#include <sdl_image.h></sdl_image.h>

#include "private.h"

#include "world.h"

#include "sprite.h"

static HeliArray cache;

static int fixsize(int x) {

	int p = (int)ceil(log2(x > 1 ? x : 1) - 0.25);

	if (p > 30) p = 30;

	return 1 << p;

}

static float colorclamp(float x)

	{ return x > 0.f ? (x < 1.f ? x : 1.f) : 0.f; }

static void mipx(float *buffer, int *w, int *h) {

	*w /= 2;

	if (*w <= 0) return;

	for(float *d = buffer, *s = buffer, *end = d + (*w)*(*h)*4; d < end; d += 4, s += 8)

		for(int i = 0; i < 4; ++i)

			d[i] = (s[i] + s[i + 4])*0.5f;

}

static void mipy(float *buffer, int *w, int *h) {

	*h /= 2;

	if (*h <= 0) return;

	int rstep = (*w)*4;

	float *d = buffer, *s0 = buffer, *s1 = s0 + rstep;

	for(float *end = d + (*h)*rstep; d < end; s0 += rstep, s1 += rstep)

		for(float *rend = d + rstep; d < rend; ++d, ++s0, ++s1)

			*d = (*s0 + *s1)*0.5f;

}

static void unloadFrame(void *x) {

	unsigned int texid = (unsigned int)(size_t)x;

	glDeleteTextures(1, &texid);

}

static unsigned int loadFrame(const char *path) {

	if (!heliStringEndsWithLowcase(path, ".png"))

		return 0;

	// load image

	SDL_Surface *surface = IMG_Load(path);

	if (!surface) {

		fprintf(stderr, "helianthus: cannot load image: %s\n", path);

		return 0;

	}

	// convert to RGBA

	if (surface->format->format != SDL_PIXELFORMAT_RGBA8888) {

		SDL_PixelFormat *format = SDL_AllocFormat(SDL_PIXELFORMAT_RGBA8888);

		SDL_Surface *converted = SDL_ConvertSurface(surface, format, 0);

		SDL_FreeFormat(format);

		SDL_FreeSurface(surface);

		surface = converted;

	}

	// convert to float and premult alpha

	SDL_LockSurface(surface);

	int w = surface->w;

	int h = surface->h;

	size_t rcount = (size_t)w*4;

	size_t count = rcount*h;

	float *buffer = (float*)malloc(count*sizeof(float));

	const unsigned char *pp = (const unsigned char *)surface->pixels;

	for(float *p = buffer, *end = p + count; p < end; pp += surface->pitch - rcount) {

		for(float *rend = p + rcount; p < rend; p += 4, pp += 4) {

			if (pp[0]) {

				float a = pp[0]/255.f;

				p[0] = pp[3]/255.f*a;

				p[1] = pp[2]/255.f*a;

				p[2] = pp[1]/255.f*a;

				p[3] = a;

			} else {

				p[0] = p[1] = p[2] = p[3] = 0;

			}

		}

	}

	SDL_UnlockSurface(surface);

	SDL_FreeSurface(surface);

	// resample to power of two

	int fw = fixsize(w);

	int fh = fixsize(h);

	if (fw != w || fh != h) {

		float *fbuffer = (float*)malloc((size_t)fw*fh*4*sizeof(float));

		double kr = (double)h/fh;

		double kc = (double)w/fw;

		for(int r = 0; r < fh; ++r) {

			for(int c = 0; c < fw; ++c) {

				double pr1 = r*kr;

				int r0 = (int)floor(pr1 + HELI_PRECISION);

				pr1 -= r0;

				int r1 = r0 + 1;

				if (r1 >= w) r1 = w - 1;

				if (r0 > r1) r0 = r1;

				double pr0 = 1 - pr1;

				double pc1 = c*kc;

				int c0 = (int)floor(pc1 + HELI_PRECISION);

				pc1 -= c0;

				int c1 = c0 + 1;

				if (c1 >= w) c1 = w - 1;

				if (c0 > c1) c0 = c1;

				double pc0 = 1 - pc1;

				float *p = fbuffer + (r*fw + c)*4;

				const float *p00 = buffer + (r0*w + c0)*4;

				const float *p01 = buffer + (r0*w + c1)*4;

				const float *p10 = buffer + (r1*w + c0)*4;

				const float *p11 = buffer + (r1*w + c1)*4;

				for(int i = 0; i < 4; ++i)

					p[i] = p00[i]*pr0*pc0

					     + p01[i]*pr0*pc1

					     + p10[i]*pr1*pc0

					     + p11[i]*pr1*pc1;

