/* 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 "graphics/managed_surface.h"
#include "common/textconsole.h"
#include "awe/gfx.h"
#include "awe/system_stub.h"

namespace Awe {

struct GraphicsSoft : public Gfx {
	typedef void (GraphicsSoft:: *drawLine)(int16 x1, int16 x2, int16 y, uint8 col);

	uint8 *_pagePtrs[4] = { nullptr };
	uint8 *_drawPagePtr = { nullptr };
	int _u = 0, _v = 0;
	int _w = 0, _h = 0;
	int _byteDepth = 0;
	Color _pal[16];
	bool _palChanged = false;

	GraphicsSoft();
	~GraphicsSoft();

	int xScale(int x) const {
		return (x * _u) >> 16;
	}
	int yScale(int y) const {
		return (y * _v) >> 16;
	}

	void setSize(int w, int h);
	void drawPolygon(uint8 color, const QuadStrip &qs);
	void drawChar(uint8 c, uint16 x, uint16 y, uint8 color);
	void drawSpriteMask(int x, int y, uint8 color, const uint8 *data);
	void drawPoint(int16 x, int16 y, uint8 color);
	void drawLineT(int16 x1, int16 x2, int16 y, uint8 color);
	void drawLineN(int16 x1, int16 x2, int16 y, uint8 color);
	void drawLineP(int16 x1, int16 x2, int16 y, uint8 color);
	uint8 *getPagePtr(uint8 page);
	int getPageSize() const {
		return _w * _h * _byteDepth;
	}
	void setWorkPagePtr(uint8 page);

	void init(int targetW, int targetH) override;

	void setFont(const uint8 *src, int w, int h) override;
	void setPalette(const Color *colors, int count) override;
	void setSpriteAtlas(const uint8 *src, int w, int h, int xSize, int ySize) override;
	void drawSprite(int buffer, int num, const Point *pt, uint8 color) override;
	void drawBitmap(int buffer, const uint8 *data, int w, int h, int fmt) override;
	void drawPoint(int buffer, uint8 color, const Point *pt) override;
	void drawQuadStrip(int buffer, uint8 color, const QuadStrip *qs) override;
	void drawStringChar(int buffer, uint8 color, char c, const Point *pt) override;
	void clearBuffer(int num, uint8 color) override;
	void copyBuffer(int dst, int src, int vscroll = 0) override;
	void drawBuffer(int num, SystemStub *stub) override;
	void drawRect(int num, uint8 color, const Point *pt, int w, int h) override;
	void drawBitmapOverlay(const Graphics::Surface &src, int fmt, SystemStub *stub) override;
};


GraphicsSoft::GraphicsSoft() {
	_fixUpPalette = FIXUP_PALETTE_NONE;
	memset(_pagePtrs, 0, sizeof(_pagePtrs));
}

GraphicsSoft::~GraphicsSoft() {
	for (int i = 0; i < 4; ++i) {
		free(_pagePtrs[i]);
		_pagePtrs[i] = nullptr;
	}
}

void GraphicsSoft::setSize(int w, int h) {
	_u = (w << 16) / GFX_W;
	_v = (h << 16) / GFX_H;
	_w = w;
	_h = h;
	_byteDepth = _format.bytesPerPixel;
	assert(_byteDepth == 1 || _byteDepth == 2);

	for (int i = 0; i < 4; ++i) {
		uint8 *tmp = (uint8 *)realloc(_pagePtrs[i], getPageSize());
		if (!tmp) {
			error("Not enough memory to allocate offscreen buffers");
		}
		_pagePtrs[i] = tmp;
		memset(_pagePtrs[i], 0, getPageSize());
	}
	setWorkPagePtr(2);
}

static uint32 calcStep(const Point &p1, const Point &p2, uint16 &dy) {
	dy = p2.y - p1.y;
	const uint16 delta = (dy <= 1) ? 1 : dy;
	return ((p2.x - p1.x) * (0x4000 / delta)) << 2;
}

void GraphicsSoft::drawPolygon(uint8 color, const QuadStrip &quadStrip) {
	QuadStrip qs = quadStrip;
	if (_w != GFX_W || _h != GFX_H) {
		for (int i = 0; i < qs.numVertices; ++i) {
			qs.vertices[i].scale(_u, _v);
		}
	}

	int i = 0;
	int j = qs.numVertices - 1;

	int16 x2 = qs.vertices[i].x;
	int16 x1 = qs.vertices[j].x;
	int16 hliney = MIN(qs.vertices[i].y, qs.vertices[j].y);

