#include "panda_qt/screen.hpp"

#include <algorithm>
#include <array>
#include <cmath>
#include <optional>
#include <QGuiApplication>
#include <QScreen>
#include <QWindow>

// OpenGL screen widget, based on https://github.com/melonDS-emu/melonDS/blob/master/src/frontend/qt_sdl/main.cpp

#ifdef PANDA3DS_ENABLE_OPENGL
bool ScreenWidget::createGLContext() {
	// List of GL context versions we will try. Anything 4.1+ is good
	static constexpr std::array<GL::Context::Version, 6> versionsToTry = {
		GL::Context::Version{GL::Context::Profile::Core, 4, 6}, GL::Context::Version{GL::Context::Profile::Core, 4, 5},
		GL::Context::Version{GL::Context::Profile::Core, 4, 4}, GL::Context::Version{GL::Context::Profile::Core, 4, 3},
		GL::Context::Version{GL::Context::Profile::Core, 4, 2}, GL::Context::Version{GL::Context::Profile::Core, 4, 1},
	};

	std::optional<WindowInfo> windowInfo = getWindowInfo();
	if (windowInfo.has_value()) {
		glContext = GL::Context::Create(*getWindowInfo(), versionsToTry);
		glContext->DoneCurrent();
	}

	return glContext != nullptr;
}

qreal ScreenWidget::devicePixelRatioFromScreen() const {
	const QScreen* screenForRatio = window()->windowHandle()->screen();
	if (!screenForRatio) {
		screenForRatio = QGuiApplication::primaryScreen();
	}

	return screenForRatio ? screenForRatio->devicePixelRatio() : static_cast<qreal>(1);
}

int ScreenWidget::scaledWindowWidth() const {
	return std::max(static_cast<int>(std::ceil(static_cast<qreal>(width()) * devicePixelRatioFromScreen())), 1);
}

int ScreenWidget::scaledWindowHeight() const {
	return std::max(static_cast<int>(std::ceil(static_cast<qreal>(height()) * devicePixelRatioFromScreen())), 1);
}

std::optional<WindowInfo> ScreenWidget::getWindowInfo() {
	WindowInfo wi;

// Windows and Apple are easy here since there's no display connection.
#if defined(_WIN32)
	wi.type = WindowInfo::Type::Win32;
	wi.window_handle = reinterpret_cast<void*>(winId());
#elif defined(__APPLE__)
	wi.type = WindowInfo::Type::MacOS;
	wi.window_handle = reinterpret_cast<void*>(winId());
#else
	QPlatformNativeInterface* pni = QGuiApplication::platformNativeInterface();
	const QString platform_name = QGuiApplication::platformName();
	if (platform_name == QStringLiteral("xcb")) {
		wi.type = WindowInfo::Type::X11;
		wi.display_connection = pni->nativeResourceForWindow("display", windowHandle());
		wi.window_handle = reinterpret_cast<void*>(winId());
	} else if (platform_name == QStringLiteral("wayland")) {
		wi.type = WindowInfo::Type::Wayland;
		QWindow* handle = windowHandle();
		if (handle == nullptr) {
			return std::nullopt;
		}

		wi.display_connection = pni->nativeResourceForWindow("display", handle);
		wi.window_handle = pni->nativeResourceForWindow("surface", handle);
	} else {
		qCritical() << "Unknown PNI platform " << platform_name;
		return std::nullopt;
	}
#endif

	wi.surface_width = static_cast<u32>(scaledWindowWidth());
	wi.surface_height = static_cast<u32>(scaledWindowHeight());
	wi.surface_scale = static_cast<float>(devicePixelRatioFromScreen());

	return wi;
}
#endif