#! /usr/bin/perl

# Interrupt List Lister
#  by E. C. Masloch, 2020 to 2026
#
# Usage of the works is permitted provided that this
# instrument is retained with the works, so that any entity
# that uses the works is notified of this instrument.
#
# DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.

use warnings;
use strict;
use utf8;
use Curses;
use Audio::Beep;
use Syntax::Keyword::Try;
use Getopt::Long;
use File::Spec;
use Switch;
use File::HomeDir;
use File::Path qw(make_path);

use Fcntl qw(SEEK_SET SEEK_CUR SEEK_END);

# binmode(STDOUT, ":utf8");
# binmode(STDERR, ":utf8");
# binmode(STDIN, ":utf8");
# use open ":encoding(utf8)";

my $datadir = File::HomeDir->my_data();
if (not defined $datadir) {
  my $datadir = File::HomeDir->my_home();
}
if (not defined $datadir) {
  die "Unable to get data directory\n";
}
my $intlistdir = File::Spec->catdir($datadir, ".intlist");
make_path($intlistdir);
my $searchhistfile = File::Spec->catfile($intlistdir, "search_history");
my $filehistfile = File::Spec->catfile($intlistdir, "file_history");

our @searchhistory = ();
our @filehistory = ();
our $searchhistff;
our $filehistff;

sub die_or_errorline {
  my $die_if_true = shift;
  my $msg = shift;
  if ($die_if_true) {
    die $msg."\n";
  } else {
    errorline($msg);
  }
}

sub rereadhistories {
  my $die_if_true = shift;

  our $searchhistff;
  if (defined $searchhistff) {
    close $searchhistff;
    $searchhistff = undef;
  }
  open($searchhistff, "+>>", $searchhistfile)
    or die_or_errorline($die_if_true, "Cannot open I/O file \"$searchhistfile\": $!");
  our $filehistff;
  if (defined $filehistff) {
    close $filehistff;
    $filehistff = undef;
  }
  open($filehistff, "+>>", $filehistfile)
    or die_or_errorline($die_if_true, "Cannot open I/O file \"$filehistfile\": $!");

  our @searchhistory;
  our @filehistory;

  if (defined $searchhistff) {
    @searchhistory = ();
    seek($searchhistff, 0, SEEK_SET);
    while (<$searchhistff>) {
      s/[\r\n]+$//;
      if (s/^\"//) {
        # "
        push(@searchhistory, $_);
      } else {
        die_or_errorline($die_if_true, "Invalid search history file content");
      }
    }
  }
  if (defined $filehistff) {
    @filehistory = ();
    seek($filehistff, 0, SEEK_SET);
    while (<$filehistff>) {
      s/[\r\n]+$//;
      if (s/^\"//) {
        # "
        push(@filehistory, $_);
      } else {
        die_or_errorline($die_if_true, "Invalid file history file content");
      }
    }
  }
}

rereadhistories(1);

sub trim {
  my $str = shift;
  $str =~ s/^\s+|\s+$//g;
  return $str;
};

sub dobeep {
  try {
    Audio::Beep::beep(400, 100);
  }
  catch {
    Curses::beep();
  }
};

our @array_listingfiles = ();
our @array_lstff = ();
our @array_drawlinestart = ();
our $activelistingfile = 0;
our @saved_array_listingfiles = ();
our @saved_array_lstff = ();
our @saved_array_drawlinestart = ();
our $saved_activelistingfile = 0;
our $statuspage_in_effect = 0;
our $D_statuspage_in_effect = 0;
our $statuspage = "";

our @array_offsets = ();
my $multi = 0;
my $multi_disable_next = 0;
my $help = 0;
my $update_opcode2line = 0;

Getopt::Long::Configure("no_auto_abbrev");

GetOptions(
	'listing=s@' => \@array_listingfiles,
	'multi!' => \$multi,
	'help|h' => \$help,
) or die;

foreach (@array_listingfiles) {
  push(@array_drawlinestart, 0);
}
foreach (@array_listingfiles) {
  push(@array_lstff, undef);
}

my $empty = shift;
if (not scalar @array_listingfiles
    or defined $empty
    or $help) {
  die("Usage: $0 --listing file.lst\n")
}

sub addnstring {
  my $line = shift;
  my $column = shift;
  my $string = shift;
  my $limit = shift;
  if (length $string > $limit) {
    $string =~ s/^(.{$limit}).*$/$1/;
  }
  addstring($line, $column, $string);
}

my $ii = 0;
foreach my $fn (@array_listingfiles) {
  open($array_lstff[$ii], "+<", $fn)
    or die "Cannot open input/output file \"$fn\": $!\n";
  binmode($array_lstff[$ii]);
  $ii += 1;
}

