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package org.glassfish.jersey.server.internal.routing;

import java.lang.reflect.Method;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.regex.MatchResult;
import java.util.stream.Collectors;

import javax.ws.rs.core.MultivaluedHashMap;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.PathSegment;
import javax.ws.rs.core.UriBuilder;

import org.glassfish.jersey.internal.util.collection.ImmutableMultivaluedMap;
import org.glassfish.jersey.message.internal.TracingLogger;
import org.glassfish.jersey.server.ContainerRequest;
import org.glassfish.jersey.server.internal.ServerTraceEvent;
import org.glassfish.jersey.server.internal.process.Endpoint;
import org.glassfish.jersey.server.model.Resource;
import org.glassfish.jersey.server.model.ResourceMethod;
import org.glassfish.jersey.server.model.ResourceMethodInvoker;
import org.glassfish.jersey.server.model.RuntimeResource;
import org.glassfish.jersey.uri.UriComponent;
import org.glassfish.jersey.uri.UriTemplate;
import org.glassfish.jersey.uri.internal.JerseyUriBuilder;

/**
 * Default implementation of the routing context as well as URI information provider.
 *
 * @author Marek Potociar (marek.potociar at oracle.com)
 */
public class UriRoutingContext implements RoutingContext {

    private final LinkedList<MatchResult> matchResults = new LinkedList<>();
    private final LinkedList<Object> matchedResources = new LinkedList<>();
    private final LinkedList<UriTemplate> templates = new LinkedList<>();

    private final MultivaluedHashMap<String, String> encodedTemplateValues = new MultivaluedHashMap<>();
    private final ImmutableMultivaluedMap<String, String> encodedTemplateValuesView =
            new ImmutableMultivaluedMap<>(encodedTemplateValues);

    private final LinkedList<String> paths = new LinkedList<>();
    private final LinkedList<RuntimeResource> matchedRuntimeResources = new LinkedList<>();
    private final LinkedList<ResourceMethod> matchedLocators = new LinkedList<>();
    private final LinkedList<Resource> locatorSubResources = new LinkedList<>();

    private final TracingLogger tracingLogger;

    private volatile ResourceMethod matchedResourceMethod = null;
    private volatile Throwable mappedThrowable = null;

    private Endpoint endpoint;

    private MultivaluedHashMap<String, String> decodedTemplateValues;
    private ImmutableMultivaluedMap<String, String> decodedTemplateValuesView;

    private ImmutableMultivaluedMap<String, String> encodedQueryParamsView;
    private ImmutableMultivaluedMap<String, String> decodedQueryParamsView;

    /**
     * Injection constructor.
     *
     * @param requestContext request reference.
     */
    public UriRoutingContext(final ContainerRequest requestContext) {
        this.requestContext = requestContext;
        this.tracingLogger = TracingLogger.getInstance(requestContext);
    }

    // RoutingContext
    @Override
    public void pushMatchResult(final MatchResult matchResult) {
        matchResults.push(matchResult);
    }

    @Override
    public void pushMatchedResource(final Object resource) {
        tracingLogger.log(ServerTraceEvent.MATCH_RESOURCE, resource);
        matchedResources.push(resource);
    }

    @Override
    public Object peekMatchedResource() {
        return matchedResources.peek();
    }

    @Override
    public void pushMatchedLocator(final ResourceMethod resourceLocator) {
        tracingLogger.log(ServerTraceEvent.MATCH_LOCATOR, resourceLocator.getInvocable().getHandlingMethod());
        matchedLocators.push(resourceLocator);
    }

    @Override
    public void pushLeftHandPath() {
        final String rightHandPath = getFinalMatchingGroup();
        final int rhpLength = (rightHandPath != null) ? rightHandPath.length() : 0;

        final String encodedRequestPath = getPath(false);

        final int length = encodedRequestPath.length() - rhpLength;
        if (length <= 0) {
            paths.addFirst("");
        } else {
            paths.addFirst(encodedRequestPath.substring(0, length));
        }
    }

    @Override
    public void pushTemplates(final UriTemplate resourceTemplate, final UriTemplate methodTemplate) {
        final Iterator<MatchResult> matchResultIterator = matchResults.iterator();
        templates.push(resourceTemplate);
        if (methodTemplate != null) {
            templates.push(methodTemplate);
            // fast-forward the match result iterator to second element in the stack
            matchResultIterator.next();
        }

        pushMatchedTemplateValues(resourceTemplate, matchResultIterator.next());
        if (methodTemplate != null) {
            // use the match result from the top of the stack
            pushMatchedTemplateValues(methodTemplate, matchResults.peek());
        }
    }

    private void pushMatchedTemplateValues(final UriTemplate template, final MatchResult matchResult) {
        int i = 1;
        for (final String templateVariable : template.getTemplateVariables()) {
            final String value = matchResult.group(i++);
            encodedTemplateValues.addFirst(templateVariable, value);
            if (decodedTemplateValues != null) {
                decodedTemplateValues.addFirst(
                        UriComponent.decode(templateVariable, UriComponent.Type.PATH_SEGMENT),
                        UriComponent.decode(value, UriComponent.Type.PATH));
            }
        }
    }

