#include "Shader.h"
#include "spdlog/spdlog.h"

#include <QFile>
#include <qglobal.h>

Shader::Shader(const QString vertexPath, const QString fragmentPath)
{
    /* 获取OpenGL上下文 */
    auto ctx = QOpenGLContext::currentContext();
    if(!ctx)
    {
        SPDLOG_ERROR("获取OpenGL上下文失败");
        return;
    }
    m_glFuncs = ctx->functions();
    SPDLOG_DEBUG("加载着色器代码");
    QByteArray vertexShaderSource;
    QByteArray fragmentShaderSource;
    if(!loadShaderSourceFromFile(vertexPath, vertexShaderSource))
    {
        SPDLOG_ERROR("加载顶点着色器失败: {}", vertexPath.toStdString());
        return;
    }
    if(!loadShaderSourceFromFile(fragmentPath, fragmentShaderSource))
    {
        SPDLOG_ERROR("加载片段着色器失败: {}", fragmentPath.toStdString());
        return;
    }

    /* 编译着色器 */
    SPDLOG_DEBUG("编译着色器...");
    GLuint vertexShader = compileShader(vertexShaderSource, GL_VERTEX_SHADER);
    GLuint fragmentShader = compileShader(fragmentShaderSource, GL_FRAGMENT_SHADER);

    /* 创建着色器程序 */
    m_programID = m_glFuncs->glCreateProgram();
    /* 将顶点着色器和片段着色器附加到着色器程序对象上 */
    m_glFuncs->glAttachShader(m_programID, vertexShader);
    m_glFuncs->glAttachShader(m_programID, fragmentShader);
    /* 链接着色器程序 */
    m_glFuncs->glLinkProgram(m_programID);
    printOpenGLLinkError(m_programID);

    /* 删除着色器对象 */
    m_glFuncs->glDeleteShader(vertexShader);
    m_glFuncs->glDeleteShader(fragmentShader);
    SPDLOG_INFO("着色器创建成功");
}

Shader::~Shader()
{

}

void Shader::use()
{
    m_glFuncs->glUseProgram(m_programID);
}

GLuint Shader::getProgramID() const
{
    return m_programID;
}

/* 设置uniform工具 */
void Shader::setBool(const QString &name, bool value) 
{
    auto location = m_glFuncs->glGetUniformLocation(m_programID, name.toStdString().c_str());
    m_glFuncs->glUniform1i(location, (int)value);
}

void Shader::setInt(const QString &name, int value) 
{
    auto location = m_glFuncs->glGetUniformLocation(m_programID, name.toStdString().c_str());
    m_glFuncs->glUniform1i(location, value);
}

void Shader::setFloat(const QString &name, float value) 
{
    auto location = m_glFuncs->glGetUniformLocation(m_programID, name.toStdString().c_str());
    m_glFuncs->glUniform1f(location, value);
}

/* 打开着色器文件，加载着色器代码 */
bool Shader::loadShaderSourceFromFile(const QString &filePath, QByteArray &outShaderSource)
{
    QFile file(filePath);
    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
    {
        SPDLOG_ERROR("无法打开着色器文件: {}", filePath.toStdString());
        SPDLOG_ERROR("错误信息: {}", file.errorString().toStdString());
        return false;
    }
    outShaderSource = file.readAll();
    file.close();
    return true;
}

/* 编译着色器 */
GLuint Shader::compileShader(const QByteArray &shaderSource, GLenum shaderType)
{
    const char* sourceCStr = shaderSource.constData();
    /* 创建着色器对象 */
    GLuint shader = m_glFuncs->glCreateShader(shaderType);
    /* 加载着色器源码 */
    m_glFuncs->glShaderSource(shader, 1, &sourceCStr, nullptr);
    /* 编译着色器 */
    m_glFuncs->glCompileShader(shader);
    printOpenGLCompileError(shader);
    return shader;
}



/* 打印编译错误 */
void Shader::printOpenGLCompileError(GLuint errorCode)
{
    int sucess;
    char infoLog[512];
    m_glFuncs->glGetShaderiv(errorCode, GL_COMPILE_STATUS, &sucess);
    if (!sucess)
    {
        m_glFuncs->glGetShaderInfoLog(errorCode, 512, nullptr, infoLog);
        SPDLOG_ERROR("OpenGL编译错误: {}", infoLog);
    }

}

/* 打印着色器链接错误 */
void Shader::printOpenGLLinkError(GLuint errorCode)
{
    int sucess;
    char infoLog[512];
    m_glFuncs->glGetProgramiv(errorCode, GL_LINK_STATUS, &sucess);
    if (!sucess)
    {
        m_glFuncs->glGetProgramInfoLog(errorCode, 512, nullptr, infoLog);
        SPDLOG_ERROR("OpenGL链接错误: {}", infoLog);
    }
}