.files/nix/packages/by-name/tmux-sessionizer/package.nix

{
  writeShellApplication,
  tmux,
  procps,
  lib,
  symlinkJoin,
}: let
  tmux-register-session = writeShellApplication {
    name = "__tmux-register-session";
    runtimeInputs = [tmux];
    text = ''
      last=/tmp/TMUX_LAST

      # bail if tmux not running
      if ! pgrep tmux >/dev/null 2>&1; then
        exit 1
      fi

      this="$(tmux display-message -p '#S')"
      if [ ! -f "$last" ] || [ "$(cat "$last")" != "$this" ]; then
          echo "$this" >"$last"
      fi
    '';
  };

  tmux-maybe-create = writeShellApplication {
    name = "__tmux-maybe-create";
    runtimeInputs = [procps tmux];
    text = ''
      session_name="$1"
      session_dir="$2"

      if ! pgrep tmux >/dev/null 2>&1 || ! tmux has -t="$session_name" 2>/dev/null; then
          tmux new-session -ds "$session_name" -c "$session_dir"
      fi
    '';
  };

  tmux-attach-or-switch = writeShellApplication {
    name = "__tmux-attach-or-switch";
    runtimeInputs = [tmux];
    text = ''
      session_name="$1"
      TMUX=''${TMUX:-}

      if [ -z "$TMUX" ]; then
          tmux attach-session -t "$session_name"
      else
          tmux switch-client -t "$session_name"
      fi
    '';
  };

  tmux-last = writeShellApplication {
    name = "tmux-last";
    text = ''
      tmux_last=/tmp/TMUX_LAST
      if [ ! -f $tmux_last ]; then
          echo "Last session is not yet set"
          return 1
      fi

      session_name="$(cat $tmux_last)"
      session_path="$session_name"
      if [ ! -d "$session_path" ]; then
        session_path="/tmp"
      fi

      # bail if not in tmux, nothing to register
      ${lib.getExe tmux-register-session} || :
      ${lib.getExe tmux-maybe-create} "$session_name" "$session_path"
      ${lib.getExe tmux-attach-or-switch} "$session_name"
    '';
  };
in
  symlinkJoin {
    name = "tmux-sessionizer";
    paths = [
      tmux-register-session
      tmux-maybe-create
      tmux-attach-or-switch
      tmux-last
    ];
  }