/*
 * Copyright 2013 Guidewire Software, Inc.
 */

package gw.util;

import gw.config.CommonServices;
import gw.fs.IDirectory;
import gw.fs.IFile;
import gw.fs.ResourcePath;
import gw.lang.reflect.module.IModule;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.jar.Attributes;
import java.util.jar.Manifest;

/**
 * Utility class to scan for certain manifest headers through the classpath.
 */
public final class Extensions {
  public static final String CONTAINS_SOURCES = "Contains-Sources";

  public static List<String> getExtensions(IDirectory dir, String headerName) {
    List<String> extensions = new ArrayList<String>();
    getExtensions(extensions, dir, headerName);
    return extensions;
  }

  public static boolean containsManifest(IDirectory dir) {
    IFile manifestFile = dir.file( "META-INF/MANIFEST.MF" );
    return manifestFile != null && manifestFile.exists();
  }

  public static void getExtensions(Collection<String> result, IDirectory dir, String headerName) {
    IFile manifestFile = dir.file( "META-INF/MANIFEST.MF" );
    if (manifestFile == null || !manifestFile.exists()) {
      return;
    }
    InputStream in = null;
    try {
      in = manifestFile.openInputStream();
      Manifest manifest = new Manifest(in);
      scanManifest(result, manifest, headerName);
    } catch (Exception e) {
      // FIXME: For some reason, WebSphere changes JARs in WEB-INF/lib, breaking signatures. So ignore errors.
      ResourcePath path = dir.getPath();
      String str = path != null ? path.getFileSystemPathString() : dir.toString();
      CommonServices.getEntityAccess().getLogger().warn("Cannot read manifest from jar " + str + ", ignoring");
    } finally {
      if (in != null) {
        try {
          in.close();
        } catch (IOException e) {
          // Ignore
        }
      }
    }
  }

  private static void scanManifest(Collection<String> result, Manifest manifest, String headerName) {
    Attributes mainAttributes = manifest.getMainAttributes();
    String valueList = mainAttributes.getValue(headerName);
    if (valueList != null) {
      for (String val : valueList.split(",")) {
        result.add(GosuStringUtil.strip(val));
      }
    }
  }

  public static List<IDirectory> getJarsWithSources(IModule module) {
    List<IDirectory> jars = new ArrayList<IDirectory>();
    for (IDirectory root : module.getJavaClassPath()) {
      List<String> extensions = new ArrayList<String>();
      Extensions.getExtensions(extensions, root, CONTAINS_SOURCES);
      if (!extensions.isEmpty()) {
        jars.add(root);
      }
    }
    return jars;
  }

  private Extensions() {
    // No instances.
  }

}