/* Cram - A texture packing system in C
 *
 * Copyright (c) 2022 Evan Hemsley
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from
 * the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software in a
 * product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * Evan "cosmonaut" Hemsley <evan@moonside.games>
 *
 */

#include "cram.h"

#ifdef _MSC_VER

#include <assert.h>
#include <stdlib.h>
#include <search.h>
#include <string.h>

#endif /* _MSC_VER */

/* TODO: ifndefs here */
#define Cram_assert assert
#define Cram_qsort qsort
#define Cram_malloc malloc
#define Cram_realloc realloc
#define Cram_free free
#define Cram_memcpy memcpy
#define Cram_memset memset
#define Cram_strdup strdup
#define Cram_max max

#define STBRP_ASSERT Cram_assert
#define STBRP_SORT Cram_qsort

#define STBRP_STATIC
#define STB_RECT_PACK_IMPLEMENTATION
#include "stb_rect_pack.h"

#define STBI_ASSERT Cram_assert
#define STBI_MALLOC Cram_malloc
#define STBI_REALLOC Cram_realloc
#define STBI_FREE Cram_free

#define STBI_ONLY_PNG
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

#define INITIAL_DATA_CAPACITY 8

/* Structures */

typedef struct Rect
{
	int32_t x, y;
	int32_t w, h;
} Rect;

typedef struct Cram_Image
{
	const char *name;
	Rect rect;
	uint8_t *pixels;
} Cram_Image;

typedef struct Cram_Internal_Context
{
	const char *name;
	uint32_t width;
	uint32_t height;

	uint32_t padding;
	uint8_t trim;

	uint8_t *pixels;

	Cram_Image *images;
	uint32_t imageCount;
	uint32_t imageCapacity;

	Cram_AtlasData *atlasData;
} Cram_Internal_Context;

/* API functions */

uint32_t Wellspring_LinkedVersion(void)
{
	return WELLSPRING_COMPILED_VERSION;
}

Cram_Context* Cram_Init(Cram_ContextCreateInfo *createInfo)
{
	Cram_Internal_Context *context = Cram_malloc(sizeof(Cram_Internal_Context));

	context->name = Cram_strdup(createInfo->name);

	context->width = createInfo->maxDimension;
	context->height = createInfo->maxDimension;

	context->padding = createInfo->padding;
	context->trim = createInfo->trim;

	context->images = Cram_malloc(INITIAL_DATA_CAPACITY * sizeof(Cram_Image));
	context->imageCapacity = INITIAL_DATA_CAPACITY;
	context->imageCount = 0;

	context->atlasData = Cram_malloc(sizeof(Cram_AtlasData));

	context->pixels = NULL;

	return (Cram_Context*) context;
}

static inline uint32_t Cram_Internal_GetPixelIndex(uint32_t x, uint32_t y, uint32_t width)
{
	return x + y * width;
}

/* width and height of source and destination rects must be the same! */
static int8_t Cram_Internal_CopyPixels(
	uint32_t *dstPixels,
	uint32_t dstPixelWidth,
	uint32_t *srcPixels,
	uint32_t srcPixelWidth,
	Rect *dstRect,
	Rect *srcRect
) {
	int32_t i, j;
	int32_t dstPixelIndex, srcPixelIndex;

	if (dstRect->w != srcRect->w || dstRect->h != srcRect->h)
	{
		return -1;
	}

	for (i = 0; i < dstRect->w; i += 1)
	{
		for (j = 0; j < dstRect->h; j += 1)
		{
			dstPixelIndex = Cram_Internal_GetPixelIndex(i + dstRect->x, j + dstRect->y, dstPixelWidth);
			srcPixelIndex = Cram_Internal_GetPixelIndex(i + srcRect->x, j + srcRect->y, srcPixelWidth);
			dstPixels[dstPixelIndex] = srcPixels[srcPixelIndex];
		}
	}

	return 0;
}

static uint8_t Cram_Internal_IsRowClear(uint32_t* pixels, uint32_t rowIndex, uint32_t width)
{
	int32_t i;

	for (i = 0; i < width; i += 1)
	{
		if ((pixels[Cram_Internal_GetPixelIndex(i, rowIndex, width)] & 0xFF) > 0)
		{
			return 0;
		}
	}

	return 1;
}

static uint8_t Cram_Internal_IsColumnClear(uint32_t* pixels, uint32_t columnIndex, uint32_t width, uint32_t height)
{
	int32_t i;

	for (i = 0; i < height; i += 1)
	{
		if ((pixels[Cram_Internal_GetPixelIndex(columnIndex, i, width)] & 0xFF) > 0)
		{
			return 0;
		}
	}

	return 1;
}

void Cram_AddFile(Cram_Context *context, const char *path)
{
	Cram_Internal_Context *internalContext = (Cram_Internal_Context*) context;
	Cram_Image *image;
	uint8_t *pixels;
	int32_t leftTrim, topTrim, rightTrim, bottomTrim;
	int32_t width, height, numChannels;
	int32_t i;

	if (internalContext->imageCapacity == internalContext->imageCount)
	{
		internalContext->imageCapacity *= 2;
		internalContext->images = Cram_realloc(internalContext->images, internalContext->imageCapacity * sizeof(Cram_Image));
	}

	image = &internalContext->images[internalContext->imageCount];

