/**
 * Copyright (c) 2026 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#pragma once
#include "error/errorgl.h"

typedef struct {
  #ifdef DUSK_OPENGL_LEGACY
    void *nothing;
  #else
    GLuint shaderProgramId;
    GLuint vertexShaderId;
    GLuint fragmentShaderId;
  #endif

  #if DUSK_OPENGL_LEGACY
    mat4 view;
    mat4 proj;
    mat4 model;
  #endif
} shadergl_t;

typedef struct {
  #ifdef DUSK_OPENGL_LEGACY
    void *nothing;
  #else
    const char_t *vert;
    const char_t *frag;
  #endif
} shaderdefinitiongl_t;

#if DUSK_OPENGL_LEGACY
  typedef struct {
    shadergl_t *boundShader;
    uint_fast8_t dirty;
  } shaderlegacygl_t;

  extern shaderlegacygl_t SHADER_LEGACY;
  
  #define SHADER_LEGACY_DIRTY_PROJ (1 << 0)
  #define SHADER_LEGACY_DIRTY_VIEW (1 << 1)
  #define SHADER_LEGACY_DIRTY_MODEL (1 << 2)
#endif

/**
 * Initializes a shader.
 * 
 * @param shader The shader to initialize.
 * @param def The definition of the shader to initialize with.
 * @return An errorret_t indicating success or failure.
 */
errorret_t shaderInitGL(shadergl_t *shader, const shaderdefinitiongl_t *def);

/**
 * Binds a shader for use in rendering.
 * 
 * @param shader The shader to bind.
 * @return An errorret_t indicating success or failure.
 */
errorret_t shaderBindGL(shadergl_t *shader);

/**
 * Retrieves the location of a shader uniform parameter.
 * 
 * @param shader The shader to query.
 * @param name The name of the uniform parameter.
 * @param location Output parameter to receive the location of the uniform.
 * @return An errorret_t indicating success or failure.
 */
errorret_t shaderParamGetLocationGL(
  shadergl_t *shader,
  const char_t *name,
  GLint *location
);

/**
 * Sets a mat4 uniform parameter in the shader.
 * 
 * @param shader The shader to update.
 * @param name The name of the uniform parameter.
 * @param mat The 4x4 matrix data to set.
 * @return An errorret_t indicating success or failure.
 */
errorret_t shaderSetMatrixGL(
  shadergl_t *shader,
  const char_t *name,
  mat4 matrix
);

/**
 * Disposes of a shader, freeing any associated resources.
 * 
 * @param shader The shader to dispose.
 */
errorret_t shaderDisposeGL(shadergl_t *shader);

#ifdef DUSK_OPENGL_LEGACY
  /**
   * During mesh rendering, this is requesting the legacy system to push all
   * shaders necessary to render the currently bound shader's matrices.
   * 
   * @return Any error state.
   */
  errorret_t shaderLegacyMatrixUpdate();
#endif