initscr();
noecho();
cbreak();
nodelay(1);
keypad(1);

my $reloadrequested = 0;
my $updaterequested = 1;
my $redrawrequested = 1;
my $winch = 0;
my $selected = 0;
my $instructionsamount = 0;
my $resultlinestart;
my $resultlineend;
my $resultfile;
my $foundamount;
my @array_linesamount = (0) x scalar @array_listingfiles;
my $drawlineend = 0;
my @stops = (0, 8);
my $highstops = 8;
my $activestop = 0;
my $saved_activestop = 0;
my $maxstop = 15;
my $activedisplacement = 0;
my $autodisplace = 1;
our $needrefresh = 0;
our $savederrorline = "";
our $savederrorlinedobeep = 1;
our $priorerrorline = "";
our $savedopcodeline = "";
our $savedopcode2line = "";
our $prioropcodeline = "";
our $prioropcode2line = "";
our $savedcommandline = "";
our $priorcommandline = "";
our $searchpattern = "";
our $abort = 0;

$SIG{'USR1'} = sub {
  $updaterequested = 1;
  $selected = 0;
  $activedisplacement = 0;
  $autodisplace = 1;
};
$SIG{'USR2'} = sub {
  $reloadrequested = 1;
  $updaterequested = 1;
  $selected = 0;
  $activedisplacement = 0;
  $autodisplace = 1;
};
$SIG{'WINCH'} = sub { $redrawrequested = 1; $winch = 1; };
$SIG{'INT'} = \&ctrlchandler;
sub ctrlchandler {
  $SIG{'INT'} = \&ctrlchandler;
  our $abort;
  $abort = 1;
}

sub errorline {
  our $savederrorline;
  our $savederrorlinedobeep;
  $savederrorline = shift;
  my $dobeep = shift;
  if (defined $dobeep) {
    $savederrorlinedobeep = $dobeep;
  }
}

sub write_errorline {
  my $dobeep = shift;
  our $savederrorlinedobeep;
  our $needrefresh;
  our $savederrorline;
  our $priorerrorline;
  my $string = $savederrorline;
  if ($string ne $priorerrorline or $redrawrequested) {
    if ($string ne $priorerrorline and length $string
        and $dobeep and $savederrorlinedobeep) {
      dobeep();
    }
    $savederrorlinedobeep = 1;
    standout();
    addstring($LINES - 2, 0, sprintf("%*s", - $COLS, $string));
    standend();
    $priorerrorline = $string;
    $needrefresh = 1;
  }
}

sub opcodeline {
  our $savedopcodeline;
  $savedopcodeline = shift;
}

sub opcode2line {
  our $savedopcode2line;
  $savedopcode2line = shift;
}

sub write_opcodeline {
  our $needrefresh;
  our $savedopcodeline;
  our $savedopcode2line;
  our $prioropcodeline;
  our $prioropcode2line;
  my $string = $savedopcodeline;
  my $string2 = $savedopcode2line;
  if ($string ne $prioropcodeline
      or $string2 ne $prioropcode2line
      or $redrawrequested) {
    addstring($LINES - 3, 0, sprintf("%*s", - ($COLS - length $string2), $string));
    addstring($LINES - 3, ($COLS - length $string2), $string2);
    $prioropcodeline = $string;
    $prioropcode2line = $string2;
    $needrefresh = 1;
  }
}

sub commandline {
  our $savedcommandline;
  $savedcommandline = shift;
}

sub write_commandline {
  our $needrefresh;
  our $savedcommandline;
  our $priorcommandline;
  my $string = $savedcommandline;
  if ($string ne $priorcommandline or $redrawrequested) {
    $priorcommandline = $string;
    my $mask = $string;
    $mask =~ s/#/ /g;
    while ($mask =~ s/^([# ]*)([^_]*)(_.)/$1.(" " x length $2)."##"/e) { next; }
    $mask =~ s/##/_/g;
    $mask =~ s/[^ _]/ /g;
    $string =~ s/_//g;
    addstring($LINES - 1, 0, sprintf("%*s", - $COLS, $string));
    while ($mask =~ s/^( *)(_+)/$1.(" " x length $2)/e) {
      chgat($LINES - 1, length $1, length $2, A_STANDOUT, 0, 0);
    }
    $needrefresh = 1;
  }
}

