demo.sh

#!/usr/bin/env bash

SCRIPT=${BASH_SOURCE}
POS_FILE=/tmp/fzf-demo-opener-pos

set_pos() {
  echo "$1" > "$POS_FILE"
}

get_pos() {
  if [[ -f $POS_FILE ]]; then
    cat "$POS_FILE"
  else
    echo 0
  fi
}

pos=$(get_pos)

if [[ $# -eq 0 ]]; then
  export SCRIPT
  set_pos $((pos - 1))
  fzf --bind 'start,tab:transform-footer($SCRIPT next),shift-tab:transform-footer($SCRIPT prev),enter:execute:$SCRIPT -- {}' \
      --bind 'click-footer:transform($SCRIPT click "$FZF_CLICK_FOOTER_WORD" {})'
  exit $?
fi


ITEMS=(vim bat less)
COUNT=${#ITEMS[@]}

print_bar() {
  local pos=$1
  local out=""
  for i in "${!ITEMS[@]}"; do
    if ((i == pos)); then
      out+=$'\e[7m'" ${ITEMS[$i]} "$'\e[0m'
    else
      out+=" ${ITEMS[$i]} "
    fi
  done
  echo "$out"
}

action=$1
if [[ $action = click ]]; then
  word="$2"
  [[ -z $word ]] && exit

  for i in "${!ITEMS[@]}"; do
    if [[ "${ITEMS[$i]}" == "$word" ]]; then
      pos=$i
      break
    fi
  done

  if [[ $FZF_KEY = double-click ]]; then
    set_pos "$pos"
    printf "execute:$SCRIPT -- %q" "$3"
  else
    set_pos $((pos - 1))
    echo "transform-footer:$SCRIPT next"
  fi
  exit
fi

case "$action" in
  next) ((pos = (pos + 1) % COUNT)) ;;
  prev) ((pos = (pos - 1 + COUNT) % COUNT)) ;;
  --)
    case "${ITEMS[$pos]}" in
      vim) vim "$2" ;;
      bat) bat --paging always "$2" ;;
      less) less "$2" ;;
    esac
    exit $?
    ;;
esac

set_pos "$pos"
print_bar "$pos"