#include <renderer/texture.h>
#include <utils/logger.h>
#include <glad/glad.h>
#define STB_IMAGE_IMPLEMENTATION
#include <stb/stb_image.h>

namespace extra2d {

// OpenGL 格式转换函数
static GLint getTextureInternalFormat(TextureFormat format) {
    switch (format) {
        case TextureFormat::RGBA8: return GL_RGBA8;
        case TextureFormat::RGB8:  return GL_RGB8;
        case TextureFormat::RGBA4: return GL_RGBA4;
        case TextureFormat::R8:    return GL_R8;
        case TextureFormat::RG8:   return GL_RG8;
        default:                   return GL_RGBA8;
    }
}

static GLenum getTextureFormat(TextureFormat format) {
    switch (format) {
        case TextureFormat::RGBA8:
        case TextureFormat::RGBA4:
            return GL_RGBA;
        case TextureFormat::RGB8:
            return GL_RGB;
        case TextureFormat::R8:
            return GL_RED;
        case TextureFormat::RG8:
            return GL_RG;
        default:
            return GL_RGBA;
    }
}

Texture::Texture() = default;

Texture::~Texture() {
    if (texture_ != 0) {
        glDeleteTextures(1, &texture_);
        texture_ = 0;
    }
}

bool Texture::loadFromFile(const std::string& path) {
    // 加载图片
    int channels;
    stbi_set_flip_vertically_on_load(true);
    unsigned char* data = stbi_load(path.c_str(), &width_, &height_, &channels, 0);
    
    if (!data) {
        E2D_LOG_ERROR("Failed to load texture: {}", path);
        return false;
    }
    
    // 根据通道数确定格式
    TextureFormat format;
    switch (channels) {
        case 1: format = TextureFormat::R8; break;
        case 2: format = TextureFormat::RG8; break;
        case 3: format = TextureFormat::RGB8; break;
        case 4: format = TextureFormat::RGBA8; break;
        default: format = TextureFormat::RGBA8; break;
    }
    
    bool result = loadFromMemory(data, width_, height_, format);
    stbi_image_free(data);
    
    if (result) {
        E2D_LOG_DEBUG("Texture loaded: {} ({}x{})", path, width_, height_);
    }
    
    return result;
}

bool Texture::loadFromMemory(const uint8_t* data, int width, int height, TextureFormat format) {
    if (texture_ != 0) {
        glDeleteTextures(1, &texture_);
        texture_ = 0;
    }
    
    width_ = width;
    height_ = height;
    format_ = format;
    
    // 创建纹理
    glGenTextures(1, &texture_);
    glBindTexture(GL_TEXTURE_2D, texture_);
    
    // 设置纹理参数
    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_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    
    // 上传纹理数据
    glTexImage2D(GL_TEXTURE_2D, 0, 
                 getTextureInternalFormat(format_), 
                 width_, height_, 0,
                 getTextureFormat(format_), 
                 GL_UNSIGNED_BYTE, data);
    
    // 生成 mipmap
    glGenerateMipmap(GL_TEXTURE_2D);
    
    glBindTexture(GL_TEXTURE_2D, 0);
    
    return true;
}

bool Texture::create(int width, int height, TextureFormat format) {
    if (texture_ != 0) {
        glDeleteTextures(1, &texture_);
        texture_ = 0;
    }
    
    width_ = width;
    height_ = height;
    format_ = format;
    
    // 创建纹理
    glGenTextures(1, &texture_);
    glBindTexture(GL_TEXTURE_2D, texture_);
    
    // 设置纹理参数
    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_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    
    // 分配纹理存储（无数据）
    glTexImage2D(GL_TEXTURE_2D, 0, 
                 getTextureInternalFormat(format_), 
                 width_, height_, 0,
                 getTextureFormat(format_), 
                 GL_UNSIGNED_BYTE, nullptr);
    
    glBindTexture(GL_TEXTURE_2D, 0);
    
    return true;
}

void Texture::bind(uint32_t slot) const {
    if (texture_ != 0) {
        glActiveTexture(GL_TEXTURE0 + slot);
        glBindTexture(GL_TEXTURE_2D, texture_);
    }
}

void Texture::unbind() const {
    glBindTexture(GL_TEXTURE_2D, 0);
}

} // namespace extra2d