#!/bin/bash

rows=$(tput lines)
cols=$(tput cols)
colors=(red green blue purple cyan yellow brown)
lock_file=
lock_file_base=/tmp/$(basename $0 .sh)

multiple=0
if [[ "$1" ]]; then
	nsingle=$1
	shift
else
	nsingle=10
fi
if [[ "$1" ]]; then
	nmultiple=$1
	shift
	if [[ $nmultiple -gt 8 ]]; then nmultiple=8; fi
else
	nmultiple=6
fi


function colorstr()
{
	local  row=$1
	local  col=$2
	local  color=$3
	local  v
	case "$color" in
	red)     v=31;;
	green)   v=34;;
	blue)    v=32;;
	purple)  v=35;;
	cyan)    v=36;;
	yellow)  v=33;;
	brown)   v=33;;
	white)   v=37;;
	*)       v=;;
	esac
	shift 3

	if [[ $multiple -ne 0 ]]; then
		touch $lock_file
		while [[ $(ls $lock_file_base.* 2>/dev/null | head -n 1) != $lock_file ]]
		do
			sleep 0.05
		done
	fi
		
	tput cup $row $col
	echo -n -e "\e["$v"m"
	set -f
	echo -n $*
	set +f
	if [[ $multiple -ne 0 ]]; then
		rm -f $lock_file
	fi
}

function center_colorstr()
{
	local  row=$1
	local  color=$2
	shift 2
	local  s="$*"
	local  slen=${#s}
	colorstr $row $(((cols / 2) - (slen / 2))) $color "$s"
}
	
function fireworks()
{
	local row=$((rows - 1))
	local col=$(((RANDOM % (cols / 2)) + (cols / 4))) 
	local height=$((RANDOM % rows - 2))
	local slant
	local h
	local color1=${colors[$((RANDOM % ${#colors[*]}))]}
	local color2=${colors[$((RANDOM % ${#colors[*]}))]}
	local color3=${colors[$((RANDOM % ${#colors[*]}))]}
	while [[ $color1 == $color2  ||  $color1 == $color3  ||  $color2 == $color3 ]]
	do
		color2=${colors[$((RANDOM % ${#colors[*]}))]}
		color3=${colors[$((RANDOM % ${#colors[*]}))]}
	done

	case $((RANDOM % 4)) in
	0) slant=-2;;
	1) slant=-1;;
	2) slant=1;;
	3) slant=2;;
	esac

	if [[ $height -gt 5 ]]; then
		h=$height

		while [[ $h -gt 0 ]]
		do
			colorstr $row $col $color1 '.'
			let row--
			if [[ $((col + slant)) -ge $((cols - 3))  ||  $((col + slant)) -le 2 ]]; then break; fi
			let col+=slant
			let h--
			sleep 0.1
		done

		if [[ $((col + slant)) -lt $((cols - 3))  &&  $((col + slant)) -gt 2 ]]; then

			h=$((height / 5))

			while [[ $h -gt 0 ]]
			do
				colorstr $row $col $color2 '.'
				let row++
				if [[ $((col + slant)) -ge $((cols - 3))  ||  $((col + slant)) -le 2 ]]; then break; fi
				let col+=slant
				let h--
				sleep 0.1
			done
		fi

		colorstr $((row)) $((col - 1)) $color3 '***'
		colorstr $((row - 1)) $((col)) $color3 '*'
		colorstr $((row + 1)) $((col)) $color3 '*'
	fi
}

for i in $(seq 1 $nsingle)
do
	clear
	fireworks
	sleep 1
done

clear

pids=
for i in $(seq 1 $nmultiple)
do
	let multiple++
	lock_file=$lock_file_base.$i
	fireworks &
	pids="$pids $!"
done

trap "kill -9 $pids 2>/dev/null" EXIT

wait $pids
sleep 3

clear
center_colorstr $((rows / 2 - 1)) red "Hope you enjoyed the show!"
center_colorstr $((rows / 2 + 1)) red "Happy 4th of July"
center_colorstr $((rows / 2 + 3)) red "Your Friends at Linux Journal"
echo

sleep 5
clear


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