/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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 3 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "ultima/ultima8/gumps/inverter_gump.h"

#include "ultima/ultima8/graphics/render_surface.h"
#include "ultima/ultima8/ultima8.h"

namespace Ultima {
namespace Ultima8 {

DEFINE_RUNTIME_CLASSTYPE_CODE(InverterGump)

InverterGump::InverterGump(int32 x, int32 y, int32 width, int32 height)
	: DesktopGump(x, y, width, height) {
	_buffer = nullptr;
}

InverterGump::~InverterGump() {
	delete _buffer;
}

static inline int getLine(int index, int n) {
	index = index % (2 * n);

	if (index >= n)
		return 2 * n - 1 - 2 * (index - n);
	else
		return 2 * index;
}

static inline int getIndex(int line, int n) {
	if (line % 2 == 0)
		return line / 2;
	else
		return 2 * n - 1 - (line / 2);
}

void InverterGump::Paint(RenderSurface *surf, int32 lerp_factor, bool scaled) {
	// Skip the clipping rect/origin setting, since they will already be set
	// correctly by our parent.
	// (Or maybe I'm just to lazy to figure out the correct coordinates
	//  to use to compensate for the flipping... -wjp :-) )

	// Don't paint if hidden
	if (IsHidden()) return;

	// Paint This
	PaintThis(surf, lerp_factor, scaled);

	// Paint children
	PaintChildren(surf, lerp_factor, scaled);
}


void InverterGump::PaintChildren(RenderSurface *surf, int32 lerp_factor, bool scaled) {
	unsigned int state = Ultima8Engine::get_instance()->getInversion();

	if (state == 0) {
		DesktopGump::PaintChildren(surf, lerp_factor, scaled);
		return;
	} else if (state == 0x8000) {
		bool old_flipped = surf->IsFlipped();
		surf->SetFlipped(!old_flipped);

		DesktopGump::PaintChildren(surf, lerp_factor, scaled);

		surf->SetFlipped(old_flipped);
		return;
	}

	int width = _dims.width(), height = _dims.height();


	// need a backbuffer
	if (!_buffer) {
		_buffer = RenderSurface::CreateSecondaryRenderSurface(width, height);
	}

	_buffer->BeginPainting();
	DesktopGump::PaintChildren(_buffer, lerp_factor, scaled);
	_buffer->EndPainting();

	// now invert-blit _buffer to screen
	int t = (state * height) / 0x10000;

	for (int i = 0; i < height; ++i) {
		int src = getLine(getIndex(i, height / 2) + t, height / 2);
//		pout << src << " -> " << i << Std::endl;
		surf->Blit(_buffer->getRawSurface(), 0, src, width, 1, 0, i);
	}
}

// Convert a parent relative point to a gump point
void InverterGump::ParentToGump(int32 &px, int32 &py, PointRoundDir) {
	px -= _x;
	px += _dims.left;
	py -= _y;
	if (Ultima8Engine::get_instance()->isInverted()) py = _dims.height() - py - 1;
	py += _dims.top;
}

// Convert a gump point to parent relative point
void InverterGump::GumpToParent(int32 &gx, int32 &gy, PointRoundDir) {
	gx -= _dims.left;
	gx += _x;
	gy -= _dims.top;
	if (Ultima8Engine::get_instance()->isInverted()) gy = _dims.height() - gy - 1;
	gy += _y;
}

void InverterGump::RenderSurfaceChanged() {
	DesktopGump::RenderSurfaceChanged();
	FORGET_OBJECT(_buffer);
}

} // End of namespace Ultima8
} // End of namespace Ultima
