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#include "applistmodel.h"
#include "appparser.h"
#include "applog.h"

#include <QtCore/QDirIterator>
#include <QtCore/QFileSystemWatcher>

static QHash<int, QByteArray> modelRoles()
{
    QHash<int, QByteArray> roles;
    roles[AppListModel::App] = "appEntry";
    roles[AppListModel::IconName] = "iconName";
    roles[AppListModel::ApplicationName] = "applicationName";
    roles[AppListModel::ApplicationId] = "applicationId";
    roles[AppListModel::ExeuctableName] = "executableName";
    roles[AppListModel::ExecutablePath] = "executablePath";
    roles[AppListModel::SourceFileName] = "sourceFileName";
    return roles;
}

QHash<int, QByteArray> AppListModel::m_roles = modelRoles();

int AppListModel::rowCount(const QModelIndex& index) const
{
    if (index.isValid())
        return 0;
    return m_rows.count();
}

QVariant AppListModel::data(const QModelIndex& index, int role) const
{
    if (!index.isValid() || index.parent().isValid())
        return QVariant();

    auto entry = m_rows[index.row()];

    switch (role) {
    case App:
        return QVariant::fromValue(entry);
    case IconName:
        return entry.iconName;
    case ApplicationName:
        return entry.appName;
    case ApplicationId:
        return entry.appId;
    case ExeuctableName:
        return entry.executableName;
    case ExecutablePath:
        return entry.executablePath;
    case SourceFileName:
        return entry.sourceFileName;
    default:
        qCWarning(apps) << "Unhandled role" << role;
        return QVariant();
    }
}

QHash<int, QByteArray> AppListModel::roleNames() const
{
    return m_roles;
}

/*!
 * Returns true if the directory can be watched
 *
 * Parse all JSON application files from the given directory
 * and monitor it for changes.
 */
bool AppListModel::addAndWatchDir(const QString& dirName)
{
    auto watcher = new QFileSystemWatcher(this);
    connect(watcher, &QFileSystemWatcher::directoryChanged, this, &AppListModel::addDir);
    auto res = watcher->addPath(dirName);
    addDir(dirName);

    qCDebug(apps) << "addAndWatchDir" << dirName << "result: " << res;
    return res;
}

void AppListModel::addFile(const QString& fileName)
{
    beginResetModel();
    doAddFile(fileName);
    endResetModel();
}

void AppListModel::addDir(const QString& dirName)
{
    QDirIterator dirIt(dirName, QDir::Files | QDir::NoDotAndDotDot | QDir::Readable);

    // We want to deal with the corner case of some files being
    // removed. One option would have been to keep a marker bit
    // inside the AppEntry but that might leak too much of the
    // implementation to the outside. Let's keep a list of file
    // names that came from the directory and remove items from
    // the list as we re-parse them. Once we are done emit the
    // signals.
    QVector<QString> deletionCandidates = entriesWithPrefix(dirName);

    beginResetModel();
    while (dirIt.hasNext()) {
        auto fileName = dirIt.next();
        if (!doAddFile(fileName))
            continue;
        deletionCandidates.removeAll(fileName);
    }
    QVector<AppEntry> removedApps = removeEntries(deletionCandidates);
    endResetModel();

    // Announce the apps we removed after the model has been updated
    for (const auto& app : removedApps) {
        qCDebug(apps) << "Going to remove entry for " << app.sourceFileName;
        emit appRemoved(app);
    }
}

bool AppListModel::doAddFile(const QString& fileName)
{
    bool ok;
    auto newEntry = AppParser::parseFile(fileName, &ok);
    if (!ok)
        return false;

    for (int i = 0; i < m_rows.count(); ++i) {
        if (m_rows[i].sourceFileName == fileName) {
            m_rows[i] = newEntry;
            return true;
        }
    }

    m_rows.push_back(newEntry);
    return true;
}

QVector<QString> AppListModel::entriesWithPrefix(const QString& prefix) const
{
    QVector<QString> entries;

    for (const AppEntry& entry : m_rows)
        if (entry.sourceFileName.startsWith(prefix))
            entries.push_back(entry.sourceFileName);
    return entries;
}

QVector<AppEntry> AppListModel::removeEntries(const QVector<QString>& fileNames)
{
    QVector<AppEntry> removedEntries(fileNames.size());

    // Rare but quadratic. The actual removal.
    for (const auto &toRemoveFile: fileNames) {
        for (int i = 0; i < m_rows.size(); ++i) {
            if (m_rows[i].sourceFileName != toRemoveFile)
                continue;
            removedEntries.append(m_rows[i]);
            m_rows.removeAt(i);
            break;
        }
    }

    return removedEntries;
}

QVariant AppListModel::findApplicationId(const QString& appId) const
{
    for (const auto& entry : m_rows) {
        if (entry.appId == appId)
            return QVariant::fromValue(entry);
    }

    return QVariant();
}