#include "anime_loader.hpp"

using ::basalt::shared::math::FloatPoint;

namespace basalt::shared::anime_loader {

#pragma region Anime Loader

    IAnimeLoader::IAnimeLoader() : status(AnimeLoaderStatus::Ready), time(0), last_index(0) {}

    IAnimeLoader::~IAnimeLoader() {}

    void IAnimeLoader::load() {
        if (this->status != AnimeLoaderStatus::Ready) throw std::runtime_error("unexpected anime loader status");

        // load by user
        internal_load();

        // check empty
        if (this->frames.empty()) throw std::runtime_error("no anime key frames.");
        // Get last frame index
        auto last_pair = this->frames.end();
        --last_pair;
        this->last_index = last_pair->first;

        // change status
        this->status = AnimeLoaderStatus::Loaded;
    }

    KeyFrameSpan IAnimeLoader::tick() {
        if (this->status != AnimeLoaderStatus::Loaded) throw std::runtime_error("unexpected anime loader status");

        // Accumulate time
        ++this->time;
        if (this->time > this->last_index) {
            this->time = 0;
        }

        // 首先用lower_bound获取到不小于自身的项目（肯定能获取到）
        auto lower_bound = this->frames.lower_bound(this->time);
        // 获取下一帧，如果没有下一帧，就转换为自身
        auto upper_bound = lower_bound;
        ++upper_bound;
        if (upper_bound == this->frames.end()) {
            upper_bound = lower_bound;
        }

        // 计算归一化时间
        FloatPoint next_time = static_cast<FloatPoint>(this->time - lower_bound->first)
                               / static_cast<FloatPoint>(upper_bound->first - lower_bound->first + 1);
        FloatPoint prev_time = static_cast<FloatPoint>(1) - next_time;

        // 返回结构
        return KeyFrameSpan{
            .prev_time = prev_time,
            .next_time = next_time,
            .prev_position = lower_bound->second.position,
            .next_position = upper_bound->second.position,
            .prev_rotation = lower_bound->second.rotation,
            .next_rotation = upper_bound->second.rotation,
        };
    }

    void IAnimeLoader::internal_load() {
        throw std::logic_error("unimplemented function");
    }

#pragma endregion

} // namespace basalt::shared::anime_loader