package repository

import (
	"codeword/internal/models"
	"context"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"time"
)

// структура для горутины чтобы ошибки не пропускать
type countResult struct {
	count int64
	err   error
}

type PromoCodeRepository struct {
	mdb *mongo.Collection
}

func NewPromoCodeRepository(mdb *mongo.Collection) *PromoCodeRepository {
	return &PromoCodeRepository{mdb: mdb}
}

func InitPromoCodeIndexes(ctx context.Context, mdb *mongo.Collection) error {
	uniqueIndexModel := mongo.IndexModel{
		Keys: bson.D{
			{Key: "codeword", Value: 1},
			{Key: "delete", Value: 1},
		},
		Options: options.Index().SetUnique(true).SetPartialFilterExpression(bson.M{"delete": false}),
	}
	_, err := mdb.Indexes().CreateOne(ctx, uniqueIndexModel)
	if err != nil {
		return err
	}

	textIndexModel := mongo.IndexModel{
		Keys: bson.D{
			{Key: "codeword", Value: "text"},
			{Key: "description", Value: "text"},
			{Key: "greetings", Value: "text"},
		},
		Options: options.Index().SetName("TextIndex"),
	}
	_, err = mdb.Indexes().CreateOne(ctx, textIndexModel)
	if err != nil {
		return err
	}

	return nil
}

func (r *PromoCodeRepository) CreatePromoCode(ctx context.Context, req *models.PromoCode) (*models.PromoCode, error) {
	req.CreatedAt = time.Now()
	req.ID = primitive.NewObjectID()
	if req.FastLinks == nil {
		req.FastLinks = []string{}
	}

	_, err := r.mdb.InsertOne(ctx, req)
	if err != nil {
		if writeErr, ok := err.(mongo.WriteException); ok {
			for _, writeError := range writeErr.WriteErrors {
				if writeError.Code == 11000 {
					return nil, ErrDuplicateCodeword
				}
			}
		}

		return nil, err
	}

	return req, nil
}

func (r *PromoCodeRepository) EditPromoCode(ctx context.Context, req *models.ReqEditPromoCode) (*models.PromoCode, error) {
	promoCodeID, err := primitive.ObjectIDFromHex(req.ID)
	if err != nil {
		return nil, err
	}

	updateFields := bson.M{}
	if req.Description != nil {
		updateFields["description"] = *req.Description
	}
	if req.Greetings != nil {
		updateFields["greetings"] = *req.Greetings
	}
	if req.DueTo != nil {
		updateFields["dueTo"] = *req.DueTo
	}
	if req.ActivationCount != nil {
		updateFields["activationCount"] = *req.ActivationCount
	}
	if req.Delete != nil {
		updateFields["delete"] = *req.Delete
	}

	if req.Bonus != nil {
		if req.Bonus.Privilege != nil {
			if req.Bonus.Privilege.PrivilegeID != "" {
				updateFields["bonus.privilege.privilegeID"] = req.Bonus.Privilege.PrivilegeID
			}
			if req.Bonus.Privilege.Amount != 0 {
				updateFields["bonus.privilege.amount"] = req.Bonus.Privilege.Amount
			}
		}
		if req.Bonus.Discount != nil {
			if req.Bonus.Discount.Layer != 0 {
				updateFields["bonus.discount.layer"] = req.Bonus.Discount.Layer
			}
			if req.Bonus.Discount.Factor != 0.0 {
				updateFields["bonus.discount.factor"] = req.Bonus.Discount.Factor
			}
			if req.Bonus.Discount.Target != "" {
				updateFields["bonus.discount.target"] = req.Bonus.Discount.Target
			}
			if req.Bonus.Discount.Threshold != 0 {
				updateFields["bonus.discount.threshold"] = req.Bonus.Discount.Threshold
			}
		}
	}

	if len(updateFields) == 0 {
		return r.GetPromoCodeByID(ctx, promoCodeID)
	}

	update := bson.M{"$set": updateFields}
	options := options.FindOneAndUpdate().SetReturnDocument(options.After)
	result := r.mdb.FindOneAndUpdate(ctx, bson.M{"_id": promoCodeID}, update, options)
	if result.Err() != nil {
		return nil, result.Err()
	}

	var updatedPromoCode models.PromoCode
	err = result.Decode(&updatedPromoCode)
	if err != nil {
		return nil, err
	}

