#!/bin/zsh


_STTY=$(stty -g)    # Save current terminal setup
#printf   "\e[2J"    # clear screen, set cursos at beginning
stty -echo -icanon  # Turn off line buffering

# VARIABLES
typeset -A IMAGE
X=0 
Y=24
snake='═'

vertical=false
forward=true
upward=true

function start_the_snake() {
	rm thesnake
	for i in {0..29}
	do
		for j in {0..79}
		do
			IMAGE["${i};${j}"]=' ' ; printf ${IMAGE["${i};${j}"]}
		done
	done
}

function save_the_snake() {
	for i in {0..29}
	do
		for j in {0..79}
		do
			printf ${IMAGE["${i};${j}"]}
		done
	done >> thesnake
}

function show_the_snake() {
	clear
	for i in {0..29}
	do
		for j in {0..79}
		do
			printf ${IMAGE["${i};${j}"]}
		done
	done
}
function at_exit() {
	printf "\e[?9l"          # Turn off mouse reading
	printf "\e[?12l\e[?25h"  # Turn on cursor
	stty "$_STTY"            # reinitialize terminal settings
	clear
	exit
}

#═ ║╒ ╓ ╔ ╕ ╖ ╗ ╘ ╙ ╚ ╛ ╜ ╝ ╞ ╟  
#╠ ╡ ╢ ╣ ╤ ╥ ╦ ╧ ╨ ╩ ╪ ╫ ╬ 

function move_snake_up() {
	if [ "$vertical" = false ] ; then
		if [ "$forward" = true ] ; then
			snake='╝'
		else
			snake='╚'
		fi
		IMAGE["${Y};${X}"]=$snake ; Y=$((Y-1)) ; vertical=true ; upward=true
	else
		snake='║' ; IMAGE["${Y};${X}"]=$snake ; Y=$((Y-1))
	fi
}

function move_snake_down() {
	if [ "$vertical" = false ] ; then
		if [ "$forward" = true ] ; then
			snake='╗'
		else
			snake='╔'
		fi
		IMAGE["${Y};${X}"]=$snake ; Y=$((Y+1)) ; vertical=true ; upward=false
	else
		snake='║' ; IMAGE["${Y};${X}"]=$snake ; Y=$((Y+1))
	fi
}

function move_snake_forward() {
	if [ "$vertical" = true ] ; then
		if [ "$upward" = true ] ; then
			snake='╔'
		else
			snake='╚'
		fi
		IMAGE["${Y};${X}"]=$snake ; X=$((X+1)) ; vertical=false ; forward=true
	else
		snake='═' ; IMAGE["${Y};${X}"]=$snake ; X=$((X+1))
	fi
}

function move_snake_backward() {
	if [ "$vertical" = true ] ; then
		if [ "$upward" = true ] ; then
			snake='╗'
		else
			snake='╝'
		fi
		IMAGE["${Y};${X}"]=$snake ; X=$((X-1)) ; vertical=false ; forward=false
	else
		snake='═' ; IMAGE["${Y};${X}"]=$snake ; X=$((X-1))
	fi
}

# Main #
start_the_snake
while read -s -k 1 cr;
do
	case "$cr" in
		w)	move_snake_up ; show_the_snake ;;
		s)  move_snake_down ; show_the_snake ;;
		a)	move_snake_backward ; show_the_snake ;;
		d)  move_snake_forward ; show_the_snake ;;
		q)	save_the_snake && at_exit ;;
	esac
done