#!/bin/sh

#

# 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"

if [ -z "$EDITOR" ]; then

    EDITOR="vi"

fi

# find decent versions of our utilities, insisting on the GNU versions where we

# need to

DIFF3=gdiff3

DIFF=gdiff

PATCH=gpatch

type $DIFF3 >/dev/null 2>&1 || DIFF3=diff3

type $DIFF  >/dev/null 2>&1 || DIFF=diff

type $PATCH  >/dev/null 2>&1 || PATCH=patch

$DIFF3 --version >/dev/null 2>&1 || DIFF3=

# Back up our file

cp "$LOCAL" "$LOCAL.orig"

# Attempt to do a non-interactive merge

if type merge > /dev/null 2>&1; then

    merge "$LOCAL" "$BASE" "$OTHER" 2> /dev/null && exit 0

    cp "$LOCAL.orig" "$LOCAL"

elif [ -n "$DIFF3" ]; then

    echo $DIFF3 -m "$LOCAL.orig" "$BASE" "$OTHER"

    $DIFF3 -m "$LOCAL.orig" "$BASE" "$OTHER" > "$LOCAL" && exit 0

    if [ $? -eq 2 ]; then

        echo "$DIFF3 failed! Exiting." 1>&2

        cp "$LOCAL.orig" "$LOCAL"

        exit 1

    fi

    cp "$LOCAL.orig" "$LOCAL"

fi

# on MacOS X try FileMerge.app, shipped with Apple's developer tools

# TODO: make proper temp files. foo.orig and foo.link are dangerous

FILEMERGE='/Developer/Applications/Utilities/FileMerge.app/Contents/MacOS/FileMerge'

if type "$FILEMERGE" > /dev/null 2>&1; then

    cp "$LOCAL.orig" "$LOCAL"

    ln "$LOCAL" "$LOCAL.link"

    # filemerge prefers the right by default

    if ! "$FILEMERGE" -left "$OTHER" -right "$LOCAL" -ancestor "$BASE" -merge "$LOCAL"

    then

        echo "FileMerge failed to launch"

        exit 1

    fi

    if ! test "$LOCAL" -ef "$LOCAL.link"

    then

        rm "$LOCAL.orig" "$LOCAL.link"

        exit 0

    else

        rm "$LOCAL.link"

        echo "$LOCAL is unchanged. Was the merge successful?"

        select answer in yes no

        do

            if test "$answer" == "yes"

            then

                rm "$LOCAL.orig"

                exit 0

            else

                exit 1

            fi

        done

        exit 1

    fi

fi

if [ -n "$DISPLAY" ]; then

    # try using kdiff3, which is fairly nice

    if type kdiff3 > /dev/null 2>&1; then

	kdiff3 --auto "$BASE" "$LOCAL" "$OTHER" -o "$LOCAL" || exit 1

	exit 0

    fi

    # try using tkdiff, which is a bit less sophisticated

    if type tkdiff > /dev/null 2>&1; then

	tkdiff "$LOCAL" "$OTHER" -a "$BASE" -o "$LOCAL" || exit 1

	exit 0

    fi

fi

# Attempt to do a merge with $EDITOR

if type merge > /dev/null 2>&1; then

    echo "conflicts detected in $LOCAL"

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

    exit 0

fi

if [ -n "$DIFF3" ]; then

    echo "conflicts detected in $LOCAL"

    $DIFF3 -m "$LOCAL.orig" "$BASE" "$OTHER" > "$LOCAL" || {

        case $? in

            1)

                $EDITOR "$LOCAL" ;;

            2)  echo "$DIFF3 failed! Exiting." 1>&2

                cp "$LOCAL.orig" "$LOCAL"

                exit 1 ;;

        esac

        exit 0

    }

fi

HGTMP=""

cleanup_exit() {

    rm -rf "$HGTMP"

}

# attempt to manually merge with diff and patch

if [ -n "$DIFF" -a -n "$PATCH" ]; then

    # Remove temporary files even if we get interrupted

    trap "cleanup_exit" 0 # normal exit

    trap "exit 1" 1 2 3 6 15 # HUP INT QUIT ABRT TERM

    HGTMP="${TMPDIR-/tmp}/hgmerge.$RANDOM.$RANDOM.$RANDOM.$$"

    (umask 077 && mkdir "$HGTMP") || {

	echo "Could not create temporary directory! Exiting." 1>&2

	exit 1

    }

    $DIFF -u "$BASE" "$OTHER" > "$HGTMP/diff" || :

    if $PATCH "$LOCAL" < "$HGTMP/diff"; then

	exit 0

    else

	# If rejects are empty after using the editor, merge was ok

	$EDITOR "$LOCAL" "$LOCAL.rej" && test -s "$LOCAL.rej" || exit 0

    fi

    exit 1

fi

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

exit 1