#include "client/rendering/Engine.h"
#include "client/Game.h"
#include "client/rendering/Mesh.h"
#include "math/Frustum.h"
#include "rendering/Framebuffer.h"
#include "rendering/Window.h"
#include "utils/Logger.h"
#include "utils/Random.h"
#include "wrapper/GL.h"

static Shader worldShader;
static Shader ssaoShader;
static Shader ssaoBlurShader;
static Shader shadowShader;
static Shader postWorldShader;
static Shader overlayShader;
static Framebuffer<5> worldBuffer;
static Framebuffer<1> ssaoBuffer;
static Framebuffer<1> ssaoBlurBuffer;
static Framebuffer<1> shadowBuffer;
static Frustum frustum{60.0f, 0.1f, 1000.0f, Window::getSize()};
static MatrixStack<16> model;
Renderer Engine::renderer;
ShaderMatrix Engine::matrix{nullptr, model, nullptr};
float Engine::lag = 0.0f;
static Texture ssaoNoise;
static Mesh rectangle;
static Matrix worldProj;
static Matrix worldView;
static Matrix worldShadowProj;
static Matrix worldShadowView;
static Matrix worldShadowProjView;
static bool useSsao = true;
static bool useShadows = false;
static float shadowRadius = 0.01f;
static float shadowBias = 0.0002f;
static bool running = true;

static Error compileShader(Shader& s, const char* name) {
    constexpr const char* prefix = "resources/shader/";
    return s.compile(StringBuffer<50>(prefix).append(name).append(".vs"),
                     StringBuffer<50>(prefix).append(name).append(".fs"));
}

static Error initShaders() {
    Error error = compileShader(worldShader, "world");
    if(error.has()) {
        return error;
    }
    error = compileShader(ssaoShader, "ssao");
    if(error.has()) {
        return error;
    }
    error = compileShader(ssaoBlurShader, "ssaoBlur");
    if(error.has()) {
        return error;
    }
    error = compileShader(shadowShader, "worldShadow");
    if(error.has()) {
        return error;
    }
    error = compileShader(postWorldShader, "worldPost");
    if(error.has()) {
        return error;
    }
    return compileShader(overlayShader, "overlay");
}

static void resizeFramebuffers(const Size& size) {
    worldBuffer.resize(size);
    ssaoBuffer.resize(size);
    ssaoBlurBuffer.resize(size);
    shadowBuffer.resize(size);
}

static Error initFramebuffers(const Size& size) {
    Error error = worldBuffer.init(
        size, TextureFormat::float32(3), TextureFormat::float32(3),
        TextureFormat::color8(4), TextureFormat::float32(1),
        TextureFormat::depth32(true));
    if(error.has()) {
        return error;
    }
    error = ssaoBuffer.init(size, TextureFormat::float32(1));
    if(error.has()) {
        return error;
    }
    error = ssaoBlurBuffer.init(size, TextureFormat::float32(1));
    if(error.has()) {
        return error;
    }
    return shadowBuffer.init(size, TextureFormat::depth32());
}

static bool initRectangle() {
    if(rectangle.init()) {
        return true;
    }
    rectangle.build(TypedBuffer<Mesh::Triangle>(2)
                        .add({{{-1.0f, -1.0f, +0.0f}, {0.0f, 0.0f}},
                              {{+1.0f, +1.0f, +0.0f}, {1.0f, 1.0f}},
                              {{-1.0f, +1.0f, +0.0f}, {0.0f, 1.0f}}})
                        .add({{{-1.0f, -1.0f, +0.0f}, {0.0f, 0.0f}},
                              {{+1.0f, -1.0f, +0.0f}, {1.0f, 0.0f}},
                              {{+1.0f, +1.0f, +0.0f}, {1.0f, 1.0f}}}));
    return false;
}

static void initNoise() {
    ssaoNoise.init(TextureFormat::float32(3), 0);
    Random r(1);
    Array<float, 48> data;
    for(int i = 0; i < 48; i++) {
        data[i] = r.nextFloat() * 2.0f - 1.0f;
    }
    ssaoNoise.setData(4, 4, data.begin());
}

bool Engine::init() {
    WindowOptions options(4, 0, {1024, 620}, false, "test");
    Error error = Window::open(options);
    if(error.has()) {
        LOG_ERROR(error.message);
        return true;
    }
    Window::show();
    error = initShaders();
    if(error.has()) {
        LOG_ERROR(error.message);
        return true;
    }
    error = initFramebuffers(Window::getSize());
    if(error.has()) {
        LOG_ERROR(error.message);
        return true;
    }
    initNoise();
    if(renderer.init() || initRectangle()) {
        return true;
    }
    return false;
}

static void renderShadow() {
    shadowBuffer.bindAndClear();
    GL::enableDepthTesting();
    shadowShader.use();
    worldShadowProjView = worldShadowProj;
    worldShadowProjView *= worldShadowView;
    shadowShader.setMatrix("projView", worldShadowProjView.getValues());
    model.clear();
    shadowShader.setMatrix("model", model.peek().getValues());
    Engine::matrix = {&shadowShader, model, &worldView};
    Game::renderWorld();
}

static void renderWorld() {
    worldBuffer.bindAndClear();
    GL::enableDepthTesting();
    worldShader.use();

