/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.apache.xml.security.stax.impl.processor.input;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;

import org.apache.xml.security.binding.excc14n.InclusiveNamespaces;
import org.apache.xml.security.binding.xmldsig.ReferenceType;
import org.apache.xml.security.binding.xmldsig.SignatureType;
import org.apache.xml.security.binding.xmldsig.TransformType;
import org.apache.xml.security.exceptions.XMLSecurityException;
import org.apache.xml.security.stax.config.ConfigurationProperties;
import org.apache.xml.security.stax.config.JCEAlgorithmMapper;
import org.apache.xml.security.stax.config.ResourceResolverMapper;
import org.apache.xml.security.stax.ext.AbstractInputProcessor;
import org.apache.xml.security.stax.ext.InboundSecurityContext;
import org.apache.xml.security.stax.ext.InputProcessorChain;
import org.apache.xml.security.stax.ext.ResourceResolver;
import org.apache.xml.security.stax.ext.Transformer;
import org.apache.xml.security.stax.ext.XMLSecurityConstants;
import org.apache.xml.security.stax.ext.XMLSecurityProperties;
import org.apache.xml.security.stax.ext.XMLSecurityUtils;
import org.apache.xml.security.stax.ext.stax.XMLSecEndElement;
import org.apache.xml.security.stax.ext.stax.XMLSecEvent;
import org.apache.xml.security.stax.ext.stax.XMLSecStartElement;
import org.apache.xml.security.stax.impl.transformer.canonicalizer.Canonicalizer20010315_Excl;
import org.apache.xml.security.stax.impl.transformer.canonicalizer.Canonicalizer20010315_OmitCommentsTransformer;
import org.apache.xml.security.stax.impl.util.DigestOutputStream;
import org.apache.xml.security.stax.impl.util.IDGenerator;
import org.apache.xml.security.stax.impl.util.KeyValue;
import org.apache.xml.security.stax.securityEvent.AlgorithmSuiteSecurityEvent;
import org.apache.xml.security.stax.securityToken.InboundSecurityToken;
import org.apache.xml.security.utils.UnsyncBufferedOutputStream;
import org.apache.xml.security.utils.XMLUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 */
public abstract class AbstractSignatureReferenceVerifyInputProcessor extends AbstractInputProcessor {

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

    protected static final Integer maximumAllowedReferencesPerManifest =
            Integer.valueOf(ConfigurationProperties.getProperty("MaximumAllowedReferencesPerManifest"));
    protected static final Integer maximumAllowedTransformsPerReference =
            Integer.valueOf(ConfigurationProperties.getProperty("MaximumAllowedTransformsPerReference"));
    protected static final Boolean doNotThrowExceptionForManifests =
            Boolean.valueOf(ConfigurationProperties.getProperty("DoNotThrowExceptionForManifests"));
    protected static final Boolean allowNotSameDocumentReferences =
            Boolean.valueOf(ConfigurationProperties.getProperty("AllowNotSameDocumentReferences"));

    private final SignatureType signatureType;
    private final InboundSecurityToken inboundSecurityToken;
    private final List<KeyValue<ResourceResolver, ReferenceType>> sameDocumentReferences;
    private final List<KeyValue<ResourceResolver, ReferenceType>> externalReferences;
    private final List<ReferenceType> processedReferences;

    public AbstractSignatureReferenceVerifyInputProcessor(
            InputProcessorChain inputProcessorChain,
            SignatureType signatureType, InboundSecurityToken inboundSecurityToken,
            XMLSecurityProperties securityProperties) throws XMLSecurityException {
        super(securityProperties);
        this.signatureType = signatureType;
        this.inboundSecurityToken = inboundSecurityToken;

        List<ReferenceType> referencesTypeList = signatureType.getSignedInfo().getReference();
        if (referencesTypeList.size() > maximumAllowedReferencesPerManifest) {
            throw new XMLSecurityException(
                    "secureProcessing.MaximumAllowedReferencesPerManifest",
                    new Object[] {referencesTypeList.size(), maximumAllowedReferencesPerManifest});
        }
        sameDocumentReferences = new ArrayList<>(referencesTypeList.size());
        externalReferences = new ArrayList<>(referencesTypeList.size());
        processedReferences = new ArrayList<>(referencesTypeList.size());