	++i;
	--j;

	drawLine pdl;
	switch (color) {
	default:
		pdl = &GraphicsSoft::drawLineN;
		break;
	case COL_PAGE:
		pdl = &GraphicsSoft::drawLineP;
		break;
	case COL_ALPHA:
		pdl = &GraphicsSoft::drawLineT;
		break;
	}

	uint32 cpt1 = x1 << 16;
	uint32 cpt2 = x2 << 16;

	int numVertices = qs.numVertices;
	while (true) {
		numVertices -= 2;
		if (numVertices == 0) {
			return;
		}
		uint16 h;
		const uint32 step1 = calcStep(qs.vertices[j + 1], qs.vertices[j], h);
		const uint32 step2 = calcStep(qs.vertices[i - 1], qs.vertices[i], h);

		++i;
		--j;

		cpt1 = (cpt1 & 0xFFFF0000) | 0x7FFF;
		cpt2 = (cpt2 & 0xFFFF0000) | 0x8000;

		if (h == 0) {
			cpt1 += step1;
			cpt2 += step2;
		} else {
			while (h--) {
				if (hliney >= 0) {
					x1 = cpt1 >> 16;
					x2 = cpt2 >> 16;
					if (x1 < _w && x2 >= 0) {
						if (x1 < 0) x1 = 0;
						if (x2 >= _w) x2 = _w - 1;
						(this->*pdl)(x1, x2, hliney, color);
					}
				}
				cpt1 += step1;
				cpt2 += step2;
				++hliney;
				if (hliney >= _h) return;
			}
		}
	}
}

void GraphicsSoft::drawChar(uint8 c, uint16 x, uint16 y, uint8 color) {
	if (x <= GFX_W - 8 && y <= GFX_H - 8) {
		x = xScale(x);
		y = yScale(y);
		const uint8 *ft = FONT + (c - 0x20) * 8;
		const int offset = (x + y * _w) * _byteDepth;
		if (_byteDepth == 1) {
			for (int j = 0; j < 8; ++j) {
				const uint8 ch = ft[j];
				for (int i = 0; i < 8; ++i) {
					if (ch & (1 << (7 - i))) {
						_drawPagePtr[offset + j * _w + i] = color;
					}
				}
			}
		} else if (_byteDepth == 2) {
			const uint16 rgbColor = _format.RGBToColor(
				_pal[color].r, _pal[color].g, _pal[color].b);

			for (int j = 0; j < 8; ++j) {
				const uint8 ch = ft[j];
				for (int i = 0; i < 8; ++i) {
					if (ch & (1 << (7 - i))) {
						((uint16 *)(_drawPagePtr + offset))[j * _w + i] = rgbColor;
					}
				}
			}
		}
	}
}
void GraphicsSoft::drawSpriteMask(int x, int y, uint8 color, const uint8 *data) {
	const int w = *data++;
	x = xScale(x - w / 2);
	const int h = *data++;
	y = yScale(y - h / 2);
	assert(_byteDepth == 1);
	for (int j = 0; j < h; ++j) {
		const int yoffset = y + j;
		for (int i = 0; i <= w / 16; ++i) {
			const uint16 mask = READ_BE_UINT16(data); data += 2;
			if (yoffset < 0 || yoffset >= _h) {
				continue;
			}
			const int xoffset = x + i * 16;
			for (int b = 0; b < 16; ++b) {
				if (xoffset + b < 0 || xoffset + b >= _w) {
					continue;
				}
				if (mask & (1 << (15 - b))) {
					_drawPagePtr[yoffset * _w + xoffset + b] = color;
				}
			}
		}
	}
}

static void blend_rgb555(uint16 *dst, const uint16 b) {
	static const uint16 RB_MASK = 0x7c1f;
	static const uint16 G_MASK = 0x03e0;
	const uint16 a = *dst;
	if ((a & 0x8000) == 0) { // use bit 15 to prevent additive blending
		uint16 r = 0x8000;
		r |= (((a & RB_MASK) + (b & RB_MASK)) >> 1) & RB_MASK;
		r |= (((a & G_MASK) + (b & G_MASK)) >> 1) & G_MASK;
		*dst = r;
	}
}

