#include "AudioDevice.hpp"
#include "Color.hpp"
#include "Keyboard.hpp"
#include "Matrix.hpp"
#include "Mesh.hpp"
#include "Model.hpp"
#include "RadiansDegrees.hpp"
#include "Vector3.hpp"
#include "raylib.h"
#include <BufferedRaylib.hpp>
#include <raylib-cpp.hpp>

#include <algorithm>
#include <cmath>
#include <concepts>
#include <functional>
#include <iostream>
#include <memory>
#include <optional>
#include <vector>

#define SKYBOX_IMPLEMENTATION
#include "skybox.hpp"

raylib::Degree angle_normalize(raylib::Degree angle) {
    float decimal = float(angle) - int(angle);
    int normalized = (int(angle) % 360 + 360) % 360;
    return raylib::Degree(normalized + decimal);
}

raylib::Vector3 velocity_from_speed_heading(float speed, raylib::Degree heading) {
    return raylib::Vector3{speed * std::sin(heading.RadianValue()), 0.0f,
                           speed * std::cos(heading.RadianValue())};
}

void DrawBoundedModel(raylib::Model &model, bool drawBoundingBox, auto transformer) {
    // store the original transform to apply a different transform to the
    // model without affecting the next time we draw
    raylib::Matrix oldTransform = model.GetTransform();

    // apply the transform that we get from whatever the transformer callback
    // gives us
    raylib::Matrix transform = transformer(model.GetTransform());

    // apply the transform that we got from the transformer to the model
    model.SetTransform(transform);

    // draw the model, passing the origin and default scale as arguments since
    // the transform is already applied to the model
    model.Draw({ 0, 0, 0 }, 1.0f, raylib::Color::White());

    // get the bounding box of the model after applying the transform
    auto box = model.GetTransformedBoundingBox();

    // draw the bounding box of the model using raylib's built in function
    if (drawBoundingBox) {
        DrawBoundingBox(box, raylib::Color::White());
    }

    // restore the model's transform to its original state so that the next time we
    // draw the model, it doesn't have the previous transform applied to it
    model.SetTransform(oldTransform);
}

struct Entity;
class Component;

class Component {
  public:
    Entity *entity = nullptr;

    virtual void Setup() = 0;
    virtual void Update(float dt) = 0;
    virtual void Cleanup() = 0;

    virtual ~Component() = default;
};

struct Entity {
    std::vector<std::shared_ptr<Component>> components;

    template <std::derived_from<Component> T> T &AddComponent() {
        auto &ptr = components.emplace_back(std::make_shared<T>());
        ptr->entity = this;
        ptr->Setup();
        return static_cast<T &>(*ptr);
    }

    template <std::derived_from<Component> T>
    std::optional<std::reference_wrapper<T>> GetComponent() const {
        for (auto &c : components) {
            T *cast = dynamic_cast<T *>(c.get());
            if (cast) {
                return *cast;
            }
        }
        return {};
    }

    void Update(float dt) {
        for (auto &c : components) {
            c->Update(dt);
        }
    }
};

template <typename T> struct Delegate {};

template <typename TReturn, typename... TArgs> struct Delegate<TReturn(TArgs...)> {
    std::vector<std::function<void(int)>> functions;

    void connect(const std::function<TReturn(TArgs...)> &func) { functions.push_back(func); }

    void operator+=(const std::function<TReturn(TArgs...)> &func) { connect(func); }

    void operator()(int arg) {
        static_assert(std::is_same_v<TReturn, void>,
                      "EC HW: Delegate only supports void return type");

        for (const auto &func : functions) {
            f(std::forward<TArgs>(arg)...);
        }
    }
};

struct TransformComponent : public Component {
    raylib::Vector3 position = {0, 0, 0};
    raylib::Degree heading = 0;

    void Setup() override {}
    void Update(float dt) override {}
    void Cleanup() override {}
};

struct RenderComponent : public Component {
    raylib::Model *model = nullptr;
    bool drawBoundingBox = false;
    float modelScale = 40.0f;

    void Setup() override {}
    void Cleanup() override {}

    void Update(float dt) override {
        if (!model) {
            return;
        }

        auto t = entity->GetComponent<TransformComponent>();
        if (!t) {
            return;
        }

