#!/bin/bash

set -eu
set -o pipefail

name="$1"
f1="$2"
f2="$5"

name1="a/$name"
name2="b/$name"


if diff "$f1" "$f2" >/dev/null
then
  exit 0
fi


exif() {
  local b=$(basename "$1")
  local d=$(mktemp -t "$b")
  exiftool "$1" | grep -v "File Name" | \
                  grep -v "Directory" | \
                  grep -v "File Inode Change" | \
                  grep -v "File Modification Date/Time" | \
                  grep -v "File Permissions" \
     >"$d"
  echo "$d"
}


diff_clean_names() {
  diff -u "$1" --label "$name1" "$2" --label "$name2" || true
}


if which -s exiftool
then
  d1=$(exif "$f1")
  d2=$(exif "$f2")
  diff_clean_names "$d1" "$d2"
else
  diff_clean_names "$f1" "$f2"
fi

if [ -z "${GIT_DIFF_IMAGE_ENABLED-}" ] || \
   ! which -s compare || \
   ! which -s montage
then
  exit 0
fi

if compare "$f1" "$f2" /dev/null
then
  exit 0
fi

bn=$(basename "$f1")
destfile=$(mktemp -t "$bn").png

compare "$f1" "$f2" png:- | \
  montage -geometry +4+4 "$f1" - "$f2" png:- >"$destfile" 2>/dev/null || true
open "$destfile"