#include <renderer/shader.h>
#include <utils/logger.h>
#include <glad/glad.h>
#include <fstream>
#include <sstream>

namespace extra2d {

Shader::Shader() = default;

Shader::~Shader() {
    if (program_ != 0) {
        glDeleteProgram(program_);
        program_ = 0;
    }
}

bool Shader::loadFromFile(const std::string& vsPath, const std::string& fsPath) {
    // 读取顶点着色器
    std::ifstream vsFile(vsPath);
    if (!vsFile.is_open()) {
        E2D_LOG_ERROR("Failed to open vertex shader: {}", vsPath);
        return false;
    }
    std::stringstream vsStream;
    vsStream << vsFile.rdbuf();
    std::string vsSource = vsStream.str();
    
    // 读取片段着色器
    std::ifstream fsFile(fsPath);
    if (!fsFile.is_open()) {
        E2D_LOG_ERROR("Failed to open fragment shader: {}", fsPath);
        return false;
    }
    std::stringstream fsStream;
    fsStream << fsFile.rdbuf();
    std::string fsSource = fsStream.str();
    
    return loadFromSource(vsSource, fsSource);
}

bool Shader::loadFromSource(const std::string& vsSource, const std::string& fsSource) {
    // 删除旧程序
    if (program_ != 0) {
        glDeleteProgram(program_);
        program_ = 0;
    }
    
    uniformCache_.clear();
    
    // 处理源码（添加版本声明）
    std::string processedVS = addVersionIfNeeded(vsSource, GL_VERTEX_SHADER);
    std::string processedFS = addVersionIfNeeded(fsSource, GL_FRAGMENT_SHADER);
    
    E2D_LOG_INFO("Compiling vertex shader...");
    // 编译顶点着色器
    GLuint vs = compileShader(GL_VERTEX_SHADER, processedVS);
    if (vs == 0) {
        E2D_LOG_ERROR("Vertex shader compilation failed");
        return false;
    }
    
    E2D_LOG_INFO("Compiling fragment shader...");
    // 编译片段着色器
    GLuint fs = compileShader(GL_FRAGMENT_SHADER, processedFS);
    if (fs == 0) {
        E2D_LOG_ERROR("Fragment shader compilation failed");
        glDeleteShader(vs);
        return false;
    }
    
    E2D_LOG_INFO("Linking shader program...");
    // 链接程序
    if (!linkProgram(vs, fs)) {
        E2D_LOG_ERROR("Shader program linking failed");
        glDeleteShader(vs);
        glDeleteShader(fs);
        return false;
    }
    
    // 清理着色器对象
    glDeleteShader(vs);
    glDeleteShader(fs);
    
    E2D_LOG_INFO("Shader program created successfully, program ID: {}", program_);
    return true;
}

void Shader::bind() const {
    if (program_ != 0) {
        glUseProgram(program_);
    }
}

void Shader::unbind() const {
    glUseProgram(0);
}

void Shader::setUniformBlock(const std::string& name, uint32_t binding) {
    if (program_ == 0) return;
    
    GLuint index = glGetUniformBlockIndex(program_, name.c_str());
    if (index != GL_INVALID_INDEX) {
        glUniformBlockBinding(program_, index, binding);
    }
}

void Shader::setInt(const std::string& name, int value) {
    GLint location = getUniformLocation(name);
    if (location != -1) {
        glUniform1i(location, value);
    }
}

void Shader::setFloat(const std::string& name, float value) {
    GLint location = getUniformLocation(name);
    if (location != -1) {
        glUniform1f(location, value);
    }
}

void Shader::setVec2(const std::string& name, float x, float y) {
    GLint location = getUniformLocation(name);
    if (location != -1) {
        glUniform2f(location, x, y);
    }
}

void Shader::setVec4(const std::string& name, float x, float y, float z, float w) {
    GLint location = getUniformLocation(name);
    if (location != -1) {
        glUniform4f(location, x, y, z, w);
    }
}

void Shader::setMat4(const std::string& name, const float* value) {
    GLint location = getUniformLocation(name);
    if (location != -1) {
        glUniformMatrix4fv(location, 1, GL_FALSE, value);
        // 调试：输出设置成功的uniform
        static int logCount = 0;
        if (logCount < 3) {
            E2D_LOG_INFO("Set uniform '{}' at location {}", name, location);
            logCount++;
        }
    } else {
        // 调试：输出未找到的uniform
        static bool loggedOnce = false;
        if (!loggedOnce) {
            E2D_LOG_WARN("Uniform '{}' not found in shader", name);
            loggedOnce = true;
        }
    }
}

GLuint Shader::compileShader(GLenum type, const std::string& source) {
    GLuint shader = glCreateShader(type);
    
    const char* src = source.c_str();
    glShaderSource(shader, 1, &src, nullptr);
    glCompileShader(shader);
    
    // 检查编译状态
    GLint success;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
    if (!success) {
        char infoLog[512];
        glGetShaderInfoLog(shader, 512, nullptr, infoLog);
        
        const char* typeStr = (type == GL_VERTEX_SHADER) ? "vertex" : "fragment";
        E2D_LOG_ERROR("{} shader compilation failed: {}", typeStr, infoLog);
        
        glDeleteShader(shader);
        return 0;
    }
    
    return shader;
}

bool Shader::linkProgram(GLuint vertexShader, GLuint fragmentShader) {
    program_ = glCreateProgram();
    glAttachShader(program_, vertexShader);
    glAttachShader(program_, fragmentShader);
    glLinkProgram(program_);
    
    // 检查链接状态
    GLint success;
    glGetProgramiv(program_, GL_LINK_STATUS, &success);
    if (!success) {
        char infoLog[512];
        glGetProgramInfoLog(program_, 512, nullptr, infoLog);
        E2D_LOG_ERROR("Shader program linking failed: {}", infoLog);
        
        glDeleteProgram(program_);
        program_ = 0;
        return false;
    }
    
    return true;
}

GLint Shader::getUniformLocation(const std::string& name) {
    if (program_ == 0) return -1;
    
    // 检查缓存
    auto it = uniformCache_.find(name);
    if (it != uniformCache_.end()) {
        return it->second;
    }
    
    // 查询 uniform 位置
    GLint location = glGetUniformLocation(program_, name.c_str());
    uniformCache_[name] = location;
    
    return location;
}

std::string Shader::addVersionIfNeeded(const std::string& source, GLenum type) {
    // 如果已经包含版本声明，直接返回
    if (source.find("#version") != std::string::npos) {
        return source;
    }
    
    // 添加 OpenGL ES 3.2 版本声明
    std::string result = "#version 320 es\n";
    
    // 片段着色器需要添加精度声明
    if (type == GL_FRAGMENT_SHADER) {
        result += "precision mediump float;\n";
    }
    
    result += source;
    return result;
}

} // namespace extra2d