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/*
 * Copyright 2012-2016 the original author or authors.
 *
 * 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
 *
 *      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 io.joshworks.snappy.loader.archive;

import io.joshworks.snappy.loader.util.AsciiBytes;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.jar.Manifest;

/**
 * {@link Archive} implementation backed by an exploded archive directory.
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 */
public class ExplodedArchive extends Archive {

    private static final Set SKIPPED_NAMES = new HashSet(
            Arrays.asList(".", ".."));

    private static final AsciiBytes MANIFEST_ENTRY_NAME = new AsciiBytes(
            "META-INF/MANIFEST.MF");

    private final File root;

    private Map entries = new LinkedHashMap();

    private Manifest manifest;

    private boolean filtered = false;

    /**
     * Create a new {@link ExplodedArchive} instance.
     *
     * @param root the root folder
     */
    public ExplodedArchive(File root) {
        this(root, true);
    }

    /**
     * Create a new {@link ExplodedArchive} instance.
     *
     * @param root      the root folder
     * @param recursive if recursive searching should be used to locate the manifest.
     *                  Defaults to {@code true}, folders with a large tree might want to set this to {code
     *                  false}.
     */
    public ExplodedArchive(File root, boolean recursive) {
        if (!root.exists() || !root.isDirectory()) {
            throw new IllegalArgumentException("Invalid source folder " + root);
        }
        this.root = root;
        buildEntries(root, recursive);
        this.entries = Collections.unmodifiableMap(this.entries);
    }

    private ExplodedArchive(File root, Map entries) {
        this.root = root;
        // The entries are pre-filtered
        this.filtered = true;
        this.entries = Collections.unmodifiableMap(entries);
    }

    private void buildEntries(File file, boolean recursive) {
        if (!file.equals(this.root)) {
            String name = file.toURI().getPath()
                    .substring(this.root.toURI().getPath().length());
            FileEntry entry = new FileEntry(new AsciiBytes(name), file);
            this.entries.put(entry.getName(), entry);
        }
        if (file.isDirectory()) {
            File[] files = file.listFiles();
            if (files == null) {
                return;
            }
            for (File child : files) {
                if (!SKIPPED_NAMES.contains(child.getName())) {
                    if (file.equals(this.root) || recursive
                            || file.getName().equals("META-INF")) {
                        buildEntries(child, recursive);
                    }
                }
            }
        }
    }

    @Override
    public URL getUrl() throws MalformedURLException {
        FilteredURLStreamHandler handler = this.filtered ? new FilteredURLStreamHandler()
                : null;
        return new URL("file", "", -1, this.root.toURI().toURL().getPath(), handler);
    }

    @Override
    public Manifest getManifest() throws IOException {
        if (this.manifest == null && this.entries.containsKey(MANIFEST_ENTRY_NAME)) {
            FileEntry entry = (FileEntry) this.entries.get(MANIFEST_ENTRY_NAME);
            FileInputStream inputStream = new FileInputStream(entry.getFile());
            try {
                this.manifest = new Manifest(inputStream);
            } finally {
                inputStream.close();
            }
        }
        return this.manifest;
    }

    @Override
    public List getNestedArchives(EntryFilter filter) throws IOException {
        List nestedArchives = new ArrayList();
        for (Entry entry : getEntries()) {
            if (filter.matches(entry)) {
                nestedArchives.add(getNestedArchive(entry));
            }
        }
        return Collections.unmodifiableList(nestedArchives);
    }

    @Override
    public Collection getEntries() {
        return Collections.unmodifiableCollection(this.entries.values());
    }

    protected Archive getNestedArchive(Entry entry) throws IOException {
        File file = ((FileEntry) entry).getFile();
        return (file.isDirectory() ? new ExplodedArchive(file)
                : new JarFileArchive(file));
    }

    @Override
    public Archive getFilteredArchive(EntryRenameFilter filter) throws IOException {
        Map filteredEntries = new LinkedHashMap();
        for (Map.Entry entry : this.entries.entrySet()) {
            AsciiBytes filteredName = filter.apply(entry.getKey(), entry.getValue());
            if (filteredName != null) {
                filteredEntries.put(filteredName, new FileEntry(filteredName,
                        ((FileEntry) entry.getValue()).getFile()));
            }
        }
        return new ExplodedArchive(this.root, filteredEntries);
    }

    /**
     * {@link URLConnection} used to represent a filtered file.
     */
    private static class FileNotFoundURLConnection extends URLConnection {

        private final String name;

        FileNotFoundURLConnection(URL url, String name) {
            super(url);
            this.name = name;
        }

        @Override
        public void connect() throws IOException {
            throw new FileNotFoundException(this.name);
        }

    }

    private class FileEntry implements Entry {

        private final AsciiBytes name;

        private final File file;

        FileEntry(AsciiBytes name, File file) {
            this.name = name;
            this.file = file;
        }

        public File getFile() {
            return this.file;
        }

        @Override
        public boolean isDirectory() {
            return this.file.isDirectory();
        }

        @Override
        public AsciiBytes getName() {
            return this.name;
        }
    }

    /**
     * {@link URLStreamHandler} that respects filtered entries.
     */
    private class FilteredURLStreamHandler extends URLStreamHandler {

        @Override
        protected URLConnection openConnection(URL url) throws IOException {
            String name = url.getPath()
                    .substring(ExplodedArchive.this.root.toURI().getPath().length());
            if (ExplodedArchive.this.entries.containsKey(new AsciiBytes(name))) {
                return new URL(url.toString()).openConnection();
            }
            return new FileNotFoundURLConnection(url, name);
        }
    }

}