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

#include "display/shader/shaderunlit.h"
#include "assert/assertgl.h"

#ifdef DUSK_OPENGL_LEGACY
  shaderdefinition_t SHADER_UNLIT_DEFINITION = { 0 };
#else
  errorret_t shaderUnlitSetTextureGL(
    shadergl_t *shader,
    const char_t *name,
    texture_t *texture
  ) {
    assertNotNull(shader, "Shader cannot be null");
    assertStrLenMin(name, 1, "Uniform name cannot be empty");
    assertStringEqual(
      name,
      SHADER_UNLIT_TEXTURE,
      "Only one texture supported in unlit shader."
    );

    GLint locTexture, locType, locColorCount, locColors;

    errorChain(shaderParamGetLocationGL(shader, "u_TextureType", &locType));
    
    // NULL textures
    if(texture == NULL) {
      glUniform1i(locType, 0);
      errorChain(errorGLCheck());
      errorOk();
    }
    
    // Set texture.
    glActiveTexture(GL_TEXTURE0);
    errorChain(errorGLCheck());
    glBindTexture(GL_TEXTURE_2D, texture->id);
    errorChain(errorGLCheck());

    errorChain(shaderParamGetLocationGL(shader, name, &locTexture));
    glUniform1i(locTexture, 0);
    errorChain(errorGLCheck());

    // Set texture type
    if(texture->format == TEXTURE_FORMAT_PALETTE) {
      glUniform1i(locType, 2);
      errorChain(errorGLCheck());

      shaderParamGetLocationGL(shader, "u_ColorCount", &locColorCount);
      glUniform1i(locColorCount, texture->palette->count);
      errorChain(errorGLCheck());

      shaderParamGetLocationGL(shader, "u_Colors", &locColors);
      GLuint paletteData[texture->palette->count];
      for(size_t i = 0; i < texture->palette->count; i++) {
        color_t color = texture->palette->colors[i];
        paletteData[i] = (
          ((uint32_t)color.r << 24) |
          ((uint32_t)color.g << 16) |
          ((uint32_t)color.b << 8)  |
          ((uint32_t)color.a << 0)
        );
      }
      glUniform1uiv(locColors, texture->palette->count, paletteData);
      errorChain(errorGLCheck());
    } else {
      glUniform1i(locType, 1);
      errorChain(errorGLCheck());
    }

    errorOk();
  }

  shaderdefinition_t SHADER_UNLIT_DEFINITION = {
    .vert =
      #ifdef DUSK_OPENGL_ES
        "#version 300 es\n"
        "precision mediump float;\n"
        // Attributes
        "layout(location = 0) in vec3 a_Pos;\n"
        "layout(location = 1) in vec2 a_TexCoord;\n"
        "layout(location = 2) in vec4 a_Color;\n"
        // Uniforms
        "uniform mat4 u_Proj;\n"
        "uniform mat4 u_View;\n"
        "uniform mat4 u_Model;\n"
        // Vertex shader outputs
        "out vec4 v_Color;\n"
        "out vec2 v_TexCoord;\n"
        "void main() {\n"
        "  gl_Position = u_Proj * u_View * u_Model * vec4(a_Pos, 1.0);\n"
        "  v_Color = a_Color;\n"
        "  v_TexCoord = a_TexCoord;\n"
        "}\n",
      #else
        "#version 330 core\n"
        // Attributes
        "layout(location = 0) in vec3 a_Pos;\n"
        "layout(location = 1) in vec2 a_TexCoord;\n"
        "layout(location = 2) in vec4 a_Color;\n"
        // Uniforms
        "uniform mat4 u_Proj;\n"
        "uniform mat4 u_View;\n"
        "uniform mat4 u_Model;\n"
        // Vertex shader outputs
        "out vec4 v_Color;\n"
        "out vec2 v_TexCoord;\n"
        "void main() {\n"
        "  gl_Position = u_Proj * u_View * u_Model * vec4(a_Pos, 1.0);\n"
        "  v_Color = a_Color;\n"
        "  v_TexCoord = a_TexCoord;\n"
        "}\n",
      #endif
    .frag =
      #ifdef DUSK_OPENGL_ES
        "#version 300 es\n"
        "precision mediump float;\n"
        // Uniforms
        "uniform sampler2D u_Texture;\n"
        "uniform int u_TextureType;\n"
        "uniform vec4 u_Colors[256];\n"// For paletted textures.
        "uniform int u_ColorCount;\n"
        // Fragment shader inputs
        "in vec4 v_Color;\n"
        "in vec2 v_TexCoord;\n"
        // Fragment shader output
        "out vec4 FragColor;\n"
        "void main() {\n"
        "  if(u_TextureType == 0) {\n"// No texture
        "    FragColor = v_Color;\n"
        "    return;\n"
        "  }\n"
        "  if(u_TextureType == 1) {\n"// Regular texture
        "    FragColor = texture(u_Texture, v_TexCoord) * v_Color;\n"
        "    return;\n"
        "  }\n"
        "  if(u_TextureType == 2) {\n"// Paletted texture
        "    vec4 texColor = texture(u_Texture, v_TexCoord);\n"
        "    int index = int(floor(texColor.r * 255.0));\n"
        "    vec4 paletteColor = u_Colors[index];\n"
        "    FragColor = paletteColor;\n"
        "    return;\n"
        "  }\n"
        "  FragColor = v_Color;\n"// Unknown texture type?
        "}\n",
      #else
        "#version 330 core\n"
        // Uniforms
        "uniform sampler2D u_Texture;\n"
        "uniform int u_TextureType;\n"
        "uniform uint u_Colors[256];\n"// For paletted textures.
        "uniform int u_ColorCount;\n"
        // Fragment shader inputs
        "in vec4 v_Color;\n"
        "in vec2 v_TexCoord;\n"
        // Fragment shader output
        "out vec4 FragColor;\n"
        "void main() {\n"
        "  if(u_TextureType == 0) {\n"// No texture
        "    FragColor = v_Color;\n"
        "    return;\n"
        "  }\n"
        "  if(u_TextureType == 1) {\n"// Regular texture
        "    FragColor = texture(u_Texture, v_TexCoord) * v_Color;\n"
        "    return;\n"
        "  }\n"
        "  if(u_TextureType == 2) {\n"// Paletted texture
        "    vec4 texColor = texture(u_Texture, v_TexCoord);\n"
        "    uint index = uint(floor(texColor.r * 255.0));\n"
        "    uint palColor = u_Colors[index];\n"
        "    float r = float((palColor >> 24) & 0xFFu) / 255.0;\n"
        "    float g = float((palColor >> 16) & 0xFFu) / 255.0;\n"
        "    float b = float((palColor >> 8)  & 0xFFu) / 255.0;\n"
        "    float a = float((palColor >> 0)  & 0xFFu) / 255.0;\n"
        "    vec4 paletteColor = vec4(r, g, b, a);\n"
        "    FragColor = paletteColor;\n"
        "    return;\n"
        "  }\n"
        "  FragColor = v_Color;\n"// Unknown texture type?
        "}\n",
      #endif

    .setTexture = shaderUnlitSetTextureGL
  };
#endif