apskel-pos-backend/internal/validator/inventory_validator.go

package validator

import (
	"errors"
	"strings"

	"apskel-pos-be/internal/constants"
	"apskel-pos-be/internal/contract"

	"github.com/google/uuid"
)

type InventoryValidator interface {
	ValidateCreateInventoryRequest(req *contract.CreateInventoryRequest) (error, string)
	ValidateUpdateInventoryRequest(req *contract.UpdateInventoryRequest) (error, string)
	ValidateListInventoryRequest(req *contract.ListInventoryRequest) (error, string)
	ValidateAdjustInventoryRequest(req *contract.AdjustInventoryRequest) (error, string)
}

type InventoryValidatorImpl struct{}

func NewInventoryValidator() *InventoryValidatorImpl {
	return &InventoryValidatorImpl{}
}

func (v *InventoryValidatorImpl) ValidateCreateInventoryRequest(req *contract.CreateInventoryRequest) (error, string) {
	if req == nil {
		return errors.New("request body is required"), constants.MissingFieldErrorCode
	}

	if req.OutletID == uuid.Nil {
		return errors.New("outlet_id is required"), constants.MissingFieldErrorCode
	}

	if req.ProductID == uuid.Nil {
		return errors.New("product_id is required"), constants.MissingFieldErrorCode
	}

	if req.Quantity < 0 {
		return errors.New("quantity must be non-negative"), constants.MalformedFieldErrorCode
	}

	if req.ReorderLevel < 0 {
		return errors.New("reorder_level must be non-negative"), constants.MalformedFieldErrorCode
	}

	return nil, ""
}

func (v *InventoryValidatorImpl) ValidateUpdateInventoryRequest(req *contract.UpdateInventoryRequest) (error, string) {
	if req == nil {
		return errors.New("request body is required"), constants.MissingFieldErrorCode
	}

	// At least one field should be provided for update
	if req.Quantity == nil && req.ReorderLevel == nil {
		return errors.New("at least one field must be provided for update"), constants.MissingFieldErrorCode
	}

	if req.Quantity != nil && *req.Quantity < 0 {
		return errors.New("quantity must be non-negative"), constants.MalformedFieldErrorCode
	}

	if req.ReorderLevel != nil && *req.ReorderLevel < 0 {
		return errors.New("reorder_level must be non-negative"), constants.MalformedFieldErrorCode
	}

	return nil, ""
}

func (v *InventoryValidatorImpl) ValidateListInventoryRequest(req *contract.ListInventoryRequest) (error, string) {
	if req == nil {
		return errors.New("request is required"), constants.MissingFieldErrorCode
	}

	if req.Page < 1 {
		return errors.New("page must be at least 1"), constants.MalformedFieldErrorCode
	}

	if req.Limit < 1 || req.Limit > 100 {
		return errors.New("limit must be between 1 and 100"), constants.MalformedFieldErrorCode
	}

	return nil, ""
}

func (v *InventoryValidatorImpl) ValidateAdjustInventoryRequest(req *contract.AdjustInventoryRequest) (error, string) {
	if req == nil {
		return errors.New("request body is required"), constants.MissingFieldErrorCode
	}

	if req.ProductID == uuid.Nil {
		return errors.New("product_id is required"), constants.MissingFieldErrorCode
	}

	if req.OutletID == uuid.Nil {
		return errors.New("outlet_id is required"), constants.MissingFieldErrorCode
	}

	if req.Delta == 0 {
		return errors.New("delta cannot be zero"), constants.MalformedFieldErrorCode
	}

	if strings.TrimSpace(req.Reason) == "" {
		return errors.New("reason is required"), constants.MissingFieldErrorCode
	}

	if len(req.Reason) < 1 || len(req.Reason) > 255 {
		return errors.New("reason must be between 1 and 255 characters"), constants.MalformedFieldErrorCode
	}

	return nil, ""
}