/*
 * 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.karaf.shell.dev;

import static java.lang.String.format;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import org.apache.felix.gogo.commands.Argument;
import org.apache.felix.gogo.commands.Command;
import org.apache.karaf.shell.console.OsgiCommandSupport;
import org.apache.karaf.shell.dev.util.Bundles;
import org.apache.karaf.shell.dev.util.Import;
import org.apache.karaf.shell.dev.util.Node;
import org.apache.karaf.shell.dev.util.Tree;
import org.osgi.framework.Bundle;
import org.osgi.framework.ServiceReference;
import org.osgi.service.packageadmin.ExportedPackage;
import org.osgi.service.packageadmin.PackageAdmin;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Command for showing the full tree of bundles that have been used to resolve
 * a given bundle.
 */
@Command(scope = "dev", name = "show-tree", description = "Shows the tree of bundles based on the wiring information.")
public class ShowBundleTree extends AbstractBundleCommand {

    private static final Logger LOGGER = LoggerFactory.getLogger(ShowBundleTree.class);

    private Tree<Bundle> tree;

    @Override
    protected void doExecute(Bundle bundle) throws Exception {
        long start = System.currentTimeMillis();
        // let's do the real work here
        printHeader(bundle);
        tree = new Tree<Bundle>(bundle);
        createTree(bundle);
        printTree(tree);
        printDuplicatePackages(tree);
        LOGGER.debug(format("Dependency tree calculated in %d ms",
                            System.currentTimeMillis() - start));
    }

    /*
     * Print the header
     */
    private void printHeader(Bundle bundle) {
        System.out.printf("Bundle %s [%s] is currently %s%n",
                bundle.getSymbolicName(),
                bundle.getBundleId(),
                Bundles.toString(bundle.getState()));
    }

    /*
     * Print the dependency tree
     */
    private void printTree(Tree<Bundle> tree) {
        System.out.printf("%n");
        tree.write(System.out, new Tree.Converter<Bundle>() {

            public String toString(Node<Bundle> node) {
                return String.format("%s [%s]",
                                     node.getValue().getSymbolicName(),
                                     node.getValue().getBundleId());
            }
        });
    }

    /*
     * Check for bundles in the tree exporting the same package
     * as a possible cause for 'Unresolved constraint...' on a uses-conflict
     */
    private void printDuplicatePackages(Tree<Bundle> tree) {
        Set<Bundle> bundles = tree.flatten();
        Map<String, Set<Bundle>> exports = new HashMap<String, Set<Bundle>>();

        for (Bundle bundle : bundles) {
            ExportedPackage[] packages = getPackageAdmin().getExportedPackages(bundle);
            if (packages != null) {
                for (ExportedPackage p : packages) {
                    if (exports.get(p.getName()) == null) {
                        exports.put(p.getName(), new HashSet<Bundle>());
                    }
                    exports.get(p.getName()).add(bundle);
                }
            }
        }

        for (String pkg : exports.keySet()) {
            if (exports.get(pkg).size() > 1) {
                System.out.printf("%n");
                System.out.printf("WARNING: multiple bundles are exporting package %s%n", pkg);
                for (Bundle bundle : exports.get(pkg)) {
                    System.out.printf("- %s%n", bundle);
                }
            }
        }
    }

    /*
     * Creates the bundle tree
     */
    protected void createTree(Bundle bundle) {
        if (bundle.getState() >= Bundle.RESOLVED) {
            createNode(tree);
        } else {
            createNodesForImports(tree, bundle);
        }
    }

    /*
     * Creates nodes for the imports of the bundle (instead of reporting wiring information
     */
    private void createNodesForImports(Node node, Bundle bundle) {
        for (Import i : Import.parse(String.valueOf(bundle.getHeaders().get("Import-Package")),
                                     String.valueOf(bundle.getHeaders().get("Export-Package")))) {
            createNodeForImport(node, bundle, i);
        }
    }

    /*
     * Create a child node for a given import (by finding a matching export in the currently installed bundles)
     */
    private void createNodeForImport(Node node, Bundle bundle, Import i) {
        ExportedPackage[] exporters = getPackageAdmin().getExportedPackages(i.getPackage());
        boolean foundMatch = false;
        if (exporters != null) {
            for (ExportedPackage ep : exporters) {
                if (i.getVersion().contains(ep.getVersion())) {
                    if (bundle.equals(ep.getExportingBundle())) {
                        foundMatch = true;
                    } else {
                        Node child = node.addChild(ep.getExportingBundle());
                        System.out.printf("- import %s: resolved using %s%n", i, ep.getExportingBundle());
                        foundMatch = true;
                        createNode(child);
                    }
                }
            }
        }
        if (!foundMatch) {
            System.out.printf("- import %s: WARNING - unable to find matching export%n", i);            
        }
    }

    /*
     * Creates a node in the bundle tree
     */
    private void createNode(Node<Bundle> node) {
        Bundle bundle = node.getValue();
        Collection<Bundle> exporters = new HashSet<Bundle>();
        exporters.addAll(getWiredBundles(bundle).values());

        for (Bundle exporter : exporters) {
            if (node.hasAncestor(exporter)) {                
                LOGGER.debug(format("Skipping %s (already exists in the current branch)", exporter));
            } else {
                boolean existing = tree.flatten().contains(exporter);
                LOGGER.debug(format("Adding %s as a dependency for %s", exporter, bundle));
                Node child = node.addChild(exporter);
                if (existing) {
                    LOGGER.debug(format("Skipping children of %s (already exists in another branch)", exporter));
                } else {
                    createNode(child);
                }
            }
        }
    }
}