// Package idempotency defines the deduplication record used by Mail Service
// acceptance flows.
package idempotency

import (
	"fmt"
	"strings"
	"time"

	"galaxy/mail/internal/domain/common"
	"galaxy/mail/internal/domain/delivery"
)

// Record stores the first accepted fingerprint bound to one `(source,
// idempotency_key)` scope.
type Record struct {
	// Source stores the frozen delivery source vocabulary value.
	Source delivery.Source

	// IdempotencyKey stores the caller-owned deduplication key.
	IdempotencyKey common.IdempotencyKey

	// DeliveryID stores the accepted delivery linked to the scope.
	DeliveryID common.DeliveryID

	// RequestFingerprint stores the stable fingerprint of the first accepted
	// request.
	RequestFingerprint string

	// CreatedAt stores when the deduplication record was created.
	CreatedAt time.Time

	// ExpiresAt stores when the deduplication record becomes invalid.
	ExpiresAt time.Time
}

// Validate reports whether Record satisfies the frozen Stage 2 structural
// invariants.
func (record Record) Validate() error {
	if !record.Source.IsKnown() {
		return fmt.Errorf("idempotency source %q is unsupported", record.Source)
	}
	if err := record.IdempotencyKey.Validate(); err != nil {
		return fmt.Errorf("idempotency key: %w", err)
	}
	if err := record.DeliveryID.Validate(); err != nil {
		return fmt.Errorf("idempotency delivery id: %w", err)
	}
	if err := validateToken("idempotency request fingerprint", record.RequestFingerprint); err != nil {
		return err
	}
	if err := common.ValidateTimestamp("idempotency created at", record.CreatedAt); err != nil {
		return err
	}
	if err := common.ValidateTimestamp("idempotency expires at", record.ExpiresAt); err != nil {
		return err
	}
	if !record.ExpiresAt.After(record.CreatedAt) {
		return fmt.Errorf("idempotency expires at must be after created at")
	}

	return nil
}

func validateToken(name string, value string) error {
	switch {
	case strings.TrimSpace(value) == "":
		return fmt.Errorf("%s must not be empty", name)
	case strings.TrimSpace(value) != value:
		return fmt.Errorf("%s must not contain surrounding whitespace", name)
	default:
		return nil
	}
}