package repositories

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"strings"
	"time"

	"gitlab.com/mbugroup/lti-api.git/internal/common/repository"
	entity "gitlab.com/mbugroup/lti-api.git/internal/entities"
	utils "gitlab.com/mbugroup/lti-api.git/internal/utils"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

type PurchaseRepository interface {
	repository.BaseRepository[entity.Purchase]
	CreateWithItems(ctx context.Context, purchase *entity.Purchase, items []*entity.PurchaseItem) error
	CreateItems(ctx context.Context, purchaseID uint, items []*entity.PurchaseItem) error
	UpdatePricing(ctx context.Context, purchaseID uint, updates []PurchasePricingUpdate) error
	UpdateReceivingDetails(ctx context.Context, purchaseID uint, updates []PurchaseReceivingUpdate) error
	DeleteItems(ctx context.Context, purchaseID uint, itemIDs []uint) error
	NextPrNumber(ctx context.Context, tx *gorm.DB) (string, error)
	NextPoNumber(ctx context.Context, tx *gorm.DB) (string, error)
	BackfillProjectFlockKandang(ctx context.Context, purchaseID uint) error
}

type PurchaseRepositoryImpl struct {
	*repository.BaseRepositoryImpl[entity.Purchase]
}

func NewPurchaseRepository(db *gorm.DB) PurchaseRepository {
	return &PurchaseRepositoryImpl{
		BaseRepositoryImpl: repository.NewBaseRepository[entity.Purchase](db),
	}
}

func (r *PurchaseRepositoryImpl) CreateWithItems(ctx context.Context, purchase *entity.Purchase, items []*entity.PurchaseItem) error {
	db := r.DB().WithContext(ctx)

	//ambil dari base repository
	if err := db.Create(purchase).Error; err != nil {
		return err
	}

	if len(items) == 0 {
		return nil
	}

	for _, item := range items {
		item.PurchaseId = purchase.Id
	}

	if err := db.Create(&items).Error; err != nil {
		return err
	}
	return nil
}

func (r *PurchaseRepositoryImpl) BackfillProjectFlockKandang(ctx context.Context, purchaseID uint) error {
	if purchaseID == 0 {
		return nil
	}

	query := `
WITH latest_pfk AS (
	SELECT pfk.id, pfk.kandang_id
	FROM project_flock_kandangs pfk
	JOIN (
		SELECT DISTINCT ON (approvable_id) approvable_id, step_name, action_at
		FROM approvals
		WHERE approvable_type = 'PROJECT_FLOCKS'
		ORDER BY approvable_id, action_at DESC
	) latest_approval ON latest_approval.approvable_id = pfk.project_flock_id
	WHERE LOWER(latest_approval.step_name) = LOWER('Aktif')
)
UPDATE purchase_items pi
SET project_flock_kandang_id = lp.id
FROM warehouses w
JOIN latest_pfk lp ON lp.kandang_id = w.kandang_id
WHERE pi.purchase_id = ?
  AND pi.project_flock_kandang_id IS NULL
  AND pi.warehouse_id = w.id;
`
	return r.DB().WithContext(ctx).Exec(query, purchaseID).Error
}

func (r *PurchaseRepositoryImpl) CreateItems(ctx context.Context, purchaseID uint, items []*entity.PurchaseItem) error {
	if len(items) == 0 {
		return nil
	}

	for _, item := range items {
		if item == nil {
			continue
		}
		item.PurchaseId = purchaseID
	}

	return r.DB().WithContext(ctx).Create(&items).Error
}

type PurchasePricingUpdate struct {
	ItemID     uint
	ProductID  *uint
	Price      float64
	TotalPrice float64
	Quantity   *float64
	TotalQty   *float64
}

type PurchaseReceivingUpdate struct {
	ItemID                uint
	ReceivedDate          *time.Time
	TravelNumber          *string
	TravelDocumentPath    *string
	VehicleNumber         *string
	ReceivedQty           *float64
	WarehouseID           *uint
	ProductWarehouseID    *uint
	ClearProductWarehouse bool
}

func (r *PurchaseRepositoryImpl) UpdatePricing(
	ctx context.Context,
	purchaseID uint,
	updates []PurchasePricingUpdate,
) error {
	if len(updates) == 0 {
		return errors.New("pricing updates cannot be empty")
	}

	db := r.DB().WithContext(ctx)

	for _, upd := range updates {
		data := map[string]interface{}{
			"price":       upd.Price,
			"total_price": upd.TotalPrice,
		}
		if upd.ProductID != nil {
			data["product_id"] = *upd.ProductID
		}
		if upd.Quantity != nil {
			data["sub_qty"] = *upd.Quantity
		}
		if upd.TotalQty != nil {
			data["total_qty"] = *upd.TotalQty
		}

		result := db.Model(&entity.PurchaseItem{}).
			Where("purchase_id = ? AND id = ?", purchaseID, upd.ItemID).
			Updates(data)
		if result.Error != nil {
			return result.Error
		}
		if result.RowsAffected == 0 {
			return gorm.ErrRecordNotFound
		}
	}

