/* vim: tabstop=4 shiftwidth=4 noexpandtab
 *
 * Graphics library
 */

#include <syscall.h>
#include <stdint.h>
#include <math.h>
#include "graphics.h"
#include "window.h"

/* Pointer to graphics memory */
void flip(gfx_context_t * ctx) {
	memcpy(ctx->buffer, ctx->backbuffer, ctx->size);
}

void clearbuffer(gfx_context_t * ctx) {
	memset(ctx->backbuffer, 0, ctx->size);
}

/* Deprecated */
gfx_context_t * init_graphics_fullscreen() {
	gfx_context_t * out = malloc(sizeof(gfx_context_t));
	out->width  = syscall_getgraphicswidth();
	out->height = syscall_getgraphicsheight();
	out->depth  = syscall_getgraphicsdepth();
	out->size   = GFX_H(out) * GFX_W(out) * GFX_B(out);
	out->buffer = (void *)syscall_getgraphicsaddress();
	out->backbuffer = out->buffer;
	return out;
}

gfx_context_t * init_graphics_fullscreen_double_buffer() {
	gfx_context_t * out = init_graphics_fullscreen();
	out->backbuffer = malloc(sizeof(uint32_t) * GFX_W(out) * GFX_H(out));
	return out;
}

gfx_context_t * init_graphics_window(window_t * window) {
	gfx_context_t * out = malloc(sizeof(gfx_context_t));
	out->width  = window->width;
	out->height = window->height;
	out->depth  = 32;
	out->size   = GFX_H(out) * GFX_W(out) * GFX_B(out);
	out->buffer = window->buffer;
	out->backbuffer = out->buffer;
	return out;
}

gfx_context_t *  init_graphics_window_double_buffer(window_t * window) {
	gfx_context_t * out = init_graphics_window(window);
	out->backbuffer = malloc(sizeof(uint32_t) * GFX_W(out) * GFX_H(out));
	return out;
}

uint32_t rgb(uint8_t r, uint8_t g, uint8_t b) {
	return 0xFF000000 + (r * 0x10000) + (g * 0x100) + (b * 0x1);
}

uint32_t alpha_blend(uint32_t bottom, uint32_t top, uint32_t mask) {
	uint8_t a = _RED(mask);
	uint8_t red = (_RED(bottom) * (256 - a) + _RED(top) * a) / 256;
	uint8_t gre = (_GRE(bottom) * (256 - a) + _GRE(top) * a) / 256;
	uint8_t blu = (_BLU(bottom) * (256 - a) + _BLU(top) * a) / 256;
	return rgb(red,gre,blu);
}

void load_sprite(sprite_t * sprite, char * filename) {
	/* Open the requested binary */
	FILE * image = fopen(filename, "r");
	size_t image_size= 0;

	fseek(image, 0, SEEK_END);
	image_size = ftell(image);
	fseek(image, 0, SEEK_SET);

	/* Alright, we have the length */
	char * bufferb = malloc(image_size);
	fread(bufferb, image_size, 1, image);
	uint16_t x = 0; /* -> 212 */
	uint16_t y = 0; /* -> 68 */
	/* Get the width / height of the image */
	signed int *bufferi = (signed int *)((uintptr_t)bufferb + 2);
	uint32_t width  = bufferi[4];
	uint32_t height = bufferi[5];
	uint16_t bpp    = bufferi[6] / 0x10000;
	uint32_t row_width = (bpp * width + 31) / 32 * 4;
	/* Skip right to the important part */
	size_t i = bufferi[2];

	sprite->width = width;
	sprite->height = height;
	sprite->bitmap = malloc(sizeof(uint32_t) * width * height);

	for (y = 0; y < height; ++y) {
		for (x = 0; x < width; ++x) {
			if (i > image_size) return;
			/* Extract the color */
			uint32_t color;
			if (bpp == 24) {
				color =	(bufferb[i   + 3 * x] & 0xFF) +
						(bufferb[i+1 + 3 * x] & 0xFF) * 0x100 +
						(bufferb[i+2 + 3 * x] & 0xFF) * 0x10000;
			} else if (bpp == 32) {
				color =	(bufferb[i   + 4 * x] & 0xFF) * 0x1000000 +
						(bufferb[i+1 + 4 * x] & 0xFF) * 0x100 +
						(bufferb[i+2 + 4 * x] & 0xFF) * 0x10000 +
						(bufferb[i+3 + 4 * x] & 0xFF) * 0x1;
			}
			/* Set our point */
			sprite->bitmap[(height - y - 1) * width + x] = color;
		}
		i += row_width;
	}
	free(bufferb);
}

static inline int32_t min(int32_t a, int32_t b) {
	return (a < b) ? a : b;
}

static inline int32_t max(int32_t a, int32_t b) {
	return (a > b) ? a : b;
}

void draw_sprite(gfx_context_t * ctx, sprite_t * sprite, int32_t x, int32_t y) {
	int32_t _left   = max(x, 0);
	int32_t _top    = max(y, 0);
	int32_t _right  = min(x + sprite->width,  ctx->width - 1);
	int32_t _bottom = min(y + sprite->height, ctx->height - 1);
	for (uint16_t _y = 0; _y < sprite->height; ++_y) {
		for (uint16_t _x = 0; _x < sprite->width; ++_x) {
			if (x + _x < _left || x + _x > _right || y + _y < _top || y + _y > _bottom)
				continue;
			if (sprite->alpha) {
				GFX(ctx, x + _x, y + _y) = alpha_blend(GFX(ctx, x + _x, y + _y), SPRITE(sprite, _x, _y), SMASKS(sprite, _x, _y));
			} else {
				if (SPRITE(sprite,_x,_y) != sprite->blank) {
					GFX(ctx, x + _x, y + _y) = SPRITE(sprite, _x, _y);
				}
			}
		}
	}
}

