/**
 * ForumServer.java  1.00  1.28.97 Michael Shoffner
 *
 * Copyright (c) 1997 Prominence Dot Com, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * for non-commercial purposes and without fee is hereby granted
 * provided that this copyright notice appears in all copies.
 *
 * http://prominence.com/                  shoffner@prominence.com
 */                   

import java.net.*;
import java.util.*;
import java.io.*;
import ForumConnectionHandler;

public class ForumServer extends Thread {

  static final String DEFAULT_FORUM_CONFIGFILE = "forum.cfg";
  static final String CONFIGFILE_THREADS = "threads";
  static final String CONFIGFILE_DATABASE = "database";

  // port for server to listen for Forum clients
  static final int FORUM_PORT = 5000;

  Hashtable articles;
  String databaseFilename;
  long connections = 0;
  long memoryLimit, diskLimit;
  Vector acl;
  ThreadGroup handlers;
  ServerSocket listener;
  String argv[];


  public ForumServer (String argv[]) {
    handlers = new ThreadGroup ("Forum Connection Handlers");
    articles = new Hashtable();
    this.argv = argv;
  }

  public void run() {
    try {
      setup (argv);
      listener = new ServerSocket (FORUM_PORT);
      while (true) {
	Socket c = listener.accept();
	if (aclCheck (c)) {
	  connections ++;
	  ForumConnectionHandler h = new ForumConnectionHandler (connections, c, memoryLimit, articles, handlers);
	  h.start();
	}
	else {
	  // could send client a "denied" message here
	  InetAddress denied = c.getInetAddress();
	  System.out.println ("Denied connection from: " + denied + ".\n");
	  try {
	    c.close();
	  } catch (IOException ex) {
	    System.out.println ("Denied close failed: " + ex + ".\n");
	  }
	}
      } 
    } catch (IOException ex) {
      // this is to ignore bug when closing down ServerSocket
      if (!(ex instanceof SocketException))
	ex.printStackTrace();
    }
    finally {
      try {
	if (listener != null)
	  listener.close();
      } catch (IOException ex) {
	System.out.println ("ServerSocket close failed.\n");
      }
      handlers.stop();
      try {
	if (databaseFilename != null && !databaseFilename.equals("")) {
	  if (diskLimitCheck())
	    dumpArticlesToDatabase (databaseFilename);
	}
	else
	  System.out.println ("Article database not saved to disk.\n");
      } catch (IOException ex) {
	System.out.println ("Article database save failed: " + ex + ".\n");
      }
      System.out.println ("The server has shut down.");
    }
  }
  

  void setup (String argv[]) throws IOException {

    // read from config file
    String configFileName = DEFAULT_FORUM_CONFIGFILE;
    if (argv.length > 0)
      configFileName = argv[0];    
    File configFile = new File (configFileName);
    if (! configFile.exists()) {
      throw new IOException ("Config file " + configFileName + " not found.\nSpecify a an alternate config file or provide a file named " + DEFAULT_FORUM_CONFIGFILE + ".\n");
    }
    Properties config = getConfig (configFile);

    // load in previous article database, ignoring old threads
    databaseFilename = config.getProperty (CONFIGFILE_DATABASE);
    String t = config.getProperty (CONFIGFILE_THREADS);
    articles = loadArticles (databaseFilename, t);

    // load in memoryLimit, diskLimit here
    // load in inbound connection ACL here
    
    // print config to console
    System.out.println ("FORUM SERVER CONFIGURATION\n");
    System.out.println ("Discussion threads:\n");
    Enumeration en = articles.keys();
    while (en.hasMoreElements())
      System.out.println (en.nextElement());

    System.out.println ("");
    System.out.println ("Database file: " + databaseFilename + "\n");
    // System.out.println ("Maximum disk usage: ");
    // System.out.println ("IP restrictions: ");
    // System.out.println ("Maximum memory usage: ");
    System.out.println ("Client connection listing:\n");
  }


  Properties getConfig (File configFile) throws IOException {
    
    Properties props = new Properties();
    FileInputStream f = new FileInputStream (configFile);
    DataInputStream dIn = null;
    try {
      dIn = new DataInputStream (f);
      String line;
      int lineNo = 0;
      while ((line = dIn.readLine()) != null) {
        ++ lineNo;
        line = line.trim();
        if ((line.length() > 0) && (!line.startsWith ("#"))) {
          int idx = line.indexOf ("=");
          if (idx >= 0)
            props.put (line.substring (0, idx).trim(), line.substring (idx + 1).trim());
          else
            throw new IOException ("line " + lineNo + " not understood: " + line + "\n");
        }
      }
    } catch (IOException ex) {
      throw new IOException ("Error reading " + configFile + ": " + ex.getMessage());
   
