// SPDX-FileCopyrightText: 2022 - 2023 UnionTech Software Technology Co., Ltd.
//
// SPDX-License-Identifier: LGPL-3.0-or-later

#ifndef DTK_DISABLE_LIBRSVG
#include <librsvg/rsvg.h>
#else
#include <QSvgRenderer>
#endif

#include "dsvgrenderer.h"

#include <QPainter>
#include <QFile>
#include <QDebug>
#include <QGuiApplication>
#include <QXmlStreamReader>

class DSvgRendererPrivate : public QObject
{
public:
    explicit DSvgRendererPrivate(DSvgRenderer *qq);

    QImage getImage(const QSize &size, const QString &elementId) const;

    RsvgHandle *handle = nullptr;
    QSize defaultSize;
    mutable QRectF viewBox;
};

DSvgRendererPrivate::DSvgRendererPrivate(DSvgRenderer *qq)
    : QObject(qq)           // qq ==> DObject
{

}

QImage DSvgRendererPrivate::getImage(const QSize &size, const QString &elementId) const
{
    QImage image(size, QImage::Format_ARGB32_Premultiplied);

    image.fill(Qt::transparent);

    cairo_surface_t *surface = cairo_image_surface_create_for_data(image.bits(), CAIRO_FORMAT_ARGB32, image.width(), image.height(), image.bytesPerLine());
    cairo_t *cairo = cairo_create(surface);
    cairo_scale(cairo, image.width() / viewBox.width(), image.height() / viewBox.height());
    cairo_translate(cairo, -viewBox.x(), -viewBox.y());

    if (elementId.isEmpty())
        rsvg_handle_render_cairo(handle, cairo);
    else
        rsvg_handle_render_cairo_sub(handle, cairo, elementId.toUtf8().constData());

    cairo_destroy(cairo);
    cairo_surface_destroy(surface);

    return image;
}

/*!
  \class Dtk::Gui::DSvgRenderer
  \inmodule dtkgui
  \brief 提供了将SVG文件的内容绘制到绘制设备上的方法.

  SVG图形可以在构造 DSvgRenderer 时加载，也可以稍后使用load（）函数加载。
  因为渲染是使用 QPainter 执行的，所以可以在 QPaintDevice 的任何子类上渲染SVG图形。
  如果加载了有效文件，则无论是在构造时还是以后某个时间，isValid（）都将返回true；否则将返回false。
  DSvgRenderer提供render（）插槽，用于使用给定的 QPainter 渲染当前文档或动画文档的当前帧
  \note 使用 DSvgRenderer 需要 librsvg库
 */

DSvgRenderer::DSvgRenderer(QObject *parent)
    : QObject(parent)
{
}

DSvgRenderer::DSvgRenderer(const QString &filename, QObject *parent)
    : DSvgRenderer(parent)
{
    load(filename);
}

DSvgRenderer::DSvgRenderer(const QByteArray &contents, QObject *parent)
    : DSvgRenderer(parent)
{
    load(contents);
}

DSvgRenderer::~DSvgRenderer()
{
    Q_D(DSvgRenderer);

    if (d->handle) {
        Q_ASSERT(isValid());
        g_object_unref(d->handle);
    }
}

bool DSvgRenderer::isValid() const
{
    Q_D(const DSvgRenderer);
    return d->handle;
}

QSize DSvgRenderer::defaultSize() const
{
    Q_D(const DSvgRenderer);
    return d->defaultSize;
}

QRect DSvgRenderer::viewBox() const
{
    Q_D(const DSvgRenderer);
    return d->handle ? d->viewBox.toRect() : QRect();
}

QRectF DSvgRenderer::viewBoxF() const
{
    Q_D(const DSvgRenderer);
    return d->handle ? d->viewBox : QRectF();
}

void DSvgRenderer::setViewBox(const QRect &viewbox)
{
    setViewBox(QRectF(viewbox));
}

void DSvgRenderer::setViewBox(const QRectF &viewbox)
{
    Q_D(DSvgRenderer);
    if (d->handle)
        d->viewBox = viewbox;
}

