#!/usr/bin/env nix-shell
#!nix-shell --pure -i bash -p opusTools ffmpeg mpv
set -u

original=$(realpath "$1")
bitrates=(16 32 64 128)

dir=$(mktemp -d)

ffmpeg -i "$original" -map_metadata -1 -vn "$dir/original.flac"
files=("$dir/original.flac")

for bitrate in "${bitrates[@]}"; do
	opusenc --bitrate "$bitrate" "$dir/original.flac" "$dir/tmp.opus"
	opusdec "$dir/tmp.opus" "$dir/tmp.wav"
	ffmpeg -i "$dir/tmp.wav" -map_metadata -1 -vn "$dir/$bitrate.flac"
	rm "$dir/tmp."*
	files+=("$dir/$bitrate.flac")
done

>results

playdir=$(mktemp -d)
while true; do
	a=${files[ $(( RANDOM % ${#files[@]} )) ]}
	b=${files[ $(( RANDOM % ${#files[@]} )) ]}
	if [ "$a" = "$b" ]; then
		continue
	fi

	ln -sf "$a" "$playdir/a"
	ln -sf "$b" "$playdir/b"

	mpv --loop-playlist --quiet "$playdir/a" "$playdir/b"
	echo -n "What was better, a or b? " >&2
	read result
	if [ "$result" = a ]; then
		echo "$a > $b" >> results
	elif [ "$result" = b ]; then
		echo "$a < $b" >> results
	else
		echo "$a ~ $b" >> results
	fi
done