void GraphicsSoft::drawPoint(int16 x, int16 y, uint8 color) {
	x = xScale(x);
	y = yScale(y);
	const int offset = (y * _w + x) * _byteDepth;
	if (_byteDepth == 1) {
		switch (color) {
		case COL_ALPHA:
			_drawPagePtr[offset] |= 8;
			break;
		case COL_PAGE:
			_drawPagePtr[offset] = *(_pagePtrs[0] + offset);
			break;
		default:
			_drawPagePtr[offset] = color;
			break;
		}
	} else if (_byteDepth == 2) {
		switch (color) {
		case COL_ALPHA: {
			const Color &c = _pal[ALPHA_COLOR_INDEX];
			const uint16 rgbColor = _format.RGBToColor(c.r, c.g, c.b);
			blend_rgb555((uint16 *)(_drawPagePtr + offset), rgbColor);
			break;
		}
		case COL_PAGE:
			*(uint16 *)(_drawPagePtr + offset) = *(uint16 *)(_pagePtrs[0] + offset);
			break;
		default: {
			const Color &c = _pal[color];
			const uint16 rgbColor = _format.RGBToColor(c.r, c.g, c.b);
			*(uint16 *)(_drawPagePtr + offset) = rgbColor;
			break;
		}
		}
	}
}

void GraphicsSoft::drawLineT(int16 x1, int16 x2, int16 y, uint8 color) {
	const int16 xmax = MAX(x1, x2);
	const int16 xmin = MIN(x1, x2);
	const int w = xmax - xmin + 1;
	const int offset = (y * _w + xmin) * _byteDepth;
	if (_byteDepth == 1) {
		for (int i = 0; i < w; ++i) {
			_drawPagePtr[offset + i] |= 8;
		}
	} else if (_byteDepth == 2) {
		const Color &c = _pal[ALPHA_COLOR_INDEX];
		const uint16 rgbColor = _format.RGBToColor(c.r, c.g, c.b);

		uint16 *p = (uint16 *)(_drawPagePtr + offset);
		for (int i = 0; i < w; ++i) {
			blend_rgb555(p + i, rgbColor);
		}
	}
}

void GraphicsSoft::drawLineN(int16 x1, int16 x2, int16 y, uint8 color) {
	const int16 xmax = MAX(x1, x2);
	const int16 xmin = MIN(x1, x2);
	const int w = xmax - xmin + 1;
	const int offset = (y * _w + xmin) * _byteDepth;
	if (_byteDepth == 1) {
		memset(_drawPagePtr + offset, color, w);
	} else if (_byteDepth == 2) {
		const Color &c = _pal[color];
		const uint16 rgbColor = _format.RGBToColor(c.r, c.g, c.b);
		uint16 *p = (uint16 *)(_drawPagePtr + offset);
		for (int i = 0; i < w; ++i) {
			p[i] = rgbColor;
		}
	}
}

void GraphicsSoft::drawLineP(int16 x1, int16 x2, int16 y, uint8 color) {
	if (_drawPagePtr == _pagePtrs[0]) {
		return;
	}
	const int16 xmax = MAX(x1, x2);
	const int16 xmin = MIN(x1, x2);
	const int w = xmax - xmin + 1;
	const int offset = (y * _w + xmin) * _byteDepth;
	memcpy(_drawPagePtr + offset, _pagePtrs[0] + offset, w * _byteDepth);
}

uint8 *GraphicsSoft::getPagePtr(uint8 page) {
	assert(page < 4);
	return _pagePtrs[page];
}

void GraphicsSoft::setWorkPagePtr(uint8 page) {
	_drawPagePtr = getPagePtr(page);
}

void GraphicsSoft::init(int targetW, int targetH) {
	Gfx::init(targetW, targetH);
	setSize(targetW, targetH);
}

void GraphicsSoft::setFont(const uint8 *src, int w, int h) {
	if (_is1991) {
		// no-op for 1991
	}
}

void GraphicsSoft::setPalette(const Color *colors, int count) {
	count = MIN(count, 16);
	for (int i = 0; i < count; i++) {
		_pal[i].r = colors[i].r;
		_pal[i].g = colors[i].g;
		_pal[i].b = colors[i].b;
	}
	_palChanged = true;
}

void GraphicsSoft::setSpriteAtlas(const uint8 *src, int w, int h, int xSize, int ySize) {
	if (_is1991) {
		// no-op for 1991
	}
}

void GraphicsSoft::drawSprite(int buffer, int num, const Point *pt, uint8 color) {
	if (_is1991) {
		if (num < SHAPES_MASK_COUNT) {
			setWorkPagePtr(buffer);
			const uint8 *data = SHAPES_MASK_DATA + SHAPES_MASK_OFFSET[num];
			drawSpriteMask(pt->x, pt->y, color, data);
		}
	}
}

