#!/bin/bash

temp_message=`mktemp`
temp_patch=`mktemp`

cleanup () {
    rm -f "$temp_message" "$temp_patch"
}

trap cleanup 0

handle_patch () {
    git mailinfo -b --scissors "$temp_message" "$temp_patch" | {
	read -r git_author
	read -r git_email
	read -r git_subject
	read -r git_datex

	printf 'From %s <%s>\n' \
	       "${git_author#Author: }" "${git_email#Email: }"
	printf '%s\n%s\n' "$git_subject" "$git_date"

	cat "$temp_message"
	echo
	# git mailinfo does not normalize the patch, and there are
	# typically indented patch statistics before the first diff.
	awk '/^diff / { printing=1 }
/^[^- ]/ { 
  if (printing) { 
    print
  } else { 
    print "error: unrecognized input before patch: " $0 > "/dev/stderr";
    exit(1)
  }
}
/^[- ]/ { if (printing) { print } }' "$temp_patch"
    }
}

if test $# -eq 0 ; then
    handle_patch
else
    for patch in "$@" ; do
	handle_patch < "$path"
	echo
    done
fi