			}

		}

		free(buffer);

		buffer = fbuffer;

		w = fw;

		h = fh;

	}

	// fix max texture size

	int maxSize = 0;

	glGetIntegerv(GL_MAX_TEXTURE_SIZE, &maxSize);

	if (maxSize < 64) maxSize = 64;

	while(w > maxSize) mipx(buffer, &w, &h);

	while(h > maxSize) mipy(buffer, &w, &h);

	// create OpenGL texture

	unsigned int texid = 0;

	glGenTextures(1, &texid);

	glBindTexture(GL_TEXTURE_2D, texid);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_LOD_BIAS, -0.7f);

	// build mip levels

	unsigned char *ibuffer = malloc((size_t)w*h*4);

	int level = 0;

	while(1) {

		float *pp = buffer;

		for(unsigned char *p = ibuffer, *end = p + (size_t)w*h*4; p < end; p += 4, pp += 4) {

			if (pp[3] > 1e-5) {

				float k = 1/pp[3];

				p[0] = (unsigned char)floor(colorclamp(pp[0]*k)*255.99);

				p[1] = (unsigned char)floor(colorclamp(pp[1]*k)*255.99);

				p[2] = (unsigned char)floor(colorclamp(pp[2]*k)*255.99);

				p[3] = (unsigned char)floor(colorclamp(pp[3])*255.99);

			} else {

				p[0] = (unsigned char)floor(colorclamp(pp[0])*255.99);

				p[1] = (unsigned char)floor(colorclamp(pp[1])*255.99);

				p[2] = (unsigned char)floor(colorclamp(pp[2])*255.99);

				p[3] = 0;

			}

		}

		glTexImage2D(GL_TEXTURE_2D, level, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ibuffer);

		++level;

		if (w <= 1 && h <= 1) break;

		if (w > 1) mipx(buffer, &w, &h);

		if (h > 1) mipy(buffer, &w, &h);

	}

	// done

	free(ibuffer);

	free(buffer);

	glBindTexture(GL_TEXTURE_2D, 0);

	return texid;

}

static HeliAnimation* load(const char *path) {

	HeliAnimation *a = calloc(1, sizeof(*a));

	a->path = heliStringCopy(path);

	Directory d = openDirectory(path);

	if (d) {

		int count = directoryGetCount(d);

		for(int i = 0; i < count; ++i) {

			char *p = heliStringConcat3(path, "/", directoryGet(d, i));

			size_t texid = loadFrame(p);

			free(p);

			if (texid) heliArrayInsert(&a->frames, -1, (void*)texid, &unloadFrame);

		}

		closeDirectory(d);

	} else {

		size_t texid = loadFrame(path);

		if (texid) {

			heliArrayInsert(&a->frames, -1, (void*)texid, &unloadFrame);

		} else {

			fprintf(stderr, "helianthus: cannot load animation by path: %s\n", path);

		}

	}

	return a;

}

static void unload(HeliAnimation *a) {

	assert(!a->refcount);

	free(a->path);

	heliArrayDestroy(&a->frames);

	free(a);

}

HeliAnimation* heliAnimationLoad(const char *path) {

	HeliPair *item = heliStringmapGet(&cache, path);

	if (!item) item = heliStringmapAdd(&cache, path, load(path), (HeliFreeCallback)&unload);

	HeliAnimation *a = (HeliAnimation*)item->value;

	++a->refcount;

	return a;

}

void heliAnimationUnref(HeliAnimation *a) {

	if (--a->refcount <= 0)

		heliStringmapRemove(&cache, a->path);

}

void heliAnimationFinish()

	{ heliArrayDestroy(&cache); }