void draw_line(gfx_context_t * ctx, int32_t x0, int32_t x1, int32_t y0, int32_t y1, uint32_t color) {
	int deltax = abs(x1 - x0);
	int deltay = abs(y1 - y0);
	int sx = (x0 < x1) ? 1 : -1;
	int sy = (y0 < y1) ? 1 : -1;
	int error = deltax - deltay;
	while (1) {
		if (x0 >= 0 && y0 >= 0 && x0 < ctx->width && y0 < ctx->height) {
			GFX(ctx, x0, y0) = color;
		}
		if (x0 == x1 && y0 == y1) break;
		int e2 = 2 * error;
		if (e2 > -deltay) {
			error -= deltay;
			x0 += sx;
		}
		if (e2 < deltax) {
			error += deltax;
			y0 += sy;
		}
	}
}

void draw_line_thick(gfx_context_t * ctx, int32_t x0, int32_t x1, int32_t y0, int32_t y1, uint32_t color, char thickness) {
	int deltax = abs(x1 - x0);
	int deltay = abs(y1 - y0);
	int sx = (x0 < x1) ? 1 : -1;
	int sy = (y0 < y1) ? 1 : -1;
	int error = deltax - deltay;
	while (1) {
		for (char j = -thickness; j <= thickness; ++j) {
			for (char i = -thickness; i <= thickness; ++i) {
				if (x0 + i >= 0 && x0 + i < ctx->width && y0 + j >= 0 && y0 + j < ctx->height) {
					GFX(ctx, x0 + i, y0 + j) = color;
				}
			}
		}
		if (x0 == x1 && y0 == y1) break;
		int e2 = 2 * error;
		if (e2 > -deltay) {
			error -= deltay;
			x0 += sx;
		}
		if (e2 < deltax) {
			error += deltax;
			y0 += sy;
		}
	}
}


void draw_fill(gfx_context_t * ctx, uint32_t color) {
	for (uint16_t y = 0; y < ctx->height; ++y) {
		for (uint16_t x = 0; x < ctx->width; ++x) {
			GFX(ctx, x, y) = color;
		}
	}
}

/* Bilinear filtering from Wikipedia */
uint32_t getBilinearFilteredPixelColor(sprite_t * tex, double u, double v) {
	u *= tex->width;
	v *= tex->height;
	int x = floor(u);
	int y = floor(v);
	if (x >= tex->width)  return 0;
	if (y >= tex->height) return 0;
	double u_ratio = u - x;
	double v_ratio = v - y;
	double u_o = 1 - u_ratio;
	double v_o = 1 - v_ratio;
	double r_ALP = 256;
	if (tex->alpha) {
		if (x == tex->width - 1 || y == tex->height - 1) return (SPRITE(tex,x,y) | 0xFF000000) & (0xFFFFFF + _RED(SMASKS(tex,x,y)) * 0x1000000);
		r_ALP = (_RED(SMASKS(tex,x,y)) * u_o + _RED(SMASKS(tex,x+1,y)) * u_ratio) * v_o + (_RED(SMASKS(tex,x,y+1)) * u_o  + _RED(SMASKS(tex,x+1,y+1)) * u_ratio) * v_ratio;
	}
	if (x == tex->width - 1 || y == tex->height - 1) return SPRITE(tex,x,y);
	double r_RED = (_RED(SPRITE(tex,x,y)) * u_o + _RED(SPRITE(tex,x+1,y)) * u_ratio) * v_o + (_RED(SPRITE(tex,x,y+1)) * u_o  + _RED(SPRITE(tex,x+1,y+1)) * u_ratio) * v_ratio;
	double r_BLU = (_BLU(SPRITE(tex,x,y)) * u_o + _BLU(SPRITE(tex,x+1,y)) * u_ratio) * v_o + (_BLU(SPRITE(tex,x,y+1)) * u_o  + _BLU(SPRITE(tex,x+1,y+1)) * u_ratio) * v_ratio;
	double r_GRE = (_GRE(SPRITE(tex,x,y)) * u_o + _GRE(SPRITE(tex,x+1,y)) * u_ratio) * v_o + (_GRE(SPRITE(tex,x,y+1)) * u_o  + _GRE(SPRITE(tex,x+1,y+1)) * u_ratio) * v_ratio;

	return rgb(r_RED,r_GRE,r_BLU) & (0xFFFFFF + (int)r_ALP * 0x1000000);
}

void draw_sprite_scaled(gfx_context_t * ctx, sprite_t * sprite, uint16_t x, uint16_t y, uint16_t width, uint16_t height) {
	int32_t _left   = max(x, 0);
	int32_t _top    = max(y, 0);
	int32_t _right  = min(x + width,  ctx->width - 1);
	int32_t _bottom = min(y + height, ctx->height - 1);
	for (uint16_t _y = 0; _y < height; ++_y) {
		for (uint16_t _x = 0; _x < width; ++_x) {
			if (x + _x < _left || x + _x > _right || y + _y < _top || y + _y > _bottom)
				continue;
			if (sprite->alpha) {
				uint32_t n_color = getBilinearFilteredPixelColor(sprite, (double)_x / (double)width, (double)_y/(double)height);
				uint32_t f_color = rgb(_ALP(n_color), 0, 0);
				GFX(ctx, x + _x, y + _y) = alpha_blend(GFX(ctx, x + _x, y + _y), n_color, f_color);
			} else {
				GFX(ctx, x + _x, y + _y) = getBilinearFilteredPixelColor(sprite, (double)_x / (double)width, (double)_y/(double)height);
			}
		}
	}
}