# https://github.com/abergs/tabstospaces/issues/4#issuecomment-524465830
our $tabstopwidth = 8;
sub replacefunc {
  our $tabstopwidth;
  my $length = shift;
  my $string = shift;
  $string =~ s/^((?:[^\t]{$tabstopwidth})*[^\t]{$length})\t/
    $1." " x ($tabstopwidth - $length)
  /e;
  return $string;
};

sub expandtabs {
  our $tabstopwidth;
  my $string = shift;
  while ($string =~ /\t/) {
      foreach my $length (0 .. $tabstopwidth - 1) {
        $string = replacefunc($length, $string);
      };
  };
  return $string;
}

sub getsearchpattern {
  my $prompt = shift;
  our $searchpattern;
  errorline($prompt);
  write_errorline(0);
  my $rc = 0;
  my $input;
  ($rc, $input) = getinput($prompt, $LINES - 2, \@searchhistory, $searchhistff);
  if ($rc == 0) {
    errorline("");
  } elsif ($rc == 1 or $rc == 2) {
    try {
      my $teststring = "";
      $teststring =~ /$input/;
      $searchpattern = $input;
      errorline("Search pattern set to \"".$searchpattern."\"", 0);
    }
    catch {
      errorline("Invalid search pattern");
      $rc = 4;
    }
  } elsif ($rc == 3) {
    errorline("No search pattern in history");
  }
  return $rc;
  # return:
  # 0 = no pattern set (aborted)
  # 1 = new pattern set
  # 2 = empty pattern selected (pattern set to last history entry)
  # 3 = empty pattern with empty history
  # 4 = invalid pattern given
}

sub getinput {
  my $prompt = shift;
  my $line = shift;
  my $history = shift;
  my $histff = shift;
  my $rc = 0;
  our $abort;
  noecho();
  nodelay(0);
  my $input = "";
  my $newinput;
  my $promptlength = length $prompt;
  my $column = $promptlength;
  my $offset = 0;
  my $lastskip = 0;
  my $redraw = 0;
  my $limit = 1025;
  my $beep = 0;
  my $edited = 0;
  my $historyindex = scalar @$history;
  move($line, $column);
  while (1) {
    if ($winch) {
      endwin();
      refresh();
      $winch = 0;
      $redraw = 1;
    }
    if ($redraw) {
      my $show = $input;
      my $col = $column;
      my $skip = 0;
      my $maxpercol = ($COLS - 1 - $promptlength);
      move($line, $promptlength);
      if (length $show > $maxpercol) {
        if ($offset >= $lastskip) {
          $col -= $lastskip;
          $skip += $lastskip;
        }
        my $maxpercolhalf = int($maxpercol / 2);
        if ($maxpercolhalf == 0) {
          $maxpercolhalf = 1;
        }
        while ($col > ($maxpercol + $promptlength)) {
          $col -= $maxpercolhalf;
          $skip += $maxpercolhalf;
        }
        if ($skip <= $lastskip
          and $col > $promptlength
          and $col == ($maxpercol + $promptlength)
          and (length $show) > ($skip + $maxpercol)) {
          $col -= 1;
          $skip += 1;
        }
      }
      $show =~ s/^.{$skip}(.*)$/$1/;
      $show =~ s/^(.{0,$maxpercol}).*$/$1/;
      $lastskip = $skip;
      addstring($show);
      standout();
      addstring(" " x ($COLS - $promptlength - length $show));
      standend();
      move($line, $col);
      $redraw = 0;
    }
    if ($beep) {
      dobeep();
      $beep = 0;
    }
    my ($ch, $key) = getchar();
    if (defined $ch) {
      if (ord($ch) == 9) {
        $beep = 1;
        next;
      }
      if (ord($ch) == 10) {
        last;
      }
      if (length $input >= $limit) {
        $beep = 1;
        next;
      }
      $edited = 1;
      $newinput = substr($input, 0, $offset);
      $newinput .= $ch;
      if ($offset < length $input) {
        $newinput .= substr($input, $offset);
      }
      $input = $newinput;
      $column += 1;
      $offset += 1;
      $redraw = 1;
    } else {
      switch($key) {
        case KEY_ENTER {
          last;
        }
        case KEY_LEFT {
          if ($offset) {
            $offset -= 1;
            $column -= 1;
            $redraw = 1;
          } else {
            dobeep();
          }
        }
        case KEY_RIGHT {
          if ($offset < length $input) {
            $offset += 1;
            $column += 1;
            $redraw = 1;
          } else {
            dobeep();
          }
        }
        case KEY_BACKSPACE {
          if ($offset) {
            $edited = 1;
            $newinput = substr($input, 0, $offset - 1);
            if ($offset < length $input) {
              $newinput .= substr($input, $offset);
            }
            $input = $newinput;
            $offset -= 1;
            $column -= 1;
            $redraw = 1;
          } else {
            if (length $input) {
              $beep = 1;
            } else {
              noecho();
              nodelay(1);
              return (0, "");
            }
          }
        }
        case KEY_DC {
          if ($offset < length $input) {
            $edited = 1;
            $newinput = substr($input, 0, $offset);
            if ($offset + 1 < length $input) {
              $newinput .= substr($input, $offset + 1);
            }
            $input = $newinput;
            $redraw = 1;
          } else {
            dobeep();
          }
        }
        case KEY_HOME {
          $offset = 0;
          $column = $promptlength;
          $redraw = 1;
        }
        case KEY_END {
          $offset = length $input;
          $column = $offset + $promptlength;
          $redraw = 1;
        }
        case KEY_UP {
          if ($edited) {
            dobeep();
          } else {
            if ($historyindex) {
              $historyindex -= 1;
              $input = $history->[$historyindex];
              $offset = length $input;
              $column = $offset + $promptlength;
              $lastskip = 0;
              $redraw = 1;
            } else {
              dobeep();
            }
          }
        }
        case KEY_DOWN {
          if ($edited) {
            dobeep();
          } else {
            if ($historyindex < scalar @$history - 1) {
              $historyindex += 1;
              $input = $history->[$historyindex];
              $offset = length $input;
              $column = $offset + $promptlength;
              $lastskip = 0;
              $redraw = 1;
            } else {
              dobeep();
            }
          }
        }
        else {
          if ($abort) {
            $abort = 0;
            noecho();
            nodelay(1);
            return (0, "");
          }
          dobeep();
        }
      }
    }
  }
  $rc = 1;
  if ($input eq "") {
    $input = $history->[$#$history];
    $rc = 2;
    if (not defined $input) {
      $input = "";
      $rc = 3;
    }
  } elsif (not scalar @$history
      or $history->[$#$history] ne $input) {
    push(@$history, $input);
    my $lasthistentry = "";
    seek($histff, 0, SEEK_SET);
    while (<$histff>) {
      s/[\r\n]+$//;
      if (s/^\"//) {
        # "
        $lasthistentry = $_;
      }
    }
    if ($lasthistentry ne $input) {
      print $histff "\"".$input."\n";
      flush $histff;
    }
  }
  noecho();
  nodelay(1);
  return ($rc, $input);
  # return:
  # 0 = no input set (aborted)
  # 1 = new input set
  # 2 = empty input selected (input set to last history entry)
  # 3 = empty input with empty history
}

