# `cdp` to activate an interactive way to navigate directories
function cdp {
	# helpers for terminal print control, key input, and other things
	ESC=$( printf "\033" )
	cursor_blink_on()	{ printf "${ESC}[?25h"; }
	cursor_blink_off()	{ printf "${ESC}[?25l"; }
	cursor_to()			{ printf "${ESC}[$1;${2:-1}H"; }
	print_option()		{ printf " $1 $(tput el)"; }
	print_selected()	{ printf "${ESC}[7m $1 ${ESC}[27m$(tput el)"; }
	get_cursor_row()	{ IFS=';' read -sdR $'?\E[6n' ROW COL; echo ${ROW#*\[}; }
	
	key_input()	{ read -sk1 'key?'
				  case $key in
					  $'\n') echo enter;;
					  ' ') echo space;;
					  0) echo 10;;
					  1|2|3|4|5|6|7|8|9) echo $key;;
					  "${ESC}")
						  read -sk2 key
						  if [[ $key = "[A" ]]; then echo up
						  elif [[ $key = "[B" ]]; then echo down
						  elif [[ $key = "[C" ]]; then echo right
						  elif [[ $key = "[D" ]]; then echo left
						  fi;;
				  esac }
	min() 		{ printf "%s\n" "$@" | sort -g | head -n1 }
	max() 		{ printf "%s\n" "$@" | sort -gr | head -n1 }
	

	# initialize persistent variables
	MAX_SIZE=10
	local prev_dir=''
	local orig_dir=$PWD

	while true; do
		# determine the options
		local subdirs=$((ls -1d */) 2> /dev/null)
		local opts=("$(tput smul)Change directory to $(tput bold)$(pwd)$(tput sgr0)$(tput el)")
		[[ ! -z $subdirs ]] && opts+=("${(f)subdirs}")
		opts+=('../')
		local num_opts=${#opts[@]}

		# initialize interaction area and screen positions of first and last row (used for overwriting)
		# note: indices are all 1-indexed with row 1 being the line displaying the working directory
		local num_opt_rows=$(min $(tput lines) $MAX_SIZE $((num_opts - 1)))
		for _ in {1..$num_opt_rows}; do echo; done
		local last_row=$(get_cursor_row)
		local first_row=$((last_row - num_opt_rows))
		cursor_to $first_row
		echo "  $opts[1]"

		# ensure cursor and input echoing back on upon a ctrl+c during read
		trap "cd $orig_dir; cursor_blink_on; stty echo; printf '\n'; return" 2
		cursor_blink_off
		
		# jump to previous dir option (if left arrow key was pressed)
		local selected=2
		for i in {2..$#opts}; do [[ $opts[$i] = $prev_dir ]] && selected=$i; done
		local inp=''

		local top_row=$(max $((selected - num_opt_rows + 2)) 2)
		while true; do
			# determine "scroll" position
			if [[ $selected -lt $top_row ]]; then top_row=$selected
			elif [[ $selected -ge $((top_row + num_opt_rows)) ]]; then top_row=$((selected - num_opt_rows + 1)); fi

			# print options by overwriting the last lines
			for opt_index in {$top_row..$((top_row + num_opt_rows - 1))}; do
				cursor_to $((first_row + opt_index - top_row + 1))
				printf " [%i] " $(((opt_index - top_row + 1) % 10))
				if [[ $opt_index -eq $selected ]]; then print_selected $opts[$((opt_index))]
				else print_option $opts[$((opt_index))]; fi
			done

			# user key control
			inp=$(key_input)
			case $inp in
				left)	[[ $PWD != $HOME ]] && break;;
				up)	((selected--)); [[ $selected -lt 2 ]] && selected=$num_opts;;
				down)	((selected++)); [[ $selected -gt $num_opts ]] && selected=2;;
				right|enter|space|1|2|3|4|5|6|7|8|9|10) break;;
			esac
		done

		# reset interaction area
		cursor_to $first_row
		for row_offset in {1..$num_opt_rows}; do cursor_to $((first_row + row_offset)); echo -n $(tput el); done
		cursor_to $first_row

		# cd accordingly
		case $inp in
			right) 	cd $opts[$selected]; prev_dir='';;
			enter) 	break;;
			space) 	cd; prev_dir='';;
			left) 	prev_dir=$(printf '%s/' "${PWD##*/}"); cd ..;;
			*) 	local dest=$opts[$((top_row + inp - 1))]
				[[ $dest == '../' ]] && prev_dir=$(printf '%s/' "${PWD##*/}")
				cd $dest;;
		esac
	done
	cursor_blink_on
}