        Iterator<ReferenceType> referenceTypeIterator = referencesTypeList.iterator();
        while (referenceTypeIterator.hasNext()) {
            ReferenceType referenceType = referenceTypeIterator.next();
            if (!doNotThrowExceptionForManifests && XMLSecurityConstants.NS_XMLDSIG_MANIFEST.equals(referenceType.getType())) {
                throw new XMLSecurityException(
                        "secureProcessing.DoNotThrowExceptionForManifests"
                );
            }
            if (referenceType.getURI() == null) {
                throw new XMLSecurityException("stax.emptyReferenceURI");
            }
            if (referenceType.getId() == null) {
                referenceType.setId(IDGenerator.generateID(null));
            }
            ResourceResolver resourceResolver =
                    ResourceResolverMapper.getResourceResolver(
                            referenceType.getURI(), inputProcessorChain.getDocumentContext().getBaseURI());

            if (resourceResolver.isSameDocumentReference()) {
                sameDocumentReferences.add(new KeyValue<ResourceResolver, ReferenceType>(resourceResolver, referenceType));
            } else {
                if (!allowNotSameDocumentReferences) {
                    throw new XMLSecurityException(
                            "secureProcessing.AllowNotSameDocumentReferences"
                    );
                }
                externalReferences.add(new KeyValue<ResourceResolver, ReferenceType>(resourceResolver, referenceType));
            }
        }
    }

    public SignatureType getSignatureType() {
        return signatureType;
    }

    public List<ReferenceType> getProcessedReferences() {
        return processedReferences;
    }

    public InboundSecurityToken getInboundSecurityToken() {
        return inboundSecurityToken;
    }

    @Override
    public XMLSecEvent processNextHeaderEvent(InputProcessorChain inputProcessorChain)
            throws XMLStreamException, XMLSecurityException {
        return inputProcessorChain.processHeaderEvent();
    }

    @Override
    public XMLSecEvent processNextEvent(InputProcessorChain inputProcessorChain)
            throws XMLStreamException, XMLSecurityException {

        XMLSecEvent xmlSecEvent = inputProcessorChain.processEvent();
        if (XMLStreamConstants.START_ELEMENT == xmlSecEvent.getEventType()) {
            XMLSecStartElement xmlSecStartElement = xmlSecEvent.asStartElement();
            List<ReferenceType> referenceTypes = resolvesResource(xmlSecStartElement);
            if (!referenceTypes.isEmpty()) {
                for (int i = 0; i < referenceTypes.size(); i++) {
                    ReferenceType referenceType = referenceTypes.get(i);

                    if (processedReferences.contains(referenceType)) {
                        throw new XMLSecurityException("signature.Verification.MultipleIDs",
                                                       new Object[] {referenceType.getURI()});
                    }
                    InternalSignatureReferenceVerifier internalSignatureReferenceVerifier =
                        getSignatureReferenceVerifier(getSecurityProperties(), inputProcessorChain,
                                                      referenceType, xmlSecStartElement);
                    if (!internalSignatureReferenceVerifier.isFinished()) {
                        internalSignatureReferenceVerifier.processEvent(xmlSecEvent, inputProcessorChain);
                        inputProcessorChain.addProcessor(internalSignatureReferenceVerifier);
                    }
                    processedReferences.add(referenceType);
                    inputProcessorChain.getDocumentContext().setIsInSignedContent(
                        inputProcessorChain.getProcessors().indexOf(internalSignatureReferenceVerifier),
                        internalSignatureReferenceVerifier);

                    processElementPath(internalSignatureReferenceVerifier.getStartElementPath(), inputProcessorChain,
                                       internalSignatureReferenceVerifier.getStartElement(), referenceType);
                }
            }
        }
        return xmlSecEvent;
    }

    protected abstract void processElementPath(
            List<QName> elementPath, InputProcessorChain inputProcessorChain, XMLSecEvent xmlSecEvent,
            ReferenceType referenceType) throws XMLSecurityException;

    protected List<ReferenceType> resolvesResource(XMLSecStartElement xmlSecStartElement) {
        List<ReferenceType> referenceTypes = Collections.emptyList();
        for (int i = 0; i < sameDocumentReferences.size(); i++) {
            KeyValue<ResourceResolver, ReferenceType> keyValue = sameDocumentReferences.get(i);

