#!/bin/bash

#

# hgmerge - default merge helper for Mercurial

#

# This tries to find a way to do three-way merge on the current system.

# The result ought to end up in $1.

set -e # bail out quickly on failure

LOCAL=$1

BASE=$2

OTHER=$3

EDITOR="${EDITOR:-vi}"

# Back up our file

cp $LOCAL $LOCAL.orig

# Attempt to do a non-interactive merge

if which merge > /dev/null ; then

    if merge $LOCAL $BASE $OTHER 2> /dev/null; then

	# success!

	exit 0

    fi

    cp $LOCAL.orig $LOCAL

elif which diff3 > /dev/null ; then

    if diff3 -m $LOCAL.orig $BASE $OTHER > $LOCAL ; then

	# success

	exit 0

    fi

    cp $LOCAL.orig $LOCAL

fi

if [ -n "$DISPLAY" ]; then

    # try using kdiff3, which is fairly nice

    if which kdiff3 > /dev/null ; then

	if kdiff3 --auto $BASE $LOCAL $OTHER -o $LOCAL ; then

	    exit 0

	else

	    exit 1

	fi

    fi

    # try using tkdiff, which is a bit less sophisticated

    if which tkdiff > /dev/null ; then

	if tkdiff $LOCAL $OTHER -a $BASE -o $LOCAL ; then

	    exit 0

	else

	    exit 1

	fi

    fi

fi

# Attempt to do a merge with $EDITOR

if which merge > /dev/null ; then

    echo "conflicts detected in $LOCAL"

    merge $LOCAL $BASE $OTHER 2>/dev/null || $EDITOR $LOCAL

    exit 0

fi

if which diff3 > /dev/null ; then

    echo "conflicts detected in $LOCAL"

    diff3 -m $LOCAL.orig $BASE $OTHER > $LOCAL || $EDITOR $LOCAL

    exit 0

fi

# attempt to manually merge with diff and patch

if which diff > /dev/null ; then

    if which patch > /dev/null ; then

	T=`mktemp`

	diff -u $BASE $OTHER > $T

	if patch $LOCAL < $T ; then

	    exit 0

	else

	    $EDITOR $LOCAL $LOCAL.rej

	fi

	rm $T

	exit 1

    fi

fi

echo "hgmerge: unable to find merge, tkdiff, kdiff3, or diff+patch!"

exit 1