#!/bin/bash

if [ -z "$1" ]; then
    echo "Usage: $0 MVIMG_xxx.jpg"
    exit 1
fi

set -eu

infile="$1"
outvid="${infile%.*}.mp4"
outpic="${infile#MV}"

if ! [ -f "$infile" ]; then
    echo "Missing input file: $infile"
    exit 1
fi

if [ -f "$outvid" ] || [ -f "$outpic" ]; then
    echo "Output files already exist! $outvid || $outpic"
    exit 1
fi

size="$(stat -c '%s' "$infile")"
revoffset="$(exiftool -m -p "\$MicroVideoOffset" "$infile")"
if [ -z "$revoffset" ] || [ "$revoffset" -le 0 ]; then
    echo "Invalid video offset: $revoffset"
    exit 1
fi
offset=$((size - revoffset))

dd if="$infile" of="$outvid" bs="$offset" skip=1
dd if="$infile" of="$outpic" bs="$offset" count=1
exiftool -overwrite_original -xmp:all= "$outpic"