os/pkgs/sway-launcher.nix

self: with self; ''
  #!/usr/bin/env zsh
  # terminal application launcher for sway, using fzf
  # original command:
  # Based on: https://github.com/swaywm/sway/issues/1367
  # bindsym $altkey+space exec termite --name=launcher -e \
  #    "bash -c 'compgen -c | sort -u | fzf --no-extended --print-query | \
  #    tail -n1 | xargs -r swaymsg -t command exec'"

  HIST_FILE="''${XDG_CACHE_HOME:-$HOME/.cache}/sway-launcher-history.txt"

  # Get shell command list
  # This may include the occasional non-executable file
  command_list=$({ whence -wm '*' | sed 's/:[^:]*$//' })

  # read existing command history
  if [ -f "$HIST_FILE" ]; then
      command_history=$(cat "$HIST_FILE")
  else
      command_history=""
  fi

  # search command list
  command_str=$(printf "%s\n" "''${command_history}" "''${command_list}" | \
      sed -E 's/^[0-9]+ (.+)$/\1/' | \
      fzf --color=16 --exact --no-extended --print-query --no-sort | \
      tail -n1) || exit 1

  if [ "$command_str" = "" ]; then
      exit 1
  fi
  # echo "Command: $command_str"

  # using \E flag from perl regex
  test "''${command_str#*\\E}" != "$command_str" && echo "command can't contain '\E'"
  test "''${command_str#*\\E}" != "$command_str" && exit 1

  # get full line from history (with count number)
  hist_line=$(echo "$command_history" | grep -Pe "^[0-9]+ \Q$command_str\E$")
  # echo "Hist Line: $hist_line"

  if [ "$hist_line" = "" ]; then
      hist_count=1
  else
      # Increment usage count
      hist_count=$(echo "$hist_line" | sed -E 's/^([0-9]+) .+$/\1/')
      hist_count=$((hist_count + 1))
      # delete line, to add updated later
      # echo "Hist Before: $command_history"
      command_history=$(echo "$command_history" | \
          grep --invert-match -Pe "^[0-9]+ \Q$command_str\E$")
      # echo "Hist After: $command_history"
  fi

  # update history
  update_line="''${hist_count} ''${command_str}"
  printf "%s\n" "''${update_line}" "''${command_history}" | \
      sort --numeric-sort --reverse > "$HIST_FILE"
  # echo "$update_line"

  # execute command
  echo "$command_str"
  ${sway}/bin/swaymsg -t command exec "$command_str"
''