sub getfiles {
  my $forcemulti = shift;
  my @files = ();
  if ($multi or defined $forcemulti and $forcemulti) {
    my $index = 0;
    foreach my $ff (@array_lstff) {
      if (defined $ff) {
        push (@files, $index);
      }
      $index += 1;
    }
  } else {
    push (@files, $activelistingfile);
  }
  return @files;
}

# my $segsel;
my $preserveerrorline = 0;

while (1) {
  if ($abort) {
    endwin();
    print("Aborting \n");
    exit(127);
  }

  my $line = 0;

  if ($winch) {
    endwin();
    refresh();
    $winch = 0;
  }

  if ($updaterequested and $statuspage_in_effect) {
    $updaterequested = 0;
    $redrawrequested = 1;
    $resultlinestart = 0;
    $resultlineend = 0;
    $resultfile = undef;
    if (not $preserveerrorline) {
      errorline("");
    }
    $preserveerrorline = 0;
    opcodeline("");

    if (1) {
      my @files = getfiles(1);
      foreach my $currentfile (@files) {
        $array_linesamount[$currentfile] = 0;
        $line = 0;
        seek($array_lstff[$currentfile], 0, SEEK_SET);
        while (readline $array_lstff[$currentfile]) {
          $line += 1;
        }
        $array_linesamount[$currentfile] = $line;
      }
    }

    my $put_into_opcode2line = "";
    $put_into_opcode2line .=
      sprintf("%-16s", "status page");
    {
      $put_into_opcode2line .=
        " " x (2+2+1+2);
    }
    opcode2line($put_into_opcode2line);
  } elsif ($updaterequested) {
    if ($reloadrequested) {
      $reloadrequested = 0;
      if (defined $array_lstff[$activelistingfile]) {
        close $array_lstff[$activelistingfile];
        $array_lstff[$activelistingfile] = undef;
      }
      if (not open($array_lstff[$activelistingfile], "+<",
          $array_listingfiles[$activelistingfile])) {
        errorline("Cannot open input/output file: $!");
        $array_lstff[$activelistingfile] = undef;
      } else {
        binmode($array_lstff[$activelistingfile]);
      }
    }
    if ($updaterequested and
      (not $multi and defined $array_lstff[$activelistingfile]
      or $multi and scalar (grep {defined $_} @array_lstff))) {
    $updaterequested = 0;
    $redrawrequested = 1;

