/*
 * 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.commons.compress.compressors;

import java.util.Collections;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

File name mapping code for the compression formats.
@ThreadSafe
Since:
1.4/**
 * File name mapping code for the compression formats.
 * @ThreadSafe
 * @since 1.4
 */
public class FileNameUtil {

    
Map from common file name suffixes to the suffixes that identify compressed
versions of those file types. For example: from ".tar" to ".tgz".
/**
     * Map from common file name suffixes to the suffixes that identify compressed
     * versions of those file types. For example: from ".tar" to ".tgz".
     */
    private final Map<String, String> compressSuffix =
        new HashMap<>();

    
Map from common file name suffixes of compressed files to the
corresponding suffixes of uncompressed files. For example: from
".tgz" to ".tar".

This map also contains format-specific suffixes like ".gz" and "-z".
These suffixes are mapped to the empty string, as they should simply
be removed from the file name when the file is uncompressed.
/**
     * Map from common file name suffixes of compressed files to the
     * corresponding suffixes of uncompressed files. For example: from
     * ".tgz" to ".tar".
     * <p>
     * This map also contains format-specific suffixes like ".gz" and "-z".
     * These suffixes are mapped to the empty string, as they should simply
     * be removed from the file name when the file is uncompressed.
     */
    private final Map<String, String> uncompressSuffix;

    
Length of the longest compressed suffix.
/**
     * Length of the longest compressed suffix.
     */
    private final int longestCompressedSuffix;

    
Length of the shortest compressed suffix.
/**
     * Length of the shortest compressed suffix.
     */
    private final int shortestCompressedSuffix;

    
Length of the longest uncompressed suffix.
/**
     * Length of the longest uncompressed suffix.
     */
    private final int longestUncompressedSuffix;

    
Length of the shortest uncompressed suffix longer than the
empty string.
/**
     * Length of the shortest uncompressed suffix longer than the
     * empty string.
     */
    private final int shortestUncompressedSuffix;

    
The format's default extension.
/**
     * The format's default extension.
     */
    private final String defaultExtension;

    
sets up the utility with a map of known compressed to
uncompressed suffix mappings and the default extension of the
format.
Params:
uncompressSuffix – Map from common file name suffixes of
compressed files to the corresponding suffixes of uncompressed
files. For example: from ".tgz" to ".tar".  This map also
contains format-specific suffixes like ".gz" and "-z".  These
suffixes are mapped to the empty string, as they should simply
be removed from the file name when the file is uncompressed.
defaultExtension – the format's default extension like ".gz"/**
     * sets up the utility with a map of known compressed to
     * uncompressed suffix mappings and the default extension of the
     * format.
     *
     * @param uncompressSuffix Map from common file name suffixes of
     * compressed files to the corresponding suffixes of uncompressed
     * files. For example: from ".tgz" to ".tar".  This map also
     * contains format-specific suffixes like ".gz" and "-z".  These
     * suffixes are mapped to the empty string, as they should simply
     * be removed from the file name when the file is uncompressed.
     *
     * @param defaultExtension the format's default extension like ".gz"
     */
    public FileNameUtil(final Map<String, String> uncompressSuffix,
                        final String defaultExtension) {
        this.uncompressSuffix = Collections.unmodifiableMap(uncompressSuffix);
        int lc = Integer.MIN_VALUE, sc = Integer.MAX_VALUE;
        int lu = Integer.MIN_VALUE, su = Integer.MAX_VALUE;
        for (final Map.Entry<String, String> ent : uncompressSuffix.entrySet()) {
            final int cl = ent.getKey().length();
            if (cl > lc) {
                lc = cl;
            }
            if (cl < sc) {
                sc = cl;
            }

            final String u = ent.getValue();
            final int ul = u.length();
            if (ul > 0) {
                if (!compressSuffix.containsKey(u)) {
                    compressSuffix.put(u, ent.getKey());
                }
                if (ul > lu) {
                    lu = ul;
                }
                if (ul < su) {
                    su = ul;
                }
            }
        }
        longestCompressedSuffix = lc;
        longestUncompressedSuffix = lu;
        shortestCompressedSuffix = sc;
        shortestUncompressedSuffix = su;
        this.defaultExtension = defaultExtension;
    }

    
Detects common format suffixes in the given file name.
Params:
fileName – name of a file
Returns:
true if the file name has a common format suffix, false otherwise/**
     * Detects common format suffixes in the given file name.
     *
     * @param fileName name of a file
     * @return {@code true} if the file name has a common format suffix,
     *         {@code false} otherwise
     */
    public boolean isCompressedFilename(final String fileName) {
        final String lower = fileName.toLowerCase(Locale.ENGLISH);
        final int n = lower.length();
        for (int i = shortestCompressedSuffix;
             i <= longestCompressedSuffix && i < n; i++) {
            if (uncompressSuffix.containsKey(lower.substring(n - i))) {
                return true;
            }
        }
        return false;
    }

    
Maps the given name of a compressed file to the name that the
file should have after uncompression. Commonly used file type specific
suffixes like ".tgz" or ".svgz" are automatically detected and
correctly mapped. For example the name "package.tgz" is mapped to
"package.tar". And any file names with the generic ".gz" suffix
(or any other generic gzip suffix) is mapped to a name without that
suffix. If no format suffix is detected, then the file name is returned
unmapped.
Params:
fileName – name of a file
Returns:
name of the corresponding uncompressed file/**
     * Maps the given name of a compressed file to the name that the
     * file should have after uncompression. Commonly used file type specific
     * suffixes like ".tgz" or ".svgz" are automatically detected and
     * correctly mapped. For example the name "package.tgz" is mapped to
     * "package.tar". And any file names with the generic ".gz" suffix
     * (or any other generic gzip suffix) is mapped to a name without that
     * suffix. If no format suffix is detected, then the file name is returned
     * unmapped.
     *
     * @param fileName name of a file
     * @return name of the corresponding uncompressed file
     */
    public String getUncompressedFilename(final String fileName) {
        final String lower = fileName.toLowerCase(Locale.ENGLISH);
        final int n = lower.length();
        for (int i = shortestCompressedSuffix;
             i <= longestCompressedSuffix && i < n; i++) {
            final String suffix = uncompressSuffix.get(lower.substring(n - i));
            if (suffix != null) {
                return fileName.substring(0, n - i) + suffix;
            }
        }
        return fileName;
    }

    
Maps the given file name to the name that the file should have after
compression. Common file types with custom suffixes for
compressed versions are automatically detected and correctly mapped.
For example the name "package.tar" is mapped to "package.tgz". If no
custom mapping is applicable, then the default ".gz" suffix is appended
to the file name.
Params:
fileName – name of a file
Returns:
name of the corresponding compressed file/**
     * Maps the given file name to the name that the file should have after
     * compression. Common file types with custom suffixes for
     * compressed versions are automatically detected and correctly mapped.
     * For example the name "package.tar" is mapped to "package.tgz". If no
     * custom mapping is applicable, then the default ".gz" suffix is appended
     * to the file name.
     *
     * @param fileName name of a file
     * @return name of the corresponding compressed file
     */
    public String getCompressedFilename(final String fileName) {
        final String lower = fileName.toLowerCase(Locale.ENGLISH);
        final int n = lower.length();
        for (int i = shortestUncompressedSuffix;
             i <= longestUncompressedSuffix && i < n; i++) {
            final String suffix = compressSuffix.get(lower.substring(n - i));
            if (suffix != null) {
                return fileName.substring(0, n - i) + suffix;
            }
        }
        // No custom suffix found, just append the default
        return fileName + defaultExtension;
    }
}