package ledger

import (
	"fmt"
	"time"
)

type SettlementStatus string

const (
	SettlementPending      SettlementStatus = "PENDING"
	SettlementSubmitted    SettlementStatus = "SUBMITTED"
	SettlementConfirmed    SettlementStatus = "CONFIRMED"
	SettlementRetryable    SettlementStatus = "RETRYABLE"
	SettlementManualReview SettlementStatus = "MANUAL_REVIEW"
)

type Settlement struct {
	ID                   string
	SourceService        string
	SourceTxID           string
	IdempotencyKey       string
	Status               SettlementStatus
	Network              string
	TransactionHash      string
	Attempts             int
	AvailableAt          time.Time
	LastError            string
	SignedTransactionXDR string
}

type SettlementStats struct {
	Pending              int64
	Retryable            int64
	ManualReview         int64
	OldestPendingSeconds int64
}

func (s Settlement) Validate() error {
	if s.ID == "" || s.SourceService == "" || s.SourceTxID == "" || s.IdempotencyKey == "" {
		return fmt.Errorf("settlement identity fields are required")
	}
	if s.Status != SettlementPending && s.Status != SettlementSubmitted && s.Status != SettlementConfirmed && s.Status != SettlementRetryable && s.Status != SettlementManualReview {
		return fmt.Errorf("invalid settlement status %q", s.Status)
	}
	if s.Attempts < 0 || s.AvailableAt.IsZero() {
		return fmt.Errorf("invalid settlement retry state")
	}
	return nil
}

func (s Settlement) Retry(now time.Time, maxAttempts int, err error) Settlement {
	s.LastError = err.Error()
	s.Status = SettlementRetryable
	if maxAttempts > 0 && s.Attempts >= maxAttempts {
		s.Status = SettlementManualReview
	}
	delay := time.Second
	for i := 1; i < s.Attempts && delay < 15*time.Minute; i++ {
		delay *= 2
	}
	if delay > 15*time.Minute {
		delay = 15 * time.Minute
	}
	s.AvailableAt = now.UTC().Add(delay)
	return s
}