
(********************************************************************)
(*                                                                  *)
(*  editline.s7i  Filter file for linewise editing with history     *)
(*  Copyright (C) 2013  Thomas Mertes                               *)
(*                                                                  *)
(*  This file is part of the Seed7 Runtime Library.                 *)
(*                                                                  *)
(*  The Seed7 Runtime Library is free software; you can             *)
(*  redistribute it and/or modify it under the terms of the GNU     *)
(*  Lesser General Public License as published by the Free Software *)
(*  Foundation; either version 2.1 of the License, or (at your      *)
(*  option) any later version.                                      *)
(*                                                                  *)
(*  The Seed7 Runtime Library 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 Lesser General Public License for more    *)
(*  details.                                                        *)
(*                                                                  *)
(*  You should have received a copy of the GNU Lesser General       *)
(*  Public License along with this program; if not, write to the    *)
(*  Free Software Foundation, Inc., 51 Franklin Street,             *)
(*  Fifth Floor, Boston, MA  02110-1301, USA.                       *)
(*                                                                  *)
(********************************************************************)


include "keybd.s7i";


(**
 *  [[file|File]] implementation type for linewise editing with history.
 *  The possibilities of editing are described in the documentation of
 *  the function [[#getln(inout_editLineFile)|getln]].
 *)
const type: editLineFile is sub null_file struct
    var file: inFile is STD_NULL;
    var file: outFile is STD_NULL;
    var boolean: allowUnicode is TRUE;
    var string: line is "";
    var boolean: lineFinished is TRUE;
    var array string: history is 0 times "";
  end struct;


(**
 *  Open an Unicode filter file for linewise editing with history.
 *  Unicode characters and editing keys are read from ''inFile''.
 *  All Unicode characters are accepted and written to ''outFile''.
 *  To avoid RANGE_ERROR use an Unicode capable file as ''outFile''.
 *  The following editing keys are accepted: Backspace, delete,
 *  home, end and the cursor keys. The history is accessed with
 *  the vertical cursor keys. Ctrl-C and ctrl-T allow terminating
 *  the program. Other keys (e.g. function keys) are ignored.
 *  Call ''openEditLine'' with
 *   IN := openEditLine(KEYBOARD, OUT);
 *  to allow editing standard console input.
 *  @return the file opened.
 *)
const func file: openEditLine (in file: inFile, in file: outFile) is func
  result
    var file: newFile is STD_NULL;
  local
    var editLineFile: new_editLineFile is editLineFile.value;
  begin
    new_editLineFile.inFile := inFile;
    new_editLineFile.outFile := outFile;
    newFile := toInterface(new_editLineFile);
  end func;


(**
 *  Open a Latin-1 filter file for linewise editing with history.
 *  Unicode characters and editing keys are read from ''inFile''.
 *  Only Latin-1 characters are accepted and written to ''outFile''.
 *  Unicode characters beyond ISO Latin-1 (ISO-8859-1) are ignored.
 *  This allows that a normal byte file is used as ''outFile''.
 *  The following editing keys are accepted: Backspace, delete,
 *  home, end and the cursor keys. The history is accessed with
 *  the vertical cursor keys. Ctrl-C and ctrl-T allow terminating
 *  the program. Other keys (e.g. function keys) are ignored.
 *  Call ''openEditLine'' with
 *   IN := openEditLineLatin1(KEYBOARD, OUT);
 *  to allow editing standard console input.
 *  @return the file opened.
 *)
const func file: openEditLineLatin1 (in file: inFile, in file: outFile) is func
  result
    var file: newFile is STD_NULL;
  local
    var editLineFile: new_editLineFile is editLineFile.value;
  begin
    new_editLineFile.inFile := inFile;
    new_editLineFile.outFile := outFile;
    new_editLineFile.allowUnicode := FALSE;
    newFile := toInterface(new_editLineFile);
  end func;


