package at.gv.egiz.moazs.backend;

import at.gv.egiz.moazs.MoaZSException;
import at.gv.egiz.moazs.repository.DeliveryRepository;
import at.gv.egiz.moazs.scheme.MsgResponse;
import at.gv.egiz.moazs.service.MsgService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.concurrent.CompletableFuture;
import java.util.function.Consumer;
import java.util.function.Function;

import static at.gv.egiz.moazs.MoaZSException.moaZSExceptionBuilder;
import static java.lang.String.format;
import static java.util.concurrent.CompletableFuture.supplyAsync;

@Component
public class MsgResponseBackend implements Consumer<String> {

    private static final Logger log = LoggerFactory.getLogger(MsgService.class);

    public static final String MOASP_SIGNATURE_INVALID_ERROR_MSG = "Signature of Msg Response " +
            "with AppDeliveryID=%s is not valid.";

    private final DeliveryRepository repository;
    private final Consumer<byte[]> signatureVerifier;
    private final Function<MsgResponse, CompletableFuture<Void>> sink;

    @Autowired
    public MsgResponseBackend(DeliveryRepository repository,
                              Consumer<byte[]> signatureVerifier,
                              Function<MsgResponse, CompletableFuture<Void>> sink) {
        this.repository = repository;
        this.signatureVerifier = signatureVerifier;
        this.sink = sink;
    }

    /**
     * Performs all {@code MsgResponse}'s Back-End Tasks, such as verifying
     * its signature and archiving the response.
     *
     * @param responseID refers to MsgResponse Object.
     */
    @Override
    public void accept(String responseID) {
        supplyAsync(() -> verify(responseID)).thenAcceptAsync(sink::apply);
    }

    public MsgResponse verify(String responseID) {

        var response = repository.retrieveResponse(responseID).get();
        var builder = moaZSExceptionBuilder().withAllParametersInAnswer(response.getAnswer());

        var binaryResponse = repository.retrieveBinaryResponse(responseID).get();

        try {
            signatureVerifier.accept(binaryResponse);
            return response;
        } catch (MoaZSException ex) {
            log.error(ex.getMessage(), ex);
            var wrappingEx = builder
                    .withMessage(format(MOASP_SIGNATURE_INVALID_ERROR_MSG, response.getAppDeliveryID()))
                    .withErrorCode(MoaZSException.ERROR_MOASP_SIGNATURE_INVALID)
                    .withCause(ex)
                    .build();

            return response.generateError(wrappingEx);
        }

    }

}