#!/bin/sh

usage() {
  cat <<EOF
Usage: $( basename $0 ) [diff-opts] [-- a8cat-opts] file1 file2

Diff two Atari ATASCII files, using a8cat(1) and diff(1).

[diff-opts] is passed through as-is to diff.
[a8cat-opts] is passed through as-is to a8cat.
EOF
  exit "$1"
}

cleanup() {
  if [ "$dir" != "" ]; then
    cd
    rm -rf "$dir"
  fi
}

if [ "$1" = "-h" -o "$1" = "--help" -o "$1" = "" ]; then
  usage 0
fi

for i in "$@"; do
  if [ -f "$i" ]; then
    if [ "$file1" = "" ]; then
      file1="$( realpath $i )"
      base1="$( basename $i )".txt
    elif [ "$file2" = "" ]; then
      file2="$( realpath $i )"
      base2="$( basename $i )".txt
    else
      usage 1
    fi
  elif [ "$i" = "--" ]; then
    opts="a8catopts"
  elif [ "$opts" = "a8catopts" ]; then
    a8catopts="$a8catopts $i"
  else
    diffopts="$diffopts $i"
  fi
done

dir="$( mktemp -d -t diffbas.XXXXXXXXXX )"
[ -d "$dir" ]
cd "$dir"
trap cleanup EXIT
set -e

a8cat $a8catopts "$file1" > $base1
a8cat $a8catopts "$file2" > $base2
diff $diffopts $base1 $base2

exit 0