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Provides a base module for the funcionality shared between LRA coordination and LRA clients
There is a newer version: 7.1.0.Final
/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2017, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package io.narayana.lra;

import javax.ws.rs.client.ClientRequestContext;
import javax.ws.rs.container.ContainerResponseContext;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.UriBuilder;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;

import static io.narayana.lra.LRAConstants.PARENT_LRA_PARAM_NAME;
import static io.narayana.lra.LRAConstants.QUERY_FIELD_SEPARATOR;
import static io.narayana.lra.LRAConstants.QUERY_PAIR_SEPARATOR;
import static org.eclipse.microprofile.lra.annotation.ws.rs.LRA.LRA_HTTP_CONTEXT_HEADER;

// similar to ThreadActionData except it need to be available on the client side
// for use by NarayanaLRAClient and ServerLRAFilter
public class Current {
    private static final ThreadLocal lraContexts = new ThreadLocal<>();

    private final Stack stack;
    private Map state;

    private Current(URI url) {
        stack = new Stack<>();
        stack.push(url);
    }

    public static Object putState(String key, Object value) {
        Current current = lraContexts.get();

        if (current != null) {
            return current.updateState(key, value);
        }

        return null;
    }

    public static Object getState(String key) {
        Current current = lraContexts.get();

        if (current != null && current.state != null) {
            return current.state.get(key);
        }

        return null;
    }

    private static String getParents(URI uri) {
        String query = uri.getQuery();

        if (query != null) {
            for (String nvpair : query.split(QUERY_PAIR_SEPARATOR)) {
                if (nvpair.startsWith(PARENT_LRA_PARAM_NAME + QUERY_FIELD_SEPARATOR)) {
                    return nvpair.split(QUERY_FIELD_SEPARATOR)[1];
                }
            }
        }

        return null;
    }

    // construct the LRA URI including the parent hierarchy as a query parameter
    public static URI buildFullLRAUrl(String baseURI, URI parentId) throws URISyntaxException {
        // is the parent part of a hierarchy
        String parents = Current.getParents(parentId); // gets the hierarchy form the query param
        // we have the hierarchy so remove the query parameter
        String gParent = new URI(parentId.getScheme(),
                parentId.getAuthority(),
                parentId.getPath(),
                null, // skip the query string
                parentId.getFragment())
                .toASCIIString();

        if (parents != null) {
            gParent += parents + ","; // , separated list of the hierarchy
        }

        return UriBuilder.fromUri(baseURI).queryParam(PARENT_LRA_PARAM_NAME, gParent).build();
    }

    // given a URL extract the immediate parent of
    public static String getFirstParent(URI parent) throws UnsupportedEncodingException {
        String query = parent == null ? null : parent.getQuery();

        if (query != null) {
            for (String param : query.split(QUERY_PAIR_SEPARATOR)) {
                if (param.startsWith(PARENT_LRA_PARAM_NAME + QUERY_FIELD_SEPARATOR)) {
                    String parents = param.split(QUERY_FIELD_SEPARATOR, 2)[1];

                    // parents is a comma separated list of parents (the first one is the direct parent)
                    if (parents != null) {
                        String[] pa = parents.split(",");

                        if (pa.length > 0) {
                            return URLDecoder.decode(pa[0], "UTF-8");
                        }
                    }

                    break;
                }
            }
        }

        return null;
    }

    public Object updateState(String key, Object value) {
        if (state == null) {
            state = new HashMap<>();
        }

        return state.put(key, value);
    }

    private static void clearContext(Current current) {
        if (current.state != null) {
            current.state.clear();
        }

        lraContexts.set(null);
    }

    public static URI peek() {
        Current current = lraContexts.get();

        return current != null ? current.stack.peek() : null;
    }

    public static URI pop() {
        Current current = lraContexts.get();
        URI lraId = null;

        if (current != null) {
            lraId = current.stack.pop(); // there must be at least one

            if (current.stack.empty()) {
                clearContext(current);
            }
        }

        return lraId;
    }

    // dissassociate an LRA from the callers thread (including any child LRAs)
    public static boolean pop(URI lra) {
        Current current = lraContexts.get();

        if (current == null || !current.stack.contains(lra)) {
            return false;
        }

        current.stack.remove(lra);

        // pop children
        // since child LRAs are contingent upon the parent, popping a parent should also pop the children

        // check every LRA associated with the calling thread and if it is a child of lra then pop it
        // the lra that is being popped is a parent of nextLRA:
        current.stack.removeIf(nextLRA -> isParentOf(lra, nextLRA));

        if (current.stack.empty()) {
            clearContext(current);
        }

        return true;
    }

    /*
     * return true if child is nested under parent
     * ie if child contains a query param matching child
     */
    private static boolean isParentOf(URI parent, URI child) {
        String qs = child.getQuery();

        if (qs == null) {
            return false; // child is top level
        }

        String theParent = parent.toASCIIString();
        String[] params = qs.split(QUERY_PAIR_SEPARATOR);

        for (String param : params) {
            String[] nvp = param.split(QUERY_FIELD_SEPARATOR);

            if (nvp.length == 2 && nvp[0].contains(PARENT_LRA_PARAM_NAME)) { // ignore null parameter values
                // Child has a parent. See if its parent matches theParent:
                try {
                    String parentCandidate = URLDecoder.decode(nvp[1], StandardCharsets.UTF_8.name());

                    if (parentCandidate.contains(theParent) || theParent.contains(parentCandidate)) {
                        return true;
                    }
                } catch (UnsupportedEncodingException ignore) {
                    // not a candidate
                }
            }
        }

        return false;
    }

    /**
     * push the current context onto the stack of contexts for this thread
     * @param lraId id of context to push (must not be null)
     */
    public static void push(URI lraId) {
        Current current = lraContexts.get();

        if (current == null) {
            lraContexts.set(new Current(lraId));
        } else {
            if (!current.stack.contains(lraId)) {
                current.stack.push(lraId);
            }
        }
    }

    public static List