package validator

import (
	"errors"
	"regexp"
	"strings"

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

type RewardValidator interface {
	ValidateCreateRewardRequest(req *contract.CreateRewardRequest) (error, string)
	ValidateUpdateRewardRequest(req *contract.UpdateRewardRequest) (error, string)
	ValidateListRewardsRequest(req *contract.ListRewardsRequest) (error, string)
	ValidateGetRewardRequest(req *contract.GetRewardRequest) (error, string)
	ValidateDeleteRewardRequest(req *contract.DeleteRewardRequest) (error, string)
}

type RewardValidatorImpl struct{}

func NewRewardValidator() RewardValidator {
	return &RewardValidatorImpl{}
}

func (v *RewardValidatorImpl) ValidateCreateRewardRequest(req *contract.CreateRewardRequest) (error, string) {
	if req == nil {
		return errors.New("request is required"), constants.ValidationErrorCode
	}

	// Validate name
	if strings.TrimSpace(req.Name) == "" {
		return errors.New("reward name is required"), constants.ValidationErrorCode
	}
	if len(req.Name) > 150 {
		return errors.New("reward name cannot exceed 150 characters"), constants.ValidationErrorCode
	}

	// Validate reward type
	if !v.isValidRewardType(req.RewardType) {
		return errors.New("invalid reward type. Valid types are: VOUCHER, PHYSICAL, DIGITAL, BALANCE"), constants.ValidationErrorCode
	}

	// Validate cost points
	if req.CostPoints <= 0 {
		return errors.New("cost points must be greater than 0"), constants.ValidationErrorCode
	}

	// Validate stock
	if req.Stock != nil && *req.Stock < 0 {
		return errors.New("stock cannot be negative"), constants.ValidationErrorCode
	}

	// Validate max per customer
	if req.MaxPerCustomer <= 0 {
		return errors.New("max per customer must be greater than 0"), constants.ValidationErrorCode
	}

	// Validate TNC if provided
	if req.Tnc != nil {
		if err := v.validateTermsAndConditions(req.Tnc); err != nil {
			return err, constants.ValidationErrorCode
		}
	}

	// Validate images if provided
	if req.Images != nil {
		if err := v.validateImages(*req.Images); err != nil {
			return err, constants.ValidationErrorCode
		}
	}

	return nil, ""
}

func (v *RewardValidatorImpl) ValidateUpdateRewardRequest(req *contract.UpdateRewardRequest) (error, string) {
	if req == nil {
		return errors.New("request is required"), constants.ValidationErrorCode
	}

	// Validate ID
	if req.ID.String() == "" {
		return errors.New("reward ID is required"), constants.ValidationErrorCode
	}

	// Validate name
	if strings.TrimSpace(req.Name) == "" {
		return errors.New("reward name is required"), constants.ValidationErrorCode
	}
	if len(req.Name) > 150 {
		return errors.New("reward name cannot exceed 150 characters"), constants.ValidationErrorCode
	}

	// Validate reward type
	if !v.isValidRewardType(req.RewardType) {
		return errors.New("invalid reward type. Valid types are: VOUCHER, PHYSICAL, DIGITAL, BALANCE"), constants.ValidationErrorCode
	}

	// Validate cost points
	if req.CostPoints <= 0 {
		return errors.New("cost points must be greater than 0"), constants.ValidationErrorCode
	}

	// Validate stock
	if req.Stock != nil && *req.Stock < 0 {
		return errors.New("stock cannot be negative"), constants.ValidationErrorCode
	}

	// Validate max per customer
	if req.MaxPerCustomer <= 0 {
		return errors.New("max per customer must be greater than 0"), constants.ValidationErrorCode
	}

	// Validate TNC if provided
	if req.Tnc != nil {
		if err := v.validateTermsAndConditions(req.Tnc); err != nil {
			return err, constants.ValidationErrorCode
		}
	}

	// Validate images if provided
	if req.Images != nil {
		if err := v.validateImages(*req.Images); err != nil {
			return err, constants.ValidationErrorCode
		}
	}

	return nil, ""
}

func (v *RewardValidatorImpl) ValidateListRewardsRequest(req *contract.ListRewardsRequest) (error, string) {
	if req == nil {
		return errors.New("request is required"), constants.ValidationErrorCode
	}