QRectF DSvgRenderer::boundsOnElement(const QString &id) const
{
    Q_D(const DSvgRenderer);
    if (!d->handle)
        return QRectF();

    const QByteArray &id_data = id.toUtf8();

    RsvgDimensionData dimension_data;

    if (!rsvg_handle_get_dimensions_sub(d->handle, &dimension_data, id_data.constData()))
        return QRectF();

    RsvgPositionData pos_data;

    if (!rsvg_handle_get_position_sub(d->handle, &pos_data, id_data.constData()))
        return QRectF();

    return QRectF(pos_data.x, pos_data.y, dimension_data.width, dimension_data.height);
}

bool DSvgRenderer::elementExists(const QString &id) const
{
    Q_D(const DSvgRenderer);
    if (!d->handle)
        return false;

    return rsvg_handle_has_sub(d->handle, id.toUtf8().constData());
}

QImage DSvgRenderer::toImage(const QSize sz, const QString &elementId) const
{
    Q_D(const DSvgRenderer);

    return d->getImage(sz, elementId);
}

static QByteArray updateXmlAttribute(const QString &contents)
{
    QByteArray data;
    QXmlStreamWriter writer(&data);
    QXmlStreamReader reader(contents);
    while(reader.readNext() != QXmlStreamReader::Invalid && !reader.atEnd()) {
        if (reader.tokenType() != QXmlStreamReader::StartElement ||
                !reader.attributes().hasAttribute("href")) {
            writer.writeCurrentToken(reader);
            continue;
        }

        for (const auto &nd : reader.namespaceDeclarations())
            writer.writeNamespace(nd.namespaceUri().toString(), nd.prefix().toString());

        writer.writeStartElement(reader.namespaceUri().toString(), reader.name().toString());

        for (const auto &attr : reader.attributes()) {
            if (attr.name() == "href") {
                writer.writeAttribute("xlink:href", attr.value().toString());
                continue;
            }
            writer.writeAttribute(attr);
        }
    }

    return data;
}

static QByteArray format(const QByteArray &contents)
{
    QXmlStreamReader reader(contents);
    while (reader.readNextStartElement()) {
        if (reader.attributes().hasAttribute("href"))
            return updateXmlAttribute(contents);
    }

    return contents;
}

bool DSvgRenderer::load(const QString &filename)
{
    QFile file(filename);

    if (file.open(QIODevice::ReadOnly)) {
        // TODO: if `href` attribute is adapted after librsvg upgrade revert me
        return load(format(file.readAll()));
    }

    return false;
}

bool DSvgRenderer::load(const QByteArray &contents)
{
    Q_D(DSvgRenderer);qDebug() << "drsvg load()";

    if (d->handle) {
        g_object_unref(d->handle);
        d->handle = nullptr;
    }

    GError *error = nullptr;
    d->handle = rsvg_handle_new_from_data((const guint8*)contents.constData(), contents.length(), &error);

    if (error) {
        qWarning("DSvgRenderer::load: %s", error->message);
        g_error_free(error);

        return false;
    }

    RsvgDimensionData rsvg_data;

    rsvg_handle_get_dimensions(d->handle, &rsvg_data);

    d->defaultSize.setWidth(rsvg_data.width);
    d->defaultSize.setHeight(rsvg_data.height);
    d->viewBox = QRectF(QPointF(0, 0), d->defaultSize);

    return true;
}

void DSvgRenderer::render(QPainter *p)
{
    render(p, QString(), QRectF());
}

void DSvgRenderer::render(QPainter *p, const QRectF &bounds)
{
    render(p, QString(), bounds);
}

void DSvgRenderer::render(QPainter *p, const QString &elementId, const QRectF &bounds)
{
    Q_D(DSvgRenderer);
    if (!d->handle)
        return;

    p->save();

    const QImage image = d->getImage(QSize(p->device()->width(), p->device()->height()), elementId);

    if (bounds.isEmpty())
        p->drawImage(0, 0, image);
    else
        p->drawImage(bounds, image);

    p->restore();
}