(**
 *  Read a line from ''inEditLine''.
 *  Before the line is sent it can be edited. It is possible to
 *  move the cursor with horizontal cursor keys. The home key and
 *  the end key move the cursor to the beginning respectively end
 *  of the input line. Characters can be inserted at the current
 *  cursor position. Backspace and delete can be used to remove
 *  characters. Vertical cursor keys allow browsing the history of
 *  input lines. Sending the line is done with enter/return ('\n').
 *  The line ending character is not copied into the string. When
 *  the function is left inEditLine.bufferChar contains '\n' or
 *  [[char#EOF|EOF]].
 *  @return the line read.
 *)
const func string: getln (inout editLineFile: inEditLine) is func
  result
    var string: line is "";
  local
    var char: ch is ' ';
    var char: response is ' ';
    var integer: pos is 1;
    var array string: history is 0 times "";
    var integer: historyPos is 0;
  begin
    if inEditLine.line = "" then
      history := inEditLine.history & [] ("");
      historyPos := length(history);
      repeat
        if pos <= length(line) then
          cursorOn(inEditLine.outFile, line[pos]);
        else
          cursorOn(inEditLine.outFile, ' ');
        end if;
        flush(inEditLine.outFile);
        ch := getc(inEditLine.inFile);
        if pos <= length(line) then
          cursorOff(inEditLine.outFile, line[pos]);
        else
          cursorOff(inEditLine.outFile, ' ');
        end if;
        if ch = KEY_BS then
          if pos > 1 then
            decr(pos);
            moveLeft(inEditLine.outFile, line[pos len 1]);
            erase(inEditLine.outFile, line[pos ..]);
            moveLeft(inEditLine.outFile, line[pos ..]);
            line := line[.. pred(pos)] & line[succ(pos) ..];
            write(inEditLine.outFile, line[pos ..]);
            moveLeft(inEditLine.outFile, line[pos ..]);
          end if;
        elsif ch = KEY_DEL then
          if pos <= length(line) then
            erase(inEditLine.outFile, line[pos ..]);
            moveLeft(inEditLine.outFile, line[pos ..]);
            line := line[.. pred(pos)] & line[succ(pos) ..];
            write(inEditLine.outFile, line[pos ..]);
            moveLeft(inEditLine.outFile, line[pos ..]);
          end if;
        elsif ch = KEY_HOME then
          moveLeft(inEditLine.outFile, line[.. pred(pos)]);
          pos := 1;
        elsif ch = KEY_END then
          write(inEditLine.outFile, line[pos ..]);
          pos := succ(length(line));
        elsif ch = KEY_LEFT then
          if pos > 1 then
            decr(pos);
            moveLeft(inEditLine.outFile, line[pos len 1]);
          end if;
        elsif ch = KEY_RIGHT then
          if pos <= length(line) then
            write(inEditLine.outFile, line[pos]);
            incr(pos);
          end if;
        elsif ch = KEY_UP then
          if historyPos > 1 then
            moveLeft(inEditLine.outFile, line[.. pred(pos)]);
            erase(inEditLine.outFile, line);
            moveLeft(inEditLine.outFile, line);
            history[historyPos] := line;
            decr(historyPos);
            line := history[historyPos];
            write(inEditLine.outFile, line);
            pos := succ(length(line));
          end if;
        elsif ch = KEY_DOWN then
          if historyPos < length(history) then
            moveLeft(inEditLine.outFile, line[.. pred(pos)]);
            erase(inEditLine.outFile, line);
            moveLeft(inEditLine.outFile, line);
            history[historyPos] := line;
            incr(historyPos);
            line := history[historyPos];
            write(inEditLine.outFile, line);
            pos := succ(length(line));
          end if;
        elsif ch = '\C' or ch = '\T' then
          write(inEditLine.outFile, " terminate (y/n)?   ");
          moveLeft(inEditLine.outFile, "  ");
          cursorOn(inEditLine.outFile, ' ');
          flush(inEditLine.outFile);
          response := getc(inEditLine.inFile);
          cursorOff(inEditLine.outFile, ' ');
          if lower(response) = 'y' then
            writeln(inEditLine.outFile, "yes  ");
            writeln(inEditLine.outFile);
            writeln(inEditLine.outFile, "*** PROGRAM TERMINATED BY USER");
            exit(PROGRAM);
          else
            backSpace(inEditLine.outFile, " terminate (y/n)? ");
            write(inEditLine.outFile, line[pos len 20]);
            moveLeft(inEditLine.outFile, line[pos len 20]);
          end if;
        elsif ch >= ' ' and ch <= '~' or ch >= '\160;' and ch <= '\255;' or
              ch >= '\256;' and ch <= '\16#10ffff;' and inEditLine.allowUnicode then
          line := line[.. pred(pos)] & str(ch) & line[pos ..];
          write(inEditLine.outFile, line[pos ..]);
          moveLeft(inEditLine.outFile, line[succ(pos) ..]);
          incr(pos);
        end if;
      until ch = KEY_NL or ch = EOF or ch = KEY_CLOSE;
      writeln(inEditLine.outFile);
      inEditLine.bufferChar := ch;
      if length(inEditLine.history) = 0 or
          inEditLine.history[length(inEditLine.history)] <> line then
        inEditLine.history &:= line;
      end if;
    else
      line := inEditLine.line;
      inEditLine.line := "";
    end if;
    inEditLine.lineFinished := FALSE;
  end func;


