/*
  Copyright 2020 Nokia
  <p>
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  <p>
  http://www.apache.org/licenses/LICENSE-2.0
  <p>
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
 */

package org.onap.cvc.csar.cc.sol004.r130206;

import org.onap.cvc.csar.CSARArchive;
import org.onap.cvc.csar.parser.SourcesParser;
import org.onap.cvc.csar.security.CertificateLoadingException;
import org.onap.cvc.csar.security.CmsSignatureData;
import org.onap.cvc.csar.security.CmsSignatureLoadingException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.nio.file.Path;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Optional;

import static org.onap.validation.csar.FileUtil.getFileNameWithoutExtension;

public class CsarSecurityValidator {

    private static final Logger LOG = LoggerFactory.getLogger(CsarSecurityValidator.class);

    private static final String EMPTY_STRING = "";
    public static final String CERTIFICATE_EXTENSION = ".cert";
    private final FileSignatureValidator fileSignatureValidator = new FileSignatureValidator();

    private final List<CSARArchive.CSARError> errors = new ArrayList<>();

    private final CSARArchive csar;
    private final Path csarRootDirectory;

    public CsarSecurityValidator(CSARArchive csar, Path csarRootDirectory) {
        this.csar = csar;
        this.csarRootDirectory = csarRootDirectory;
    }

    public List<CSARArchive.CSARError> validate() throws IOException, NoSuchAlgorithmException {
        this.errors.clear();
        if (containsCms()) {
            validateCsarSecurity();
        } else if (containAnySecurityElements()) {
            this.errors.add(new Error.CSARErrorUnableToFindCms());
        } else {
            this.errors.add(new Error.CSARWarningNoSecurity());
        }
        return errors;
    }

    private boolean containAnySecurityElements() {
        return (containsToscaMeta() && containsCertificateInTosca()) ||
            containsCertificateInRootCatalog() ||
            containsPerArtifactSecurity();
    }

    private void validateCsarSecurity() throws NoSuchAlgorithmException, IOException {
        try {
            CmsSignatureData signatureData = this.fileSignatureValidator.createSignatureDataForManifestFile(csar.getManifestMfFile());
            if (signatureData.getCertificate().isPresent()) {
                validateCertificationUsingCmsCertificate(signatureData);
            } else if (containsToscaMeta()) {
                validateCertificationUsingTosca(signatureData);
            } else if (containsCertificateInRootCatalog()) {
                validateCertificationUsingCertificateFromRootDirectory(signatureData);
            } else {
                this.errors.add(new Error.CSARErrorUnableToFindCertificate());
            }
        } catch (CmsSignatureLoadingException e) {
            LOG.error("Unable to load CMS!", e);
            this.errors.add(new Error.CSARErrorUnableToLoadCms());
        }
    }

    private boolean containsCms() {
        String cms = csar.getManifest().getCms();
        return cms != null && !cms.equals(EMPTY_STRING);
    }

    private boolean containsToscaMeta() {
        return csar.getToscaMetaFile() != null;
    }

    private boolean containsCertificateInTosca() {
        String certificate = csar.getToscaMeta().getEntryCertificate();
        return certificate != null && !certificate.equals(EMPTY_STRING);
    }

    private boolean containsCertificateInRootCatalog() {
        File potentialCertificateFileInRootDirectory = getCertificateFromRootDirectory();
        return potentialCertificateFileInRootDirectory.exists();
    }

    private boolean containsPerArtifactSecurity() {
        return csar.getManifest().getSources().stream().anyMatch(
            source ->
                !source.getAlgorithm().equals(EMPTY_STRING) ||
                    !source.getHash().equals(EMPTY_STRING) ||
                    !source.getCertificate().equals(EMPTY_STRING) ||
                    !source.getSignature().equals(EMPTY_STRING)
        );
    }

