package tender_submission

import (
	"errors"
	"fmt"
	"strings"
)

var (
	ErrTenderSubmissionNotFound = errors.New("tender submission not found")
	ErrTenderSubmissionExists   = errors.New("tender submission already exists for this tender and company")
	ErrInvalidStatus            = errors.New("invalid tender submission status")
	ErrInvalidStage             = errors.New("invalid tender submission stage")
	ErrTenderNotFound           = errors.New("tender not found")
	ErrApprovalRequired         = errors.New("tender must be approved before starting submission workflow")
	ErrInvalidStatusTransition  = errors.New("invalid status transition")
	ErrTerminalStatus           = errors.New("tender submission is in a terminal state and cannot be updated")
	ErrConcurrentUpdate         = errors.New("tender submission was modified concurrently")
)

// InvalidStatusTransitionError is returned when a status change is not allowed.
type InvalidStatusTransitionError struct {
	CurrentStatus string
	NewStatus     string
	Allowed       []string
}

func (e *InvalidStatusTransitionError) Error() string {
	if len(e.Allowed) == 0 {
		return fmt.Sprintf("Tender submission status is already %s and cannot be changed", e.CurrentStatus)
	}
	return fmt.Sprintf(
		"Cannot change tender submission status from %s to %s. Allowed next statuses: %s",
		e.CurrentStatus,
		e.NewStatus,
		strings.Join(e.Allowed, ", "),
	)
}

func NewInvalidStatusTransitionError(currentStatus, newStatus string, allowed []string) *InvalidStatusTransitionError {
	return &InvalidStatusTransitionError{
		CurrentStatus: currentStatus,
		NewStatus:     newStatus,
		Allowed:       allowed,
	}
}