#!/usr/bin/env bash
#
# Pull and merge changes from a remote branch to the local repository.
# Copyright (c) Petr Baudis, 2005
#
# Takes the branch name as an argument, defaulting to 'origin'.
#
# This is similar to running cg-fetch and cg-merge commands successively.
# Please refer to the documentation of those commands for more details
# about the operation. Note that if you are not doing own development
# but only following some project, it is recommended to use this command
# instead of `cg-fetch` + `cg-merge` since `cg-update` can handle some
# additional corner cases (in particular, if the remote branch rebases,
# `cg-update` will fast-forward instead of doing a tree merge and diverging).
#
# Note that in the GIT newspeak, the operation being performed by cg-update
# is now called 'pull', even though in the past, 'pull' was the name for
# the operation being now done by cg-fetch, which is even still aliased
# to cg-pull. Please do not let this confuse you. (Cogito won't call this
# 'update' operation 'pull', since about everyone but GIT and BK users uses
# it in the 'fetch' meaning.)
#
# OPTIONS
# -------
# -f:: Force the complete fetch even if the heads are the same.
#	Force the complete fetch even if the heads are the same.
#
# --squash:: Use "squash" merge to record pending commits as a single merge commit
#	"Squash" merge - condense all the to-be-merged commits to a single
#	merge commit. This is not to be used lightly; see the cg-merge
#	documenation for further details.
#
# -v:: Enable verbosity
#	Display more verbose output - most notably list all the files
#	touched by the pulled changes.
#
# ENVIRONMENT
# -----------
# CGFETCH_FLAGS::
#	Additional flags to pass cg-fetch (useful e.g. for -v -v).

USAGE="cg-update [-f] [--squash] [-v] [BRANCH_NAME]"
_git_requires_root=1

. "${COGITO_LIB}"cg-Xlib || exit 1

force=
squash=
verbose=
while optparse; do
	if optparse -f; then
		force=-f
	elif optparse --squash; then
		squash=--squash
	elif optparse -v; then
		verbose=-v
	else
		optfail
	fi
done

name="${ARGS[0]}"
[ "$name" ] || { [ -s "$_git/branches/origin" ] && name=origin; }
[ "$name" ] || die "where to update from?"

# cg-merge can do better decision about fast-forwarding if it sees this.
[ -s "$_git/refs/heads/$name" ] && export _cg_orig_head="$(cat "$_git/refs/heads/$name")"

if [ -s "$_git/branches/$name" ]; then
	cg-fetch $CGFETCH_FLAGS $force "$name" || exit 1
else
	echo "Updating from a local branch."
fi
echo
echo "Applying changes..."
cg-merge $squash $verbose "$name"