    private void validateCertificationUsingCmsCertificate(CmsSignatureData signatureData)
        throws NoSuchAlgorithmException, IOException {
        validateAllSources();
        validateFileSignature(signatureData);
        if (containsCertificateInTosca()) {
            this.errors.add(new Error.CSARErrorEntryCertificateIsDefinedDespiteTheCms());
            if (csar.getFileFromCsar(csar.getToscaMeta().getEntryCertificate()).exists()) {
                this.errors.add(new Error.CSARErrorEntryCertificateIsPresentDespiteTheCms());
            }
        }
        if (containsCertificateInRootCatalog()) {
            this.errors.add(new Error.CSARErrorRootCertificateIsPresentDespiteTheCms());
        }
    }

    private void validateCertificationUsingTosca(CmsSignatureData signatureData)
        throws NoSuchAlgorithmException, IOException {
        Optional<Path> pathToCert = loadCertificateFromTosca();
        if (pathToCert.isPresent()) {
            validateAllSources(pathToCert.get());
            signatureData.loadCertificate(pathToCert.get());
            validateFileSignature(signatureData);
        }
        if (containsCertificateInRootCatalog() && rootCertificateIsNotReferredAsToscaEtsiEntryCertificate()) {
            this.errors.add(new Error.CSARErrorRootCertificateIsPresentDespiteTheEtsiEntryCertificate());
        }
    }

    private Optional<Path> loadCertificateFromTosca() {
        if (csar.getToscaMeta().getEntryCertificate() != null) {
            final Path absolutePathToEntryCertificate = csar.getFileFromCsar(csar.getToscaMeta().getEntryCertificate()).toPath();
            if (absolutePathToEntryCertificate.toFile().exists()) {
                return Optional.of(absolutePathToEntryCertificate);
            } else {
                this.errors.add(new Error.CSARErrorUnableToFindEntryCertificate());
                return Optional.empty();
            }
        } else {
            this.errors.add(new Error.CSARErrorUnableToFindCertificateEntryInTosca());
            return Optional.empty();
        }
    }

    private boolean rootCertificateIsNotReferredAsToscaEtsiEntryCertificate() {
        String pathToRootCertificate = getCertificateFromRootDirectory().getPath();
        String pathToEntryEtsiCertificate = csar.getFileFromCsar(csar.getToscaMeta().getEntryCertificate()).getPath();
        return !pathToRootCertificate.equals(pathToEntryEtsiCertificate);
    }

    private void validateCertificationUsingCertificateFromRootDirectory(CmsSignatureData signatureData)
        throws NoSuchAlgorithmException, IOException {
        Optional<Path> pathToCert = loadCertificateFromRootDirectory();
        if (pathToCert.isPresent()) {
            validateAllSources(pathToCert.get());
            signatureData.loadCertificate(pathToCert.get());
            validateFileSignature(signatureData);
        }
    }

    private void validateFileSignature(CmsSignatureData signatureData) {
        final boolean isValid = this.fileSignatureValidator.isValid(signatureData);
        if (!isValid) {
            this.errors.add(new Error.CSARErrorInvalidSignature());
        }
    }

    private Optional<Path> loadCertificateFromRootDirectory() {
        try {
            Path pathToCertificateInRootDirectory = getCertificateFromRootDirectory().toPath();
            return Optional.of(pathToCertificateInRootDirectory);
        } catch (CertificateLoadingException e) {
            LOG.error("Unable to read ETSI entry certificate file!", e);
            return Optional.empty();
        }
    }

    private File getCertificateFromRootDirectory() {
        String nameOfCertificate =
            getFileNameWithoutExtension(csar.getManifestMfFile().getName()) + CERTIFICATE_EXTENSION;
        return csar.getFileFromCsar(nameOfCertificate);
    }

    private void validateAllSources()
        throws NoSuchAlgorithmException, IOException {
        this.errors.addAll(createCsarSourcesValidator().validate());
    }

    private void validateAllSources(Path commonCertificate)
        throws NoSuchAlgorithmException, IOException {
        this.errors.addAll(createCsarSourcesValidator().validate(commonCertificate));
    }

    private CsarSourcesSecurityValidator createCsarSourcesValidator() {
        final CSARArchive.Manifest manifest = csar.getManifest();
        final Map<String, Map<String, List<String>>> nonMano = manifest.getNonMano();
        final List<SourcesParser.Source> sources = manifest.getSources();
        return new CsarSourcesSecurityValidator(nonMano, sources, csarRootDirectory);
    }

}