package processor

import (
	"context"
	"errors"

	"github.com/google/uuid"
)

var (
	// ErrVoucherProviderRejected is what an adapter wraps when the provider definitely
	// will not issue the voucher: out of stock, the product retired, the request
	// refused. The redemption fails and the EnakPoint go back.
	ErrVoucherProviderRejected = errors.New("voucher provider refused")
	// ErrVoucherProviderNotFound is what an adapter's Lookup wraps when the provider
	// has no record of the redemption: the issue request never reached it.
	ErrVoucherProviderNotFound = errors.New("voucher provider has no such redemption")
)

// VoucherIssueRequest is one redemption of an EXTERNAL voucher sent to its provider.
type VoucherIssueRequest struct {
	// The provider's idempotency key: asking twice for the same redemption must give
	// the same voucher, never a second one (docs/rfc-enakgame.md §7.5).
	RedemptionID uuid.UUID
	// The provider's own reference of the product, from vouchers.provider_ref.
	ProviderRef *string
	VoucherID   uuid.UUID
	FaceValue   int64
	CustomerID  uuid.UUID
}

// VoucherIssue is what a provider handed out.
type VoucherIssue struct {
	Code string
	// The provider's reference of this issue, for support and reconciliation.
	Ref string
}

// VoucherProvider issues EXTERNAL vouchers (EG-801). Adapters classify every outcome
// through the error they return:
//
//   - nil: issued.
//   - wrapping ErrVoucherProviderRejected: definitely not issued, and never will be.
//   - wrapping ErrVoucherProviderNotFound (Lookup only): the provider never got it.
//   - anything else, a timeout above all: unknown. The redemption stays PENDING and
//     the recovery job asks again.
type VoucherProvider interface {
	Issue(ctx context.Context, req VoucherIssueRequest) (*VoucherIssue, error)
	Lookup(ctx context.Context, req VoucherIssueRequest) (*VoucherIssue, error)
}

// VoucherProviders are the adapters by the name vouchers.provider holds.
type VoucherProviders map[string]VoucherProvider

// voucherIssueOutcome is how one call to a provider ended.
type voucherIssueOutcome int

const (
	voucherIssued voucherIssueOutcome = iota
	voucherRejected
	voucherUnknown
	voucherNotFound
)

func classifyVoucherIssue(issue *VoucherIssue, err error) voucherIssueOutcome {
	switch {
	case err == nil && issue != nil && issue.Code != "":
		return voucherIssued
	case errors.Is(err, ErrVoucherProviderRejected):
		return voucherRejected
	case errors.Is(err, ErrVoucherProviderNotFound):
		return voucherNotFound
	}
	// An error of any other kind, or a success without a code, settles nothing.
	return voucherUnknown
}