	// Validate pagination
	if req.Page < 1 {
		return errors.New("page must be greater than 0"), constants.ValidationErrorCode
	}
	if req.Limit < 1 {
		return errors.New("limit must be greater than 0"), constants.ValidationErrorCode
	}
	if req.Limit > 100 {
		return errors.New("limit cannot exceed 100"), constants.ValidationErrorCode
	}

	// Validate reward type filter if provided
	if req.RewardType != "" && !v.isValidRewardType(req.RewardType) {
		return errors.New("invalid reward type filter. Valid types are: VOUCHER, PHYSICAL, DIGITAL, BALANCE"), constants.ValidationErrorCode
	}

	// Validate points range if provided
	if req.MinPoints != nil && req.MaxPoints != nil {
		if *req.MinPoints > *req.MaxPoints {
			return errors.New("min points cannot be greater than max points"), constants.ValidationErrorCode
		}
		if *req.MinPoints < 0 {
			return errors.New("min points cannot be negative"), constants.ValidationErrorCode
		}
		if *req.MaxPoints < 0 {
			return errors.New("max points cannot be negative"), constants.ValidationErrorCode
		}
	}

	return nil, ""
}

func (v *RewardValidatorImpl) ValidateGetRewardRequest(req *contract.GetRewardRequest) (error, string) {
	if req == nil {
		return errors.New("request is required"), constants.ValidationErrorCode
	}

	if req.ID.String() == "" {
		return errors.New("reward ID is required"), constants.ValidationErrorCode
	}

	return nil, ""
}

func (v *RewardValidatorImpl) ValidateDeleteRewardRequest(req *contract.DeleteRewardRequest) (error, string) {
	if req == nil {
		return errors.New("request is required"), constants.ValidationErrorCode
	}

	if req.ID.String() == "" {
		return errors.New("reward ID is required"), constants.ValidationErrorCode
	}

	return nil, ""
}

func (v *RewardValidatorImpl) isValidRewardType(rewardType string) bool {
	validTypes := []string{"VOUCHER", "PHYSICAL", "DIGITAL", "BALANCE"}
	return contains(validTypes, rewardType)
}

func (v *RewardValidatorImpl) validateTermsAndConditions(tnc *contract.TermsAndConditionsStruct) error {
	if tnc == nil {
		return nil
	}

	// Validate expiry days
	if tnc.ExpiryDays < 0 {
		return errors.New("expiry days cannot be negative")
	}

	// Validate sections
	if len(tnc.Sections) == 0 {
		return errors.New("terms and conditions must have at least one section")
	}

	for i, section := range tnc.Sections {
		if strings.TrimSpace(section.Title) == "" {
			return errors.New("section title is required")
		}
		if len(section.Rules) == 0 {
			return errors.New("section must have at least one rule")
		}
		for j, rule := range section.Rules {
			if strings.TrimSpace(rule) == "" {
				return errors.New("rule cannot be empty")
			}
			if len(rule) > 500 {
				return errors.New("rule cannot exceed 500 characters")
			}
			// Validate rule content (basic validation)
			if len(rule) < 10 {
				return errors.New("rule must be at least 10 characters long")
			}
			_ = j // Avoid unused variable warning
		}
		_ = i // Avoid unused variable warning
	}

	return nil
}

func (v *RewardValidatorImpl) validateImages(images []string) error {
	if len(images) == 0 {
		return errors.New("at least one image is required")
	}

	for i, imgURL := range images {
		if strings.TrimSpace(imgURL) == "" {
			return errors.New("image URL is required")
		}

		// Validate URL format (basic validation)
		if !v.isValidURL(imgURL) {
			return errors.New("invalid image URL format")
		}

		_ = i // Avoid unused variable warning
	}

	return nil
}

func (v *RewardValidatorImpl) isValidURL(url string) bool {
	// Basic URL validation regex
	urlRegex := regexp.MustCompile(`^https?://[^\s/$.?#].[^\s]*$`)
	return urlRegex.MatchString(url)
}