(**
 *  Read a character from ''inEditLine''.
 *  @return the character read, or [[char#EOF|EOF]] at the end of the file.
 *)
const func char: getc (inout editLineFile: inEditLine) is func
  result
    var char: ch is ' ';
  local
    var integer: number is 0;
  begin
    if inEditLine.lineFinished then
      inEditLine.line := getln(inEditLine);
    end if;
    if inEditLine.line = "" then
      ch := inEditLine.bufferChar;
      inEditLine.lineFinished := TRUE;
    else
      ch := inEditLine.line[1];
      inEditLine.line := inEditLine.line[2 ..];
    end if;
  end func;


(**
 *  Read a [[string]] with maximum length from ''inEditLine''.
 *  @return the string read.
 *  @exception RANGE_ERROR The length is negative.
 *)
const func string: gets (inout editLineFile: inEditLine, in integer: length) is func
  result
    var string: stri is "";
  begin
    if length < 0 then
      raise RANGE_ERROR;
    else
      if inEditLine.lineFinished then
        inEditLine.line := getln(inEditLine);
      end if;
      stri := inEditLine.line[.. length];
      inEditLine.line := inEditLine.line[succ(length) ..];
      while length(stri) < length do
        stri &:= inEditLine.bufferChar;
        inEditLine.lineFinished := TRUE;
        if length(stri) < length then
          inEditLine.line := getln(inEditLine);
          stri &:= inEditLine.line[.. length - length(stri)];
          inEditLine.line := inEditLine.line[succ(length - length(stri)) ..];
        end if;
      end while;
    end if;
  end func;


(**
 *  Determine the end-of-file indicator.
 *  The end-of-file indicator is set if at least one request to read
 *  from the file failed.
 *  @return TRUE if the end-of-file indicator is set, FALSE otherwise.
 *)
const func boolean: eof (in editLineFile: inEditLine) is
  return inEditLine.lineFinished and inEditLine.bufferChar = EOF;


(**
 *  Determine if at least one character can be read successfully.
 *  This function allows a file to be handled like an iterator.
 *  @return FALSE if ''getc'' would return [[char#EOF|EOF]],
 *          TRUE otherwise.
 *)
const func boolean: hasNext (in editLineFile: inEditLine) is
  return inEditLine.bufferChar = EOF;


const func string: readPassword (inout file: aFile) is DYNAMIC;


const func string: readPassword (inout editLineFile: inEditLine) is func
  result
    var string: line is "";
  local
    var char: ch is ' ';
    var integer: pos is 1;
   begin
    repeat
      if pos <= length(line) then
        cursorOn(inEditLine.outFile, '*');
      else
        cursorOn(inEditLine.outFile, ' ');
      end if;
      flush(inEditLine.outFile);
      ch := getc(inEditLine.inFile);
      if pos <= length(line) then
        cursorOff(inEditLine.outFile, '*');
      else
        cursorOff(inEditLine.outFile, ' ');
      end if;
      if ch = KEY_BS then
        if pos > 1 then
          decr(pos);
          moveLeft(inEditLine.outFile, line[pos len 1]);
          erase(inEditLine.outFile, line[pos ..]);
          moveLeft(inEditLine.outFile, line[pos ..]);
          line := line[.. pred(pos)] & line[succ(pos) ..];
          write(inEditLine.outFile, "*" mult length(line[pos ..]));
          moveLeft(inEditLine.outFile, line[pos ..]);
        end if;
      elsif ch = KEY_DEL then
        if pos <= length(line) then
          erase(inEditLine.outFile, line[pos ..]);
          moveLeft(inEditLine.outFile, line[pos ..]);
          line := line[.. pred(pos)] & line[succ(pos) ..];
          write(inEditLine.outFile, "*" mult length(line[pos ..]));
          moveLeft(inEditLine.outFile, line[pos ..]);
        end if;
      elsif ch = KEY_HOME then
        moveLeft(inEditLine.outFile, line[.. pred(pos)]);
        pos := 1;
      elsif ch = KEY_END then
        write(inEditLine.outFile, line[pos ..]);
        pos := succ(length(line));
      elsif ch = KEY_LEFT then
        if pos > 1 then
          decr(pos);
          moveLeft(inEditLine.outFile, line[pos len 1]);
        end if;
      elsif ch = KEY_RIGHT then
        if pos <= length(line) then
          write(inEditLine.outFile, "*");
          incr(pos);
        end if;
      elsif ch >= ' ' and ch <= '~' or ch >= '\160;' and ch <= '\255;' or
            ch >= '\256;' and ch <= '\16#10ffff;' and inEditLine.allowUnicode then
        line := line[.. pred(pos)] & str(ch) & line[pos ..];
        write(inEditLine.outFile, "*" mult length(line[pos ..]));
        moveLeft(inEditLine.outFile, line[succ(pos) ..]);
        incr(pos);
      end if;
    until ch = KEY_NL or ch = EOF;
    writeln(inEditLine.outFile);
    inEditLine.bufferChar := ch;
    inEditLine.line := "";
    inEditLine.lineFinished := FALSE;
  end func;
