feat: auto zellij script

nixosConfigurations/gerg-desktop/main.nix

@@ -130,6 +130,27 @@
       silent = true;
     };
 
+
+    zsh = {
+      interactiveShellInit =
+        let
+          monitorScript = pkgs.replaceVarsWith {
+            src = ./monitor.ps;
+            replacements = builtins.mapAttrs (_: lib.getExe) {
+              inherit (pkgs) perl xdotool;
+            };
+            isExecutable = true;
+          };
+        in
+        ''
+          if [[ -z "$ZELLIJ" ]]; then
+            MONITOR="$(${monitorScript} || true)"
+            zellij attach -c "''${MONITOR:+"$MONITOR@"}$USER"
+            exit
+          fi
+        '';
+    };
+
     nix-index = {
       enable = true;
       package = nix-index-database.packages.nix-index-with-db;

nixosConfigurations/gerg-desktop/monitor.ps

@@ -0,0 +1,45 @@
+#!@perl@
+
+use strict;
+
+my %M;    # hash to hold keys from 'xdotool getmouselocation --shell'
+my $pipe; # file handle for the pipes we're going to open
+
+# get the current cursor location into $M{X} and $M{Y}
+open($pipe, "-|", qw(@xdotool@ getmouselocation --shell)) ||
+    die "couldn't open pipe from xdotool: $!\n";
+
+while(<$pipe>) {
+  chomp;
+  my($key, $val) = split /=/;
+  $M{$key} = $val;
+};
+close($pipe);
+
+# compare mouse location to monitor co-ordinates
+open($pipe, "-|", "xrandr") ||
+    die "couldn't open pipe from xrandr: $!\n";
+
+while(<$pipe>) {
+  my ($display, $width, $height, $x_offset, $y_offset);
+
+  next unless m/ connected /;
+  my @F = split;
+  $display = $F[0];
+
+  # co-ordinates are on fourth field (F[3]) on the primary display
+  # or on third field (F[2]) on non-primary displays. Perl arrays
+  # start from zero, not one (same as in bash).
+  if ($F[2] eq "primary") {
+    ($width, $height, $x_offset, $y_offset) = split /[x+]/, $F[3];
+  } else {
+    ($width, $height, $x_offset, $y_offset) = split /[x+]/, $F[2];
+  };
+
+  if ($M{X} >= $x_offset && $M{X} <= $width + $x_offset &&
+      $M{Y} >= $y_offset && $M{Y} <= $height + $y_offset) {
+    print "$display\n";
+    last;
+  };
+};
+close($pipe);