add vim-tmux-navigator for easier windowing

dotfiles/neovim/default.nix

@@ -44,6 +44,7 @@
       better-escape-nvim
       which-key-nvim
       comment-nvim
+      vim-tmux-navigator
 
       # Text editing (wait isn't that just all of vim?)
       fidget-nvim

dotfiles/tmux/default.nix

@@ -77,6 +77,29 @@ in
       set-option -g status-right-length 70
       set-window-option -g window-status-format '#[bg=colour8]#[fg=colour3] #I #[fg=colour15]#W#[fg=colour5]#F# '
       set-window-option -g window-status-current-format '#[bg=colour8]#[fg=colour3] #I #[bg=colour7]#[fg=colour8] #W#[fg=colour0]#F #[bg=colour8]'
+
+      # Smart pane switching with awareness of Vim splits.
+      # See: https://github.com/christoomey/vim-tmux-navigator
+      is_vim="ps -o state= -o comm= -t '#{pane_tty}' \
+          | grep -iqE '^[^TXZ ]+ +(\\S+\\/)?g?(view|l?n?vim?x?)(diff)?$'"
+      bind-key -n 'C-h' if-shell "$is_vim" 'send-keys C-h'  'select-pane -L'
+      bind-key -n 'C-j' if-shell "$is_vim" 'send-keys C-j'  'select-pane -D'
+      bind-key -n 'C-k' if-shell "$is_vim" 'send-keys C-k'  'select-pane -U'
+      bind-key -n 'C-l' if-shell "$is_vim" 'send-keys C-l'  'select-pane -R'
+      tmux_version='$(tmux -V | sed -En "s/^tmux ([0-9]+(.[0-9]+)?).*/\1/p")'
+      if-shell -b '[ "$(echo "$tmux_version < 3.0" | bc)" = 1 ]' \
+          "bind-key -n 'C-\\' if-shell \"$is_vim\" 'send-keys C-\\'  'select-pane -l'"
+      if-shell -b '[ "$(echo "$tmux_version >= 3.0" | bc)" = 1 ]' \
+          "bind-key -n 'C-\\' if-shell \"$is_vim\" 'send-keys C-\\\\'  'select-pane -l'"
+
+      bind-key -T copy-mode-vi 'C-h' select-pane -L
+      bind-key -T copy-mode-vi 'C-j' select-pane -D
+      bind-key -T copy-mode-vi 'C-k' select-pane -U
+      bind-key -T copy-mode-vi 'C-l' select-pane -R
+      bind-key -T copy-mode-vi 'C-\' select-pane -l
+
+      bind-key C-l send-keys 'C-l'
+      bind-key C-\\ send-keys 'C-\\'
     '';
   };
 }