	/* image->name = Cram_Internal_GetTrimmedPath(); */

	pixels = stbi_load(
		path,
		&width,
		&height,
		&numChannels,
		STBI_rgb_alpha
	);

	/* Check for trim */
	if (internalContext->trim)
	{
		topTrim = 0;
		for (i = 0; i < height; i += 1)
		{
			if (!Cram_Internal_IsRowClear(pixels, i, width))
			{
				topTrim = i;
				break;
			}
		}

		leftTrim = 0;
		for (i = 0; i < width; i += 1)
		{
			if (!Cram_Internal_IsColumnClear(pixels, i, width, height))
			{
				leftTrim = i;
				break;
			}
		}

		bottomTrim = height;
		for (i = height - 1; i >= topTrim; i -= 1)
		{
			if (!Cram_Internal_IsRowClear(pixels, i, width))
			{
				bottomTrim = i;
				break;
			}
		}

		rightTrim = width;
		for (i = width - 1; i >= leftTrim; i -= 1)
		{
			if (!Cram_Internal_IsColumnClear(pixels, i, width, height))
			{
				rightTrim = i;
				break;
			}
		}

		image->rect.x = leftTrim;
		image->rect.y = topTrim;
		image->rect.w = rightTrim - leftTrim;
		image->rect.h = bottomTrim - topTrim;
	}
	else
	{
		image->rect.x = 0;
		image->rect.y = 0;
		image->rect.w = width;
		image->rect.h = height;
	}

	/* copy */
	image->pixels = Cram_malloc(image->rect.w * image->rect.h * 4);

	Rect dstRect;
	dstRect.x = 0;
	dstRect.y = 0;
	dstRect.w = image->rect.w;
	dstRect.h = image->rect.h;
	Cram_Internal_CopyPixels((uint32_t*) image->pixels, image->rect.w, (uint32_t*) pixels, width, &dstRect, &image->rect);

	stbi_image_free(pixels);

	internalContext->imageCount += 1;
}

int8_t Cram_Pack(Cram_Context *context)
{
	stbrp_context rectPackContext;
	Cram_Internal_Context *internalContext = (Cram_Internal_Context*) context;
	uint32_t numNodes = internalContext->width;
	stbrp_node *nodes = Cram_malloc(sizeof(stbrp_node) * numNodes);
	stbrp_rect *rects = Cram_malloc(sizeof(stbrp_rect) * internalContext->imageCount);
	stbrp_rect *rect;
	Rect dstRect, srcRect;
	int32_t i;
	uint32_t maxWidth = 0;
	uint32_t maxHeight = 0;

	stbrp_init_target(&rectPackContext, internalContext->width, internalContext->height, nodes, numNodes);

	for (i = 0; i < internalContext->imageCount; i += 1)
	{
		rect = &rects[i];

		rect->w = internalContext->images[i].rect.w + internalContext->padding;
		rect->h = internalContext->images[i].rect.h + internalContext->padding;
	}

	stbrp_pack_rects(&rectPackContext, rects, internalContext->imageCount);

	for (i = 0; i < internalContext->imageCount; i += 1)
	{
		rect = &rects[i];

		if (rect->was_packed)
		{
			internalContext->images[i].rect.x = rect->x;
			internalContext->images[i].rect.y = rect->y;

			maxWidth = Cram_max(maxWidth, rect->x + rect->w);
			maxHeight = Cram_max(maxHeight, rect->y + rect->h);
		}
		else
		{
			return -1;
		}
	}

	internalContext->width = maxWidth;
	internalContext->height = maxHeight;

	internalContext->pixels = Cram_realloc(internalContext->pixels, internalContext->width * internalContext->height * 4);
	Cram_memset(internalContext->pixels, 0, internalContext->width * internalContext->height * 4);

	for (i = 0; i < internalContext->imageCount; i += 1)
	{
		dstRect.x = internalContext->images[i].rect.x;
		dstRect.y = internalContext->images[i].rect.y;
		dstRect.w = internalContext->images[i].rect.w;
		dstRect.h = internalContext->images[i].rect.h;

		srcRect.x = 0;
		srcRect.y = 0;
		srcRect.w = internalContext->images[i].rect.w;
		srcRect.h = internalContext->images[i].rect.h;

		Cram_Internal_CopyPixels(
			(uint32_t*) internalContext->pixels,
			internalContext->width,
			(uint32_t*) internalContext->images[i].pixels,
			internalContext->images[i].rect.w,
			&dstRect,
			&srcRect
		);
	}

	Cram_free(nodes);
	Cram_free(rects);

	return 0;
}

void Cram_GetPixelData(Cram_Context *context, uint8_t **pPixels, uint32_t *pWidth, uint32_t *pHeight)
{
	Cram_Internal_Context *internalContext = (Cram_Internal_Context*) context;
	*pPixels = internalContext->pixels;
	*pWidth = internalContext->width;
	*pHeight = internalContext->height;
}

void Cram_GetAtlasData(Cram_Context *context, Cram_AtlasData **pAtlasData)
{
	*pAtlasData = ((Cram_Internal_Context*) context)->atlasData;
}

void Cram_Destroy(Cram_Context *context)
{
	Cram_Internal_Context *internalContext = (Cram_Internal_Context*) context;

	if (internalContext->pixels != NULL)
	{
		Cram_free(internalContext);
	}

	Cram_free(internalContext->images);
	Cram_free(internalContext->atlasData);
	Cram_free(internalContext);
}