package srv_aicomment

import (
	"time"

	"videoweb/pub/models/playletmod"
)

func PlayletPublishedAt(playlet *playletmod.Playlet) time.Time {
	if playlet == nil {
		return time.Time{}
	}
	if !playlet.OnlineAt.IsZero() {
		return playlet.OnlineAt
	}
	if !playlet.ReviewAt.IsZero() {
		return playlet.ReviewAt
	}
	return playlet.CreatedAt
}

func ScatteredCommentTime(publishedAt, endAt time.Time, objectID, commentID int64, index, total int) time.Time {
	if total <= 0 || index < 0 || index >= total || publishedAt.IsZero() || !publishedAt.Before(endAt) {
		return endAt
	}

	span := endAt.Sub(publishedAt)
	segment := span / time.Duration(total)
	segmentStart := segment * time.Duration(index)
	segmentEnd := segment * time.Duration(index+1)
	if index == total-1 {
		segmentEnd = span
	}
	width := segmentEnd - segmentStart
	if width <= 0 {
		return publishedAt.Add(segmentStart)
	}

	seed := scatterSeed(objectID, commentID, int64(index))
	offset := time.Duration(seed % uint64(width))
	return publishedAt.Add(segmentStart + offset)
}

func scatterSeed(values ...int64) uint64 {
	const (
		offsetBasis = uint64(1469598103934665603)
		prime       = uint64(1099511628211)
	)
	hash := offsetBasis
	for _, value := range values {
		hash ^= uint64(value)
		hash *= prime
	}
	return hash
}