    $resultlinestart = 0;
    $resultlineend = 0;
    $resultfile = undef;
    $foundamount = 0;

    if (not $preserveerrorline) {
      errorline("");
    }
    $preserveerrorline = 0;
    opcodeline("");

    if (not $array_drawlinestart[$activelistingfile]) {
      $array_drawlinestart[$activelistingfile] = 1;
    }

    if (1) {
      my @files = getfiles(1);
      foreach my $currentfile (@files) {
        $array_linesamount[$currentfile] = 0;
        $line = 0;
        seek($array_lstff[$currentfile], 0, SEEK_SET);
        while (readline $array_lstff[$currentfile]) {
          $line += 1;
        }
        $array_linesamount[$currentfile] = $line;
      }
      $update_opcode2line = 1;
      next;
    }

    }
  }

  my $currentfile = $activelistingfile;
  if ($redrawrequested and defined $array_lstff[$currentfile]) {
    my $drawing = 0;
    my $drawingresult = 0;
    my $drawinghighlight = 0;
    my $newdrawlinestart;
    my $newdrawlineend;
    my $drawnline = 0;
    my $ii = 0;
    my $jj = 0;
    $line = 0;
    seek($array_lstff[$currentfile], 0, SEEK_SET);
    while (readline $array_lstff[$currentfile]) {
      $line += 1;
      if ($line == $array_drawlinestart[$currentfile]) {
        $drawing = 1;
      }
      if ($drawnline > ($LINES - 4)) {
        last;
      }
      if ($drawing) {
        my $withtabs = $_;
        $withtabs =~ s/[\r\n]+$//;
        my $expanded = expandtabs($withtabs);
        my $maskopcodes = "";
        my $masksearchresult = "";
        if (defined $searchpattern and $searchpattern ne "") {
          my $searching = $withtabs;
          while ($searching =~ /$searchpattern/) {
            $masksearchresult .= " " x length $`;
            $masksearchresult .= "_" x length $&;
            $searching = $';
            if (substr($searchpattern, 0, 1) eq '^') {
              last;
            }
          }
	  # $withtabs = has the tab stops to expand
	  # $masksearchresult = has the blanks or underscores
	  #  at the corresponding positions

sub replacefuncwithcontent {
  our $tabstopwidth;
  my $length = shift;
  my $stringtabs = shift;
  my $stringcontent = shift;
  my $newstringcontent = "";
  my $part;
  if ($stringtabs =~ s/^((?:[^\t]{$tabstopwidth})*[^\t]{$length})\t/
    $1." " x ($tabstopwidth - $length)
  /e) {
    $part = substr($stringcontent, 0, length $1);
    $newstringcontent .= $part;
    if (length $stringcontent > length $1) {
      $part = substr($stringcontent, length $1, 1);
      if (defined $part) {
        $newstringcontent .= $part x ($tabstopwidth - $length);
      }
      $part = substr($stringcontent, (length $1) + 1);
      if (defined $part) {
        $newstringcontent .= $part;
      }
    }
    $stringcontent = $newstringcontent;
  }
  return $stringtabs, $stringcontent;
};

sub expandtabswithcontent {
  our $tabstopwidth;
  my $stringtabs = shift;
  my $stringcontent = shift;
  while ($stringtabs =~ /\t/) {
    foreach my $length (0 .. $tabstopwidth - 1) {
      ($stringtabs, $stringcontent) =
        replacefuncwithcontent($length, $stringtabs, $stringcontent);
    };
  };
  return $stringcontent;
}
          if ($withtabs =~ /\t/) {
            $masksearchresult = expandtabswithcontent($withtabs, $masksearchresult);
          }
        }
        my $maskhighlight = "";
        if ($activestop) {
          my $stop;
          if ($activestop <= $#stops) {
            $stop = $stops[$activestop];
          } else {
            $stop = $stops[$#stops] + $highstops * ($activestop - $#stops);
          }
          $expanded =~ s/^.{0,$stop}//;
          $maskopcodes =~ s/^.{0,$stop}//;
          $masksearchresult =~ s/^.{0,$stop}//;
          $maskhighlight =~ s/^.{0,$stop}//;
        }
        addnstring($drawnline, 0, $expanded."\n", $COLS);
        while ($maskopcodes =~ s/^( *)(_+)/$1.(" " x length $2)/e) {
          chgat($drawnline, length $1, length $2, A_NORMAL, 0, 0);
        }
        my $searchhighlight = $drawingresult ? A_NORMAL : A_STANDOUT;
        while ($masksearchresult =~ s/^( *)(_+)/$1.(" " x length $2)/e) {
          chgat($drawnline, length $1, length $2, $searchhighlight, 0, 0);
        }
        while ($maskhighlight =~ s/^( *)(_+)/$1.(" " x length $2)/e) {
          chgat($drawnline, length $1, length $2, $searchhighlight, 0, 0);
        }
        if (length $expanded >= $COLS) {
          addstring($drawnline, $COLS - 1, ">");
          chgat($drawnline, $COLS - 1, 1, A_STANDOUT, 0, 0);
        }
        $drawnline += 1;
      }
    }
    while ($drawnline <= ($LINES - 4)) {
      addnstring($drawnline, 0, " " x $COLS, $COLS);
      $drawnline += 1;
    }
    $needrefresh = 1;
  }