        TransformComponent &tf = t->get();

        DrawBoundedModel(*model, drawBoundingBox, [&tf, this](raylib::Matrix transform) {
            return transform.RotateY(tf.heading)
                .Scale(modelScale, modelScale, modelScale)
                .Translate(tf.position);
        });
    }
};

struct PhysicsComponent : public Component {
    raylib::Vector3 velocity = {0, 0, 0};
    float maxSpeed = 300.0f;
    float acceleration = 100.0f;
    float turningRate = 90.0f;

    void Setup() override {}
    void Cleanup() override {}

    void Update(float dt) override {
        auto t = entity->GetComponent<TransformComponent>();
        if (!t) {
            return;
        }
        t->get().position = t->get().position + velocity * dt;
    }
};

struct OrientedPhysicsComponent : public PhysicsComponent {
    float speed = 0.0f;

    void Setup() override {}
    void Cleanup() override {}

    void Update(float dt) override {
        auto t = entity->GetComponent<TransformComponent>();
        if (!t) {
            return;
        }

        TransformComponent &tf = t->get();

        speed = std::clamp(speed, -maxSpeed, maxSpeed);

        velocity = velocity_from_speed_heading(speed, tf.heading);

        tf.position = tf.position + velocity * dt;
    }
};

struct FollowComponent : public Component {
    Entity *target = nullptr;
    float hoverHeight = 200.0f;
    float speed = 0.0f;
    float maxSpeed = 250.0f;
    float acceleration = 80.0f;
    float turningRate = 120.0f;
    float epsilon = 8.0f;

    void Setup() override {}
    void Cleanup() override {}

    void Update(float dt) override {
        if (!target) {
            return;
        }

        auto myT = entity->GetComponent<TransformComponent>();
        auto targetT = target->GetComponent<TransformComponent>();
        if (!myT || !targetT) {
            return;
        }

        TransformComponent &myTf = myT->get();
        TransformComponent &targetTf = targetT->get();

        raylib::Vector3 desired = {targetTf.position.x, targetTf.position.y + hoverHeight,
                                   targetTf.position.z};

        raylib::Vector3 toDesired = desired - myTf.position;
        float distXZ = std::sqrt(toDesired.x * toDesired.x + toDesired.z * toDesired.z);

        if (distXZ > epsilon) {
            float desiredHeadingRad = std::atan2(toDesired.x, toDesired.z);
            raylib::Degree desiredHeading = raylib::Degree(desiredHeadingRad * RAD2DEG);

            float diff = float(desiredHeading) - float(myTf.heading);

            // norm to [-180, 180] for shortest turn direction
            angle_normalize(raylib::Degree(diff + 180) - raylib::Degree(180));

            float maxTurn = turningRate * dt;
            float turn = std::clamp(diff, -maxTurn, maxTurn);
            myTf.heading = angle_normalize(myTf.heading + raylib::Degree(turn));

            speed = std::min(speed + acceleration * dt, maxSpeed);
        } else {
            speed = std::max(speed - acceleration * dt, 0.0f);
        }

        raylib::Vector3 move = velocity_from_speed_heading(speed, myTf.heading);

        myTf.position.x += move.x * dt;
        myTf.position.z += move.z * dt;

        float yDiff = desired.y - myTf.position.y;
        myTf.position.y += yDiff * 5.0f * dt;
    }
};

struct InputComponent : public Component {
    raylib::BufferedInput *input = nullptr;
    bool isActive = false;

    float axisForward = 0.0f;
    float axisTurn = 0.0f;
    bool keySpace = false;

    void Setup() override {
        if (!input) {
            return;
        }

        input->actions["forward"].AddCallback(
            [this](float state, float delta) { axisForward = state; });

        input->actions["turn"].AddCallback([this](float state, float delta) { axisTurn = state; });

        input->actions["space"].AddCallback(
            [this](float state, float delta) { keySpace = (state > 0.0f); });
    }

    void Cleanup() override {}

    void Update(float dt) override {
        if (!isActive) {
            return;
        }

