#!/bin/sh

src=$1
dst=${1%.*}.mp4
bak=${1%.*}.orig.${1##*.}

sqldb=convert.db

sqlinit() {
	[ -f "$1" ] || sqlite3 "$1" 'CREATE TABLE encodings(path TEXT PRIMARY KEY NOT NULL, orig TEXT, backup TEXT, origsize INT, newsize INT)'
}

restore() {
	mv "$bak" "$src"
}

sqlinit "$sqldb"

[ -f "$src" ] || exec echo "fail to open $dst"
[ -f "$bak" ] && exec echo "backup $bak already exists"

exist=$(sqlite3 "$sqldb" "SELECT count(*) FROM encodings WHERE path = '$dst' OR orig = '$src'")

[ "$exist" -gt 0 ] && exec echo "$dst already converted"

mv "$src" "$bak"

echo "Converting \"$dst\""
if ffmpeg -v 16 -y -i "$bak" -crf 22 -preset:v slow -c:a libfdk_aac -vbr 4 "$dst"; then
	origsize=$(stat "$bak" -c %s)
	newsize=$(stat "$dst" -c %s)
	save=$((newsize * 100 / origsize))

	echo "$((origsize >> 20)) => $((newsize >> 20)) MB, $save %"

	if [ $save -le 90 ]; then
		sqlite3 "$sqldb" "INSERT INTO encodings VALUES('$dst', '$src', '$bak', $origsize, $newsize)"
	else
		echo 'restoring old file'
		sqlite3 "$sqldb" "INSERT INTO encodings VALUES('$src', NULL, NULL, NULL, NULL)"
		restore
	fi
else
	echo 'error, restoring'
	restore
fi