/*
 *  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.tools.ant.taskdefs.condition;

import java.io.File;
import java.io.IOException;
import java.util.Enumeration;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.taskdefs.ManifestTask;
import org.apache.tools.ant.types.DataType;
import org.apache.tools.zip.ZipEntry;
import org.apache.tools.zip.ZipFile;

/**
 * Checks whether a jarfile is signed: if the name of the
 * signature is passed, the file is checked for presence of that
 * particular signature; otherwise the file is checked for the
 * existence of any signature.
 */
public class IsSigned extends DataType implements Condition {

    private static final String SIG_START = "META-INF/";
    private static final String SIG_END = ".SF";
    private static final int    SHORT_SIG_LIMIT = 8;

    private String name;
    private File file;

    /**
     * The jarfile that is to be tested for the presence
     * of a signature.
     * @param file jarfile to be tested.
     */
    public void setFile(File file) {
        this.file = file;
    }

   /**
     * The signature name to check jarfile for.
     * @param name signature to look for.
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * Returns <code>true</code> if the file exists and is signed with
     * the signature specified, or, if <code>name</code> wasn't
     * specified, if the file contains a signature.
     * @param zipFile the zipfile to check
     * @param name the signature to check (may be killed)
     * @return true if the file is signed.
     * @throws IOException on error
     */
    public static boolean isSigned(File zipFile, String name)
        throws IOException {
        try (ZipFile jarFile = new ZipFile(zipFile)) {
            if (null == name) {
                Enumeration<ZipEntry> entries = jarFile.getEntries();
                while (entries.hasMoreElements()) {
                    String eName = entries.nextElement().getName();
                    if (eName.startsWith(SIG_START)
                        && eName.endsWith(SIG_END)) {
                        return true;
                    }
                }
                return false;
            }
            name = replaceInvalidChars(name);
            boolean shortSig = jarFile.getEntry(SIG_START
                        + name.toUpperCase()
                        + SIG_END) != null;
            boolean longSig = false;
            if (name.length() > SHORT_SIG_LIMIT) {
                longSig = jarFile.getEntry(
                    SIG_START
                    + name.substring(0, SHORT_SIG_LIMIT).toUpperCase()
                    + SIG_END) != null;
            }

            return shortSig || longSig;
        }
    }

    /**
     * Returns <code>true</code> if the file exists and is signed with
     * the signature specified, or, if <code>name</code> wasn't
     * specified, if the file contains a signature.
     * @return true if the file is signed.
     */
    @Override
    public boolean eval() {
        if (file == null) {
            throw new BuildException("The file attribute must be set.");
        }
        if (!file.exists()) {
            log("The file \"" + file.getAbsolutePath()
                + "\" does not exist.", Project.MSG_VERBOSE);
            return false;
        }

        boolean r = false;
        try {
            r = isSigned(file, name);
        } catch (IOException e) {
            log("Got IOException reading file \"" + file.getAbsolutePath()
                + "\"" + e, Project.MSG_WARN);
        }

        if (r) {
            log("File \"" + file.getAbsolutePath() + "\" is signed.",
                Project.MSG_VERBOSE);
        }
        return r;
    }

    private static String replaceInvalidChars(final String name) {
        StringBuilder sb = new StringBuilder();
        final int len = name.length();
        boolean changes = false;
        for (int i = 0; i < len; i++) {
            final char ch = name.charAt(i);
            if (ManifestTask.VALID_ATTRIBUTE_CHARS.indexOf(ch) < 0) {
                sb.append("_");
                changes = true;
            } else {
                sb.append(ch);
            }
        }
        return changes ? sb.toString() : name;
    }
}
