package validator

import (
	"errors"
	"fmt"
	"strings"

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

	"github.com/google/uuid"
)

type ExpenseValidator interface {
	ValidateCreateExpenseRequest(req *contract.CreateExpenseRequest) (error, string)
	ValidateUpdateExpenseRequest(req *contract.UpdateExpenseRequest) (error, string)
	ValidateListExpenseRequest(req *contract.ListExpenseRequest) (error, string)
}

type ExpenseValidatorImpl struct{}

func NewExpenseValidator() *ExpenseValidatorImpl {
	return &ExpenseValidatorImpl{}
}

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

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

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

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

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

	if _, err := uuid.Parse(req.OutletID); err != nil {
		return errors.New("outlet_id must be a valid UUID"), constants.MalformedFieldErrorCode
	}

	if req.Status != nil && !constants.IsValidExpenseStatus(constants.ExpenseStatus(*req.Status)) {
		return errors.New("status must be one of: draft, sent, approved, cancel"), constants.MalformedFieldErrorCode
	}

	if req.Total <= 0 {
		return errors.New("total must be greater than 0"), constants.MalformedFieldErrorCode
	}

	if req.Tax < 0 {
		return errors.New("tax cannot be negative"), constants.MalformedFieldErrorCode
	}

	if len(req.Items) == 0 {
		return errors.New("at least one item is required"), constants.MissingFieldErrorCode
	}

	for i, item := range req.Items {
		if strings.TrimSpace(item.ChartOfAccountID) == "" {
			return fmt.Errorf("item %d: chart_of_account_id is required", i), constants.MissingFieldErrorCode
		}
		if strings.TrimSpace(item.PurchaseCategoryID) == "" {
			return fmt.Errorf("item %d: purchase_category_id is required", i), constants.MissingFieldErrorCode
		}
		if strings.TrimSpace(item.Item) == "" {
			return fmt.Errorf("item %d: item is required", i), constants.MissingFieldErrorCode
		}
		if _, err := uuid.Parse(item.ChartOfAccountID); err != nil {
			return fmt.Errorf("item %d: chart_of_account_id must be a valid UUID", i), constants.MalformedFieldErrorCode
		}
		if _, err := uuid.Parse(item.PurchaseCategoryID); err != nil {
			return fmt.Errorf("item %d: purchase_category_id must be a valid UUID", i), constants.MalformedFieldErrorCode
		}
		if item.Amount <= 0 {
			return fmt.Errorf("item %d: amount must be greater than 0", i), constants.MalformedFieldErrorCode
		}
	}

	return nil, ""
}

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

	if req.Receiver != nil && strings.TrimSpace(*req.Receiver) == "" {
		return errors.New("receiver cannot be empty"), constants.MalformedFieldErrorCode
	}

	if req.CodeNumber != nil && strings.TrimSpace(*req.CodeNumber) == "" {
		return errors.New("code_number cannot be empty"), constants.MalformedFieldErrorCode
	}

	if req.Status != nil && !constants.IsValidExpenseStatus(constants.ExpenseStatus(*req.Status)) {
		return errors.New("status must be one of: draft, sent, approved, cancel"), constants.MalformedFieldErrorCode
	}

	if req.OutletID != nil {
		if strings.TrimSpace(*req.OutletID) == "" {
			return errors.New("outlet_id cannot be empty"), constants.MalformedFieldErrorCode
		}
		if _, err := uuid.Parse(*req.OutletID); err != nil {
			return errors.New("outlet_id must be a valid UUID"), constants.MalformedFieldErrorCode
		}
	}

	if req.Total != nil && *req.Total <= 0 {
		return errors.New("total must be greater than 0"), constants.MalformedFieldErrorCode
	}

	if req.Tax != nil && *req.Tax < 0 {
		return errors.New("tax cannot be negative"), constants.MalformedFieldErrorCode
	}

	if req.Items != nil {
		for i, item := range req.Items {
			if item.ChartOfAccountID != nil {
				if strings.TrimSpace(*item.ChartOfAccountID) == "" {
					return fmt.Errorf("item %d: chart_of_account_id cannot be empty", i), constants.MalformedFieldErrorCode
				}
				if _, err := uuid.Parse(*item.ChartOfAccountID); err != nil {
					return fmt.Errorf("item %d: chart_of_account_id must be a valid UUID", i), constants.MalformedFieldErrorCode
				}
			}
			if item.PurchaseCategoryID == nil {
				return fmt.Errorf("item %d: purchase_category_id is required", i), constants.MissingFieldErrorCode
			}
			if strings.TrimSpace(*item.PurchaseCategoryID) == "" {
				return fmt.Errorf("item %d: purchase_category_id cannot be empty", i), constants.MalformedFieldErrorCode
			}
			if _, err := uuid.Parse(*item.PurchaseCategoryID); err != nil {
				return fmt.Errorf("item %d: purchase_category_id must be a valid UUID", i), constants.MalformedFieldErrorCode
			}
			if item.Item != nil && strings.TrimSpace(*item.Item) == "" {
				return fmt.Errorf("item %d: item cannot be empty", i), constants.MalformedFieldErrorCode
			}
			if item.Amount != nil && *item.Amount <= 0 {
				return fmt.Errorf("item %d: amount must be greater than 0", i), constants.MalformedFieldErrorCode
			}
		}
	}

	return nil, ""
}

func (v *ExpenseValidatorImpl) ValidateListExpenseRequest(req *contract.ListExpenseRequest) (error, string) {
	if req == nil {
		return errors.New("request body 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
	}

	if req.Status != "" && !constants.IsValidExpenseStatus(constants.ExpenseStatus(req.Status)) {
		return errors.New("status must be one of: draft, sent, approved, cancel"), constants.MalformedFieldErrorCode
	}

	return nil, ""
}