            ResourceResolver resolver = keyValue.getKey();
            boolean resourceMatches = false;
            try {
                // A reflection hack to avoid breaking the ResourceResolver interface for SANTUARIO-407.
                Method m = resolver.getClass().getMethod("matches", XMLSecStartElement.class, QName.class);
                if (m != null
                    && (Boolean)m.invoke(resolver, xmlSecStartElement, getSecurityProperties().getIdAttributeNS())) {
                    if (referenceTypes == Collections.<ReferenceType>emptyList()) {
                        referenceTypes = new ArrayList<>();
                    }
                    referenceTypes.add(keyValue.getValue());
                    resourceMatches = true;
                }
            } catch (NoSuchMethodException ex) {
                // No need to report this
            } catch (InvocationTargetException ex) {
                // No need to report this
            } catch (IllegalAccessException ex) {
                // No need to report this
            }

            if (!resourceMatches && keyValue.getKey().matches(xmlSecStartElement)) {
                if (referenceTypes == Collections.<ReferenceType>emptyList()) {
                    referenceTypes = new ArrayList<>();
                }
                referenceTypes.add(keyValue.getValue());
            }
        }
        return referenceTypes;
    }

    @Override
    public void doFinal(InputProcessorChain inputProcessorChain) throws XMLStreamException, XMLSecurityException {
        inputProcessorChain.doFinal();

        for (int i = 0; i < sameDocumentReferences.size(); i++) {
            KeyValue<ResourceResolver, ReferenceType> keyValue = sameDocumentReferences.get(i);
            if (!processedReferences.contains(keyValue.getValue())) {
                throw new XMLSecurityException("stax.signature.unprocessedReferences");
            }
        }

        if (!externalReferences.isEmpty()) {
            for (int i = 0; i < externalReferences.size(); i++) {
                KeyValue<ResourceResolver, ReferenceType> keyValue = externalReferences.get(i);
                verifyExternalReference(
                        inputProcessorChain,
                        keyValue.getKey().getInputStreamFromExternalReference(),
                        keyValue.getValue());
                processedReferences.add(keyValue.getValue());
            }

            for (int i = 0; i < externalReferences.size(); i++) {
                KeyValue<ResourceResolver, ReferenceType> keyValue = externalReferences.get(i);
                if (!processedReferences.contains(keyValue.getValue())) {
                    throw new XMLSecurityException("stax.signature.unprocessedReferences");
                }
            }
        }
    }

    protected InternalSignatureReferenceVerifier getSignatureReferenceVerifier(
            XMLSecurityProperties securityProperties, InputProcessorChain inputProcessorChain,
            ReferenceType referenceType, XMLSecStartElement startElement) throws XMLSecurityException {
        return new InternalSignatureReferenceVerifier(securityProperties, inputProcessorChain, referenceType, startElement);
    }

    protected void verifyExternalReference(InputProcessorChain inputProcessorChain, InputStream inputStream,
                                         ReferenceType referenceType) throws XMLSecurityException, XMLStreamException {

        try (BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
            DigestOutputStream digestOutputStream =
                    createMessageDigestOutputStream(referenceType, inputProcessorChain.getSecurityContext());
            UnsyncBufferedOutputStream bufferedDigestOutputStream =
                    new UnsyncBufferedOutputStream(digestOutputStream)) {

            if (referenceType.getTransforms() != null) {
                Transformer transformer =
                        buildTransformerChain(referenceType, bufferedDigestOutputStream, inputProcessorChain, null);
                transformer.transform(bufferedInputStream);
                bufferedDigestOutputStream.close();
            } else {
                XMLSecurityUtils.copy(bufferedInputStream, bufferedDigestOutputStream);
                bufferedDigestOutputStream.close();
            }
            compareDigest(digestOutputStream.getDigestValue(), referenceType);
        } catch (IOException e) {
            throw new XMLSecurityException(e);
        }
    }

    protected DigestOutputStream createMessageDigestOutputStream(ReferenceType referenceType, InboundSecurityContext inboundSecurityContext)
            throws XMLSecurityException {

        String digestMethodAlgorithm = referenceType.getDigestMethod().getAlgorithm();
        String jceName = JCEAlgorithmMapper.translateURItoJCEID(digestMethodAlgorithm);
        String jceProvider = JCEAlgorithmMapper.getJCEProviderFromURI(digestMethodAlgorithm);
        if (jceName == null) {
            throw new XMLSecurityException("algorithms.NoSuchMap",
                                           new Object[] {digestMethodAlgorithm});
        }

        AlgorithmSuiteSecurityEvent algorithmSuiteSecurityEvent = new AlgorithmSuiteSecurityEvent();
        algorithmSuiteSecurityEvent.setAlgorithmURI(digestMethodAlgorithm);
        algorithmSuiteSecurityEvent.setAlgorithmUsage(XMLSecurityConstants.SigDig);
        algorithmSuiteSecurityEvent.setCorrelationID(referenceType.getId());
        inboundSecurityContext.registerSecurityEvent(algorithmSuiteSecurityEvent);

