#include "animationsystem.h"

#include <fstream>
#include <sstream>
#include <json.hpp>

#include "mesh.h"
#include "stringutils.h"
#include "worldmanager.h"
#include "world.h"
#include "assetmanager.h"
#include "entityparser.h"

Cinematic* AnimationSystem::loadCinematic(const std::string& path) {
    std::ifstream file("data/" + path);
    if(!file)
        return nullptr;

    nlohmann::json json;
    file >> json;

    auto cinematic = new Cinematic();
    for(auto shotObject : json["shots"]) {
        Shot* shot = new Shot();
        shot->start = shotObject["start"];
        shot->end = shotObject["end"];
        shot->world = shotObject["world"];

        for(auto entityObject : shotObject["entities"]) {
            CinematicEntity entity;
            entity.data = entityObject;

            shot->entities.push_back(entity);
        }

        for(auto animationObject : shotObject["animations"]) {
            auto animation = new Animation();
            animation->targetName = animationObject["target"];
            animation->targetComponent = animationObject["targetComponent"];

            const auto property = animationObject["property"];
            if(property == "position")
                animation->property = AnimationProperty::Position;
            else if(property == "target")
                animation->property = AnimationProperty::Target;
            else if(property == "fov")
                animation->property = AnimationProperty::FoV;

            for(auto keyframeObject : animationObject["keyframes"]) {
                Keyframe keyframe;
                keyframe.time = keyframeObject["time"];

                if(animation->property == AnimationProperty::Position || animation->property == AnimationProperty::Target) {
                    auto tokens = tokenize(keyframeObject["value"]);

                    keyframe.valueVec3[0] = atof(tokens[0].c_str());
                    keyframe.valueVec3[1] = atof(tokens[1].c_str());
                    keyframe.valueVec3[2] = atof(tokens[2].c_str());

                    animation->keyframes.push_back(keyframe);
                } else if(animation->property == AnimationProperty::FoV) {
                    keyframe.valueInt = keyframeObject["value"];

                    animation->keyframes.push_back(keyframe);
                }
            }

            shot->animations.push_back(animation);
        }

        cinematic->shots.push_back(shot);
    }

    preloadShot(cinematic->shots[0]);
    loadShot(cinematic->shots[0]);

    return cinematic;
}

void AnimationSystem::update(Cinematic* cinematic, float deltaTime) {
    float endTime = 0.0f;
    for(uint32_t i = 0; i < cinematic->shots.size(); i++) {
        // load the shot before it happens
        if((i + 1) <= cinematic->shots.size() && i == (currentShot + 1)  && !cinematic->shots[currentShot + 1]->loaded) {
            preloadShot(cinematic->shots[currentShot + 1]);
            cinematic->shots[currentShot + 1]->loaded = true;
        }

        if(i > currentShot && animationTime > cinematic->shots[i]->start) {
            unloadShot(cinematic->shots[currentShot]);
            currentShot = i;
            loadShot(cinematic->shots[i]);
        }
    }

    for(auto animation : cinematic->shots[currentShot]->animations) {
        unsigned int frameIndex = 0;
        for(size_t i = 0; i < animation->keyframes.size(); i++) {
            if(animationTime < animation->keyframes[i + 1].time) {
                frameIndex = i;
                break;
            }
        }

        const auto currentFrame = animation->keyframes[frameIndex];
        const auto nextFrame = animation->keyframes[(frameIndex + 1) % animation->keyframes.size()];

        const float delta = (animationTime - currentFrame.time) / (nextFrame.time - currentFrame.time);

        switch(animation->property) {
            case AnimationProperty::Position:
            {
                auto pos = currentFrame.valueVec3 + delta * (nextFrame.valueVec3 - currentFrame.valueVec3);

                if(animation->targetComponent == "Transform") {
                    TransformComponent* transform = ECS::getComponent<TransformComponent>(animation->target);
                    transform->position = pos;
                }
            }
            break;
            case AnimationProperty::Target:
            {
                auto pos = currentFrame.valueVec3 + delta * (nextFrame.valueVec3 - currentFrame.valueVec3);

                if(animation->targetComponent == "Camera") {
                    CameraComponent* camera = ECS::getComponent<CameraComponent>(animation->target);
                    camera->target = pos;
                }
            }
            break;
            case AnimationProperty::FoV:
            {
                auto pos = currentFrame.valueInt + delta * (nextFrame.valueInt - currentFrame.valueInt);

                if(animation->targetComponent == "Camera") {
                    CameraComponent* camera = ECS::getComponent<CameraComponent>(animation->target);
                    camera->fov = pos;
                }
            }
            break;
        }
    }

    animationTime += deltaTime;
}

void AnimationSystem::preloadShot(Shot* shot) {
    worldManager.loadWorld(shot->world);

    for(auto cimEntity : shot->entities) {
        EntityID entity = parseEntity(cimEntity.data, worldManager.getWorld(shot->world));

        for(auto animation : shot->animations) {
            if(animation->targetName == ECS::getComponent<InfoComponent>(entity)->name)
                animation->target = entity;
        }

        shot->loadedEntities.push_back(entity);
    }
}

void AnimationSystem::loadShot(Shot* shot) {
    worldManager.switchWorld(shot->world);
}

void AnimationSystem::unloadShot(Shot* shot) {
    World* world = worldManager.getCurrentWorld();

    for(auto entity : shot->loadedEntities)
        ECS::destroyEntity(entity);
}