package customer

import (
	"context"
	"errors"
	"strings"
)

var errCompanyNotAssigned = errors.New("company is not assigned to customer")

// pickActiveCompanyID chooses the company context for a customer request.
// When requestedCompanyID is set it must be in assigned; otherwise a still-valid
// token company is kept; if the token company was removed, the first assignment is used.
func pickActiveCompanyID(assigned []string, tokenCompanyID, requestedCompanyID string) (string, error) {
	if len(assigned) == 0 {
		return "", nil
	}

	requested := strings.TrimSpace(requestedCompanyID)
	if requested != "" {
		for _, id := range assigned {
			if id == requested {
				return requested, nil
			}
		}
		return "", errCompanyNotAssigned
	}

	token := strings.TrimSpace(tokenCompanyID)
	if token != "" {
		for _, id := range assigned {
			if id == token {
				return token, nil
			}
		}
	}

	return assigned[0], nil
}

// ResolveActiveCompanyID resolves the active company for an authenticated customer.
func (s *customerService) ResolveActiveCompanyID(ctx context.Context, customerID, tokenCompanyID, requestedCompanyID string) (string, error) {
	customer, err := s.repository.GetByID(ctx, customerID)
	if err != nil {
		return "", errors.New("customer not found")
	}

	return pickActiveCompanyID(customer.Companies, tokenCompanyID, requestedCompanyID)
}