        MessageDigest messageDigest;
        try {
            if (jceProvider != null) {
                messageDigest = MessageDigest.getInstance(jceName, jceProvider);
            } else {
                messageDigest = MessageDigest.getInstance(jceName);
            }
        } catch (NoSuchAlgorithmException e) {
            throw new XMLSecurityException(e);
        } catch (NoSuchProviderException e) {
            throw new XMLSecurityException(e);
        }

        return new DigestOutputStream(messageDigest);
    }

    protected Transformer buildTransformerChain(ReferenceType referenceType, OutputStream outputStream,
                                                InputProcessorChain inputProcessorChain,
                                                InternalSignatureReferenceVerifier internalSignatureReferenceVerifier)
            throws XMLSecurityException {

        // If no Transforms then just default to an Inclusive without comments transform
        if (referenceType.getTransforms() == null || referenceType.getTransforms().getTransform().isEmpty()) {

            AlgorithmSuiteSecurityEvent algorithmSuiteSecurityEvent = new AlgorithmSuiteSecurityEvent();
            algorithmSuiteSecurityEvent.setAlgorithmURI(XMLSecurityConstants.NS_C14N_OMIT_COMMENTS);
            algorithmSuiteSecurityEvent.setAlgorithmUsage(XMLSecurityConstants.SigTransform);
            algorithmSuiteSecurityEvent.setCorrelationID(referenceType.getId());
            inputProcessorChain.getSecurityContext().registerSecurityEvent(algorithmSuiteSecurityEvent);

            Transformer transformer = new Canonicalizer20010315_OmitCommentsTransformer();
            transformer.setOutputStream(outputStream);
            return transformer;
        }

        List<TransformType> transformTypeList = referenceType.getTransforms().getTransform();

        if (transformTypeList.size() == 1 &&
                XMLSecurityConstants.NS_XMLDSIG_ENVELOPED_SIGNATURE.equals(transformTypeList.get(0).getAlgorithm())) {
            TransformType transformType = new TransformType();
            transformType.setAlgorithm(XMLSecurityConstants.NS_C14N_OMIT_COMMENTS);
            transformTypeList.add(transformType);
        }

        if (transformTypeList.size() > maximumAllowedTransformsPerReference) {
            throw new XMLSecurityException(
                    "secureProcessing.MaximumAllowedTransformsPerReference",
                    new Object[] {transformTypeList.size(), maximumAllowedTransformsPerReference});
        }

        Transformer parentTransformer = null;
        for (int i = transformTypeList.size() - 1; i >= 0; i--) {
            TransformType transformType = transformTypeList.get(i);

            String algorithm = transformType.getAlgorithm();

            AlgorithmSuiteSecurityEvent algorithmSuiteSecurityEvent = new AlgorithmSuiteSecurityEvent();
            algorithmSuiteSecurityEvent.setAlgorithmURI(algorithm);
            algorithmSuiteSecurityEvent.setAlgorithmUsage(XMLSecurityConstants.SigTransform);
            algorithmSuiteSecurityEvent.setCorrelationID(referenceType.getId());
            inputProcessorChain.getSecurityContext().registerSecurityEvent(algorithmSuiteSecurityEvent);

            InclusiveNamespaces inclusiveNamespacesType =
                    XMLSecurityUtils.getQNameType(transformType.getContent(),
                            XMLSecurityConstants.TAG_c14nExcl_InclusiveNamespaces);

            Map<String, Object> transformerProperties = null;
            if (inclusiveNamespacesType != null) {
                transformerProperties = new HashMap<>();
                transformerProperties.put(
                        Canonicalizer20010315_Excl.INCLUSIVE_NAMESPACES_PREFIX_LIST,
                        inclusiveNamespacesType.getPrefixList());
            }

            if (parentTransformer != null) {
                parentTransformer = XMLSecurityUtils.getTransformer(
                        parentTransformer, null, transformerProperties, algorithm, XMLSecurityConstants.DIRECTION.IN);
            } else {
                parentTransformer =
                        XMLSecurityUtils.getTransformer(
                                null, outputStream, transformerProperties, algorithm, XMLSecurityConstants.DIRECTION.IN);
            }
        }
        return parentTransformer;
    }

    protected void compareDigest(byte[] calculatedDigest, ReferenceType referenceType) throws XMLSecurityException {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Calculated Digest: {}", XMLUtils.encodeToString(calculatedDigest));
            LOG.debug("Stored Digest: {}", XMLUtils.encodeToString(referenceType.getDigestValue()));
        }

