import java.io.*;
import java.util.*;
import java.util.jar.*;

import org.apache.bcel.*;
import org.apache.bcel.classfile.*;
import org.apache.bcel.generic.*;

/**
 * Creates a GraphViz graph of the packages for the given jar files.
 * Example usage:
 *
 *  % java MakePackageGraph example1.jar example2.jar
 *
 * This requires the BCEL.
 */
public final class MakePackageGraph {

  public static void main(String[] args) throws Exception {
    new MakePackageGraph().process(args);
  }

  private final Graph classGraph = new Graph();

  void process(String[] args) throws Exception {
    if (args.length == 0) {
      System.err.println("Usage: java " + getClass().getName() + " <jar-1> <jar-2> ... <jar-n>");
      return;
    }
    for (String arg : args) process(arg);
    dump();
  }

  private void dump() {
    outln("digraph g {");
    for (Map.Entry<String,Set<String>> e : classGraph.adj.entrySet()) {
      String from = e.getKey();
      Set<String> tos = e.getValue();
      for (String to : tos) {
        if (to.equals("")) continue;
        if (from.equals(to)) continue;
        if (from.startsWith("java")) continue;
        if (to.startsWith("java")) continue;
        outln("  " + safeForGraphviz(from) + " -> " + safeForGraphviz(to) + ";");
      }
    }
    outln("}");
  }

  private String safeForGraphviz(String s) {
    return s.replaceAll("\\.","_");
  }

  private void outln(String s) {
    System.out.println(s);
  }

  private void process(String fileName) throws Exception {
    File f = new File(fileName);
    if (f.isDirectory()) {
      processDirectory(f);
    } else {
      processJarfile(f);      
    }
  }

  private void processDirectory(File dir) throws Exception {

  }

  private void processJarfile(File jar) throws Exception {
    JarFile jf = new JarFile(jar);
    for (Enumeration en = jf.entries(); en.hasMoreElements();) {
      processClass(((JarEntry)en.nextElement()).getName());
    }
  }

  private boolean processClass(String classFileName) throws Exception {
    if (!classFileName.endsWith(".class")) return false;
    processClass(Repository.lookupClass
                 (classFileName.substring(0, classFileName.length()-6).replace("/",".")));
    return true;
  }

  private void processClass(JavaClass clazz) {
    if (clazz == null) return;
    try {
      processClassInternal(clazz);
    } catch (Exception e) {
      // ignore
    }
  }

  private void processClassInternal(JavaClass clazz) throws Exception {
    String className = clazz.getClassName();
    for (Field f : clazz.getFields()) {
      process(className,f.getType());
    }
    for (Method m : clazz.getMethods()) {
      process(className, m.getReturnType());
      for (Type t : m.getArgumentTypes()) {
        process(className,t);
      }
    }
    processClass(clazz.getSuperClass());
    for (JavaClass c : clazz.getInterfaces()) {
      processClass(c);
    }
  }

  private void process(String fromClass, Type t) {
    process(fromClass,String.valueOf(t));
  }

  private void process(String fromClass, String toClass) {
    classGraph.addEdge(getPackage(fromClass),getPackage(toClass));
  }

  private String getPackage(String className) {
    int ilast = className.lastIndexOf(".");
    return ilast == -1 ? "" : className.substring(0,ilast);
  }

  /**
   * A simple graph of Strings.
   */
  private static class Graph {
    final Map<String,Set<String>> adj = new HashMap<String,Set<String>>();
    void addEdge(String from, String to) {
      Set<String> edges = adj.get(from);
      if (edges == null) {
        adj.put(from, edges = new HashSet<String>());
      }
      edges.add(to);
    }
  }
}