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Telnet server for the JSimpleDB Command Line Interface (CLI).
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/*
 * Copyright (C) 2015 Archie L. Cobbs. All rights reserved.
 */

package org.jsimpledb.cli.telnet;

import com.google.common.base.Preconditions;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

import org.dellroad.nvt4j.Terminal;
import org.dellroad.nvt4j.impl.TerminalImpl;
import org.jsimpledb.JSimpleDB;
import org.jsimpledb.cli.Console;
import org.jsimpledb.core.Database;
import org.jsimpledb.kv.KVDatabase;

import jline.TerminalFactory;

/**
 * A {@link Console} connected to a telnet client via a {@link Socket}.
 *
 * 
 * This class can be used to implement an embedded CLI console within an application, accessed via telnet. For example:
 * 
 *      // Accept a new connection
 *      final Socket socket = ...
 *
 *      // Set up telnet CLI console
 *      final TelnetConsole console = TelnetConsole.create(database, socket);
 *      console.getSession().loadFunctionsFromClasspath();
 *      console.getSession().loadCommandsFromClasspath();
 *
 *      // Run the console
 *      console.run();
 * 
 */
public final class TelnetConsole extends Console {

    /**
     * Internal constructor.
     */
    private TelnetConsole(KVDatabase kvdb, Database db, JSimpleDB jdb, InputStream input, OutputStream output,
      jline.Terminal terminal, String encoding, String appName) throws IOException {
        super(kvdb, db, jdb, input, output, terminal, encoding, appName);
    }

    /**
     * Simplified factory method for {@link org.jsimpledb.SessionMode#KEY_VALUE} mode.
     *
     * @param kvdb key/value {@link KVDatabase}
     * @param socket socket connected to telnet client
     * @return new telnet console instance
     * @throws IOException if an I/O error occurs
     */
    public static TelnetConsole create(KVDatabase kvdb, Socket socket) throws IOException {
        return TelnetConsole.create(kvdb, null, null, socket.getInputStream(), socket.getOutputStream(), null, null);
    }

    /**
     * Simplified factory method for {@link org.jsimpledb.SessionMode#CORE_API} mode.
     *
     * @param db core API {@link Database}
     * @param socket socket connected to telnet client
     * @return new telnet console instance
     * @throws IOException if an I/O error occurs
     */
    public static TelnetConsole create(Database db, Socket socket) throws IOException {
        return TelnetConsole.create(null, db, null, socket.getInputStream(), socket.getOutputStream(), null, null);
    }

    /**
     * Simplified factory method for {@link org.jsimpledb.SessionMode#JSIMPLEDB} mode.
     *
     * @param jdb {@link JSimpleDB} database
     * @param socket socket connected to telnet client
     * @return new telnet console instance
     * @throws IOException if an I/O error occurs
     */
    public static TelnetConsole create(JSimpleDB jdb, Socket socket) throws IOException {
        return TelnetConsole.create(null, null, jdb, socket.getInputStream(), socket.getOutputStream(), null, null);
    }

    /**
     * Generic factory method.
     *
     * @param kvdb {@link KVDatabase} for {@link org.jsimpledb.SessionMode#KEY_VALUE} (otherwise must be null)
     * @param db {@link Database} for {@link org.jsimpledb.SessionMode#CORE_API} (otherwise must be null)
     * @param jdb {@link JSimpleDB} for {@link org.jsimpledb.SessionMode#JSIMPLEDB} (otherwise must be null)
     * @param input console input
     * @param output console output
     * @param encoding character encoding for {@code terminal}, or null for default
     * @param appName JLine application name, or null for none
     * @return new telnet console instance
     * @throws IOException if an I/O error occurs
     * @throws IllegalArgumentException if not exactly one of {@code kvdb}, {@code db} or {@code jdb} is not null
     */
    public static TelnetConsole create(KVDatabase kvdb, Database db, JSimpleDB jdb, InputStream input, OutputStream output,
      String encoding, String appName) throws IOException {

        // Set up nvt4j; ignore the initial clear & reposition
        final Terminal nvt4jTerminal = new TerminalImpl(input, output) {

            private boolean cleared;
            private boolean moved;

            @Override
            public void clear() throws IOException {
                if (this.cleared)
                    super.clear();
                this.cleared = true;
            }

            @Override
            public void move(int row, int col) throws IOException {
                if (this.moved)
                    super.move(row, col);
                this.moved = true;
            }
        };
        nvt4jTerminal.put(TerminalImpl.AUTO_WRAP_ON);
        nvt4jTerminal.setCursor(true);

        // Have JLine do input & output through telnet terminal
        final InputStream jlineInput = new InputStream() {
            @Override
            public int read() throws IOException {
                return nvt4jTerminal.get();
            }
        };
        final OutputStream jlineOutput = new OutputStream() {
            @Override
            public void write(int value) throws IOException {
                nvt4jTerminal.put(value);
            }
        };

        // Build console
        return new TelnetConsole(kvdb, db, jdb, jlineInput, jlineOutput,
          new TelnetTerminal(TerminalFactory.get(), nvt4jTerminal), encoding, appName);
    }

// ForwardingTerminal

    /**
     * Wrapper class for a JLine {@link jline.Terminal} that forwards all methods to the wrapped delegate.
     */
    public static class ForwardingTerminal implements jline.Terminal {

        protected final jline.Terminal terminal;

        public ForwardingTerminal(jline.Terminal terminal) {
            Preconditions.checkArgument(terminal != null, "null terminal");
            this.terminal = terminal;
        }

        @Override
        public void init() throws Exception {
            this.terminal.init();
        }

        @Override
        public void restore() throws Exception {
            this.terminal.restore();
        }

        @Override
        public void reset() throws Exception {
            this.terminal.reset();
        }

        @Override
        public boolean isSupported() {
            return this.terminal.isSupported();
        }

        @Override
        public int getWidth() {
            return this.terminal.getWidth();
        }

        @Override
        public int getHeight() {
            return this.terminal.getHeight();
        }

        @Override
        public boolean isAnsiSupported() {
            return this.terminal.isAnsiSupported();
        }

        @Override
        public OutputStream wrapOutIfNeeded(OutputStream out) {
            return this.terminal.wrapOutIfNeeded(out);
        }

        @Override
        public InputStream wrapInIfNeeded(InputStream in) throws IOException {
            return this.terminal.wrapInIfNeeded(in);
        }

        @Override
        public boolean hasWeirdWrap() {
            return this.terminal.hasWeirdWrap();
        }

        @Override
        public boolean isEchoEnabled() {
            return this.terminal.isEchoEnabled();
        }

        @Override
        public void setEchoEnabled(boolean enabled) {
            this.terminal.setEchoEnabled(enabled);
        }

        @Override
        public String getOutputEncoding() {
            return this.terminal.getOutputEncoding();
        }
    }

// TelnetTerminal

    /**
     * JLine {@link jline.Terminal} that gets window size information from an associated nvt4j {@link Terminal}.
     */
    public static class TelnetTerminal extends ForwardingTerminal {

        private final Terminal nvt;

        public TelnetTerminal(jline.Terminal terminal, Terminal nvt) {
            super(terminal);
            Preconditions.checkArgument(nvt != null, "null nvt");
            this.nvt = nvt;
        }

        @Override
        public int getWidth() {
            final int width = this.nvt.getColumns();
            return width > 0 ? width : super.getWidth();
        }

        @Override
        public int getHeight() {
            final int height = this.nvt.getRows();
            return height > 0 ? height : super.getHeight();
        }

        // TODO: echoEnabled <-> EchoOptionHandler, possibly others
    }
}