  if ($multi_disable_next) {
    $multi_disable_next = 0;
    $multi = 0;
  }

  my $command = "_(_Q_)uit";
  if ($statuspage_in_effect) {
    $command .= " _(_X_) Close Status Page";
  } else {
    $command .= " _(_R_)eload";
    if ($#array_listingfiles) {
      if ($multi) {
        $command .= " Un_(_m_)ulti";
      } else {
        $command .= " _(_M_)ulti";
      }
      if (not $multi) {
        $command .= " _(_C_)ycle";
      }
      if ($activelistingfile) {
        $command .= " _(_S_)witch";
      }
    }
  }
  if ($activestop < $maxstop) {
    $command .= " _(_-_>_) Stop";
  }
  if ($activestop > 0) {
    $command .= " _(_<_-_) Stop";
  }
  commandline($command);

  if ($update_opcode2line) {
    $update_opcode2line = 0;
    my $put_into_opcode2line = "";
    if ($#array_listingfiles) {
      $put_into_opcode2line .=
        sprintf("%2u/%2u  ", $activelistingfile + 1, scalar @array_listingfiles);
    }
    $put_into_opcode2line .=
      sprintf("%12s", ( File::Spec->splitpath($array_listingfiles[$activelistingfile]) )[-1]);
    opcode2line($put_into_opcode2line);
  }

  write_errorline(1);
  write_opcodeline();
  write_commandline();
  move($LINES - 1, $COLS - 1);

  if ($needrefresh) {
    refresh();
  }
  $redrawrequested = 0;

