#include "shader_utils.hpp"
#include <spdlog/spdlog.h>
#include <fstream>
#include <sstream>

namespace shader {

std::string loadFile(const char* path) {
    std::ifstream file(path);
    if (!file.is_open()) {
        spdlog::error("Failed to open shader file: {}", path);
        throw std::runtime_error(std::string("Cannot open shader: ") + path);
    }
    
    std::stringstream buffer;
    buffer << file.rdbuf();
    return buffer.str();
}

GLuint compileShader(GLenum type, const char* source) {
    GLuint shader = glCreateShader(type);
    glShaderSource(shader, 1, &source, nullptr);
    glCompileShader(shader);
    
    GLint success = 0;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
    if (!success) {
        char log[512];
        glGetShaderInfoLog(shader, 512, nullptr, log);
        spdlog::error("Shader compilation failed:\n{}", log);
        glDeleteShader(shader);
        throw std::runtime_error("Shader compilation failed");
    }
    
    return shader;
}

GLuint linkProgram(GLuint vertShader, GLuint fragShader) {
    GLuint program = glCreateProgram();
    glAttachShader(program, vertShader);
    glAttachShader(program, fragShader);
    glLinkProgram(program);
    
    GLint success = 0;
    glGetProgramiv(program, GL_LINK_STATUS, &success);
    if (!success) {
        char log[512];
        glGetProgramInfoLog(program, 512, nullptr, log);
        spdlog::error("Program linking failed:\n{}", log);
        glDeleteProgram(program);
        throw std::runtime_error("Program linking failed");
    }
    
    return program;
}

GLuint createProgram(const char* vertPath, const char* fragPath) {
    std::string vertSource = loadFile(vertPath);
    std::string fragSource = loadFile(fragPath);
    
    GLuint vertShader = compileShader(GL_VERTEX_SHADER, vertSource.c_str());
    GLuint fragShader = compileShader(GL_FRAGMENT_SHADER, fragSource.c_str());
    
    GLuint program = linkProgram(vertShader, fragShader);
    
    glDeleteShader(vertShader);
    glDeleteShader(fragShader);
    
    return program;
}

void checkGLError(const char* op) {
    GLenum err;
    while ((err = glGetError()) != GL_NO_ERROR) {
        spdlog::error("GL error after {}: 0x{:x}", op, err);
    }
}

} // namespace shader