void GraphicsSoft::drawBitmap(int buffer, const uint8 *data, int w, int h, int fmt) {
	switch (_byteDepth) {
	case 1:
		if (fmt == FMT_CLUT && _w == w && _h == h) {
			memcpy(getPagePtr(buffer), data, w * h);
			return;
		}
		break;
	case 2:
		if (fmt == FMT_RGB555 && _w == w && _h == h) {
			memcpy(getPagePtr(buffer), data, getPageSize());
			return;
		}
		break;
	default:
		break;
	}
	warning("GraphicsSoft::drawBitmap() unhandled fmt %d w %d h %d", fmt, w, h);
}

void GraphicsSoft::drawPoint(int buffer, uint8 color, const Point *pt) {
	setWorkPagePtr(buffer);
	drawPoint(pt->x, pt->y, color);
}

void GraphicsSoft::drawQuadStrip(int buffer, uint8 color, const QuadStrip *qs) {
	setWorkPagePtr(buffer);
	drawPolygon(color, *qs);
}

void GraphicsSoft::drawStringChar(int buffer, uint8 color, char c, const Point *pt) {
	setWorkPagePtr(buffer);
	drawChar(c, pt->x, pt->y, color);
}

void GraphicsSoft::clearBuffer(int num, uint8 color) {
	if (_byteDepth == 1) {
		memset(getPagePtr(num), color, getPageSize());
	} else if (_byteDepth == 2) {
		const Color &c = _pal[color];
		const uint16 rgbColor = _format.RGBToColor(c.r, c.g, c.b);
		uint16 *p = (uint16 *)getPagePtr(num);
		for (int i = 0; i < _w * _h; ++i) {
			p[i] = rgbColor;
		}
	}
}

void GraphicsSoft::copyBuffer(int dst, int src, int vscroll) {
	if (vscroll == 0) {
		memcpy(getPagePtr(dst), getPagePtr(src), getPageSize());
	} else if (vscroll >= -199 && vscroll <= 199) {
		const int dy = yScale(vscroll);
		if (dy < 0) {
			memcpy(getPagePtr(dst), getPagePtr(src) - dy * _w * _byteDepth, (_h + dy) * _w * _byteDepth);
		} else {
			memcpy(getPagePtr(dst) + dy * _w * _byteDepth, getPagePtr(src), (_h - dy) * _w * _byteDepth);
		}
	}
}

void GraphicsSoft::drawBuffer(int num, SystemStub *stub) {
	int w, h;
	float ar[4];
	stub->prepareScreen(w, h, ar);

	if (_palChanged) {
		stub->setPalette(_pal);
		_palChanged = false;
	}

	Graphics::Surface s;
	s.setPixels(getPagePtr(num));
	s.w = s.pitch = w;
	s.h = h;
	s.format = (_byteDepth == 1) ?
		Graphics::PixelFormat::createFormatCLUT8() :
		_format;

	stub->setScreenPixels(s);
	stub->updateScreen();
}

void GraphicsSoft::drawRect(int num, uint8 color, const Point *pt, int w, int h) {
	assert(_byteDepth == 2);
	setWorkPagePtr(num);

	const Color &c = _pal[color];
	const uint16 rgbColor = _format.RGBToColor(c.r, c.g, c.b);
	const int x1 = xScale(pt->x);
	const int y1 = yScale(pt->y);
	const int x2 = xScale(pt->x + w - 1);
	const int y2 = yScale(pt->y + h - 1);
	// horizontal
	for (int x = x1; x <= x2; ++x) {
		*(uint16 *)(_drawPagePtr + (y1 * _w + x) * _byteDepth) = rgbColor;
		*(uint16 *)(_drawPagePtr + (y2 * _w + x) * _byteDepth) = rgbColor;
	}
	// vertical
	for (int y = y1; y <= y2; ++y) {
		*(uint16 *)(_drawPagePtr + (y * _w + x1) * _byteDepth) = rgbColor;
		*(uint16 *)(_drawPagePtr + (y * _w + x2) * _byteDepth) = rgbColor;
	}
}

void GraphicsSoft::drawBitmapOverlay(const Graphics::Surface &src, int fmt, SystemStub *stub) {
	if (fmt == FMT_RGB555) {
		stub->setScreenPixels(src);
		stub->updateScreen();
	}
}

Gfx *GraphicsSoft_create() {
	return new GraphicsSoft();
}

} // namespace Awe