	return &updatedPromoCode, nil
}

func (r *PromoCodeRepository) GetPromoCodeByID(ctx context.Context, promoCodeID primitive.ObjectID) (*models.PromoCode, error) {
	var promoCode models.PromoCode
	err := r.mdb.FindOne(ctx, bson.M{"_id": promoCodeID}).Decode(&promoCode)
	if err != nil {
		if err == mongo.ErrNoDocuments {
			return nil, ErrPromoCodeNotFound
		}

		return nil, err
	}

	return &promoCode, nil
}

func (r *PromoCodeRepository) GetPromoCodesList(ctx context.Context, req *models.GetPromoCodesListReq) ([]models.PromoCode, int64, error) {
	filter := bson.M{}

	if req.Filter.Text != "" {
		filter["$text"] = bson.M{"$search": req.Filter.Text}
	}

	if req.Filter.Active {
		filter["delete"] = false
		filter["outdated"] = false
		filter["offLimit"] = false
	} else {
		filter["$or"] = []interface{}{
			bson.M{"delete": true},
			bson.M{"outdated": true},
			bson.M{"offLimit": true},
		}
	}

	opt := options.Find().SetSkip(int64(req.Page * req.Limit)).SetLimit(int64(req.Limit))

	var countChan = make(chan countResult)
	go func() {
		defer close(countChan)
		count, err := r.mdb.CountDocuments(ctx, filter)
		countChan <- countResult{count, err}
	}()

	cursor, err := r.mdb.Find(ctx, filter, opt)
	if err != nil {
		return nil, 0, err
	}
	defer cursor.Close(ctx)

	var promoCodes = make([]models.PromoCode, 0, 10)
	for cursor.Next(ctx) {
		var p models.PromoCode
		if err := cursor.Decode(&p); err != nil {
			return nil, 0, err
		}
		promoCodes = append(promoCodes, p)
	}

	if err := cursor.Err(); err != nil {
		return nil, 0, err
	}

	result := <-countChan
	if result.err != nil {
		return nil, 0, result.err
	}
	count := result.count

	return promoCodes, count, nil
}

func (r *PromoCodeRepository) ActivatePromo(ctx context.Context, req *models.ActivateReq) (*models.PromoCode, error) {
	var promoCode models.PromoCode

	var filter bson.M
	if req.Codeword != "" {
		filter = bson.M{
			"codeword": req.Codeword,
		}
	} else if req.FastLink != "" {
		filter = bson.M{
			"fastLinks": req.FastLink,
		}
	}

	opts := options.FindOneAndUpdate().SetReturnDocument(options.After)

	err := r.mdb.FindOneAndUpdate(ctx, filter, bson.M{"$inc": bson.M{"activationCount": -1}}, opts).Decode(&promoCode)
	if err != nil {
		if err == mongo.ErrNoDocuments {
			return nil, ErrPromoCodeNotFound
		}
		return nil, err
	}

	if promoCode.ActivationCount <= 0 && promoCode.DueTo > time.Now().Unix() {
		if !promoCode.OffLimit {
			update := bson.M{"$set": bson.M{"offLimit": true}}
			_, err := r.mdb.UpdateOne(ctx, filter, update)
			if err != nil {
				return nil, err
			}
		}
	}
	return &promoCode, nil
}

func (r *PromoCodeRepository) IncreaseActivationCount(ctx context.Context, promoCodeID primitive.ObjectID) error {
	filter := bson.M{"_id": promoCodeID}
	update := bson.M{"$inc": bson.M{"activationCount": 1}}
	_, err := r.mdb.UpdateOne(ctx, filter, update)
	if err != nil {
		return err
	}

	return nil
}

func (r *PromoCodeRepository) DeletePromoCode(ctx context.Context, promoCodeID string) error {
	id, err := primitive.ObjectIDFromHex(promoCodeID)
	if err != nil {
		return err
	}

	result, err := r.mdb.UpdateOne(
		ctx,
		bson.M{"_id": id, "delete": false},
		bson.M{"$set": bson.M{"delete": true}},
	)
	if err != nil {
		return err
	}

	if result.MatchedCount == 0 {
		return ErrPromoCodeNotFound
	}

	return nil
}

func (r *PromoCodeRepository) AddFastLink(ctx context.Context, promoCodeID primitive.ObjectID, xid string) error {
	filter := bson.M{"_id": promoCodeID, "delete": false}
	update := bson.M{"$push": bson.M{"fastLinks": xid}}

	result, err := r.mdb.UpdateOne(ctx, filter, update)
	if err != nil {
		return err
	}

	if result.MatchedCount == 0 {
		return ErrPromoCodeNotFound
	}

	return nil
}