package order

import (
	"context"
	"fmt"
)

// PassthroughProvider records an already-settled authorization and capture without
// calling an external provider. It is the bridge between the checkout grain's
// externally-processed payments (Klarna, Adyen) and the order grain's event log:
// the payment was already settled by the provider, so the order grain just needs
// to record the facts.
//
// Create one per order with the exact provider name, reference and amount the
// external processor returned. Refund returns an error — use the external
// processor's own refund API for that. Void is a no-op.
type PassthroughProvider struct {
	name      string
	reference string
	amount    int64
}

// NewPassthroughProvider returns a provider that records provider/ref/amount
// for both authorize and capture. amount is in minor currency units (öre).
func NewPassthroughProvider(providerName, reference string, amount int64) *PassthroughProvider {
	return &PassthroughProvider{
		name:      providerName,
		reference: reference,
		amount:    amount,
	}
}

var _ PaymentProvider = (*PassthroughProvider)(nil)

func (p *PassthroughProvider) Name() string { return p.name }

func (p *PassthroughProvider) Authorize(_ context.Context, _ string, _ int64, _ string) (Authorization, error) {
	return Authorization{
		Provider:  p.name,
		Reference: p.reference,
		Amount:    p.amount,
	}, nil
}

func (p *PassthroughProvider) Capture(_ context.Context, _ string, _ int64) (Capture, error) {
	if p.reference == "" {
		return Capture{}, fmt.Errorf("passthrough: capture requires a processor reference")
	}
	return Capture{
		Provider:  p.name,
		Reference: p.reference,
		Amount:    p.amount,
	}, nil
}

func (p *PassthroughProvider) Refund(_ context.Context, _ string, _ int64) (RefundResult, error) {
	return RefundResult{}, fmt.Errorf("passthrough: refund not implemented — use the external provider directly")
}

func (p *PassthroughProvider) Void(_ context.Context, _ string) error { return nil }