  my ($in, $out) = ('', '');
  vec($in, fileno(STDIN), 1) = 1;
  select($out = $in, undef, undef, 1);
  KEYINPUT:
  while ((my $key = getch()) ne ERR) {
    my $originalkey = $key;
    if ($key ge 'A' and $key le 'Z') {
      $key = chr(ord($key) - ord('A') + ord('a'));
    }
    if ($key eq 'q') {
      endwin();
      print("Exiting \n");
      exit;
    } elsif ($key eq 'r' and not $statuspage_in_effect) {
      $reloadrequested = 1;
      $updaterequested = 1;
      $selected = 0;
      $activedisplacement = 0;
      last;
    } elsif ($key eq 'c' and not $statuspage_in_effect) {
      if ($multi) {
        dobeep();
      } else {
        if ($originalkey eq 'c') {
          if ($activelistingfile < $#array_listingfiles) {
            $activelistingfile += 1;
          } else {
            $activelistingfile = 0;
          }
        } else {
          if ($activelistingfile > 0) {
            $activelistingfile -= 1;
          } else {
            $activelistingfile = $#array_listingfiles;
          }
        }
        if (not defined $array_lstff[$activelistingfile]) {
          errorline("Input file not opened");
        } else {
          $updaterequested = 1;
          $selected = 0;
          $activedisplacement = 0;
        }
      }
      last;
    } elsif ($key eq 's' and not $statuspage_in_effect) {
      if (not $#array_listingfiles) {
        errorline("Missing additional listing file for switching");
      } elsif (not $activelistingfile) {
        errorline("Listing file is already first in list");
      } else {
        @array_listingfiles[$activelistingfile - 1,$activelistingfile]
          = @array_listingfiles[$activelistingfile,$activelistingfile - 1];
        @array_drawlinestart[$activelistingfile - 1,$activelistingfile]
          = @array_drawlinestart[$activelistingfile,$activelistingfile - 1];
        @array_lstff[$activelistingfile - 1,$activelistingfile]
          = @array_lstff[$activelistingfile,$activelistingfile - 1];
        if ($resultfile == $activelistingfile) {
          $resultfile -= 1;
        }
        $activelistingfile -= 1;
        $updaterequested = 1;
        last;
      }
    } elsif ($key eq 'o' and not $statuspage_in_effect) {
      my $prompt = "Filename: ";
      errorline($prompt);
      write_errorline(0);
      my $rc = 0;
      my $input;
      ($rc, $input) = getinput($prompt, $LINES - 2, \@filehistory, $filehistff);
      if ($rc == 0) {
        errorline("");
      } elsif ($rc == 1 or $rc == 2) {
        my $ii = 0;
        foreach my $fn (@array_listingfiles) {
          if ($fn eq $input) {
            errorline("File already opened");
            $preserveerrorline = 1;
            $rc = 5;
            if ($activelistingfile != $ii) {
              $activelistingfile = $ii;
              if (not defined $array_lstff[$activelistingfile]) {
                errorline("Input file not opened");
              } else {
                $updaterequested = 1;
                $selected = 0;
                $activedisplacement = 0;
              }
            } else {
              $updaterequested = 1;
              $selected = 0;
              $activedisplacement = 0;
            }
            last KEYINPUT;
          }
          $ii += 1;
        }
        my $ff;
        if (not open($ff, "+<", $input)) {
          errorline("Cannot open input/output file: $!");
        } else {
          binmode($ff);
          errorline("");
          $array_listingfiles[scalar @array_listingfiles] = $input;
          $array_lstff[scalar @array_listingfiles] = $ff;
          $array_drawlinestart[scalar @array_listingfiles] = 0;
          if (1 or not $multi) {
            $activelistingfile = scalar @array_listingfiles;
          }
          {
            $updaterequested = 1;
            $selected = 0;
            $activedisplacement = 0;
          }
        }
      } elsif ($rc == 3) {
        errorline("No filename in history");
      }
      last;
    } elsif ($key eq 'e' and not $statuspage_in_effect) {
      if (not $#array_listingfiles) {
        errorline("Must leave open at least one file");
      } else {
        if (defined $array_lstff[$activelistingfile]) {
          close $array_lstff[$activelistingfile];
          $array_lstff[$activelistingfile] = undef;
        }
        splice @array_listingfiles, $activelistingfile, 1;
        splice @array_lstff, $activelistingfile, 1;
        splice @array_drawlinestart, $activelistingfile, 1;
        if ($resultfile == scalar @array_listingfiles) {
          $resultfile = undef;
        }
        if ($activelistingfile == scalar @array_listingfiles) {
          $activelistingfile -= 1;
        }
        if (not defined $array_lstff[$activelistingfile]) {
          errorline("Input file not opened");
        } else {
          $updaterequested = 1;
          $selected = 0;
          $activedisplacement = 0;
        }
      }
    } elsif ($key eq 'h') {
      rereadhistories(0);
    } elsif ($key eq 'm' and not $statuspage_in_effect) {
      $multi = 1 - $multi;
    } elsif ($key eq 'a' and not $statuspage_in_effect) {
      $multi = 1;
      $multi_disable_next = 1;
      $updaterequested = 1;
    } elsif ($key eq KEY_LEFT) {
      if ($activestop > 0) {
        $activestop -= 1;
        $redrawrequested = 1;
      } else {
        dobeep();
      }
      last;
    } elsif ($key eq KEY_RIGHT) {
      if ($activestop < $maxstop) {
        $activestop += 1;
        $redrawrequested = 1;
      } else {
        dobeep();
      }
      last;
    } elsif ($key eq chr(9)) {
      if ($activestop < $#stops) {
        $activestop += 1;
      } else {
        $activestop = 0;
      }
      $redrawrequested = 1;
      last;
    } elsif ($key eq '/' or $key eq '?') {
      my $rc = getsearchpattern($key);
      if ($rc == 1 or $rc == 2) {
        if (1 and