    } finally {
      if (dIn != null)
	dIn.close();
    }
    return props;
  }
  
  
  boolean aclCheck (Socket c) {
    // unimplemented
    return true;
  }

  boolean diskLimitCheck() {
    // unimplemented
    return true;
  }


  Hashtable loadArticles (String dbfn, String t) throws IOException {
    Hashtable returnArticles = new Hashtable();

    if (t == null || t.equals("")) {
      throw new RuntimeException ("You must define at least one discussion thread in the configuration file.\n");
    }
    else {
      StringTokenizer strtok = new StringTokenizer (t, ",");
      while (strtok.hasMoreTokens()) 
	returnArticles.put (strtok.nextToken(), new Vector());
    }

    if (dbfn != null && !dbfn.equals("")) {
      File db = new File (dbfn);
      System.out.println ("Threads loaded from filesystem:\n");
      try {
	FileInputStream f = new FileInputStream (db);
	DataInputStream dIn = new DataInputStream (f);
	int numThreads = 0;
	  numThreads = dIn.readInt();
	  for (int i = 1; i <= numThreads; i++) {
	    String thread = dIn.readUTF();
	    Vector v = new Vector();
	    int numArts = 0;
	    numArts = dIn.readInt();
	    for (int j = 1; j <= numArts; j++) {
	      String art = dIn.readUTF();
	      v.addElement (art);
	    }
	    if (returnArticles.get (thread) != null) {
	      returnArticles.put (thread, v);
	      System.out.println ("Thread '" + thread + "' picked up from database file.\n");     
	    }
	    else 
	      System.out.println ("Thread '" + thread + "' ignored.\n");
	  }
      } catch (IOException ex) {
	System.out.println ("Exception '" + ex + "' encountered while attempting to load articles from database " + dbfn + ".\n");
      }
    }
    return returnArticles;
  }

  void dumpArticlesToDatabase (String dbfn) throws IOException {

    if (articlesIsEmpty (articles)) {
      System.out.println ("No articles to save to database file.\n");
      return;
    }

    /*
       ** database structure 
       int: number of threads 
       string: threads 1 name
       int: number of thread 1 articles
       thread 1's articles 
       etc.
    */

    int numThreads = articles.size();
    Enumeration threads = articles.keys();
    File db = new File (dbfn);

    DataOutputStream dOut = null;
    try {
      FileOutputStream f = new FileOutputStream (db);
      dOut = new DataOutputStream (f);
     
     // record the number of threads
      dOut.writeInt (numThreads);

      // put each thread in, followed by its articles
      while (threads.hasMoreElements()) {
        String curThread = (String) threads.nextElement();
        dOut.writeUTF (curThread);
	Vector curThreadArts = (Vector) articles.get (curThread);
        dOut.writeInt (curThreadArts.size());
	Enumeration allArts = curThreadArts.elements();
	while (allArts.hasMoreElements()) {
	  String art = (String) allArts.nextElement();
	  dOut.writeUTF (art);
	}
      }
      System.out.println ("Article database written to " + dbfn + ".\n");
    }
    catch (IOException ex) {
      throw new IOException ("Exception " + ex + " encountered while attempting to write to file " + dbfn + ".\n");
    }
    finally {
      try {
      if (dOut != null)
	dOut.close();
      } catch (IOException ex) {
        throw new IOException ("Exception " + ex + " was encountered while attempting to close file " + dbfn + ".\n");
      }
    }
  }


  boolean articlesIsEmpty (Hashtable a) {
    boolean result = true;
    if (a == null || a.size() == 0) 
       return true;
    Enumeration en = a.keys();
    while (en.hasMoreElements()) {
      Vector threadArts = (Vector) a.get (en.nextElement());
      if (threadArts.size() > 0) {
	result = false;
	break;
      }
    }
    return result;
  }

  
  public static void main (String argv[]) throws IOException {
    ForumServer accept = new ForumServer (argv);
    accept.start();
    
    // listen for keypress
    while (true) {
      Thread.yield();
      if (System.in.available() != 0) {
	while (System.in.available() > 0)
	  System.in.read();
	accept.stop();
      break;
      }
    }
  }
}