package service

import (
	"context"
	"errors"
	"testing"
)

type fakeCardToIBANClient struct {
	iban            string
	err             error
	called          bool
	receivedCard    string
	receivedContext context.Context
}

func (f *fakeCardToIBANClient) Convert(
	ctx context.Context,
	cardNumber string,
) (string, error) {
	f.called = true
	f.receivedCard = cardNumber
	f.receivedContext = ctx

	return f.iban, f.err
}

func TestCardServiceConvertCardToIBANSuccess(t *testing.T) {
	client := &fakeCardToIBANClient{
		iban: "IR123456789012345678901234",
	}

	service := NewCardService(client)

	cardNumber := "6037991234567890"

	iban, err := service.ConvertCardToIBAN(
		context.Background(),
		cardNumber,
	)

	if err != nil {
		t.Fatalf("ConvertCardToIBAN() unexpected error: %v", err)
	}

	if iban != client.iban {
		t.Errorf(
			"ConvertCardToIBAN() iban = %q, want %q",
			iban,
			client.iban,
		)
	}

	if !client.called {
		t.Error("expected client to be called")
	}

	if client.receivedCard != cardNumber {
		t.Errorf(
			"client received card = %q, want %q",
			client.receivedCard,
			cardNumber,
		)
	}
}

func TestCardServiceRejectsInvalidCardBeforeClientCall(t *testing.T) {
	client := &fakeCardToIBANClient{}

	service := NewCardService(client)

	_, err := service.ConvertCardToIBAN(
		context.Background(),
		"123",
	)

	if err == nil {
		t.Fatal("expected validation error")
	}

	if client.called {
		t.Error("client should not be called for an invalid card")
	}
}

func TestCardServiceReturnsClientError(t *testing.T) {
	clientErr := errors.New("upstream unavailable")

	client := &fakeCardToIBANClient{
		err: clientErr,
	}

	service := NewCardService(client)

	_, err := service.ConvertCardToIBAN(
		context.Background(),
		"6037991234567890",
	)

	if err == nil {
		t.Fatal("expected client error")
	}

	if !errors.Is(err, clientErr) {
		t.Errorf(
			"ConvertCardToIBAN() error = %v, want wrapped %v",
			err,
			clientErr,
		)
	}
}

func TestCardServicePassesContextToClient(t *testing.T) {
	client := &fakeCardToIBANClient{
		iban: "IR123456789012345678901234",
	}

	service := NewCardService(client)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	_, err := service.ConvertCardToIBAN(
		ctx,
		"6037991234567890",
	)

	if err != nil {
		t.Fatalf("ConvertCardToIBAN() unexpected error: %v", err)
	}

	if client.receivedContext != ctx {
		t.Error("service did not pass the request context to the client")
	}
}