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/*
  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.tomitribe.util;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;

public class JarLocation {

    private JarLocation() {
        // no-op
    }

    public static File get() {
        return jarLocation(JarLocation.class);
    }

    public static File jarLocation(final Class clazz) {
        try {
            final String classFileName = clazz.getName().replace(".", "/") + ".class";

            final ClassLoader loader = clazz.getClassLoader();
            URL url;
            if (loader != null) {
                url = loader.getResource(classFileName);
            } else {
                url = clazz.getResource(classFileName);
            }

            if (url == null) {
                throw new IllegalStateException("classloader.getResource(classFileName) returned a null URL");
            }

            if ("jar".equals(url.getProtocol())) {
                final String spec = url.getFile();

                int separator = spec.indexOf('!');
                /*
                 * REMIND: we don't handle nested JAR URLs
                 */
                if (separator == -1) {
                    throw new MalformedURLException("no ! found in jar url spec:" + spec);
                }

                url = new URL(spec.substring(0, separator++));

                return new File(decode(url.getFile()));

            } else if ("file".equals(url.getProtocol())) {
                return toFile(classFileName, url);
            } else {
                throw new IllegalArgumentException("Unsupported URL scheme: " + url.toExternalForm());
            }
        } catch (final RuntimeException e) {
            throw e;
        } catch (final Exception e) {
            throw new IllegalStateException(e);
        }
    }

    private static File toFile(final String classFileName, final URL url) {
        String path = url.getFile();
        path = path.substring(0, path.length() - classFileName.length());
        return new File(decode(path));
    }


    public static String decode(final String fileName) {
        if (fileName.indexOf('%') == -1) return fileName;

        final StringBuilder result = new StringBuilder(fileName.length());
        final ByteArrayOutputStream out = new ByteArrayOutputStream();

        for (int i = 0; i < fileName.length(); ) {
            final char c = fileName.charAt(i);

            if (c == '%') {
                out.reset();
                do {
                    if (i + 2 >= fileName.length()) {
                        throw new IllegalArgumentException("Incomplete % sequence at: " + i);
                    }

                    final int d1 = Character.digit(fileName.charAt(i + 1), 16);
                    final int d2 = Character.digit(fileName.charAt(i + 2), 16);

                    if (d1 == -1 || d2 == -1) {
                        throw new IllegalArgumentException("Invalid % sequence (" + fileName.substring(i, i + 3) + ") at: " + String.valueOf(i));
                    }

                    out.write((byte) ((d1 << 4) + d2));

                    i += 3;

                } while (i < fileName.length() && fileName.charAt(i) == '%');


                result.append(out.toString());

                continue;
            } else {
                result.append(c);
            }

            i++;
        }
        return result.toString();
    }

}