# TerminalStream.java

    /*
    ** Module   : TerminalStream.java
    ** Abstract :
    **
    ** Copyright (c) 2008-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --JPRM-- ----------------------------Description----------------------------
    ** 001 SIY 20080314   @37452 Created initial version
    **                           Ref: #37453
    ** 002 GES 20080327   @37699 Removed direct use of the native interfaces
    **                           in toolkit. This makes the result more
    **                           abstract and safer for I18N purposes. But
    **                           it should be noted that this case should
    **                           not have any direct use of the CHARVA code
    **                           at all because that is a dependency that is
    **                           inappropriate for the util package and the
    **                           streams implementation.
    ** 003 NVS 20090216   @41321 Terminal stream shouldn't use the interactive
    **                           output driver. Now using the direct output
    **                           driver instead.
    ** 004 SIY 20100619          Switching to own implementation of character UI.
    ** 005 SIY 20100804          Changes in imports.
    ** 006 SVL 20110403          Added write(byte[]) function.
    ** 007 SIY 20110112          Changes related to new color handling scheme.
    ** 008 CA  20140730          Protected stream close/cleanup code from raised conditions, to allow
    **                           close/cleanup fully complete even if conditions were raised.
    ** 009 CA  20140805          ChUI-specific classes are explicitly imported, to isolate their usage.
    **                           For now, this class works only with a ChUI driver, but this needs to
    **                           be improved, to allow GUI driver support.
    ** 010 HC  20140911          GUI coordinate support - data types refactoring.
    ** 011 HC  20151013          Changes to extend GUI multi-window focus management and ACTIVE-
    **                           WINDOW system handle processing to modal windows.
    ** 012 OM  20170622          Implemented peekCh() method.
    ** 013 ECF 20171026          Added write(byte[], int, int) method.
    ** 014 EVL 20220325          Base refactoring for Stream based classes getting single byte and array of bytes.
    ** 015 GBB 20240912          Replacing OutputManager dependency with the new interface Terminal.
    */

    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
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    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.util;

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

    import com.goldencode.p2j.ui.*;
    import com.goldencode.p2j.ui.chui.*;
    import com.goldencode.p2j.ui.client.*;
    import com.goldencode.p2j.ui.client.chui.driver.ChuiOutputManager;

    /**
     * This class provides support for stream redirected to the interactive
     * terminal. This stream behaves as something in the middle between stream and
     * interactive terminal. It displays output as regular stream (for example
     * like {@link FileStream}), but processes pause as interactive terminal.
     * <p>
     * Terminal stream handles paging differently than regular stream. In
     * particular, it has different default page size dictated by terminal height
     * and each page triggers a pause which requires user action (pressing a key).
     *
     * @author  SIY
     */
    public class TerminalStream
    extends Stream
    {
       /** Track start of the output is started. */
       private boolean outputStarted = false;

       /** Reference to toolkit. */
       private ChuiOutputManager tk;

       /** Reference to interactive output worker. */
       private BasePrimitives worker;

       /** Screen buffer. */
       private char[] buffer;

       /** Number of screen rows. */
       private int rows;

       /** Number of screen columns. */
       private int cols;

       /** Start of the buffer. */
       private int start = 0;

       /** Cursor position. */
       private int cursor = 0;

       /**
        * Constructor.
        *
        * @param    terminal
        *           Provides access to terminal features and helpers.
        */
       public TerminalStream(Terminal terminal)
       {
          tk = (ChuiOutputManager) terminal.getOutputManager();
          worker = tk.getDirectOutput();

          cols = worker.screenWidth();
          rows = worker.screenHeight();
          buffer = new char[cols * rows];
          double height = WindowManager.resolveWindow().getScreenDimension().height;
          int nheight = tk.coordinates().heightToNative(height);
          cursor = nheight * cols;
          Arrays.fill(buffer, ' ');
       }

       /**
        * Sets the current page size in lines.
        *
        * @param    sz
        *           The number of lines per page.
        */
       @Override
       void rawSetPageSize(int sz)
       {
          // use terminal height as a default value
          if (sz == SET_PAGED_DEFAULT)
          {
             double h = WindowManager.resolveWindow().getScreenDimension().height;
             sz = tk.coordinates().heightToNative(h) - 2;
          }

          super.rawSetPageSize(sz);
       }

       /**
        * Assigns the internal stream reference to the given reference, in
        * actuality this has no effect.
        *
        * @param    stream
        *           The new internal stream reference to use for all operations,
        *           ignored.
        */
       @Override
       public void assign(Stream stream)
       throws UnsupportedOperationException
       {
          // nothing to do
       }

