#!/bin/sh

#	NAME
#        git-catchup - Rebase onto a "mainline" branch.
#
# SYNOPSIS
#        git catchup [<repository> <refspec>]
#        git catchup <refspec>
#
# DESCRIPTION
#        Incorporate upstream mainline changes into the current branch by
#        performing a git-pull(1) --rebase --autostash with the rebase in
#        interactive mode configured to output to STDOUT rather than open a
#        terminal. Logs changes from the merge-base of <respository>/<refspec>
#        and HEAD before and after catching up.
#
#        <repository> should be the name of a remote repository as passed to git-
#        fetch(1). <refspec> can name an arbitrary remote ref (for example, the
#        name of a tag), but usually it is the name of a branch in the remote
#        repository.
#
#        Default value for <repository> is read from the "remote" configuration
#        for the current branch as set by git-branch(1) --track. Default value
#        for <refspec> is "master".

set -e

remote="$1"
parent="$2"

if [ -z "$parent" ]; then
	parent=${remote:="master"}
	remote=$(git config branch.$parent.remote)
	remote=${remote:="origin"}
fi

previous_head_sha=$(git rev-parse HEAD)

__git_update_prettyprint_log () {
  format=$(
    git config --get pretty.update ||
    echo "%C(yellow)%h%Cblue%d%Creset %s - %C(white)%an %Cgreen(%cr)%Creset")

  merge_base_sha=$(git merge-base "$previous_head_sha" "$remote/$parent")
	# Use the last commit on a merged branch if merge-base is a merge
	if git rev-parse $merge_base_sha^2 > /dev/null 2>&1; then
		merge_base_sha=$(git rev-parse $merge_base_sha^2)
	fi
  git log --format="$format" --graph "$merge_base_sha".."$remote_sha" "$merge_base_sha".."$previous_head_sha"
}

git -c core.editor="grep --invert-match '^#'" pull --rebase=interactive --autostash $remote $parent

remote_sha=$(git rev-parse HEAD)
__git_update_prettyprint_log