package validator

import (
	"errors"
	"strings"
	"time"

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

	"github.com/google/uuid"
)

type CashAdvanceValidator interface {
	ValidateCreateCashAdvanceRequest(req *contract.CreateCashAdvanceRequest) (error, string)
	ValidateUpdateCashAdvanceRequest(req *contract.UpdateCashAdvanceRequest) (error, string)
	ValidateListCashAdvancesRequest(req *contract.ListCashAdvancesRequest) (error, string)
}

type CashAdvanceValidatorImpl struct{}

func NewCashAdvanceValidator() *CashAdvanceValidatorImpl {
	return &CashAdvanceValidatorImpl{}
}

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

	if strings.TrimSpace(req.CodeNumber) == "" {
		return errors.New("code_number is required"), constants.MissingFieldErrorCode
	}
	if len(req.CodeNumber) > 50 {
		return errors.New("code_number must be at most 50 characters"), constants.MalformedFieldErrorCode
	}

	if req.OutletID != nil && *req.OutletID == uuid.Nil {
		return errors.New("outlet_id cannot be empty"), constants.MalformedFieldErrorCode
	}

	// A cash advance is cash handed to a team, so the team is not optional here the way
	// it is on a purchase order: allowClear stays false and an empty scope is rejected.
	if err, code := validatePurchaseTeamSelection(&req.TeamScope, req.TeamCategoryID, false); err != nil {
		return err, code
	}

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

	issuedDate, err := time.Parse("2006-01-02", strings.TrimSpace(req.IssuedDate))
	if err != nil {
		return errors.New("issued_date must be in YYYY-MM-DD format"), constants.MalformedFieldErrorCode
	}

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

		dueDate, err := time.Parse("2006-01-02", *req.DueDate)
		if err != nil {
			return errors.New("due_date must be in YYYY-MM-DD format"), constants.MalformedFieldErrorCode
		}
		if dueDate.Before(issuedDate) {
			return errors.New("due_date must be after issued_date"), constants.MalformedFieldErrorCode
		}
	}

	if req.Status != nil && !constants.IsValidCashAdvanceStatus(*req.Status) {
		return errors.New("status must be one of: " + strings.Join(constants.GetAllCashAdvanceStatuses(), ", ")), constants.MalformedFieldErrorCode
	}

	return nil, ""
}

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

	if req.CodeNumber != nil {
		if strings.TrimSpace(*req.CodeNumber) == "" {
			return errors.New("code_number cannot be empty"), constants.MalformedFieldErrorCode
		}
		if len(*req.CodeNumber) > 50 {
			return errors.New("code_number must be at most 50 characters"), constants.MalformedFieldErrorCode
		}
	}

	// The team can be moved but never dropped, so clearing is not allowed here either.
	if err, code := validatePurchaseTeamSelection(req.TeamScope, req.TeamCategoryID, false); err != nil {
		return err, code
	}

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

	if req.ReturnedAmount != nil && *req.ReturnedAmount < 0 {
		return errors.New("returned_amount must be greater than or equal to 0"), constants.MalformedFieldErrorCode
	}

	var issuedDate *time.Time
	if req.IssuedDate != nil {
		if strings.TrimSpace(*req.IssuedDate) == "" {
			return errors.New("issued_date cannot be empty"), constants.MalformedFieldErrorCode
		}
		parsed, err := time.Parse("2006-01-02", *req.IssuedDate)
		if err != nil {
			return errors.New("issued_date must be in YYYY-MM-DD format"), constants.MalformedFieldErrorCode
		}
		issuedDate = &parsed
	}

	if req.DueDate != nil {
		if strings.TrimSpace(*req.DueDate) == "" {
			return errors.New("due_date cannot be empty"), constants.MalformedFieldErrorCode
		}
		dueDate, err := time.Parse("2006-01-02", *req.DueDate)
		if err != nil {
			return errors.New("due_date must be in YYYY-MM-DD format"), constants.MalformedFieldErrorCode
		}
		if issuedDate != nil && dueDate.Before(*issuedDate) {
			return errors.New("due_date must be after issued_date"), constants.MalformedFieldErrorCode
		}
	}

	if req.Status != nil && !constants.IsValidCashAdvanceStatus(*req.Status) {
		return errors.New("status must be one of: " + strings.Join(constants.GetAllCashAdvanceStatuses(), ", ")), constants.MalformedFieldErrorCode
	}

	return nil, ""
}

func (v *CashAdvanceValidatorImpl) ValidateListCashAdvancesRequest(req *contract.ListCashAdvancesRequest) (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.IsValidCashAdvanceStatus(req.Status) {
		return errors.New("status must be one of: " + strings.Join(constants.GetAllCashAdvanceStatuses(), ", ")), constants.MalformedFieldErrorCode
	}

	if req.SettlementStatus != "" && !constants.IsValidCashAdvanceSettlementStatus(req.SettlementStatus) {
		return errors.New("settlement_status must be one of: " + strings.Join(constants.GetAllCashAdvanceSettlementStatuses(), ", ")), constants.MalformedFieldErrorCode
	}

	if req.Team != "" {
		if req.TeamScope != "" || req.TeamCategoryID != nil {
			return errors.New("team cannot be combined with team_scope or team_category_id"), constants.MalformedFieldErrorCode
		}

		// Every cash advance has a team, so unlike purchases there is nothing to filter
		// for "no team yet": only Pusat or a category id make sense here.
		if req.Team != constants.PurchaseTeamScopeCentral {
			if categoryID, err := uuid.Parse(req.Team); err != nil || categoryID == uuid.Nil {
				return errors.New("team must be either central or a category id"), constants.MalformedFieldErrorCode
			}
		}
	}

	if req.TeamScope != "" {
		validScopes := []string{constants.PurchaseTeamScopeCategory, constants.PurchaseTeamScopeCentral}
		if !contains(validScopes, req.TeamScope) {
			return errors.New("team_scope must be one of: category, central"), constants.MalformedFieldErrorCode
		}

		if req.TeamScope == constants.PurchaseTeamScopeCentral && req.TeamCategoryID != nil {
			return errors.New("team_category_id must be empty when team_scope is central"), constants.MalformedFieldErrorCode
		}
	}

	if req.TeamCategoryID != nil && *req.TeamCategoryID == uuid.Nil {
		return errors.New("team_category_id cannot be empty"), constants.MalformedFieldErrorCode
	}

	if req.StartDate != nil && req.EndDate != nil && req.EndDate.Before(*req.StartDate) {
		return errors.New("end_date must be after start_date"), constants.MalformedFieldErrorCode
	}

	return nil, ""
}