/*
 * ConnectBot: simple, powerful, open-source SSH client for Android
 * Copyright 2007 Kenny Root, Jeffrey Sharkey
 *
 * 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.five_ten_sg.connectbot.transport;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.nio.charset.Charset;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.five_ten_sg.connectbot.R;
import com.five_ten_sg.connectbot.bean.HostBean;
import com.five_ten_sg.connectbot.service.TerminalBridge;
import com.five_ten_sg.connectbot.service.TerminalManager;
import com.five_ten_sg.connectbot.util.HostDatabase;

import android.content.Context;
import android.net.Uri;
import android.util.Log;

import de.mud.telnet.TelnetProtocolHandler;


/**
 * Telnet transport implementation.<br/>
 * Original idea from the JTA telnet package (de.mud.telnet)
 *
 * @author Kenny Root
 *
 */
public class Telnet extends AbsTransport {
    private static final String TAG = "ConnectBot.Telnet";
    private static final String PROTOCOL = "telnet";
    private static final int DEFAULT_PORT = 23;

    private TelnetProtocolHandler handler;
    private Socket                socket;
    private InputStream           is;
    private OutputStream          os;
    private int                   width;
    private int                   height;
    private boolean               connected = false;

    static final Pattern hostmask;
    static {
        hostmask = Pattern.compile("^([0-9a-z.-]+)(:(\\d+))?$", Pattern.CASE_INSENSITIVE);
    }

    public Telnet() {
        handler = new TelnetProtocolHandler() {
            /** get the current terminal type */
            @Override
            public String getTerminalType() {
                return getEmulation();
            }
            /** get the current window size */
            @Override
            public int[] getWindowSize() {
                return new int[] { width, height };
            }
            /** notify about local echo */
            @Override
            public void setLocalEcho(boolean echo) {
                /* EMPTY */
            }
            /** write data to our back end */
            @Override
            public void write(byte[] b) throws IOException {
                if (os != null)
                    os.write(b);
            }
            /** sent on IAC EOR (prompt terminator for remote access systems). */
            @Override
            public void notifyEndOfRecord() {
            }
            @Override
            protected String getCharsetName() {
                Charset charset = bridge.getCharset();

                if (charset != null)
                    return charset.name();
                else
                    return "";
            }
        };
    }


    public static String getProtocolName() {
        return PROTOCOL;
    }


    public Uri getUri(String input) {
        Matcher matcher = hostmask.matcher(input);

        if (!matcher.matches())
            return null;

        StringBuilder sb = new StringBuilder();
        sb.append(PROTOCOL)
        .append("://")
        .append(matcher.group(1));
        String portString = matcher.group(3);
        int port = DEFAULT_PORT;

        if (portString != null) {
            try {
                port = Integer.parseInt(portString);

                if (port < 1 || port > 65535) {
                    port = DEFAULT_PORT;
                }
            }
            catch (NumberFormatException nfe) {
                // Keep the default port
            }
        }

        if (port != DEFAULT_PORT) {
            sb.append(':');
            sb.append(port);
        }

        sb.append("/#")
        .append(Uri.encode(input));
        Uri uri = Uri.parse(sb.toString());
        return uri;
    }


    @Override
    public void connect() {
        try {
            socket = new Socket(host.getHostname(), host.getPort());
            connected = true;
            is = socket.getInputStream();
            os = socket.getOutputStream();
            bridge.onConnected();
        }
        catch (UnknownHostException e) {
            Log.d(TAG, "IO Exception connecting to host", e);
        }
        catch (IOException e) {
            Log.d(TAG, "IO Exception connecting to host", e);
        }
    }


    @Override
    public boolean willBlock() {
        if (is == null) return true;
        try {
            return is.available() == 0;
        } catch (Exception e) {
            return true;
        }
    }


    @Override
    public int read(byte[] buffer, int start, int len) throws IOException {
        /* process all already read bytes */
        int n = 0;

        do {
            n = handler.negotiate(buffer, start);

            if (n > 0)
                return n;
        }
        while (n == 0);

        while (n <= 0) {
            do {
                n = handler.negotiate(buffer, start);

                if (n > 0)
                    return n;
            }
            while (n == 0);

            n = is.read(buffer, start, len);

            if (n < 0) {
                bridge.dispatchDisconnect(false);
                throw new IOException("Remote end closed connection.");
            }

            handler.inputfeed(buffer, start, n);
            n = handler.negotiate(buffer, start);
        }

        return n;
    }


    @Override
    public void write(byte[] buffer) throws IOException {
        try {
            if (os != null)
                os.write(buffer);
        }
        catch (SocketException e) {
            bridge.dispatchDisconnect(false);
        }
    }


    @Override
    public void write(int c) throws IOException {
        try {
            if (os != null)
                os.write(c);
        }
        catch (SocketException e) {
            bridge.dispatchDisconnect(false);
        }
    }


    @Override
    public void flush() throws IOException {
        os.flush();
    }


    @Override
    public void close() {
        connected = false;

        if (socket != null)
            try {
                socket.close();
                socket = null;
            }
            catch (IOException e) {
                Log.d(TAG, "Error closing telnet socket.", e);
            }
    }


    @Override
    public void setDimensions(int columns, int rows, int width, int height) {
        try {
            handler.setWindowSize(columns, rows);
        }
        catch (IOException e) {
            Log.e(TAG, "Couldn't resize remote terminal", e);
        }
    }


    @Override
    public int getDefaultPort() {
        return DEFAULT_PORT;
    }

    @Override
    public boolean isConnected() {
        return connected;
    }

    @Override
    public boolean isSessionOpen() {
        return isConnected();
    }

    @Override
    public boolean isAuthenticated() {
        return isConnected();
    }


    @Override
    public String getDefaultNickname(String username, String hostname, int port) {
        if (port == DEFAULT_PORT) {
            return String.format("%s", hostname);
        }
        else {
            return String.format("%s:%d", hostname, port);
        }
    }


    @Override
    public void getSelectionArgs(Uri uri, Map<String, String> selection) {
        selection.put(HostDatabase.FIELD_HOST_PROTOCOL, PROTOCOL);
        selection.put(HostDatabase.FIELD_HOST_NICKNAME, uri.getFragment());
        selection.put(HostDatabase.FIELD_HOST_HOSTNAME, uri.getHost());
        int port = uri.getPort();

        if (port < 0)
            port = DEFAULT_PORT;

        selection.put(HostDatabase.FIELD_HOST_PORT, Integer.toString(port));
    }


    @Override
    public HostBean createHost(Uri uri) {
        HostBean host = new HostBean();
        host.setProtocol(PROTOCOL);
        host.setHostname(uri.getHost());
        int port = uri.getPort();

        if (port < 0)
            port = DEFAULT_PORT;

        host.setPort(port);
        String nickname = uri.getFragment();

        if (nickname == null || nickname.length() == 0) {
            host.setNickname(getDefaultNickname(host.getUsername(),
                                                host.getHostname(), host.getPort()));
        }
        else {
            host.setNickname(uri.getFragment());
        }

        return host;
    }


    public String getFormatHint(Context context) {
        return String.format("%s:%s",
                             context.getString(R.string.format_hostname),
                             context.getString(R.string.format_port));
    }

    @Override
    public boolean usesNetwork() {
        return true;
    }
}