// GLESRenderer.cpp
#include "EngineFrame/Render/GLESRenderer.h"
#include <iostream>
#include <algorithm>
#include <glm/ext/matrix_float4x4.hpp>
#include <glm/ext/matrix_transform.hpp>
#include <glm/ext/matrix_clip_space.hpp>
#include <glm/gtc/type_ptr.hpp>

// 顶点着色器源码
const char *vertexShaderSource = R"(
    #version 300 es
    precision mediump float;
    
    layout(location = 0) in vec2 aPosition;
    layout(location = 1) in vec2 aTexCoord;
    
    out vec2 vTexCoord;
    
    uniform mat4 uProjection;
    uniform mat4 uModel;
    
    void main() {
        gl_Position = uProjection * uModel * vec4(aPosition, 0.0, 1.0);
        vTexCoord = aTexCoord;
    }
)";

// 片段着色器源码
const char *fragmentShaderSource = R"(
    #version 300 es
    precision mediump float;
    
    in vec2 vTexCoord;
    out vec4 FragColor;
    
    uniform sampler2D uTexture;
    uniform vec4 uColor;
    
    void main() {
        FragColor = texture(uTexture, vTexCoord) * uColor;
    }
)";

GLESRenderer::GLESRenderer(SDL_Window *window) : m_window(window), m_glContext(nullptr)
{
}

GLESRenderer::~GLESRenderer()
{
    if (m_glContext)
    {
        SDL_GL_DeleteContext(m_glContext);
    }

    glDeleteProgram(m_shaderProgram);
    glDeleteShader(m_vertexShader);
    glDeleteShader(m_fragmentShader);
    glDeleteBuffers(1, &m_vbo);
    glDeleteVertexArrays(1, &m_vao);
}

bool GLESRenderer::Initialize()
{
    // 设置 OpenGL ES 属性
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);

    // 创建 OpenGL ES 上下文
    m_glContext = SDL_GL_CreateContext(m_window);
    if (!m_glContext)
    {
        std::cerr << "Failed to create OpenGL ES context: " << SDL_GetError() << std::endl;
        return false;
    }

    // 初始化 GLEW (如果需要) 或者直接使用 OpenGL ES 函数

    // 创建着色器程序
    if (!CreateShaderProgram())
    {
        std::cerr << "Failed to create shader program" << std::endl;
        return false;
    }

    // 设置视口
    int w, h;
    SDL_GetWindowSize(m_window, &w, &h);
    glViewport(0, 0, w, h);

    // 设置正交投影
    SetOrthographicProjection(w, h);

    // 启用混合
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    // 创建VAO和VBO
    glGenVertexArrays(1, &m_vao);
    glGenBuffers(1, &m_vbo);

    glBindVertexArray(m_vao);
    glBindBuffer(GL_ARRAY_BUFFER, m_vbo);

    // 设置顶点属性指针
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void *)(2 * sizeof(float)));
    glEnableVertexAttribArray(1);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);

    return true;
}

void GLESRenderer::Clear()
{
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // 清空批处理
    m_renderBatch.clear();
}

void GLESRenderer::Present()
{
    // 按Z顺序排序
    std::stable_sort(m_renderBatch.begin(), m_renderBatch.end(),
                     [](const RenderCommand &a, const RenderCommand &b)
                     {
                         return a.z_order < b.z_order;
                     });

    // 使用着色器程序
    glUseProgram(m_shaderProgram);

    // 设置投影矩阵
    GLint projLoc = glGetUniformLocation(m_shaderProgram, "uProjection");
    // 这里需要设置正交投影矩阵

    // 渲染批处理中的所有命令
    for (const auto &cmd : m_renderBatch)
    {
        // 绑定纹理
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, cmd.texture);
        glUniform1i(glGetUniformLocation(m_shaderProgram, "uTexture"), 0);