        // might not be efficient
        auto oriented = entity->GetComponent<OrientedPhysicsComponent>();
        auto tf = entity->GetComponent<TransformComponent>();
        if (!tf) {
            return;
        }

        if (oriented) {
            OrientedPhysicsComponent &phys = oriented->get();

            float forward = axisForward;
            float turn = axisTurn;

            phys.speed += forward * phys.acceleration * dt;
            tf->get().heading =
                angle_normalize(tf->get().heading + raylib::Degree(turn * phys.turningRate * dt));

            if (keySpace) {
                phys.speed *= std::pow(0.05f, dt);
            }
        } else {
            auto phys = entity->GetComponent<PhysicsComponent>();
            if (!phys) {
                return;
            }

            PhysicsComponent &p = phys->get();

            float spd = std::sqrt(p.velocity.x * p.velocity.x + p.velocity.z * p.velocity.z);
            float forward = axisForward;
            float turn = axisTurn;

            spd += forward * p.acceleration * dt;
            tf->get().heading =
                angle_normalize(tf->get().heading + raylib::Degree(turn * p.turningRate * dt));

            if (keySpace) {
                spd *= std::pow(0.05f, dt);
            }

            spd = std::clamp(spd, -p.maxSpeed, p.maxSpeed);
            p.velocity = velocity_from_speed_heading(spd, tf->get().heading);
        }
    }
};

int main() {
    raylib::Window window(800, 600, "CS381 - Assignment 5");
    window.SetState(FLAG_WINDOW_RESIZABLE);
    raylib::AudioDevice audio;

    raylib::Model penguinModel("models/penguin.glb");
    raylib::Model eagleModel("models/eagle.glb");

    auto defaultPenguinTf = (raylib::Transform)penguinModel.GetTransform();
    defaultPenguinTf = defaultPenguinTf.RotateY(raylib::Degree(90));
    penguinModel.SetTransform(defaultPenguinTf);

    raylib::Model ground = raylib::Mesh::Plane(10000, 10000, 50, 50, 25);
    raylib::Texture snowTexture("textures/snow.jpg");
    ground.GetMaterials()[0].maps[MATERIAL_MAP_DIFFUSE].texture = snowTexture;

    cs381::SkyBox skybox("textures/skybox.png");

    raylib::Camera3D camera({0, 400, -768}, {0, -8, 0}, {0, 1, 0}, 45.0f);

    raylib::BufferedInput input;

    input.actions["forward"] =
        raylib::Action::button_axis({raylib::Button::key(KEY_W)}, {raylib::Button::key(KEY_S)})
            .move();
    input.actions["turn"] =
        raylib::Action::button_axis({raylib::Button::key(KEY_A)}, {raylib::Button::key(KEY_D)})
            .move();
    input.actions["space"] = raylib::Action::key(KEY_SPACE).move();
    input.actions["tab"] = raylib::Action::key(KEY_TAB).move();

    std::vector<Entity> entities;
    entities.reserve(10);

    auto makePenguin = [&](float xPos, float maxSpeed, float acceleration,
                           float turningRate) -> Entity & {
        Entity &e = entities.emplace_back();

        auto &tf = e.AddComponent<TransformComponent>();
        tf.position = raylib::Vector3(xPos, 0.0f, 0.0f);
        tf.heading = raylib::Degree(90.0f); // face right

        auto &phys = e.AddComponent<OrientedPhysicsComponent>();
        phys.maxSpeed = maxSpeed;
        phys.acceleration = acceleration;
        phys.turningRate = turningRate;

        auto &render = e.AddComponent<RenderComponent>();
        render.model = &penguinModel;

        auto &inp = e.AddComponent<InputComponent>();
        inp.input = &input;
        inp.Setup();

        return e;
    };

