/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "texture.h"
#include "assert/assert.h"
#include "util/memory.h"
#include "util/math.h"
#include "display/palette/palettelist.h"

const texture_t *TEXTURE_BOUND = NULL;

void textureInit(
  texture_t *texture,
  const int32_t width,
  const int32_t height,
  const textureformat_t format,
  const texturedata_t data
) {
  assertNotNull(texture, "Texture cannot be NULL");
  assertTrue(width > 0 && height > 0, "width/height must be greater than 0");

  memoryZero(texture, sizeof(texture_t));
  texture->width = width;
  texture->height = height;

  #if PSP
    assertTrue(
      width == mathNextPowTwo(width),
      "Width must be powers of 2 for PSP"
    );
    assertTrue(
      height == mathNextPowTwo(height),
      "Height must be powers of 2 for PSP"
    );
  #endif

  #if DISPLAY_SDL2
    glGenTextures(1, &texture->id);
    glBindTexture(GL_TEXTURE_2D, texture->id);

    switch(format) {
      case TEXTURE_FORMAT_RGBA:
        assertNotNull(data.rgba.colors, "RGBA texture data cannot be NULL");
        glTexImage2D(
          GL_TEXTURE_2D, 0, format, width, height, 0,
          format, GL_UNSIGNED_BYTE, (void*)data.rgba.colors
        );
        break;

      case TEXTURE_FORMAT_ALPHA:
        assertNotNull(data.alpha.data, "Alpha texture data cannot be NULL");
        glTexImage2D(
          GL_TEXTURE_2D, 0, format, width, height, 0,
          format, GL_UNSIGNED_BYTE, (void*)data.alpha.data
        );
        break;

      case TEXTURE_FORMAT_PALETTE:
        assertNotNull(data.palette.data, "Palette texture data cannot be NULL");
        assertTrue(
          data.palette.palette < PALETTE_LIST_COUNT,
          "Palette index out of range"
        );

        const palette_t *pal = PALETTE_LIST[data.palette.palette];
        assertNotNull(pal, "Palette cannot be NULL");
        GLenum err = glGetError();
        if (err != GL_NO_ERROR) {
          assertUnreachable("GL Error before setting color table");
        }

        // Do we support paletted textures?
        bool_t havePalTex = false;
        GLint mask = 0;
        glGetIntegerv(GL_CONTEXT_PROFILE_MASK, &mask);
        if(mask & GL_CONTEXT_CORE_PROFILE_BIT) {
          GLint n=0; glGetIntegerv(GL_NUM_EXTENSIONS, &n);
          for (GLint i=0; i<n; ++i) {
            const char* e = (const char*)glGetStringi(GL_EXTENSIONS, i);
            if (e && strcmp(e, "GL_EXT_paletted_texture")==0) { havePalTex = true; break; }
          }
        } else {
          const char* ext = (const char*)glGetString(GL_EXTENSIONS);
          havePalTex = ext && strstr(ext, "GL_EXT_paletted_texture");
        }

        if(!havePalTex) {
          // Not supported, convert to RGBA using lookup
          color_t formatted[width * height];
          for(int32_t i = 0; i < width * height; i++) {
            uint8_t index = data.palette.data[i];
            assertTrue(
              index < pal->colorCount,
              "Palette index out of range"
            );
            formatted[i] = pal->colors[index];
          }
          glTexImage2D(
            GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0,
            GL_RGBA, GL_UNSIGNED_BYTE, (void*)formatted
          );
        } else {
          // Supported.
          glColorTableEXT(
            GL_TEXTURE_2D, GL_RGBA, pal->colorCount, GL_RGBA,
            GL_UNSIGNED_BYTE, (const void*)pal->colors
          );
          glTexImage2D(
            GL_TEXTURE_2D,
            0, GL_COLOR_INDEX8_EXT,
            width, height,
            0, GL_COLOR_INDEX8_EXT,
            GL_UNSIGNED_BYTE, (void*)data.palette.data
          );
        }

        break;

      default:
        assertUnreachable("Unknown texture format");
        break;
    }

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
    
    glBindTexture(GL_TEXTURE_2D, 0);
  #endif
}

void textureBind(const texture_t *texture) {
  if(TEXTURE_BOUND == texture) return;

  if(texture == NULL) {
    #if DISPLAY_SDL2
      glDisable(GL_TEXTURE_2D);
    #endif
    TEXTURE_BOUND = NULL;
    return;
  }

  assertTrue(
    texture->id != 0,
    "Texture ID must not be 0"
  );
  assertTrue(
    texture->width > 0 && texture->height > 0,
    "Texture width and height must be greater than 0"
  );

  #if DISPLAY_SDL2
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, texture->id);
  #endif
  TEXTURE_BOUND = texture;
}

void textureDispose(texture_t *texture) {
  assertNotNull(texture, "Texture cannot be NULL");
  assertTrue(texture->id != 0, "Texture ID must not be 0");

  #if DISPLAY_SDL2
    glDeleteTextures(1, &texture->id);
  #endif
}