#include <QHash>
#include <QtDebug>
#include <QFile>
#include <QDir>
#include <QIcon>
#include <QResource>
#include <QFileInfo>
#include <QCryptographicHash>

#include "globals.h"
#include "sessionsiconholder.h"
#include "sessiontreemodel.h"
#include "filedownloader.h"

SessionsIconHolder* SessionsIconHolder::instance = nullptr;

static inline QString url2filename(const QString& url) {
    return TEMP_PATH_ICONS + QString(QCryptographicHash::hash(url.toUtf8(), QCryptographicHash::Md5).toHex());
}

SessionsIconHolder::SessionsIconHolder() {
    QDir().mkpath(TEMP_PATH_ICONS);
}

QIcon SessionsIconHolder::getIcon(const QString& name) {
    // check if icon was loaded before
    if (icons.contains(name)) {
        return icons[name];
    }

    // else load icon from resource
    QIcon icon;
    QString resName(":" + name.toLower());
    if (QResource(resName).isValid()) {
        icon = QIcon(resName);
    } else if (QFileInfo(name).isAbsolute() && QFile::exists(name)) {
        // absolute icon path and file exists
        icon = QIcon(name);
    } else {
        icon = QIcon();
    }

    // insert icon to hash table
    icons.insert(name, icon);
    return icon;
}

QIcon SessionsIconHolder::getIcon(const QUrl& url) {
    // check if icon was loaded before
    if (icons.contains(url.toString())) {
        return icons[url.toString()];
    }

    // search the icon in the tmp folder
    QString strUrl(url.toString());
    QString file_path(url2filename(strUrl));

    if (QFile::exists(file_path)) {
        QIcon icon(file_path);
        icons.insert(strUrl, icon);
        return icon;
    }
    // Put empty icon in map while we're downloading, so successive calls won't trigger
    // more downloads before the running download finishes
    icons.insert(strUrl, QIcon());

    // else load icon from url
    // TODO add '--url-icon' command line option we want to reintroduce this feature (currently not used).
    FileDownloader::download(url, [this, url](QNetworkReply::NetworkError, const QByteArray &downloadedData) {
        // save the data to disk
        QString strUrl(url.toString());
        QString file_path(url2filename(strUrl));
        QFile file(file_path);
        if (!file.open(QFile::WriteOnly)) {
            if (g_debugMode) {
                qDebug() << "Could not write file: " << file_path;
            }
            return;
        }
        file.write(downloadedData);

        if (file.write(downloadedData) != downloadedData.length()) {
            if (g_debugMode) {
                qDebug() << "Could not write file: " << file_path;
            }
            return;
        }

        file.close();

        QIcon icon(file_path);
        icons.insert(strUrl, icon);

        emit iconDownloaded(url, icon);
    });

    return QIcon();
}