#!/bin/sh

set -e

if [ "$#" != 4 ]
then
    echo Bad args >&2
    exit 1
fi

cd "$1"
US=`git rev-parse HEAD`

cd "$2"
THEM=`git rev-parse HEAD`

OUTPUT="$3"

DO_WHAT="$4"

[ "$US" == "$THEM" ] && exit 0

echo                     >  "$OUTPUT.new"
echo "New patches in $2" >> "$OUTPUT.new"
echo                     >> "$OUTPUT.new"
git log "$US.."          >> "$OUTPUT.new"

if [ "$DO_WHAT" = "mail" ]
then
    touch -d "30 days ago" "$OUTPUT.old"

    [ -f "$OUTPUT" ] && cmp -s "$OUTPUT" "$OUTPUT.new" && [ "$OUTPUT.old" -ot "$OUTPUT.new" ] && exit 0

    mv "$OUTPUT.new" "$OUTPUT"
    mail -s "New patches in $2" cvs-ghc@haskell.org < "$OUTPUT"
else
    echo "=========="
    echo "$OUTPUT"
    echo
    cat "$OUTPUT.new"
fi