    @Override
    public String getFinalMatchingGroup() {
        final MatchResult mr = matchResults.peek();
        if (mr == null) {
            return null;
        }

        final String finalGroup = mr.group(mr.groupCount());
        // We have found a match but the right hand path pattern did not match anything
        // so just returning an empty string as a final matching group result.
        // Otherwise a non-empty patterns would fail to match the right-hand-path properly.
        // See also PatternWithGroups.match(CharSequence) implementation.
        return finalGroup == null ? "" : finalGroup;
    }

    @Override
    public LinkedList<MatchResult> getMatchedResults() {
        return matchResults;
    }

    @Override
    public void setEndpoint(final Endpoint endpoint) {
        this.endpoint = endpoint;
    }

    @Override
    public Endpoint getEndpoint() {
        return endpoint;
    }

    @Override
    public void setMatchedResourceMethod(final ResourceMethod resourceMethod) {
        tracingLogger.log(ServerTraceEvent.MATCH_RESOURCE_METHOD, resourceMethod.getInvocable().getHandlingMethod());
        this.matchedResourceMethod = resourceMethod;
    }

    @Override
    public void pushMatchedRuntimeResource(final RuntimeResource runtimeResource) {
        if (tracingLogger.isLogEnabled(ServerTraceEvent.MATCH_RUNTIME_RESOURCE)) {
            tracingLogger.log(ServerTraceEvent.MATCH_RUNTIME_RESOURCE,
                    runtimeResource.getResources().get(0).getPath(),
                    runtimeResource.getResources().get(0).getPathPattern().getRegex(),
                    matchResults.peek().group()
                            .substring(0, matchResults.peek().group().length() - getFinalMatchingGroup().length()),
                    matchResults.peek().group());
        }

        this.matchedRuntimeResources.push(runtimeResource);
    }

    @Override
    public void pushLocatorSubResource(final Resource subResourceFromLocator) {
        this.locatorSubResources.push(subResourceFromLocator);
    }

    // UriInfo
    private final ContainerRequest requestContext;

    @Override
    public URI getAbsolutePath() {
        return requestContext.getAbsolutePath();
    }

    @Override
    public UriBuilder getAbsolutePathBuilder() {
        return new JerseyUriBuilder().uri(getAbsolutePath());
    }

    @Override
    public URI getBaseUri() {
        return requestContext.getBaseUri();
    }

    @Override
    public UriBuilder getBaseUriBuilder() {
        return new JerseyUriBuilder().uri(getBaseUri());
    }

    @Override
    public List<Object> getMatchedResources() {
        return Collections.unmodifiableList(matchedResources);
    }

    @Override
    public List<String> getMatchedURIs() {
        return getMatchedURIs(true);
    }

    private static final Function<String, String> PATH_DECODER = input -> UriComponent.decode(input, UriComponent.Type.PATH);

    @Override
    public List<String> getMatchedURIs(final boolean decode) {
        final List<String> result;
        if (decode) {
            result = paths.stream().map(PATH_DECODER).collect(Collectors.toList());
        } else {
            result = paths;
        }
        return Collections.unmodifiableList(result);
    }

    @Override
    public String getPath() {
        return requestContext.getPath(true);
    }

    @Override
    public String getPath(final boolean decode) {
        return requestContext.getPath(decode);
    }

    @Override
    public MultivaluedMap<String, String> getPathParameters() {
        return getPathParameters(true);
    }

    @Override
    public MultivaluedMap<String, String> getPathParameters(final boolean decode) {
        if (decode) {
            if (decodedTemplateValuesView != null) {
                return decodedTemplateValuesView;
            } else if (decodedTemplateValues == null) {
                decodedTemplateValues = new MultivaluedHashMap<>();
                for (final Map.Entry<String, List<String>> e : encodedTemplateValues.entrySet()) {
                    decodedTemplateValues.put(
                            UriComponent.decode(e.getKey(), UriComponent.Type.PATH_SEGMENT),
                            // we need to keep the ability to add new entries
                            e.getValue().stream().map(s -> UriComponent.decode(s, UriComponent.Type.PATH))
                             .collect(Collectors.toCollection(ArrayList::new)));
                }
            }
            decodedTemplateValuesView = new ImmutableMultivaluedMap<>(decodedTemplateValues);

            return decodedTemplateValuesView;
        } else {
            return encodedTemplateValuesView;
        }
    }

    @Override
    public List<PathSegment> getPathSegments() {
        return getPathSegments(true);
    }

    @Override
    public List<PathSegment> getPathSegments(final boolean decode) {
        final String requestPath = requestContext.getPath(false);
        return Collections.unmodifiableList(UriComponent.decodePath(requestPath, decode));
    }

    @Override
    public MultivaluedMap<String, String> getQueryParameters() {
        return getQueryParameters(true);
    }

