#!/usr/bin/env bash

# Modified from https://github.com/paulotome/emacstool

# test args
if [ ! ${#} -ge 2 ]; then
    echo 1>&2 "Usage: ${0} LOCAL REMOTE [MERGED BASE]"
    echo 1>&2 "       (LOCAL, REMOTE, MERGED, BASE can be provided by \`git mergetool'.)"
    exit 1
fi

# tools
emacsclient=$(which emacsclient)
basename=$(which basename)
cp=$(which cp)
mktemp=$(which mktemp)

# args
_LOCAL=${1}
_REMOTE=${2}
if [ "${3}" ] ; then
    _MERGED=${3}
else
    _MERGED=${_REMOTE}
fi
if [ "${4}" ] && [ -r "${4}" ] ; then
    _BASE=${4}
    _EDIFF=ediff-merge-files-with-ancestor
    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\" \"${_BASE}\" nil \"${_MERGED}\""
elif [ "${_REMOTE}" = "${_MERGED}" ] ; then
    _EDIFF=ediff
    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\""
else
    _EDIFF=ediff-merge-files
    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\" nil \"${_MERGED}\""
fi

# console vs. X
if [ "${TERM}" = "linux" ]; then
    unset DISPLAY
    emacsclientOPTS="-t"
else
    emacsclientOPTS="-c"
fi

# run emacsclient
${emacsclient} ${emacsclientOPTS} -a "" -e "(${_EVAL})" 2>&1

# check modified file
if [ ! "$(grep -Ec '^(<<<<<<<|=======|>>>>>>>|####### Ancestor)' "${_MERGED}")" = 0 ]; then
    _MERGEDSAVE=$(${mktemp} --tmpdir "$(${basename} "${_MERGED}")".XXXXXXXXXX)
    ${cp} "${_MERGED}" "${_MERGEDSAVE}"
    echo 1>&2 "Oops! Conflict markers detected in $_MERGED."
    echo 1>&2 "Saved your changes to ${_MERGEDSAVE}"
    echo 1>&2 "Exiting with code 1."
    exit 1
fi

exit 0