            (not $multi and defined $array_lstff[$activelistingfile]
            or $multi and scalar (grep {defined $_} @array_lstff))) {
          my $lastresultline = 0;
          my $lastresultfile;
          my @files = getfiles();
          PATTERNSEARCHFILES:
          foreach my $currentfile (@files) {
            my $line = 0;
            seek($array_lstff[$currentfile], 0, SEEK_SET);
            PATTERNSEARCHSINGLEFILE:
            while (readline $array_lstff[$currentfile]) {
              $line += 1;
              if (
    $key eq '?' and $rc == 2
and ($currentfile == $activelistingfile
     and $line < $array_drawlinestart[$activelistingfile]
    or $currentfile < $activelistingfile
    )
 or $key eq '?' and $rc == 1
and ($currentfile == $activelistingfile
     and $line <= $array_drawlinestart[$activelistingfile]
    or $currentfile < $activelistingfile
    )
 or $key eq '/' and $rc == 2
and ($currentfile == $activelistingfile
     and $line > $array_drawlinestart[$activelistingfile]
    or $currentfile > $activelistingfile
    )
 or $key eq '/' and $rc == 1
and ($currentfile == $activelistingfile
     and $line >= $array_drawlinestart[$activelistingfile]
    or $currentfile > $activelistingfile
    )
) {
                my $withtabs = $_;
                $withtabs =~ s/[\r\n]+$//;
                if ($withtabs =~ /$searchpattern/) {
                  $lastresultline = $line;
                  $lastresultfile = $currentfile;
                  if ($key eq '/') {
                    last PATTERNSEARCHFILES;
                  }
                }
              }
            }
          }
          if ($lastresultline) {
            if ($lastresultfile == $activelistingfile and
                $array_drawlinestart[$activelistingfile] == $lastresultline) {
              dobeep();
            }
            $activelistingfile = $lastresultfile;
            $array_drawlinestart[$activelistingfile] = $lastresultline;
            $updaterequested = 1;
          } else {
            errorline("Pattern not found");
            dobeep();
          }
        }
        $redrawrequested = 1;
        last;
      }
    } elsif ($key eq 'x') {
      if ($statuspage_in_effect) {
        close $array_lstff[0];
        @array_listingfiles = @saved_array_listingfiles;
        @array_lstff = @saved_array_lstff;
        @array_drawlinestart = @saved_array_drawlinestart;
        $activelistingfile = $saved_activelistingfile;
        $activestop = $saved_activestop;
        @saved_array_listingfiles = ();
        @saved_array_lstff = ();
        @saved_array_drawlinestart = ();
        $saved_activelistingfile = 0;
        $saved_activestop = 0;
        $statuspage_in_effect = 0;
      } else {
        $statuspage = "";
        $statuspage .=
"Status page\n"
."\n"
."Open files:\n";
        my $ii = 0;
        foreach my $fn (@array_listingfiles) {
          $ii += 1;
          $statuspage .= sprintf(" %2u  ", $ii)."\"".$fn."\"\n";
        }
        my $ff;
        if (not open($ff, '<', \$statuspage)) {
          errorline("Internal error opening status page");
          last;
        }
        @saved_array_listingfiles = @array_listingfiles;
        @saved_array_lstff = @array_lstff;
        @saved_array_drawlinestart = @array_drawlinestart;
        $saved_activelistingfile = $activelistingfile;
        $saved_activestop = $activestop;
        @array_listingfiles = ("status page");
        @array_lstff = ($ff);
        @array_drawlinestart = (1);
        $activelistingfile = 0;
        $activestop = 0;
        $statuspage_in_effect = 1;
      }
      $updaterequested = 1;
      last;
    } elsif (1) {
      if ($key eq KEY_UP) {
        if ($array_drawlinestart[$activelistingfile] > 1) {
          $array_drawlinestart[$activelistingfile] -= 1;
          $redrawrequested = 1;
          last;
        } else {
          dobeep();
        }
      } elsif ($key eq KEY_DOWN) {
        if (($array_drawlinestart[$activelistingfile] + $LINES - 5) < $array_linesamount[$activelistingfile]) {
          $array_drawlinestart[$activelistingfile] += 1;
          $redrawrequested = 1;
          last;
        } else {
          dobeep();
        }
      } elsif ($key eq KEY_PPAGE) {
        if ($array_drawlinestart[$activelistingfile] > 1) {
          if ($array_drawlinestart[$activelistingfile] >= ($LINES - 5)) {
            $array_drawlinestart[$activelistingfile] -= ($LINES - 5);
          } else {
            $array_drawlinestart[$activelistingfile] = 1;
          }
          $redrawrequested = 1;
          last;
        } else {
          dobeep();
        }
      } elsif ($key eq KEY_NPAGE) {
        if (($array_drawlinestart[$activelistingfile] + $LINES - 5) < $array_linesamount[$activelistingfile]) {
          if (($array_drawlinestart[$activelistingfile] + $LINES - 5 + $LINES - 5) <= ($array_linesamount[$activelistingfile])) {
            $array_drawlinestart[$activelistingfile] += ($LINES - 5);
          } elsif ($array_linesamount[$activelistingfile] >= $LINES - 5) {
            $array_drawlinestart[$activelistingfile] = $array_linesamount[$activelistingfile] - ($LINES - 5);
          } else {
            $array_drawlinestart[$activelistingfile] = 1;
          }
          $redrawrequested = 1;
          last;
        } else {
          dobeep();
        }
      } elsif ($originalkey eq 'g') {
        $array_drawlinestart[$activelistingfile] = 1;
        $redrawrequested = 1;
        last;
      } elsif ($originalkey eq 'G') {
        if ($array_linesamount[$activelistingfile] >= ($LINES - 5)) {
          $array_drawlinestart[$activelistingfile] = $array_linesamount[$activelistingfile] - ($LINES - 5);
        } else {
          $array_drawlinestart[$activelistingfile] = 1;
        }
        $redrawrequested = 1;
        last;
      } else {
        dobeep();
      }
    }
  }
}