    @Override
    public MultivaluedMap<String, String> getQueryParameters(final boolean decode) {
        if (decode) {
            if (decodedQueryParamsView != null) {
                return decodedQueryParamsView;
            }

            decodedQueryParamsView =
                    new ImmutableMultivaluedMap<>(UriComponent.decodeQuery(getRequestUri(), true));

            return decodedQueryParamsView;
        } else {
            if (encodedQueryParamsView != null) {
                return encodedQueryParamsView;
            }

            encodedQueryParamsView =
                    new ImmutableMultivaluedMap<>(UriComponent.decodeQuery(getRequestUri(), false));

            return encodedQueryParamsView;

        }
    }

    /**
     * Invalidate internal URI component cache views.
     * <p>
     * This method needs to be called if request URI information changes.
     * </p>
     */
    public void invalidateUriComponentViews() {
        this.decodedQueryParamsView = null;
        this.encodedQueryParamsView = null;
    }

    @Override
    public URI getRequestUri() {
        return requestContext.getRequestUri();
    }

    @Override
    public UriBuilder getRequestUriBuilder() {
        return UriBuilder.fromUri(getRequestUri());
    }

    // ExtendedUriInfo
    @Override
    public Throwable getMappedThrowable() {
        return mappedThrowable;
    }

    @Override
    public void setMappedThrowable(final Throwable mappedThrowable) {
        this.mappedThrowable = mappedThrowable;
    }

    @Override
    public List<UriTemplate> getMatchedTemplates() {
        return Collections.unmodifiableList(templates);
    }

    @Override
    public List<PathSegment> getPathSegments(final String name) {
        return getPathSegments(name, true);
    }

    @Override
    public List<PathSegment> getPathSegments(final String name, final boolean decode) {
        final int[] bounds = getPathParameterBounds(name);
        if (bounds != null) {
            final String path = matchResults.getLast().group();
            // Work out how many path segments are up to the start
            // and end position of the matching path parameter value
            // This assumes that the path always starts with a '/'
            int segmentsStart = 0;
            for (int x = 0; x < bounds[0]; x++) {
                if (path.charAt(x) == '/') {
                    segmentsStart++;
                }
            }
            int segmentsEnd = segmentsStart;
            for (int x = bounds[0]; x < bounds[1]; x++) {
                if (path.charAt(x) == '/') {
                    segmentsEnd++;
                }
            }

            return getPathSegments(decode).subList(segmentsStart - 1, segmentsEnd);
        } else {
            return Collections.emptyList();
        }
    }

    private int[] getPathParameterBounds(final String name) {
        final Iterator<UriTemplate> templatesIterator = templates.iterator();
        final Iterator<MatchResult> matchResultsIterator = matchResults.iterator();
        while (templatesIterator.hasNext()) {
            MatchResult mr = matchResultsIterator.next();
            // Find the index of path parameter
            final int pIndex = getLastPathParameterIndex(name, templatesIterator.next());
            if (pIndex != -1) {
                int pathLength = mr.group().length();
                int segmentIndex = mr.end(pIndex + 1);
                final int groupLength = segmentIndex - mr.start(pIndex + 1);

                // Find the absolute position of the end of the
                // capturing group in the request path
                while (matchResultsIterator.hasNext()) {
                    mr = matchResultsIterator.next();
                    segmentIndex += mr.group().length() - pathLength;
                    pathLength = mr.group().length();
                }
                return new int[] {segmentIndex - groupLength, segmentIndex};
            }
        }
        return null;
    }

    private int getLastPathParameterIndex(final String name, final UriTemplate t) {
        int i = 0;
        int pIndex = -1;
        for (final String parameterName : t.getTemplateVariables()) {
            if (parameterName.equals(name)) {
                pIndex = i;
            }
            i++;
        }
        return pIndex;
    }

    @Override
    public Method getResourceMethod() {
        return endpoint instanceof ResourceMethodInvoker
                ? ((ResourceMethodInvoker) endpoint).getResourceMethod() : null;
    }

    @Override
    public Class<?> getResourceClass() {
        return endpoint instanceof ResourceMethodInvoker
                ? ((ResourceMethodInvoker) endpoint).getResourceClass() : null;
    }

    @Override
    public List<RuntimeResource> getMatchedRuntimeResources() {
        return this.matchedRuntimeResources;
    }

    @Override
    public ResourceMethod getMatchedResourceMethod() {
        return matchedResourceMethod;
    }

    @Override
    public List<ResourceMethod> getMatchedResourceLocators() {
        return matchedLocators;
    }

    @Override
    public List<Resource> getLocatorSubResources() {
        return locatorSubResources;
    }

    @Override
    public Resource getMatchedModelResource() {
        return matchedResourceMethod == null ? null : matchedResourceMethod.getParent();
    }

    @Override
    public URI resolve(final URI uri) {
        return UriTemplate.resolve(getBaseUri(), uri);
    }

    @Override
    public URI relativize(URI uri) {
        if (!uri.isAbsolute()) {
            uri = resolve(uri);
        }

        return UriTemplate.relativize(getRequestUri(), uri);
    }
}
