// This file Copyright © Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.

#include "IconCache.h"

#ifdef _WIN32
#include <windows.h>
#include <shellapi.h>
#endif

#include <QApplication>
#include <QFile>
#include <QFileIconProvider>
#include <QFileInfo>
#include <QIcon>
#include <QMimeDatabase>
#include <QObject>
#include <QPainter>
#include <QPixmap>
#include <QStyle>

#ifdef _WIN32
#include <QPixmapCache>
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
#include <QImage>
#else
#include <QtWin>
#endif
#endif

#include <optional>
#include <utility>

/***
****
***/

IconCache& IconCache::get()
{
    // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
    static auto& singleton = *new IconCache();
    return singleton;
}

QIcon IconCache::guessMimeIcon(QString const& filename, QIcon fallback) const
{
    QIcon icon;

#ifdef _WIN32

    if (!filename.isEmpty())
    {
        QFileInfo const file_info(filename);

        addAssociatedFileIcon(file_info, SHGFI_SMALLICON, icon);
        addAssociatedFileIcon(file_info, 0, icon);
        addAssociatedFileIcon(file_info, SHGFI_LARGEICON, icon);
    }

#else

    icon = getMimeIcon(filename);

#endif

    if (icon.isNull())
    {
        icon = std::move(fallback);
    }

    return icon;
}

QIcon IconCache::getMimeTypeIcon(QString const& mime_type_name, bool multifile) const
{
    auto& icon = (multifile ? name_to_emblem_icon_ : name_to_icon_)[mime_type_name];

    if (!icon.isNull())
    {
        return icon;
    }

    if (!multifile)
    {
        QMimeDatabase const mime_db;
        auto const type = mime_db.mimeTypeForName(mime_type_name);
        icon = getThemeIcon(type.iconName());

        if (icon.isNull())
        {
            icon = getThemeIcon(type.genericIconName());
        }

        if (icon.isNull())
        {
            icon = file_icon_;
        }

        return icon;
    }

    auto const mime_icon = getMimeTypeIcon(mime_type_name, false);
    for (auto const& size : { QSize{ 24, 24 }, QSize{ 32, 32 }, QSize{ 48, 48 } })
    {
        // upper left corner
        auto const folder_size = size / 2;
        auto const folder_rect = QRect{ QPoint{}, folder_size };

        // fullsize
        auto const mime_size = size;
        auto const mime_rect = QRect{ QPoint{}, mime_size };

        // build the icon
        auto pixmap = QPixmap{ size };
        pixmap.fill(Qt::transparent);
        auto painter = QPainter{ &pixmap };
        painter.setRenderHints(QPainter::SmoothPixmapTransform);
        painter.drawPixmap(folder_rect, folder_icon_.pixmap(folder_size));
        painter.drawPixmap(mime_rect, mime_icon.pixmap(mime_size));
        icon.addPixmap(pixmap);
    }

    return icon;
}

QIcon IconCache::getThemeIcon(QString const& name, std::optional<QStyle::StandardPixmap> const& fallback) const
{
    return getThemeIcon(name, name + QStringLiteral("-symbolic"), fallback);
}

/***
****
***/

#ifdef _WIN32

void IconCache::addAssociatedFileIcon(QFileInfo const& file_info, unsigned int icon_size, QIcon& icon) const
{
    QString const pixmap_cache_key = QStringLiteral("tr_file_ext_") + QString::number(icon_size) + QLatin1Char('_') +
        file_info.suffix();

    QPixmap pixmap;

    if (!QPixmapCache::find(pixmap_cache_key, &pixmap))
    {
        auto const filename = file_info.fileName().toStdWString();

        SHFILEINFO shell_file_info;

        if (::SHGetFileInfoW(
                filename.data(),
                FILE_ATTRIBUTE_NORMAL,
                &shell_file_info,
                sizeof(shell_file_info),
                SHGFI_ICON | icon_size | SHGFI_USEFILEATTRIBUTES) != 0)
        {
            if (shell_file_info.hIcon != nullptr)
            {
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
                pixmap = QPixmap::fromImage(QImage::fromHICON(shell_file_info.hIcon));
#else
                pixmap = QtWin::fromHICON(shell_file_info.hIcon);
#endif
                ::DestroyIcon(shell_file_info.hIcon);
            }
        }

        QPixmapCache::insert(pixmap_cache_key, pixmap);
    }

    if (!pixmap.isNull())
    {
        icon.addPixmap(pixmap);
    }
}

#else

QIcon IconCache::getMimeIcon(QString const& filename) const
{
    if (suffixes_.empty())
    {
        for (auto const& type : QMimeDatabase{}.allMimeTypes())
        {
            auto const tmp = type.suffixes();
            suffixes_.insert(tmp.begin(), tmp.end());
        }
    }

    auto const ext = QFileInfo{ filename }.suffix();
    if (suffixes_.count(ext) == 0)
    {
        return {};
    }

    QIcon& icon = ext_to_icon_[ext];
    if (icon.isNull()) // cache miss
    {
        QMimeDatabase const mime_db;
        auto const type = mime_db.mimeTypeForFile(filename, QMimeDatabase::MatchExtension);
        if (icon.isNull())
        {
            icon = getThemeIcon(type.iconName());
        }

        if (icon.isNull())
        {
            icon = getThemeIcon(type.genericIconName());
        }

        if (icon.isNull())
        {
            icon = {};
        }
    }

    return icon;
}

#endif

QIcon IconCache::getThemeIcon(
    QString const& name,
    QString const& fallbackName,
    std::optional<QStyle::StandardPixmap> const& fallbackPixmap) const
{
    auto const rtl_suffix = QApplication::layoutDirection() == Qt::RightToLeft ? QStringLiteral("-rtl") : QString{};

    auto icon = QIcon::fromTheme(name + rtl_suffix);

    if (icon.isNull())
    {
        icon = QIcon::fromTheme(fallbackName + rtl_suffix);
    }

    if (icon.isNull() && fallbackPixmap.has_value())
    {
        icon = QApplication::style()->standardIcon(*fallbackPixmap, nullptr);
    }

    return icon;
}
