#!/bin/bash

## USAGE:
## To make this be invoked when you run `git mergetool`, add the following
## to your git configuration file, such as ~/.gitconfig :
# [merge]
# 	tool = ediff
#
# [mergetool "ediff"]
# 	cmd = /path/to/plume-lib/bin/ediff-merge-script "$LOCAL" "$REMOTE" "$MERGED" "$BASE"
# 	trustExitCode = true

## USER CUSTOMAZATION:
## Choose emacs or emacsclient.  emacsclient starts up faster, but emacs gives a
## fresh context and avoids cluttering the original emacs with merge buffers.
_EMACSCLIENT=emacs
# _EMACSCLIENT=emacsclient


# This script is originally from
#   http://stackoverflow.com/questions/1817370/using-ediff-as-git-mergetool
# I have extended so it handles both emacs and emacsclient,
# and made other improvements.


# test args
if [ ! ${#} -ge 3 ]; 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
_BASENAME=basename
_CP=/bin/cp
_EGREP=/bin/egrep
_MKTEMP=/bin/mktemp

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

_EVAL_PREFIX="(defun ediff-write-merge-buffer ()\
    (let ((file ediff-merge-store-file))\
      (set-buffer ediff-buffer-C)\
      (write-region (point-min) (point-max) file)\
      (message \"Merge buffer saved in: %s\" file)\
      (set-buffer-modified-p nil)))\
  (setq ediff-quit-merge-hook 'ediff-write-merge-buffer)"

if [[ $_EMACSCLIENT == *"emacsclient"* ]]; then
  ## emacsclient only, not emacs
  # console vs. X
  if [ "${TERM}" = "linux" ]; then
      unset DISPLAY
      _EMACSCLIENTOPTS='-t -a \"\"'
  else
      _EMACSCLIENTOPTS='-c -a \"\"'
  fi
else
  ## emacs only, not emacsclient
  _EVAL_PREFIX2="(setq ediff-quit-hook 'kill-emacs)"
fi

# run emacs or emacsclient
# # For debugging
# echo ${_EMACSCLIENT} ${_EMACSCLIENTOPTS} --eval "(progn ${_EVAL_PREFIX} ${_EVAL_PREFIX2} ${_EVAL})"
${_EMACSCLIENT} ${_EMACSCLIENTOPTS} --eval "(progn ${_EVAL_PREFIX} ${_EVAL_PREFIX2} ${_EVAL})" 2>&1


# check modified file
if [ ! $(egrep -c '^(<<<<<<<|=======|>>>>>>>|####### Ancestor)$' ${_MERGED}) = 0 ]; then
    _MERGEDSAVE=$(${_MKTEMP} --tmpdir `${_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

# It would not be appropriate for this script to do the merge, because
# this script is called on each file individually.
echo 1>&2 "Merge succeeded."
echo 1>&2 "Don't forget to commit changes."

exit 0