#!/bin/sh
# git pumm BRANCH - show conflicts of dry-run merge of BRANCH into HEAD

set -e

fail() { echo ${0##*/}: 1>&2 "$*"; exit 1; }

ref=$(git rev-parse --symbolic-full-name $1@{u} 2>/dev/null) ||
  ref=$(git rev-parse --symbolic-full-name $1)

case "$ref" in
  refs/remotes/*/*)
    branch=${ref#refs/remotes/}
    repo=${branch%%/*}
    branch=${branch#*/}
    git fetch -q $repo $branch
    git merge-tree $(git merge-base HEAD $repo/$branch) HEAD $repo/$branch
    ;;
  refs/heads/*)
    branch=${ref#refs/heads/}
    git merge-tree $(git merge-base HEAD $branch) HEAD $branch
    ;;
  *) fail "couldn't detect upstream repo"
esac | git -p column