// Copyright (c) 2021 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#pragma once
#include "../libs.h"

#define TEXTURE_SLOTS_MAX 8

/** Texture slot that a texture can be bound to */
typedef GLuint textureslot_t;

/**
 * Structure detailing information about a texture.
 * Because we plan to upload the pixels of a texture into the GPU, we don't
 * store the pixels in memory because we don't need to!
 */
typedef struct {
  /** Width (in pixels) of the texture */
  int32_t width;
  /** Height (in pixels) of the texture */
  int32_t height;
  /** Texture ID on the GPU */
  GLuint id;
} texture_t;

/** Information about a single pixel. */
typedef struct {
  /** RGBA Color values */
  uint8_t r, g, b, a;
} pixel_t;

#define PIXEL_COLOR_WHITE ((pixel_t){ .r = 255, .g = 255, .b = 255, .a = 255 })
#define PIXEL_COLOR_RED ((pixel_t){ .r = 255, .g = 0, .b = 0, .a = 255 })
#define PIXEL_COLOR_GREEN ((pixel_t){ .r = 0, .g = 255, .b = 0, .a = 255 })
#define PIXEL_COLOR_BLUE ((pixel_t){ .r = 0, .g = 0, .b = 255, .a = 255 })
#define PIXEL_COLOR_BLACK ((pixel_t){ .r = 0, .g = 0, .b = 0, .a = 255 })
#define PIXEL_COLOR_TRANSPARENT ((pixel_t){ .r = 0, .g = 0, .b = 0, .a = 0 })

/**
 * Initializes a texture that can be written in to.
 * 
 * @param texture Texture to initialize.
 * @param width Width of the texture (in pixels).
 * @param height Height of the texture (in pixels).
 * @param pixels Default pixel array, set to NULL to set all pixel data to 0.
 */
void textureInit(texture_t *texture, int32_t width, int32_t height,
  pixel_t *pixels
);

/**
 * Bind a texture on to a given texture slot.
 * 
 * @param texture Texture to bind.
 * @param slot Slot to bind the texture to.
 */
void textureBind(texture_t *texture, textureslot_t slot);

/**
 * Buffer pixel data onto the GPU. Pixel buffering is rather costly so avoid
 * doing this too often.
 * 
 * @param texture Texture to buffer in to.
 * @param x X coordinate in texture space to render to.
 * @param y Y coordinate in texture space to render to.
 * @param width Width of the pixel region you're buffering.
 * @param height Height of the pixel region you're buffering.
 * @param pixels Array of pixels to buffer onto the GPU.
 */
void textureBufferPixels(texture_t *texture,
  int32_t x, int32_t y, int32_t width, int32_t height, pixel_t *pixels
);

/**
 * Clean a previously created texture.
 * 
 * @param texture Texture to clean up.
 */
void textureDispose(texture_t *texture);