/*
 * Copyright 2012-present Facebook, Inc.
 *
 * 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 com.facebook.buck.java;

import com.facebook.buck.step.ExecutionContext;
import com.facebook.buck.step.Step;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableSet;

import java.io.IOException;
import java.nio.file.Path;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Pattern;

import javax.annotation.Nullable;

/**
 * Creates a JAR file from a collection of directories/ZIP/JAR files.
 */
public class JarDirectoryStep implements Step {

  /** Where to write the new JAR file. */
  private final Path pathToOutputFile;

  /** A collection of directories/ZIP/JAR files to include in the generated JAR file. */
  private final ImmutableSet<Path> entriesToJar;

  /** If specified, the Main-Class to list in the manifest of the generated JAR file. */
  @Nullable
  private final String mainClass;

  /** If specified, the Manifest file to use for the generated JAR file.  */
  @Nullable
  private final Path manifestFile;
  /** Indicates that manifest merging should occur. Defaults to true. */
  private final boolean mergeManifests;
  /** Set of regex blacklist of whiched matched files will not be included in generated JAR. */
  private final ImmutableSet<Pattern> blacklist;

  public JarDirectoryStep(
      Path pathToOutputFile,
      Set<Path> entriesToJar,
      @Nullable String mainClass,
      @Nullable Path manifestFile) {
    this(pathToOutputFile, entriesToJar, mainClass, manifestFile, true, ImmutableSet.<String>of());
  }

  /**
   * Creates a JAR from the specified entries (most often, classpath entries).
   * <p>
   * If an entry is a directory, then its files are traversed and added to the generated JAR.
   * <p>
   * If an entry is a file, then it is assumed to be a ZIP/JAR file, and its entries will be read
   * and copied to the generated JAR.
   * @param pathToOutputFile The directory that contains this path must exist before this command is
   *     executed.
   * @param entriesToJar Paths to directories/ZIP/JAR files.
   * @param mainClass If specified, the value for the Main-Class attribute in the manifest of the
   *     generated JAR.
   * @param manifestFile If specified, the path to the manifest file to use with this JAR.
   */
  public JarDirectoryStep(Path pathToOutputFile,
                          Set<Path> entriesToJar,
                          @Nullable String mainClass,
                          @Nullable Path manifestFile,
                          boolean mergeManifests,
                          Set<String> blacklist) {
    this.pathToOutputFile = pathToOutputFile;
    this.entriesToJar = ImmutableSet.copyOf(entriesToJar);
    this.mainClass = mainClass;
    this.manifestFile = manifestFile;
    this.mergeManifests = mergeManifests;
    this.blacklist = convertRegexesToPatterns(blacklist);
  }

  private ImmutableSet<Pattern> convertRegexesToPatterns(Set<String> regexes) {
    Set<Pattern> patterns = new HashSet<>();
    for (String regex : regexes) {
      patterns.add(Pattern.compile(regex));
    }
    return ImmutableSet.copyOf(patterns);
  }

  private String getJarArgs() {
    String result = "cf";
    if (manifestFile != null) {
      result += "m";
    }
    return result;
  }

  @Override
  public String getShortName() {
    return "jar";
  }

  @Override
  public String getDescription(ExecutionContext context) {
    return String.format("jar %s %s %s %s",
        getJarArgs(),
        pathToOutputFile,
        manifestFile != null ? manifestFile : "",
        Joiner.on(' ').join(entriesToJar));
  }

  @Override
  public int execute(ExecutionContext context) {
    try {
      JarDirectoryStepHelper.createJarFile(
          pathToOutputFile,
          entriesToJar,
          mainClass,
          manifestFile,
          mergeManifests,
          blacklist,
          context);
    } catch (IOException e) {
      e.printStackTrace(context.getStdErr());
      return 1;
    }
    return 0;
  }
}