	return nil
}

func (r *PurchaseRepositoryImpl) UpdateReceivingDetails(
	ctx context.Context,
	purchaseID uint,
	updates []PurchaseReceivingUpdate,
) error {
	if len(updates) == 0 {
		return errors.New("receiving updates cannot be empty")
	}

	db := r.DB().WithContext(ctx)

	for _, upd := range updates {
		data := map[string]interface{}{}

		if upd.ReceivedDate != nil {
			data["received_date"] = upd.ReceivedDate
		}
		if upd.TravelNumber != nil {
			data["travel_number"] = upd.TravelNumber
		}
		if upd.TravelDocumentPath != nil {
			data["travel_number_docs"] = upd.TravelDocumentPath
		}
		if upd.VehicleNumber != nil {
			data["vehicle_number"] = upd.VehicleNumber
		}
		if upd.ReceivedQty != nil {
			data["total_qty"] = upd.ReceivedQty
		}
		if upd.WarehouseID != nil && *upd.WarehouseID != 0 {
			data["warehouse_id"] = upd.WarehouseID
		}

		if upd.ProductWarehouseID != nil {
			data["product_warehouse_id"] = *upd.ProductWarehouseID
		} else if upd.ClearProductWarehouse {
			data["product_warehouse_id"] = gorm.Expr("NULL")
		}

		if len(data) == 0 {
			continue
		}

		result := db.Model(&entity.PurchaseItem{}).
			Where("purchase_id = ? AND id = ?", purchaseID, upd.ItemID).
			Updates(data)
		if result.Error != nil {
			return result.Error
		}
		if result.RowsAffected == 0 {
			return gorm.ErrRecordNotFound
		}
	}

	return nil
}

func (r *PurchaseRepositoryImpl) DeleteItems(ctx context.Context, purchaseID uint, itemIDs []uint) error {
	if len(itemIDs) == 0 {
		return errors.New("itemIDs cannot be empty")
	}

	return r.DB().WithContext(ctx).
		Where("purchase_id = ? AND id IN ?", purchaseID, itemIDs).
		Delete(&entity.PurchaseItem{}).Error
}

func (r *PurchaseRepositoryImpl) NextPrNumber(ctx context.Context, tx *gorm.DB) (string, error) {
	return r.generateSequentialNumber(ctx, tx, "pr_number", utils.PurchasePRNumberPrefix, utils.PurchaseNumberPadding)
}

func (r *PurchaseRepositoryImpl) NextPoNumber(ctx context.Context, tx *gorm.DB) (string, error) {
	return r.generateSequentialNumber(ctx, tx, "po_number", utils.PurchasePONumberPrefix, utils.PurchaseNumberPadding)
}

func (r *PurchaseRepositoryImpl) generateSequentialNumber(ctx context.Context, tx *gorm.DB, column, prefix string, padding int) (string, error) {
	db := tx
	if db == nil {
		db = r.DB()
	}

	var values []string
	err := db.WithContext(ctx).
		Model(&entity.Purchase{}).
		Where(fmt.Sprintf("%s LIKE ?", column), prefix+"%").
		Select(column).
		Order(fmt.Sprintf("%s DESC", column)).
		Limit(20).
		Clauses(clause.Locking{Strength: "UPDATE"}).
		Pluck(column, &values).Error
	if err != nil {
		return "", err
	}

	next := 1
	for _, value := range values {
		if number, ok := parseNumericSuffix(value, prefix); ok {
			next = number + 1
			break
		}
	}

	const maxAttempts = 20
	for attempt := 0; attempt < maxAttempts; attempt++ {
		candidate := fmt.Sprintf("%s%0*d", prefix, padding, next)
		exists, err := r.numberExists(ctx, db, column, candidate)
		if err != nil {
			return "", err
		}
		if !exists {
			return candidate, nil
		}
		next++
	}

	return "", fmt.Errorf("unable to generate unique %s", column)
}

func (r *PurchaseRepositoryImpl) numberExists(ctx context.Context, db *gorm.DB, column, value string) (bool, error) {
	var count int64
	if err := db.WithContext(ctx).
		Model(&entity.Purchase{}).
		Where(fmt.Sprintf("%s = ?", column), value).
		Count(&count).Error; err != nil {
		return false, err
	}
	return count > 0, nil
}

func parseNumericSuffix(value, prefix string) (int, bool) {
	if !strings.HasPrefix(value, prefix) {
		return 0, false
	}
	suffix := strings.TrimPrefix(value, prefix)
	if suffix == "" {
		return 0, false
	}
	trimmed := strings.TrimLeft(suffix, "0")
	if trimmed == "" {
		trimmed = "0"
	}
	number, err := strconv.Atoi(trimmed)
	if err != nil {
		return 0, false
	}
	return number, true
}