#include "hwcursor.hpp"

#include <cstdint>
#include <tuple>

#if SDL_VERSION_ATLEAST(2, 0, 0)
#include <SDL_mouse.h>
#include <SDL_render.h>
#include <SDL_surface.h>
#endif

#include "DiabloUI/diabloui.h"

#include "appfat.h"
#include "cursor.h"
#include "engine.h"
#include "utils/display.h"
#include "utils/sdl_bilinear_scale.hpp"
#include "utils/sdl_wrap.h"

namespace devilution {
namespace {
CursorInfo CurrentCursorInfo;

#if SDL_VERSION_ATLEAST(2, 0, 0)
SDLCursorUniquePtr CurrentCursor;

enum class HotpointPosition {
	TopLeft,
	Center,
};

Size ScaledSize(Size size)
{
	if (renderer != nullptr) {
		float scaleX;
		float scaleY;
		SDL_RenderGetScale(renderer, &scaleX, &scaleY);
		size.width = static_cast<int>(size.width * scaleX);
		size.height = static_cast<int>(size.height * scaleY);
	}
	return size;
}

bool IsCursorSizeAllowed(Size size)
{
	if (*sgOptions.Graphics.hardwareCursorMaxSize <= 0)
		return true;
	size = ScaledSize(size);
	return size.width <= *sgOptions.Graphics.hardwareCursorMaxSize
	    && size.height <= *sgOptions.Graphics.hardwareCursorMaxSize;
}

Point GetHotpointPosition(const SDL_Surface &surface, HotpointPosition position)
{
	switch (position) {
	case HotpointPosition::TopLeft:
		return { 0, 0 };
	case HotpointPosition::Center:
		return { surface.w / 2, surface.h / 2 };
	}
	app_fatal("Unhandled enum value");
}

bool ShouldUseBilinearScaling()
{
	return *sgOptions.Graphics.scaleQuality != ScalingQuality::NearestPixel;
}

bool SetHardwareCursor(SDL_Surface *surface, HotpointPosition hotpointPosition)
{
	SDLCursorUniquePtr newCursor;
	const Size size { surface->w, surface->h };
	const Size scaledSize = ScaledSize(size);

	if (size == scaledSize) {
		const Point hotpoint = GetHotpointPosition(*surface, hotpointPosition);
		newCursor = SDLCursorUniquePtr { SDL_CreateColorCursor(surface, hotpoint.x, hotpoint.y) };
	} else {
		// SDL does not support BlitScaled from 8-bit to RGBA.
		SDLSurfaceUniquePtr converted { SDL_ConvertSurfaceFormat(surface, SDL_PIXELFORMAT_ARGB8888, 0) };

		SDLSurfaceUniquePtr scaledSurface = SDLWrap::CreateRGBSurfaceWithFormat(0, scaledSize.width, scaledSize.height, 32, SDL_PIXELFORMAT_ARGB8888);
		if (ShouldUseBilinearScaling()) {
			BilinearScale32(converted.get(), scaledSurface.get());
		} else {
			SDL_BlitScaled(converted.get(), nullptr, scaledSurface.get(), nullptr);
		}
		const Point hotpoint = GetHotpointPosition(*scaledSurface, hotpointPosition);
		newCursor = SDLCursorUniquePtr { SDL_CreateColorCursor(scaledSurface.get(), hotpoint.x, hotpoint.y) };
	}
	if (newCursor == nullptr)
		return false;
	SDL_SetCursor(newCursor.get());
	CurrentCursor = std::move(newCursor);
	return true;
}

bool SetHardwareCursorFromSprite(int pcurs)
{
	const bool isItem = !MyPlayer->HoldItem.isEmpty();
	if (isItem && !*sgOptions.Graphics.hardwareCursorForItems)
		return false;

	const int outlineWidth = isItem ? 1 : 0;

	auto size = GetInvItemSize(pcurs);
	size.width += 2 * outlineWidth;
	size.height += 2 * outlineWidth;

	if (!IsCursorSizeAllowed(size))
		return false;

	OwnedSurface out { size };
	SDL_SetSurfacePalette(out.surface, Palette.get());

	// Transparent color must not be used in the sprite itself.
	// Colors 1-127 are outside of the UI palette so are safe to use.
	constexpr std::uint8_t TransparentColor = 1;
	SDL_FillRect(out.surface, nullptr, TransparentColor);
	SDL_SetColorKey(out.surface, 1, TransparentColor);
	CelDrawCursor(out, { outlineWidth, size.height - outlineWidth }, pcurs);

	const bool result = SetHardwareCursor(out.surface, isItem ? HotpointPosition::Center : HotpointPosition::TopLeft);
	return result;
}
#endif

} // namespace

CursorInfo GetCurrentCursorInfo()
{
	return CurrentCursorInfo;
}

void SetHardwareCursor(CursorInfo cursorInfo)
{
#if SDL_VERSION_ATLEAST(2, 0, 0)
	CurrentCursorInfo = cursorInfo;
	switch (cursorInfo.type()) {
	case CursorType::Game:
		CurrentCursorInfo.SetEnabled(SetHardwareCursorFromSprite(cursorInfo.id()));
		break;
	case CursorType::UserInterface:
		// ArtCursor is null while loading the game on the progress screen,
		// called via palette fade from ShowProgress.
		CurrentCursorInfo.SetEnabled(
		    ArtCursor.surface != nullptr && IsCursorSizeAllowed(Size { ArtCursor.surface->w, ArtCursor.surface->h })
		    && SetHardwareCursor(ArtCursor.surface.get(), HotpointPosition::TopLeft));
		break;
	case CursorType::Unknown:
		CurrentCursorInfo.SetEnabled(false);
		break;
	}
	if (!CurrentCursorInfo.Enabled())
		SetHardwareCursorVisible(false);
#endif
}

} // namespace devilution