        // 计算模型矩阵（位置、旋转、缩放）
        glm::mat4 model = glm::mat4(1.0f);
        model = glm::translate(model, glm::vec3(cmd.dstrect.x, cmd.dstrect.y, 0.0f));

        if (cmd.angle != 0)
        {
            // 应用旋转
            model = glm::translate(model, glm::vec3(cmd.center.x, cmd.center.y, 0.0f));
            model = glm::rotate(model, glm::radians(static_cast<float>(cmd.angle)), glm::vec3(0.0f, 0.0f, 1.0f));
            model = glm::translate(model, glm::vec3(-cmd.center.x, -cmd.center.y, 0.0f));
        }

        model = glm::scale(model, glm::vec3(cmd.dstrect.w, cmd.dstrect.h, 1.0f));

        // 设置模型矩阵
        GLint modelLoc = glGetUniformLocation(m_shaderProgram, "uModel");
        glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));

        // 绘制矩形
        glBindVertexArray(m_vao);
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
        glBindVertexArray(0);
    }

    // 交换缓冲区
    SDL_GL_SwapWindow(m_window);
}

void GLESRenderer::RenderCopy(GLuint texture, const SDL_Rect *srcrect, const SDL_Rect *dstrect)
{
    RenderCommand cmd;
    cmd.texture = texture;
    if (dstrect)
        cmd.dstrect = *dstrect;
    cmd.angle = 0;
    cmd.flip = SDL_FLIP_NONE;
    cmd.z_order = 0; // 需要从Sprite获取Z顺序

    m_renderBatch.push_back(cmd);
}

void GLESRenderer::RenderCopyEx(GLuint texture, const SDL_Rect *srcrect, const SDL_Rect *dstrect,
                                double angle, const SDL_Point *center, SDL_RendererFlip flip)
{
    RenderCommand cmd;
    cmd.texture = texture;
    if (dstrect)
        cmd.dstrect = *dstrect;
    cmd.angle = angle;
    if (center)
        cmd.center = *center;
    cmd.flip = flip;
    cmd.z_order = 0; // 需要从Sprite获取Z顺序

    m_renderBatch.push_back(cmd);
}

bool GLESRenderer::CompileShader(const char *source, GLenum type, GLuint &shader)
{
    shader = glCreateShader(type);
    glShaderSource(shader, 1, &source, NULL);
    glCompileShader(shader);

    GLint success;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        GLchar infoLog[512];
        glGetShaderInfoLog(shader, 512, NULL, infoLog);
        std::cerr << "Shader compilation failed: " << infoLog << std::endl;
        return false;
    }

    return true;
}

bool GLESRenderer::LinkProgram(GLuint program)
{
    glLinkProgram(program);

    GLint success;
    glGetProgramiv(program, GL_LINK_STATUS, &success);
    if (!success)
    {
        GLchar infoLog[512];
        glGetProgramInfoLog(program, 512, NULL, infoLog);
        std::cerr << "Program linking failed: " << infoLog << std::endl;
        return false;
    }

    return true;
}

bool GLESRenderer::CreateShaderProgram()
{
    if (!CompileShader(vertexShaderSource, GL_VERTEX_SHADER, m_vertexShader))
    {
        return false;
    }

    if (!CompileShader(fragmentShaderSource, GL_FRAGMENT_SHADER, m_fragmentShader))
    {
        return false;
    }

    m_shaderProgram = glCreateProgram();
    glAttachShader(m_shaderProgram, m_vertexShader);
    glAttachShader(m_shaderProgram, m_fragmentShader);

    if (!LinkProgram(m_shaderProgram))
    {
        return false;
    }

    glDeleteShader(m_vertexShader);
    glDeleteShader(m_fragmentShader);

    return true;
}

void GLESRenderer::SetOrthographicProjection(int width, int height)
{
    // 设置正交投影矩阵
    glm::mat4 projection = glm::ortho(0.0f, static_cast<float>(width),
                                      static_cast<float>(height), 0.0f,
                                      -1.0f, 1.0f);

    glUseProgram(m_shaderProgram);
    GLint projLoc = glGetUniformLocation(m_shaderProgram, "uProjection");
    glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
}