/*
 * Copyright (C) by Oleksandr Zolotov <alex@nextcloud.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 "iconutils.h"

#include <theme.h>

#include <QFile>
#include <QLoggingCategory>
#include <QPainter>
#include <QPixmapCache>
#include <QSvgRenderer>

namespace {
QString findSvgFilePath(const QString &fileName, const QStringList &possibleColors)
{
    QString result;
    result = QString{OCC::Theme::themePrefix} + fileName;
    if (QFile::exists(result)) {
        return result;
    } else {
        for (const auto &color : possibleColors) {
            result = QString{OCC::Theme::themePrefix} + color + QStringLiteral("/") + fileName;

            if (QFile::exists(result)) {
                return result;
            }
        }
        result.clear();
    }

    return result;
}
}

namespace OCC {
namespace Ui {
namespace IconUtils {
Q_LOGGING_CATEGORY(lcIconUtils, "nextcloud.gui.iconutils", QtInfoMsg)
QPixmap pixmapForBackground(const QString &fileName, const QColor &backgroundColor)
{
    Q_ASSERT(!fileName.isEmpty());

    const auto pixmapColor = backgroundColor.isValid() && !Theme::isDarkColor(backgroundColor)
        ? QColorConstants::Svg::black
        : QColorConstants::Svg::white;
    ;
    return createSvgPixmapWithCustomColorCached(fileName, pixmapColor);
}

QImage createSvgImageWithCustomColor(const QString &fileName, const QColor &customColor, QSize *originalSize, const QSize &requestedSize)
{
    Q_ASSERT(!fileName.isEmpty());
    Q_ASSERT(customColor.isValid());

    QImage result{};

    if (fileName.isEmpty() || !customColor.isValid()) {
        qWarning(lcIconUtils) << "invalid fileName or customColor";
        return result;
    }

    // some icons are present in white or black only, so, we need to check both when needed
    const auto iconBaseColors = QStringList{QStringLiteral("black"), QStringLiteral("white")};

    // check if there is an existing image matching the custom color
    {
        const auto customColorName = [&customColor]() {
            auto result = customColor.name();
            if (result.startsWith(QStringLiteral("#"))) {
                if (result == QStringLiteral("#000000")) {
                    result = QStringLiteral("black");
                }
                if (result == QStringLiteral("#ffffff")) {
                    result = QStringLiteral("white");
                }
            }
            return result;
        }();

        if (iconBaseColors.contains(customColorName)) {
            result = QImage{QString{OCC::Theme::themePrefix} + customColorName + QStringLiteral("/") + fileName};
            if (!result.isNull()) {
                return result;
            }
        }
    }
    
    // find the first matching svg file
    const auto sourceSvg = findSvgFilePath(fileName, iconBaseColors);

    Q_ASSERT(!sourceSvg.isEmpty());
    if (sourceSvg.isEmpty()) {
        qWarning(lcIconUtils) << "Failed to find base SVG file for" << fileName;
        return result;
    }

    result = drawSvgWithCustomFillColor(sourceSvg, customColor, originalSize, requestedSize);

    Q_ASSERT(!result.isNull());
    if (result.isNull()) {
        qWarning(lcIconUtils) << "Failed to load pixmap for" << fileName;
    }

    return result;
}

QPixmap createSvgPixmapWithCustomColorCached(const QString &fileName, const QColor &customColor, QSize *originalSize, const QSize &requestedSize)
{
    QPixmap cachedPixmap;

    const auto customColorName = customColor.name();

    const QString cacheKey = fileName + QStringLiteral(",") + customColorName;

    // check for existing QPixmap in cache
    if (QPixmapCache::find(cacheKey, &cachedPixmap)) {
        if (originalSize) {
            *originalSize = {};
        }
        return cachedPixmap;
    }

    cachedPixmap = QPixmap::fromImage(createSvgImageWithCustomColor(fileName, customColor, originalSize, requestedSize));

    if (!cachedPixmap.isNull()) {
        QPixmapCache::insert(cacheKey, cachedPixmap);
    }

    return cachedPixmap;
}

QImage drawSvgWithCustomFillColor(
    const QString &sourceSvgPath, const QColor &fillColor, QSize *originalSize, const QSize &requestedSize)
{
    QSvgRenderer svgRenderer;

    if (!svgRenderer.load(sourceSvgPath)) {
        qCWarning(lcIconUtils) << "Could no load initial SVG image";
        return {};
    }

    const auto reqSize = requestedSize.isValid() ? requestedSize : svgRenderer.defaultSize();

    if (originalSize) {
        *originalSize = svgRenderer.defaultSize();
    }

    // render source image
    QImage svgImage(reqSize, QImage::Format_ARGB32);
    {
        QPainter svgImagePainter(&svgImage);
        svgImage.fill(Qt::GlobalColor::transparent);
        svgRenderer.render(&svgImagePainter);
    }

    // draw target image with custom fillColor
    QImage image(reqSize, QImage::Format_ARGB32);
    image.fill(QColor(fillColor));
    {
        QPainter imagePainter(&image);
        imagePainter.setCompositionMode(QPainter::CompositionMode_DestinationIn);
        imagePainter.drawImage(0, 0, svgImage);
    }

    return image;
}
}
}
}
