package de.mlessmann.certassist.service;

import de.mlessmann.certassist.except.CommandLineOperationException;
import de.mlessmann.certassist.models.*;
import de.mlessmann.certassist.openssl.*;
import de.mlessmann.certassist.repositories.CertificateRepository;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.time.OffsetDateTime;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.StreamSupport;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.lang.NonNull;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Service;

@Slf4j
@Service
@RequiredArgsConstructor
public class CertificateCreationService {

    private final CertificateRepository certificateRepository;
    private final OpenSSLService openSSLService;
    private final PassphraseService passphraseService;
    private final Pattern CERT_START_PATTERN = Pattern.compile("-+BEGIN CERTIFICATE-+");
    private final Pattern CERT_END_PATTERN = Pattern.compile("-+END CERTIFICATE-+");

    public Certificate createCertificate(final CertificateInfo certificateInfo) {
        final Certificate certificate = createEntityFromRequest(certificateInfo);

        try (OpenSSLCertificateResult certificateCreatorResult = openSSLService.createCertificate(certificateInfo);) {
            Path keyPath = certificateCreatorResult.certificateKeyPath();
            certificate.setFingerprint(certificateCreatorResult.fingerprint());
            if (keyPath != null) {
                certificate.setPrivateKey(Files.readAllBytes(keyPath));
            }
            certificate.setCert(Files.readAllBytes(certificateCreatorResult.certificatePath()));
        } catch (CommandLineOperationException | IOException e) {
            throw new IllegalStateException("Failed to create certificate!", e);
        }

        certificateRepository.save(certificate);
        return certificate;
    }

    private Certificate createEntityFromRequest(CertificateInfo certificateInfo) {
        final Certificate certificate = new Certificate();
        certificate.setType(mapCertificateRequestType(certificateInfo.getType()));
        certificate.setSubjectCommonName(certificateInfo.getSubject().getCommonName());
        certificate.setTrustingAuthority(certificateInfo.getTrustingAuthority());
        certificate.setRequestedKeyLength(certificateInfo.getRequestedKeyLength());
        certificate.setNotBefore(OffsetDateTime.now());
        certificate.setNotAfter(OffsetDateTime.now().plusDays(certificateInfo.getRequestedValidityDays()));

        final CertificateInfoSubject subjectInfo = certificateInfo.getSubject();
        certificate.setSubjectEmailAddress(subjectInfo.getEmailAddress());
        certificate.setSubjectOrganization(subjectInfo.getOrganization());
        certificate.setSubjectOrganizationalUnit(subjectInfo.getOrganizationalUnit());
        certificate.setSubjectCountry(subjectInfo.getCountry());
        certificate.setSubjectState(subjectInfo.getState());
        certificate.setSubjectLocality(subjectInfo.getLocality());

        final CertificateInfoExtension extension = certificateInfo.getExtension();
        if (extension != null) {
            final CertificateExtension certificateExtension = new CertificateExtension();
            certificateExtension.setIdentifier("alternativeNames");
            certificateExtension.setValue(String.join(",", extension.getAlternativeDnsNames()));
            certificate.setCertificateExtension(List.of(certificateExtension));
        }
        return certificate;
    }

    private Certificate createEntityFromInfo(X509CertificateInfo info) {
        final Certificate certificate = new Certificate();
        certificate.setType(
            mapCertificateRequestType(
                info.issuer() != null
                    ? CertificateInfo.RequestType.NORMAL_CERTIFICATE
                    : CertificateInfo.RequestType.STANDALONE_CERTIFICATE
            )
        );
        certificate.setSubjectCommonName(info.subject().getCommonName());
        certificate.setTrustingAuthority(info.issuer().getCommonName());
        certificate.setRequestedKeyLength(-1);
        certificate.setNotBefore(info.notBefore());
        certificate.setNotAfter(info.notAfter());

        final CertificateInfoSubject subjectInfo = info.subject();
        certificate.setSubjectEmailAddress(subjectInfo.getEmailAddress());
        certificate.setSubjectOrganization(subjectInfo.getOrganization());
        certificate.setSubjectOrganizationalUnit(subjectInfo.getOrganizationalUnit());
        certificate.setSubjectCountry(subjectInfo.getCountry());
        certificate.setSubjectState(subjectInfo.getState());
        certificate.setSubjectLocality(subjectInfo.getLocality());

        final CertificateInfoExtension extension = info.extensions().getFirst();
        if (extension != null) {
            final CertificateExtension certificateExtension = new CertificateExtension();
            certificateExtension.setIdentifier("alternativeNames");
            certificateExtension.setValue(String.join(",", extension.getAlternativeDnsNames()));
            certificate.setCertificateExtension(List.of(certificateExtension));
        }
        return certificate;
    }

    @NonNull
    public Certificate importCertificate(
        @NonNull Path certificate,
        @Nullable Path keyFile,
        @Nullable String keyPassphrase
    ) {
        try {
            String fingerprint = openSSLService.getCertificateFingerprint(certificate);
            Certificate entity = createEntityFromInfo(openSSLService.getCertificateInfo(certificate));
            entity.setFingerprint(fingerprint);
            entity.setCert(Files.readAllBytes(certificate));
            if (keyFile != null) {
                entity.setPrivateKey(Files.readAllBytes(keyFile));
            }
            if (StringUtils.isNotBlank(keyPassphrase)) {
                passphraseService.storePassphrase("cert:" + fingerprint, keyPassphrase);
            }
            return certificateRepository.save(entity);
        } catch (CommandLineOperationException | IOException e) {
            throw new RuntimeException("Unable to import certificate", e);
        }
    }

    public List<Certificate> importCertificateTrustBundle(@NonNull Path bundleFile) {
        try {
            Map<String, Certificate> certsInBundle = new HashMap<>();
            String pemContent = Files.readString(bundleFile);
            Matcher beginMatcher = CERT_START_PATTERN.matcher(pemContent);

            while (beginMatcher.find()) {
                int startIdx = beginMatcher.start();
                Matcher endMatcher = CERT_END_PATTERN.matcher(pemContent);
                if (!endMatcher.find(startIdx)) {
                    throw new IllegalStateException("Certificate has a startIdx but not an end??");
                }
                int endIdx = endMatcher.end();
                String singleCert = pemContent.substring(startIdx, endIdx);
                String fingerprint = openSSLService.getCertificateFingerprint(singleCert);
                Certificate entity = createEntityFromInfo(openSSLService.getCertificateInfo(singleCert));
                entity.setFingerprint(fingerprint);
                entity.setCert(singleCert.getBytes());
                certsInBundle.put(fingerprint, entity);
                log.debug("Found certificate in bundle at {} to {}: {}", startIdx, endIdx, fingerprint);
            }

            var saveResult = certificateRepository.saveAll(certsInBundle.values());
            return StreamSupport.stream(saveResult.spliterator(), false).toList();
        } catch (CommandLineOperationException | IOException e) {
            throw new RuntimeException("Unable to import certificate", e);
        }
    }

    private CertificateType mapCertificateRequestType(CertificateInfo.RequestType requestType) {
        return switch (requestType) {
            case ROOT_AUTHORITY -> CertificateType.ROOT_CA;
            case STANDALONE_CERTIFICATE -> CertificateType.STANDALONE_CERT;
            case NORMAL_CERTIFICATE -> CertificateType.SIGNED_CERT;
        };
    }
}