#include "tweening.h"

#include "animationRules.h"

JoiningContinuousTimeline<Shape> insertTweens(const JoiningContinuousTimeline<Shape>& animation) {
    const centiseconds minTweenDuration = 4_cs;
    const centiseconds maxTweenDuration = 8_cs;

    JoiningContinuousTimeline<Shape> result(animation);

    for_each_adjacent(
        animation.begin(),
        animation.end(),
        [&](const auto& first, const auto& second) {
            auto pair = getTween(first.getValue(), second.getValue());
            if (!pair) return;

            Shape tweenShape;
            TweenTiming tweenTiming;
            std::tie(tweenShape, tweenTiming) = *pair;
            TimeRange firstTimeRange = first.getTimeRange();
            TimeRange secondTimeRange = second.getTimeRange();

            centiseconds tweenStart, tweenDuration;
            switch (tweenTiming) {
                case TweenTiming::Early: {
                    tweenDuration = std::min(firstTimeRange.getDuration() / 3, maxTweenDuration);
                    tweenStart = firstTimeRange.getEnd() - tweenDuration;
                    break;
                }
                case TweenTiming::Centered: {
                    tweenDuration = std::min(
                        {firstTimeRange.getDuration() / 4,
                         secondTimeRange.getDuration() / 4,
                         maxTweenDuration}
                    );
                    tweenStart = firstTimeRange.getEnd() - tweenDuration / 2;
                    break;
                }
                case TweenTiming::Late: {
                    tweenDuration = std::min(secondTimeRange.getDuration() / 3, maxTweenDuration);
                    tweenStart = secondTimeRange.getStart();
                    break;
                }
                default: {
                    throw std::runtime_error("Unexpected tween timing.");
                }
            }

            if (tweenDuration < minTweenDuration) return;

            result.set(tweenStart, tweenStart + tweenDuration, tweenShape);
        }
    );

    return result;
}