHash::hash(block, QCryptographicHash::Sha1);

    if (sha1Sum != sha1s.at(pieceIndex))

        return false;

    verifiedPieces.setBit(pieceIndex);

    return true;

}

void FileManager::wakeUp()

{

    QMutexLocker locker(&mutex);

    wokeUp = false;

    cond.wakeOne();

}