       /**
        * The number of bytes available to be immediately read without blocking.
        *
        * @return   always 0.
        */
       @Override
       public long available()
       throws IOException
       {
          return 0;
       }

       /**
        * Closes the stream and releases OS resources associated with it, in
        * actuality this has no effect.
        */
       @Override
       public void close()
       {
          // nothing to do
       }

       /**
        * Closes the input stream and releases OS resources associated with it,
        * in actuality this has no effect.
        */
       @Override
       public void closeIn()
       {
          // nothing to do
       }

       /**
        * Closes the output stream and clears the interactive terminal screen.
        */
       @Override
       public void closeOut()
       {
          if (outputStarted)
          {
             ThinClient cli = ThinClient.getInstance();
             int saveId = cli.switchOutput(-1, false);
             cli.refreshScreen();
             cli.switchOutput(saveId, false);
          }
       }

       /**
        * The length of the stream in bytes.
        *
        * @return   always 0.
        */
       @Override
       public long getLen()
       throws UnsupportedOperationException,
              IOException
       {
          return 0;
       }

       /**
        * The 0-based offset into the stream at which the next read or write will
        * occur.
        *
        * @return   always 0.
        */
       @Override
       public long getPos()
       throws UnsupportedOperationException,
              IOException
       {
          return 0;
       }

       /**
        * State of the input side of the stream.
        *
        * @return   always <code>false</code>
        */
       @Override
       public boolean isIn()
       {
          return false;
       }

       /**
        * State of the output side of the stream.
        *
        * @return   always <code>false</code>
        */
       @Override
       public boolean isOut()
       {
          return true;
       }

       /**
        * Peeks at the character from the current read position in the stream.
        *
        * @return   always -2 (simulates an {@code EOF}).
        */
       @Override
       public int peekCh()
       {
          return -2;
       }

       /**
        * Read a character from the current read position in the stream.
        *
        * @return   always -2 (simulates an <code>EOF</code>).
        */
       @Override
       public int readCh()
       {
          return -2;
       }

       /**
        * Read a single byte from the underlying stream.
        *
        * @return   A single byte from the stream, -1 on any failure and -2 upon an {@code EOF}.
        */
       @Override
       public int readByte()
       {
          return -2;
       }

       /**
        * Read all characters from the current read position in the stream to the
        * next line separator (as determined by the <code>File.separator</code>
        * or to the <code>EOF</code>. Any line separator character(s) and the
        * <code>EOF</code> character are not returned.  In actuality this has no
        * effect.
        *
        * @return   always throws an <code>EOFException</code>.
        */
       @Override
       public String readLn()
       throws EOFException,
              IOException,
              InterruptedException
       {
          throw new EOFException("There is no stream.");
       }

       /**
        * Truncates or extends the stream to the specified length if this stream
        * supports such an operation, in actuality this has no effect.
        *
        * @param    len
        *           Ignored.
        */
       @Override
       public void setLen(long len)
       throws UnsupportedOperationException,
              IOException
       {
          // nothing to do
       }

       /**
        * Moves the current read/write position to the specified absolute 0-based
        * offset, in actuality this has no effect.
        *
        * @param    pos
        *           The new read/write position in the stream.
        */
       @Override
       public void setPos(long pos)
       throws UnsupportedOperationException,
              IOException
       {
          // nothing to do
       }

       /**
        * Write the given string to the output stream.
        *
        * @param    data
        *           The data to be written.
        *
        * @throws   IOException
        *           If an I/O error occurs.
        */
       @Override
       public void write(String data)
       throws IOException
       {
          if (data == null)
          {
             return;
          }

          syncTeletypeString(data);
       }

       /**
        * Write the given byte array to the output stream.
        *
        * @param    data
        *           The data to be written.
        *
        * @throws   IOException
        *           If an I/O error occurs.
        */
       public void write(byte[] data)
       throws IOException
       {
          if (data == null)
          {
             return;
          }

          for (byte b : data)
          {
             syncTeletype((char) b);
          }
       }

