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

public class KaZaServer implements Runnable
{
    public static final int LISTEN_PORT = 3442;
    private ServerSocket m_serverSocket;
    private HashMap<String, ClientInfo> m_clientData;
    private Vector<Socket> m_peerGroupLeaders;

    public void run()
    {
        try {
            m_serverSocket = new ServerSocket(LISTEN_PORT);

            /* porcess connection requests */
            for (;;)
            {
                Socket clientSocket = m_serverSocket.accept();

                Thread thread = new Thread(new ClientHandler(clientSocket));
                thread.start();
            }
        } catch (IOException ioe) {
            System.out.println("KaZaServer: IO Exception!");
            ioe.printStackTrace();
            return;
        }
    }

    public void connectToPeerGroupLeader(String peerName)
    {
        Socket s;
        try
        {
            s = new Socket(peerName, LISTEN_PORT);
            DataOutputStream os = new DataOutputStream(s.getOutputStream());
            os.writeBytes("USER KaZaServer\n");
        }
        catch (Exception e)
        {
            return;
        }
        synchronized (m_peerGroupLeaders)
        {
            m_peerGroupLeaders.add(s);
        }
    }

    public void close()
    {
    }

    public String[] getClientList()
    {
        Set<String> s;
        synchronized (m_clientData)
        {
            s = m_clientData.keySet();
        }
        return (String[]) s.toArray();
    }

    private class ClientInfo
    {
        String userName = "Anonymous";
        HashMap<String, String> files = new HashMap<String, String>();
    }

    private class ClientHandler implements Runnable
    {
        private Socket m_socket;
        private String m_clientIP;
        ClientInfo m_clientInfo;

        public ClientHandler(Socket socket)
        {
            m_socket = socket;
            m_clientIP = m_socket.getInetAddress().getHostAddress();
            synchronized (m_clientData)
            {
                if (!m_clientData.containsKey(m_clientIP))
                { 
                    m_clientData.put(socket.getInetAddress().getHostAddress(),
                            new ClientInfo());
                }
                m_clientInfo = m_clientData.get(m_clientIP);
            }
        }

        public void run()
        {
            try
            {
                BufferedReader br = new BufferedReader(
                                        new InputStreamReader(
                                            m_socket.getInputStream()));
                DataOutputStream os = new DataOutputStream(
                                          m_socket.getOutputStream());

                /* loop processing client messages */
                for (;;)
                {
                    String inLine = br.readLine();

                    StringTokenizer tokens = new StringTokenizer(inLine);
                    if (!tokens.hasMoreTokens())
                        continue;

                    String opCode = tokens.nextToken();
                    opCode = opCode.toUpperCase();
                    if (opCode.equals("HELO"))
                    {
                        /* user is announcing his or her username */
                        synchronized (m_clientData)
                        {
                            m_clientInfo.userName = inLine.substring(5);
                        }
                    }
                    else if (opCode.equals("DESC"))
                    {
                        /* user is giving us a description of a file */
                        String fileName = inLine.substring(5);
                        String fileDesc = br.readLine();
                        synchronized (m_clientData)
                        {
                            m_clientInfo.files.put(fileName, fileDesc);
                        }
                    }
                    else if (opCode.equals("SRCH"))
                    {
                        /* user is requesting a search */
                        if (tokens.hasMoreTokens())
                        {
                            int depth = Integer.parseInt(tokens.nextToken());
                            if (tokens.hasMoreTokens())
                            {
                                String query = tokens.nextToken();
                                String searchResults = performSearch(depth, query);
                                os.writeBytes(searchResults);
                                os.writeBytes(".\n");
                            }
                        }
                    }
                }
            } catch (Exception e) { }
        }
    }

    private String performSearch(int depth, String query)
    {
        String results = "";
        String querylc = query.toLowerCase();
        if (depth > 0)
        {
            synchronized (m_peerGroupLeaders)
            {
                for (Socket s : m_peerGroupLeaders)
                {
                    String peerResults =
                        getSearchResultsFromPeerGroupLeader(s, depth-1, query);
                    results += peerResults;
                }
            }
        }

        /* now search my own file list */
        synchronized (m_clientData)
        {
            Set<String> clients = m_clientData.keySet();
            for (String clientIP : clients)
            {
                HashMap<String, String> files = m_clientData.get(clientIP).files;
                Set<String> clientFiles = files.keySet();
                for (String fileName : clientFiles)
                {
                    String fnamelc = fileName.toLowerCase();
                    if ( (fnamelc.indexOf(querylc) >= 0) ||
                         (files.get(fileName).toLowerCase().indexOf(querylc) >= 0) )
                    {
                        results += clientIP + "|" +
                                   m_clientData.get(clientIP).userName + "|" +
                                   fileName + "|" +
                                   files.get(fileName) + "\n";
                    }
                }
            }
        }
        return results;
    }

    private String getSearchResultsFromPeerGroupLeader(Socket s, int depth,
                                                       String query)
    {
        String searchResults = "";
        try
        {
            BufferedReader br = new BufferedReader(
                                    new InputStreamReader(
                                        s.getInputStream()));
            DataOutputStream os = new DataOutputStream(s.getOutputStream());

            os.writeBytes("SRCH " + depth + " " + query);
            for (;;)
            {
                String inLine = br.readLine();
                if (inLine.equals("."))
                    break;
                searchResults += inLine + "\n";
            }
        }
        catch (Exception e)
        {
            return "";
        }
        return searchResults;
    }
}