#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_RESIZE_IMPLEMENTATION
#include <stb_image.h>
#include <stb_image_resize.h>
#include <stdbool.h>
#include <dragonstd/tree.h>
#include "client/client_config.h"
#include "client/opengl.h"
#include "client/texture.h"

static Tree textures;

typedef struct {
	char *path;
	Texture texture;
} TextureLookup;

static int cmp_texture(TextureLookup *texture, char *path)
{
	return strcmp(texture->path, path);
}

static bool lookup_texture(char *path, Texture **texture)
{
	TreeNode **node = tree_nfd(&textures, path, &cmp_texture);

	if (*node) {
		*texture = &((TextureLookup *) (*node)->dat)->texture;
		return true;
	}

	TextureLookup *lookup = malloc(sizeof *lookup);
	lookup->path = strdup(path);
	*texture = &lookup->texture;

	tree_nmk(&textures, node, lookup);
	return false;
}

static void delete_texture(TextureLookup *lookup)
{
	free(lookup->path);
	texture_destroy(&lookup->texture);
	free(lookup);
}

__attribute__((constructor(101))) static void textures_init()
{
	tree_ini(&textures);
}

__attribute__((destructor)) static void textures_deinit()
{
	tree_clr(&textures, &delete_texture, NULL, NULL, 0);
}

Texture *texture_load(char *path, bool mipmap)
{
	Texture *texture;
	if (lookup_texture(path, &texture))
		return texture;

	unsigned char *data = stbi_load(path,
		&texture->width, &texture->height, &texture->channels, 0);
	if (!data) {
		fprintf(stderr, "[error] failed to load texture %s\n", path);
		abort();
	}

	texture_upload(texture, data, GL_RGBA, mipmap);
	stbi_image_free(data);

	return texture;
}

static inline int least_common_multiple(int a, int b)
{
	int high, low;
	if (a > b) {
		high = a;
		low = b;
	} else {
		high = b;
		low = a;
	}

	int lcm = high;
	while (lcm % low)
		lcm += high;
	return lcm;
}

Texture *texture_load_cubemap(char *path, bool bilinear_filter)
{
	Texture *texture;
	if (lookup_texture(path, &texture))
		return texture;

	glGenTextures(1, &texture->txo); GL_DEBUG
	glBindTexture(GL_TEXTURE_CUBE_MAP, texture->txo); GL_DEBUG

	const char *directions[6] = {
		"right",
		"left",
		"top",
		"bottom",
		"front",
		"back",
	};

	typedef struct {
		unsigned char *data;
		int width, height, channels;
	} CubemapFace;

	CubemapFace faces[6];
	int size = 1;

	for (int i = 0; i < 6; i++) {
		char filename[strlen(path) + 1 + strlen(directions[i]) + 1 + 3 + 1];
		sprintf(filename, "%s/%s.png", path, directions[i]);

		if (!(faces[i].data = stbi_load(filename,
				&faces[i].width, &faces[i].height, &faces[i].channels, 0))) {
			fprintf(stderr, "[error] failed to load texture %s\n", filename);
			abort();
		}

		size = least_common_multiple(size, faces[i].width);
		size = least_common_multiple(size, faces[i].height);
	}

	for (int i = 0; i < 6; i++) {
		unsigned char *data = faces[i].data;

		bool resize = faces[i].width != size || faces[i].height != size;
		if (resize) {
			data = malloc(size * size * faces[i].channels);

			stbir_resize_uint8_generic(
				faces[i].data, faces[i].width, faces[i].height, 0,
				data, size, size, 0,
				faces[i].channels, STBIR_ALPHA_CHANNEL_NONE, 0,
				STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR,
				NULL);
		}

		glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGBA,
			size, size, 0, GL_RGBA, GL_UNSIGNED_BYTE, data); GL_DEBUG

		stbi_image_free(faces[i].data);
		if (resize)
			stbi_image_free(data);
	}

	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, bilinear_filter ? GL_LINEAR : GL_NEAREST); GL_DEBUG
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, bilinear_filter ? GL_LINEAR : GL_NEAREST); GL_DEBUG
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); GL_DEBUG
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); GL_DEBUG
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); GL_DEBUG

	return texture;
}

void texture_upload(Texture *texture, unsigned char *data, GLenum format, bool mipmap)
{
	glGenTextures(1, &texture->txo); GL_DEBUG
	glBindTexture(GL_TEXTURE_2D, texture->txo); GL_DEBUG

	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, (mipmap && client_config.mipmap)
		? GL_NEAREST_MIPMAP_NEAREST : GL_NEAREST); GL_DEBUG
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); GL_DEBUG
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); GL_DEBUG
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); GL_DEBUG

	glTexImage2D(GL_TEXTURE_2D, 0, format,
		texture->width, texture->height, 0, format, GL_UNSIGNED_BYTE, data); GL_DEBUG
	glGenerateMipmap(GL_TEXTURE_2D); GL_DEBUG
}

void texture_destroy(Texture *texture)
{
	glDeleteTextures(1, &texture->txo); GL_DEBUG
}