       /**
        * Write the specified range of bytes from the given byte array to the output stream.
        *
        * @param    data
        *           The data to be written.
        * @param    off
        *           Starting offset in data from which to read bytes to be written. Must be
        *           non-negative and {@code &lt; data.length}.
        * @param    len
        *           Length of data to be written. Must be non-negative and {@code &lt;= (data.length
        *           - offset)}.
        *
        * @throws   IOException
        *           If an I/O error occurs.
        */
       public void write(byte[] data, int off, int len)
       throws IOException
       {
          if (data == null)
          {
             return;
          }

          for (int i = off; i < len; i++)
          {
             syncTeletype((char) data[i]);
          }
       }

       /**
        * Write the given byte to the output stream.
        *
        * @param    b
        *           The byte to be written.
        *
        * @throws   IOException
        *           If an I/O error occurs.
        */
       @Override
       public void writeByte(byte b)
       throws IOException
       {
          syncTeletype((char) b);
       }

       /**
        * Write the given character to the output stream.
        *
        * @param    ch
        *           The character to be written.
        *
        * @throws   IOException
        *           If an I/O error occurs.
        */
       @Override
       public void writeCh(char ch)
       throws IOException
       {
          syncTeletype(ch);
       }

       /**
        * Simulate TTY output.
        *
        * @param   ch
        *          Character to write to the stream.
        */
       private void teletype(char ch)
       {
          // form feed
          if (ch == '\f')
          {
             insertFormFeed();
             ThinClient.getInstance().pauseAfterPage();
             return;
          }
          else if (ch == '\n')
          {
             int delta = cols - (cursor % cols);

             Arrays.fill(buffer, cursor, cursor + delta, ' ');

             cursor += delta;
          }
          else
             buffer[cursor++] = ch;

          if (cursor >= buffer.length || cursor == start)
          {
             cursor = start;
             start += cols;

             if (start >= buffer.length)
                start = 0;

             Arrays.fill(buffer, cursor, cursor + cols, ' ');
          }
       }

       /**
        * Insert 4 empty lines.
        */
       private void insertFormFeed()
       {
          syncTeletypeString("\n\n\n\n");
       }

       /**
        * Simulate TTY output of single character and synchronize terminal when
        * processing is finished.
        *
        * @param   ch
        *          Character to write to the stream.
        */
       private void syncTeletype(char ch)
       {
          Syncronizer sync = new Syncronizer();

          teletype(ch);

          sync.refresh();
       }

       /**
        * Simulate TTY output of string and synchronize terminal when processing
        * is finished.
        *
        * @param   data
        *          The characters to write to the stream.
        */
       private void syncTeletypeString(String data)
       {
          Syncronizer sync = new Syncronizer();

          try
          {
             for (char c : data.toCharArray())
                teletype(c);
          }
          finally
          {
             sync.refresh();
          }
       }

       /**
        * Refresh content of entire screen.
        */
       private void refreshScreen()
       {
          for(int i = 0; i < rows; i++)
             refreshRow(i);
       }

       /**
        * Refresh content of specified row.
        *
        * @param   row
        *          Row number to refresh.
        */
       private void refreshRow(int row)
       {
          if (row < 0 || row >= rows)
             return;

          int rowStart = (start + row * cols) % buffer.length;
          String str = new String(buffer, rowStart, cols);
          worker.cursorAt(0, row);
          worker.append(str, Color.DEFAULT);
       }

       /**
        * This class handles saving buffer state and refreshing terminal as
        * necessary.
        */
       class Syncronizer
       {
          /** Saved buffer start pointer. */
          private int saveStart;
          /** Saved cursor position. */
          private int saveCursor;

          /**
           * Construct an instance and save buffer state variables.
           */
          Syncronizer()
          {
             saveStart  = start;
             saveCursor = cursor;

             if (!outputStarted)
             {
                outputStarted = true;

                tk.clearScreen();
             }
          }

          /**
           * Refresh terminal as necessary.
           */
          void refresh()
          {
             if (saveStart != start)
                refreshScreen();
             else
                refreshRow((saveCursor - start)/cols);

             worker.sync();
          }
       }
    }