    Matrix rWorldShadowProjView;
    rWorldShadowProjView.scale(0.5f).translate(Vector3(0.5f, 0.5f, 0.5f));
    rWorldShadowProjView *= worldShadowProjView;

    worldShader.setMatrix("projViewShadow", rWorldShadowProjView.getValues());
    worldShader.setMatrix("proj", worldProj.getValues());
    worldView = Matrix();
    worldShader.setMatrix("view", worldView.getValues());
    model.clear();
    worldShader.setMatrix("model", model.peek().getValues());
    shadowBuffer.bindTextureTo(0, 1);
    worldShader.setInt("shadows", useShadows);
    worldShader.setFloat("radius", shadowRadius);
    worldShader.setFloat("zbias", shadowBias);
    Engine::matrix = {&worldShader, model, &worldView};
    Game::renderWorld();
}

static void renderSSAO() {
    ssaoShader.use();

    Matrix rProj;
    rProj.scale(0.5f).translate(Vector3(0.5f, 0.5f, 0.5f));
    rProj *= worldProj;

    ssaoShader.setMatrix("proj", rProj.getValues());
    ssaoShader.setInt("width", Window::getSize().width);
    ssaoShader.setInt("height", Window::getSize().height);
    worldBuffer.bindTextureTo(0, 0);
    worldBuffer.bindTextureTo(4, 1);
    ssaoNoise.bindTo(2);
    ssaoBuffer.bindAndClear();
    rectangle.draw();

    ssaoBlurShader.use();
    ssaoBuffer.bindTextureTo(0, 0);
    ssaoBlurBuffer.bindAndClear();
    rectangle.draw();
}

static void renderPostWorld() {
    GL::bindMainFramebuffer();
    GL::clear();
    postWorldShader.use();
    worldBuffer.bindTextureTo(2, 0);
    ssaoBlurBuffer.bindTextureTo(0, 1);
    worldBuffer.bindTextureTo(3, 2);
    worldBuffer.bindTextureTo(1, 3);
    postWorldShader.setInt("ssao", useSsao);
    postWorldShader.setInt("shadows", useShadows);
    rectangle.draw();
}

static void renderOverlay() {
    GL::disableDepthTesting();
    overlayShader.use();

    Matrix m;
    m.scale(Vector3(2.0f / Window::getSize().width,
                    -2.0f / Window::getSize().height, 1.0f))
        .translate(Vector3(-1.0f, 1.0f, 0.0f));
    overlayShader.setMatrix("view", m.getValues());
    model.clear();
    overlayShader.setMatrix("model", model.peek().getValues());

    GL::enableBlending();
    Engine::matrix = {&overlayShader, model, &m};
    Game::renderOverlay();
    GL::disableBlending();
}

static void updateWorldProjection() {
    worldProj = frustum.updateProjection();

    if(!useShadows) {
        return;
    }

    worldShadowProj.set(0, Vector4(2.0f / 40.0f, 0.0f, 0.0f, 0.0f));
    worldShadowProj.set(1, Vector4(0.0f, 2.0f / 30.0f, 0.0f, 0.0f));
    worldShadowProj.set(2, Vector4(0.0f, 0.0f, -2.0f / (1000.0f - 0.1f), 0.0f));
    worldShadowProj.set(3, Vector4(0.0f, 0.0f, 0.0f, 1.0f));
}

static void updateWorldView() {
    if(!useShadows) {
        return;
    }

    Vector3 right(0.939693f, 0.0f, -0.34202f);
    Vector3 back(0.280166f, 0.573576f, 0.769751f);
    Vector3 up(-0.196175f, 0.819152f, -0.538986f);
    Vector3 center(16.0f, 24.0f, 24.0f);

    worldShadowView.set(
        0, Vector4(right[0], right[1], right[2], right.dot(-center)));
    worldShadowView.set(1, Vector4(up[0], up[1], up[2], up.dot(-center)));
    worldShadowView.set(2,
                        Vector4(back[0], back[1], back[2], back.dot(-center)));
    worldShadowView.set(3, Vector4(0.0f, 0.0f, 0.0f, 1.0f));
}

static void startRender() {
    if(Window::hasSizeChanged()) {
        GL::setViewport(Window::getSize().width, Window::getSize().height);
        resizeFramebuffers(Window::getSize());
    }
    GL::printError("loop error");

    updateWorldProjection();
    updateWorldView();

    if(useShadows) {
        renderShadow();
    }
    renderWorld();
    if(useSsao) {
        renderSSAO();
    }
    renderPostWorld();
    renderOverlay();
}

static void render(float lag) {
    Engine::lag = lag;
    startRender();
}

static void tick() {
    Game::tick();
}

static bool isRunning() {
    return running && !Window::shouldClose();
}

void Engine::run() {
    Window::run<isRunning, tick, render>(50'000'000);
}

void Engine::stop() {
    running = false;
}