    // helper to add an eagle that follows a specific penguin entity
    auto makeEagle = [&](Entity &penguin, float xPos) -> Entity & {
        Entity &e = entities.emplace_back();

        auto &tf = e.AddComponent<TransformComponent>();
        tf.position = raylib::Vector3(xPos, 200.0f, 0.0f);
        tf.heading = raylib::Degree(90.0f);

        auto &follow = e.AddComponent<FollowComponent>();
        follow.target = &penguin;
        follow.maxSpeed = 220.0f;
        follow.acceleration = 70.0f;
        follow.turningRate = 100.0f;
        follow.hoverHeight = 200.0f;

        auto &render = e.AddComponent<RenderComponent>();
        render.model = &eagleModel;

        auto &inp = e.AddComponent<InputComponent>();
        inp.input = &input;
        inp.Setup();

        return e;
    };

    Entity &p0 = makePenguin(-400.0f, 50.0f, 50.0f, 90.0f);
    Entity &p1 = makePenguin(-200.0f, 350.0f, 140.0f, 60.0f);
    Entity &p2 = makePenguin(0.0f, 150.0f, 220.0f, 200.0f);
    Entity &p3 = makePenguin(200.0f, 450.0f, 60.0f, 45.0f);
    Entity &p4 = makePenguin(400.0f, 800.0f, 4000.0f, 500.0f);

    makeEagle(p0, -400.0f);
    makeEagle(p1, -200.0f);
    makeEagle(p2, 0.0f);
    makeEagle(p3, 200.0f);
    makeEagle(p4, 400.0f);

    int selectedIdx = 0;

    input.actions["tab"].AddPressedCallback([&]() {
        auto &old = entities[selectedIdx];
        if (auto r = old.GetComponent<RenderComponent>()) {
            r->get().drawBoundingBox = false;
        }
        if (auto i = old.GetComponent<InputComponent>()) {
            i->get().isActive = false;
        }

        selectedIdx = (selectedIdx + 1) % (int)entities.size();

        auto &current = entities[selectedIdx];
        if (auto r = current.GetComponent<RenderComponent>()) {
            r->get().drawBoundingBox = true;
        }
        if (auto i = current.GetComponent<InputComponent>()) {
            i->get().isActive = true;
        }
    });

    if (auto r = entities[selectedIdx].GetComponent<RenderComponent>()) {
        r->get().drawBoundingBox = true;
    }

    if (auto i = entities[selectedIdx].GetComponent<InputComponent>()) {
        i->get().isActive = true;
    }

    window.SetTargetFPS(60);

    while (!window.ShouldClose()) {
        float dt = window.GetFrameTime();

        input.PollEvents();

        window.BeginDrawing();
        window.ClearBackground(raylib::Color::Gray());

        // could probably make the camera be an entity and have a transform
        // and have a camera component but nah
        if (auto tf = entities[selectedIdx].GetComponent<TransformComponent>()) {
            TransformComponent &actualTfForReal = tf->get();
            raylib::Vector3 forward = velocity_from_speed_heading(1.0f, actualTfForReal.heading);

            const float camDistance = 768.0f;
            const float camHeight = 400.0f;

            camera.SetPosition({actualTfForReal.position.x - forward.x * camDistance,
                                actualTfForReal.position.y + camHeight,
                                actualTfForReal.position.z - forward.z * camDistance});

            camera.SetTarget({actualTfForReal.position.x, actualTfForReal.position.y - 8.0f,
                              actualTfForReal.position.z});
        }

        camera.BeginMode();

        skybox.Draw();
        ground.Draw({0, 0, 0}, 1.0f, raylib::Color::White());

        for (Entity &e : entities) {
            e.Update(dt);
        }

        camera.EndMode();

        window.EndDrawing();
    }

    return 0;
}