        if (!MessageDigest.isEqual(referenceType.getDigestValue(), calculatedDigest)) {
            throw new XMLSecurityException(
                    "signature.Verification.InvalidDigestOrReference",
                    new Object[] {referenceType.getURI()});
        }
    }

    public class InternalSignatureReferenceVerifier extends AbstractInputProcessor {
        private ReferenceType referenceType;
        private Transformer transformer;
        private DigestOutputStream digestOutputStream;
        private OutputStream bufferedDigestOutputStream;
        private List<QName> startElementPath;
        private XMLSecStartElement startElement;
        private int elementCounter;
        private boolean finished = false;

        public InternalSignatureReferenceVerifier(
                XMLSecurityProperties securityProperties, InputProcessorChain inputProcessorChain,
                ReferenceType referenceType, XMLSecStartElement startElement) throws XMLSecurityException {

            super(securityProperties);
            this.setStartElement(startElement);
            this.setReferenceType(referenceType);
            this.digestOutputStream = createMessageDigestOutputStream(referenceType, inputProcessorChain.getSecurityContext());
            this.bufferedDigestOutputStream = new UnsyncBufferedOutputStream(this.getDigestOutputStream());
            this.transformer = buildTransformerChain(referenceType, bufferedDigestOutputStream, inputProcessorChain);
        }

        public Transformer buildTransformerChain(ReferenceType referenceType, OutputStream outputStream, InputProcessorChain inputProcessorChain)
                throws XMLSecurityException {
            return AbstractSignatureReferenceVerifyInputProcessor.this.buildTransformerChain(
                    referenceType, outputStream, inputProcessorChain, this);
        }

        @Override
        public XMLSecEvent processNextHeaderEvent(InputProcessorChain inputProcessorChain)
                throws XMLStreamException, XMLSecurityException {
            return inputProcessorChain.processHeaderEvent();
        }

        @Override
        public XMLSecEvent processNextEvent(InputProcessorChain inputProcessorChain)
                throws XMLStreamException, XMLSecurityException {
            XMLSecEvent xmlSecEvent = inputProcessorChain.processEvent();
            processEvent(xmlSecEvent, inputProcessorChain);
            return xmlSecEvent;
        }

        public void processEvent(XMLSecEvent xmlSecEvent, InputProcessorChain inputProcessorChain)
            throws XMLStreamException, XMLSecurityException {

            getTransformer().transform(xmlSecEvent);
            if (XMLStreamConstants.START_ELEMENT == xmlSecEvent.getEventType()) {
                this.elementCounter++;
            } else if (XMLStreamConstants.END_ELEMENT == xmlSecEvent.getEventType()) {
                XMLSecEndElement xmlSecEndElement = xmlSecEvent.asEndElement();
                this.elementCounter--;

                if (this.elementCounter == 0 && xmlSecEndElement.getName().equals(startElement.getName())) {
                    getTransformer().doFinal();
                    try {
                        getBufferedDigestOutputStream().close();
                    } catch (IOException e) {
                        throw new XMLSecurityException(e);
                    }

                    compareDigest(this.getDigestOutputStream().getDigestValue(), getReferenceType());

                    inputProcessorChain.removeProcessor(this);
                    inputProcessorChain.getDocumentContext().unsetIsInSignedContent(this);
                    setFinished(true);
                }
            }
        }

        public boolean isFinished() {
            return finished;
        }

        public void setFinished(boolean finished) {
            this.finished = finished;
        }

        public ReferenceType getReferenceType() {
            return referenceType;
        }

        public void setReferenceType(ReferenceType referenceType) {
            this.referenceType = referenceType;
        }

        public Transformer getTransformer() {
            return transformer;
        }

        public void setTransformer(Transformer transformer) {
            this.transformer = transformer;
        }

        public DigestOutputStream getDigestOutputStream() {
            return digestOutputStream;
        }

        public void setDigestOutputStream(DigestOutputStream digestOutputStream) {
            this.digestOutputStream = digestOutputStream;
        }

        public OutputStream getBufferedDigestOutputStream() {
            return bufferedDigestOutputStream;
        }

        public void setBufferedDigestOutputStream(OutputStream bufferedDigestOutputStream) {
            this.bufferedDigestOutputStream = bufferedDigestOutputStream;
        }

        public XMLSecStartElement getStartElement() {
            return startElement;
        }

        public void setStartElement(XMLSecStartElement startElement) {
            this.startElementPath = startElement.getElementPath();
            this.startElement = startElement;
        }

        public List<QName> getStartElementPath() {
            return startElementPath;
        }
    }
}