flake.nix

# this flake installs tmux and sets up a basic tmux config for testing the plugin integration
{
  inputs = {
    nixpkgs = { url = "github:nixos/nixpkgs/nixos-unstable"; };
    flake-utils = { url = "github:numtide/flake-utils"; };
  };
  outputs = { nixpkgs, flake-utils, ... }:
    flake-utils.lib.eachDefaultSystem (system:
      let
        pkgs = import nixpkgs { inherit system; };
        tmux_conf = pkgs.writeText "tmux.conf" ''
          # Smart pane switching with awareness of Vim splits.

          bind-key -n C-h if -F "#{@pane-is-vim}" 'send-keys C-h'  'select-pane -L'
          bind-key -n C-j if -F "#{@pane-is-vim}" 'send-keys C-j'  'select-pane -D'
          bind-key -n C-k if -F "#{@pane-is-vim}" 'send-keys C-k'  'select-pane -U'
          bind-key -n C-l if -F "#{@pane-is-vim}" 'send-keys C-l'  'select-pane -R'

          bind-key -n M-h if -F "#{@pane-is-vim}" 'send-keys M-h' 'resize-pane -L 3'
          bind-key -n M-j if -F "#{@pane-is-vim}" 'send-keys M-j' 'resize-pane -D 3'
          bind-key -n M-k if -F "#{@pane-is-vim}" 'send-keys M-k' 'resize-pane -U 3'
          bind-key -n M-l if -F "#{@pane-is-vim}" 'send-keys M-l' 'resize-pane -R 3'

          tmux_version='$(tmux -V | sed -En "s/^tmux ([0-9]+(.[0-9]+)?).*/\1/p")'
          if-shell -b '[ "$(echo "$tmux_version < 3.0" | bc)" = 1 ]' \
              "bind-key -n 'C-\\' if -F \"#{@pane-is-vim}\" 'send-keys C-\\'  'select-pane -l'"
          if-shell -b '[ "$(echo "$tmux_version >= 3.0" | bc)" = 1 ]' \
              "bind-key -n 'C-\\' if -F \"#{@pane-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

          # split panes using | and -
          bind | split-window -h -l 75 -c '#{pane_current_path}'
          bind - split-window -v -l 25 -c '#{pane_current_path}'

          # Make undercurls work properly in Neovim
          # Undercurl support
          set -as terminal-overrides ',*:Smulx=\E[4::%p1%dm'
          # Underscore colours - needs tmux-3.0
          set -as terminal-overrides ',*:Setulc=\E[58::2::%p1%{65536}%/%d::%p1%{256}%/%{255}%&%d::%p1%{255}%&%d%;m'
        '';
      in {
        devShells.default = pkgs.mkShell {
          name = "shell with tmux";

          packages = with pkgs; [ tmux stylua luajitPackages.luacheck ];

          shellHook = ''
            alias tmux="tmux -f ${tmux_conf}"
            alias :q="exit"
          '';
        };
      });
}