package playletser

import (
	"context"
	"time"
	"videoweb/pub/common/srvdef"
	"videoweb/pub/models/playletmod"

	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo/options"
)

const operateRandomModulus int64 = 2147483647

func operateListFilter(typ int64) bson.M {
	filter := homeUpPlayletFilter(nil)
	if typ == operateListOriginal {
		filter[playletmod.FN.Playlet.IsRecommend] = true
	}
	return filter
}

func operateListSort(typ int64) bson.D {
	if typ == operateListHot {
		return bson.D{{Key: playletmod.FN.Playlet.HeatValue, Value: -1}, {Key: playletmod.FN.Playlet.Id, Value: -1}}
	}
	return playletRecentlyUpdatedSort()
}

// findRandomOperatePlaylets 按每日固定的伪随机顺序分页查询短剧
func findRandomOperatePlaylets(ctx context.Context, filter bson.M, skip, limit int64, now time.Time) (playletmod.PlayletList, *srvdef.SrvErr) {
	var rows []struct {
		Id int64 `bson:"_id"`
	}
	if err := playletmod.AggregatePlaylet(ctx, &rows, operateRandomPipeline(filter, skip, limit, now)); err != nil {
		return nil, err
	}
	ids := make([]int64, 0, len(rows))
	for _, row := range rows {
		ids = append(ids, row.Id)
	}
	if len(ids) == 0 {
		return make(playletmod.PlayletList, 0), nil
	}
	queryFilter := bson.M{playletmod.FN.Playlet.Id: bson.M{"$in": ids}}
	for key, value := range filter {
		queryFilter[key] = value
	}
	list, err := playletmod.FindManyPlaylet(ctx, queryFilter, options.Find().SetProjection(playletHomeProjection))
	if err != nil {
		return nil, err
	}
	byID := make(map[int64]*playletmod.Playlet, len(list))
	for _, item := range list {
		if item != nil {
			byID[item.Id] = item
		}
	}
	ordered := make(playletmod.PlayletList, 0, len(ids))
	for _, id := range ids {
		if item := byID[id]; item != nil {
			ordered = append(ordered, item)
		}
	}
	return ordered, nil
}

func operateRandomPipeline(filter bson.M, skip, limit int64, now time.Time) []bson.M {
	day := (now.Unix() + 8*60*60) / (24 * 60 * 60)
	factor := int64(48271) + day%997*2767
	idMod := bson.M{"$mod": bson.A{"$_id", operateRandomModulus}}
	score := bson.M{"$mod": bson.A{bson.M{"$multiply": bson.A{idMod, factor}}, operateRandomModulus}}
	return []bson.M{
		{"$match": filter},
		{"$project": bson.M{"_id": 1}},
		{"$addFields": bson.M{"randomScore": score}},
		{"$sort": bson.D{{Key: "randomScore", Value: 1}, {Key: "_id", Value: 1}}},
		{"$skip": skip},
		{"$limit": limit},
	}
}