#!/c/opt/perl64/bin/perl
BEGIN {(*STDERR = *STDOUT) || die;}

=head

Switch between gVim and Bash on Windows via Ctrl-Z and fg
---------------------------------------------------------

This script helps move between gvim and a bash-shell on
Windows using the commands Ctrl-Z and fg.

My work-flow involves spending almost all my time in gvim on Windows.
Although I have some tools to help me remain in gvim while performing
tasks outside of gvim, I occasionally have to move to a bash shell.
Although there are situations -- such as those involving gvim with no
file open (issue: implementation does not look for the correct gVim
title) or multiple gvim or bash windows (issue: implementation does not
offer choice among multiple windows) -- where the implementation is not
fully effective, it is satisfactory for my needs.

Usage:
-----

A) The following gVim mappings:

     nnoremap <c-z> :silent !perl c:\opt\bin\czfg.pl 0 % %:p:h %:p:t<cr>
     nnoremap <s-z> :silent !perl c:\opt\bin\czfg.pl 0 % %:p:h %:p:t register<cr>

   assume that this script is located at c:\opt\bin\czfg.pl

B) Before this script can be used, both gVim and bash windows must exist.

C) The first time this script is used to switch between gVim and bash,
   it must be from gVim, and the command to be issued -- as per the above
   mapping -- is the normal mode command <Shift-Z>.  Doing so will
   not only switch focus to the bash window but also define an alias fg
   to get back to gVim from bash.

D) Subsequent switches between gVim and bash would be via <Ctrl-Z> and fg.

Non-perl Alternatives:
---------------------

1) In Windows 7, the bash and gVim windows can be pinned to the task-
   bar, say, as the first and second applications respectively.  Then
   the <Win-1> and <Win-2> activate either the bash or the gVim window.
   If multiple bash or gVim windows are present, use <Ctrl-Win-1> and
   <Ctrl-Win-2>.

2) The console ConEmu is getting better at supporting 256 colors for
   console vim, but wasn't quite there as of November 3, 2013:
   https://groups.google.com/d/msg/conemu_ml/nThX05Kal0E/AEOkK3Px6dYJ

=cut

use diagnostics;
use warnings;
use strict;
$| = 1;
#-----------------------------------------------------
use Win32;
use Win32::GuiTest qw(
                         SetForegroundWindow
                         GetChildWindows
                         GetWindowText
                         SendKeys
                         SetFocus
                         ShowWindow
                         SW_RESTORE
                         EnableWindow
                     );

defined $ARGV[ 0 ] or exit;
my $win_id       = $ARGV[ 0 ];
my $buf_str      = $ARGV[ 1 ];
my $win_str_p    = $ARGV[ 2 ];
my $win_str_f    = $ARGV[ 3 ];
my $register     = $ARGV[ 4 ];

# if called via fg in bash, go back to gVim and exit
if( ! $buf_str )
{
   SetFocus( $win_id );
   ShowWindow( $win_id,  SW_RESTORE );
   EnableWindow( $win_id,  1 );
   SetForegroundWindow( $win_id );
   exit;
}

# if here, script has been called from gVim

# gVim window name has path within brackets
   $win_str_p  =  "($win_str_p)";

# For use in pattern matching, escape '\', '(' and ')'.
   $win_str_p  =~  s,\\,\\\\,g;
   $win_str_p  =~  s,\(,\\(,;
   $win_str_p  =~  s,\),\\),;

# clean up buffer paths that are relative to local directory
   $buf_str      =~ s,^\.,,;
   $buf_str      =~ s,^\\,,;
   $buf_str      =~ s,^/,,;

# For files in local directory, don't use path component for gVim window name
( $buf_str !~ /\\/ ) and ( $buf_str !~ /\// ) and $win_str_p = '';

my $go_back_to   = '';
my $go_to        = '';

# undocumented feature: user can specify target of fg command
$win_id and $go_back_to = $win_id;

# Get id of gVim and bash windows by iterating through all windows
for my $a_window ( GetChildWindows(0) )
{
   my $foo = GetWindowText($a_window);

   # get first match to gVim window title
   if( ( ! $go_back_to          ) and
       ( $foo =~ m/gvim/i       ) and
       ( $foo =~ m/$win_str_f/i ) and
       ( $foo =~ m/$win_str_p/i ) )  # empty string will match
   {
        $go_back_to  =  $a_window;
   }

   # get first match to bash window title
   if(  ( ! $go_to       ) and
        ( $foo eq 'bash' ) )  # reset any messed up title via: echo -ne "\033]0;bash\007"
   {
        $go_to  =  $a_window;
   }
}

# bring the bash window forward
SetFocus( $go_to );
ShowWindow( $go_to,  SW_RESTORE );
EnableWindow( $go_to,  1 );
SetForegroundWindow( $go_to );

# Done unless user has requested that the alias fg be created
$register and ( $register eq 'register' ) or exit;

# If here, need to build and issue the command to create the alias fg

# Assuming script is not in path, get full path to script
my $script = Cwd::abs_path( $0 ); # didn't work: File::Spec->rel2abs( $0 );

# Convert '\' to '/' for use in bash
$script =~ s,\\,/,g; # weird: have seen Cwd::abs_path use both '\' and '/'

# create the alias fg
  SendKeys("alias fg=\'$script $go_back_to\'\n");

__END__