package com.juick.server;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.juick.server.api.activity.model.Context;
import com.juick.server.api.activity.model.Person;
import com.juick.service.activities.DeleteUserEvent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Component;
import org.springframework.web.client.HttpClientErrorException;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;
import org.tomitribe.auth.signatures.Signature;
import org.tomitribe.auth.signatures.Signer;
import org.tomitribe.auth.signatures.Verifier;

import javax.inject.Inject;
import java.io.IOException;
import java.net.URI;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SignatureException;
import java.time.Instant;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.Map;
import java.util.Optional;

@Component
public class SignatureManager {
    private static final Logger logger = LoggerFactory.getLogger(ActivityPubManager.class);
    @Inject
    private KeystoreManager keystoreManager;
    @Inject
    private ObjectMapper jsonMapper;
    @Inject
    private ApplicationEventPublisher applicationEventPublisher;

    public void post(Person from, Person to, Context data) throws IOException {
        UriComponentsBuilder uriComponentsBuilder = UriComponentsBuilder.fromUriString(to.getInbox());
        URI inbox = uriComponentsBuilder.build().toUri();
        Instant now = Instant.now();
        String requestDate = DateTimeFormatter.RFC_1123_DATE_TIME.withZone(ZoneId.of("UTC")).format(now);
        Signature templateSignature = new Signature(from.getPublicKey().getId(), "rsa-sha256", null,
                "(request-target)", "host", "date");
        Signer signer = new Signer(keystoreManager.getPrivateKey(), templateSignature);
        Map<String, String> headers = new HashMap<>();
        headers.put("host", inbox.getHost());
        headers.put("date", requestDate);
        Signature signature = signer.sign("POST", inbox.getPath(), headers);
        HttpHeaders requestHeaders = new HttpHeaders();
        requestHeaders.add("Content-Type", Context.ACTIVITY_JSON_MEDIA_TYPE);
        requestHeaders.add("Date", requestDate);
        requestHeaders.add("Signature", signature.toString().substring(10));
        HttpEntity<Context> request = new HttpEntity<>(Context.build(data), requestHeaders);
        //boolean valid = verifySignature(Signature.fromString(requestHeaders.getFirst("Signature")),
          //      keystoreManager.getPublicKey(), "POST", inbox.getPath(), headers);
        logger.info("Sending context: {}", jsonMapper.writeValueAsString(data));
        ResponseEntity<Void> response = new RestTemplate().postForEntity(inbox, request, Void.class);
        logger.info("accepted follower: {}", response.getStatusCodeValue());
    }
    public boolean verifySignature(String signatureString, URI actor, String method, String path, Map<String, String> headers) {
        Optional<Context> context = getContext(actor);
        if (context.isPresent() && context.get() instanceof Person) {
            Person person = (Person) context.get();
            Key key = KeystoreManager.publicKeyOf(person);
            Verifier verifier = new Verifier(key, Signature.fromString(signatureString));
            try {
                boolean result = verifier.verify(method, path, headers);
                logger.info("signature is valid: {}", result);
                return result;
            } catch (NoSuchAlgorithmException | SignatureException | IOException e) {
                logger.info("signature exception", e);
                return false;
            }
        }
        logger.info("person not found");
        return false;
    }
    public Optional<Context> getContext(URI contextUri) {
        try {
            return Optional.of(new RestTemplate().getForEntity(contextUri, Context.class).getBody());
        } catch (HttpClientErrorException e) {
            logger.warn("Cannot identify {}", contextUri);
            if (e.getStatusCode().equals(HttpStatus.GONE)) {
                logger.warn("Server report {} is gone, deleting", contextUri);
                applicationEventPublisher.publishEvent(new DeleteUserEvent(this, contextUri.toASCIIString()));
            }
        }
        return Optional.empty();
    }
}