#!/bin/bash
# Graph animation of input data

DEBUG=1
VERBOSE=0                                                           
X=( \| / - \\ )
CONTAINER=mp4

err() { printf "$0[error]: %s\n" "$*" >&2; exit 2; }
warn() { printf "$0[warning]: %s\n" "$*" >&2; } 
debug() { ((DEBUG)) && printf "$0[debug]: %s\n" "$*" >&2; }
verbose() { ((VERBOSE)) && printf "$0[info]: %s\n" "$*" >&2; }
vprintf() { ((VERBOSE)) && printf "$@" >&2; }
help() { printf '%s\n' "
Usage:  $0 [-v] [-c ext] datafile...
        $0 -h

        -v     ... verbose
        -c ext ... container extension
        -h     ... this help
"; }

while getopts hvc: opt
do
   case $opt in
      h) help; exit 0;;
      v) ((VERBOSE++));;
      c) CONTAINER=$OPTARG;;
      \?) help >&2; exit 1;;
   esac
done
shift $(( OPTIND-1 ))

tmp=$( mktemp -d ) || err "Cannot create temporary directory"
trap 'debug "Cleanup"; rm -rf "$tmp"' EXIT
debug "Temporary directory: $tmp"

if [ $# -eq 0 ]
then
   help >&2
   err "Datafile missing"
fi

for data
do

	[ -f "$data" ] || err "File '$data' does not exist"
	[ -r "$data" ] || err "File '$data' is not readable"
	[ -s "$data" ] || err "File '$data' is empty"
	egrep -v '^-?[0-9]*\.?[0-9]+$' "$data" && err "Bad '$data' format"

	lines=$( wc -l < "$data" )
	digits=${#lines}
	range=$( sort -n "$data" | sed -n '1h;${H;g;s/\n/:/p}' )

	# Prepare separate frames
	# For each frame
	vprintf "$0[verbose]: Done       "
	for (( i=1; i<=lines; i++ ))
	do
		# Prepare data
		# Run gnuplot to make single frame
		(( p=100*i/lines ))
		vprintf '\b\b\b\b\b\b%s %3d%%' "${X[i%4]}" "$p"

		{
		cat <<-GP
			set terminal png
			set output "$tmp/$( printf "%0${digits}d.png" $i )"
			plot [0:$lines][$range] '-' with lines
			GP
		head -n "$i" "$data"
		} | gnuplot
	done

	# Join frames into animation
	ffmpeg -y -i "$tmp/%0${digits}d.png" "$data.$CONTAINER"

done