#!/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

MERGE="merge"

DIFF3="gdiff3"

DIFF="gdiff"

PATCH="gpatch"

type "$MERGE" >/dev/null 2>&1 || MERGE=

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

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

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

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

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

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

# find optional visual utilities

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

KDIFF3="kdiff3"

TKDIFF="tkdiff"

MELD="meld"

type "$FILEMERGE" >/dev/null 2>&1 || FILEMERGE=

type "$KDIFF3"    >/dev/null 2>&1 || KDIFF3=

type "$TKDIFF"    >/dev/null 2>&1 || TKDIFF=

type "$MELD"      >/dev/null 2>&1 || MELD=

# random part of names

RAND="$RANDOM$RANDOM"

# temporary directory for diff+patch merge

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

# backup file

BACKUP="$LOCAL.orig.$RAND"

# file used to test for file change

CHGTEST="$LOCAL.chg.$RAND"

# put all your required cleanup here

cleanup() {

    rm -f "$BACKUP" "$CHGTEST"

    rm -rf "$HGTMP"

}

# functions concerning program exit

success() {

    cleanup

    exit 0

}

failure() {

    echo "merge failed" 1>&2

    mv "$BACKUP" "$LOCAL"

    cleanup

    exit 1

}

# Ask if the merge was successful

ask_if_merged() {

    while true; do

        echo "$LOCAL seems unchanged."

        echo "Was the merge successful? [y/n]"

        read answer

        case "$answer" in

            y*|Y*) success;;

            n*|N*) failure;;

        esac

    done

}

# Clean up when interrupted

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

# Back up our file (and try hard to keep the mtime unchanged)

mv "$LOCAL" "$BACKUP"

cp "$BACKUP" "$LOCAL"

# Attempt to do a non-interactive merge

if [ -n "$MERGE" -o -n "$DIFF3" ]; then

    if [ -n "$MERGE" ]; then

        $MERGE "$LOCAL" "$BASE" "$OTHER" 2> /dev/null && success

    elif [ -n "$DIFF3" ]; then

        $DIFF3 -m "$BACKUP" "$BASE" "$OTHER" > "$LOCAL" && success

    fi

    if [ $? -gt 1 ]; then

        echo "automatic merge failed! Exiting." 1>&2

        failure

    fi

fi

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

if [ -n "$FILEMERGE" ]; then

    cp "$BACKUP" "$LOCAL"

    cp "$BACKUP" "$CHGTEST"

    # filemerge prefers the right by default

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

    [ $? -ne 0 ] && echo "FileMerge failed to launch" && failure

    test "$LOCAL" -nt "$CHGTEST" && success || ask_if_merged

fi

if [ -n "$DISPLAY" ]; then

    # try using kdiff3, which is fairly nice

    if [ -n "$KDIFF3" ]; then

        success

    fi

    # try using tkdiff, which is a bit less sophisticated

    if [ -n "$TKDIFF" ]; then

        success

    fi

    if [ -n "$MELD" ]; then

        cp "$BACKUP" "$CHGTEST"

        # protect our feet - meld allows us to save to the left file

        cp "$BACKUP" "$LOCAL.tmp.$RAND"

        # Meld doesn't have automatic merging, so to reduce intervention

        # use the file with conflicts

        $MELD "$LOCAL.tmp.$RAND" "$LOCAL" "$OTHER" || failure

        # Also it doesn't return good error code

        test "$LOCAL" -nt "$CHGTEST" && success || ask_if_merged

    fi

fi

# Attempt to do a merge with $EDITOR

if [ -n "$MERGE" -o -n "$DIFF3" ]; then

    echo "conflicts detected in $LOCAL"

    cp "$BACKUP" "$CHGTEST"

    $EDITOR "$LOCAL" || failure

    # Some editors do not return meaningful error codes

    # Do not take any chances

    test "$LOCAL" -nt "$CHGTEST" && success || ask_if_merged

fi

# attempt to manually merge with diff and patch

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

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

        echo "Could not create temporary directory $HGTMP" 1>&2

        failure

    }

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

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

        success

    else

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

        $EDITOR "$LOCAL" "$LOCAL.rej" || failure

        test -s "$LOCAL.rej" || success

    fi

    failure

fi

echo

echo "hgmerge: unable to find any merge utility!"

echo "supported programs:"

echo "merge, FileMerge, tkdiff, kdiff3, meld, diff+patch"

echo

failure