#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
# Fetch one or more remote refs and merge it/them into the current HEAD.

USAGE='[-n | --no-stat] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s strategy]... [<fetch-options>] <repo> <head>...'
LONG_USAGE='Fetch one or more remote refs and merge it/them into the current HEAD.'
SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
. git-sh-setup
set_reflog_action "pull $*"
require_work_tree
cd_to_toplevel


die_conflict () {
    git diff-index --cached --name-status -r --ignore-submodules HEAD --
    if [ $(git config --bool --get advice.resolveConflict || echo true) = "true" ]; then
	die "Pull is not possible because you have unmerged files.
Please, fix them up in the work tree, and then use 'git add/rm <file>'
as appropriate to mark resolution, or use 'git commit -a'."
    else
	die "Pull is not possible because you have unmerged files."
    fi
}

die_merge () {
    if [ $(git config --bool --get advice.resolveConflict || echo true) = "true" ]; then
	die "You have not concluded your merge (MERGE_HEAD exists).
Please, commit your changes before you can merge."
    else
	die "You have not concluded your merge (MERGE_HEAD exists)."
    fi
}

test -z "$(git ls-files -u)" || die_conflict
test -f "$GIT_DIR/MERGE_HEAD" && die_merge

strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
log_arg= verbosity= progress= recurse_submodules=
merge_args=
curr_branch=$(git symbolic-ref -q HEAD)
curr_branch_short="${curr_branch#refs/heads/}"
rebase=$(git config --bool branch.$curr_branch_short.rebase)
dry_run=
while :
do
	case "$1" in
	-q|--quiet)
		verbosity="$verbosity -q" ;;
	-v|--verbose)
		verbosity="$verbosity -v" ;;
	--progress)
		progress=--progress ;;
	-n|--no-stat|--no-summary)
		diffstat=--no-stat ;;
	--stat|--summary)
		diffstat=--stat ;;
	--log|--no-log)
		log_arg=$1 ;;
	--no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
		no_commit=--no-commit ;;
	--c|--co|--com|--comm|--commi|--commit)
		no_commit=--commit ;;
	--sq|--squ|--squa|--squas|--squash)
		squash=--squash ;;
	--no-sq|--no-squ|--no-squa|--no-squas|--no-squash)
		squash=--no-squash ;;
	--ff)
		no_ff=--ff ;;
	--no-ff)
		no_ff=--no-ff ;;
	--ff-only)
		ff_only=--ff-only ;;
	-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
		--strateg=*|--strategy=*|\
	-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
		case "$#,$1" in
		*,*=*)
			strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
		1,*)
			usage ;;
		*)
			strategy="$2"
			shift ;;
		esac
		strategy_args="${strategy_args}-s $strategy "
		;;
	-X*)
		case "$#,$1" in
		1,-X)
			usage ;;
		*,-X)
			xx="-X $(git rev-parse --sq-quote "$2")"
			shift ;;
		*,*)
			xx=$(git rev-parse --sq-quote "$1") ;;
		esac
		merge_args="$merge_args$xx "
		;;
	-r|--r|--re|--reb|--reba|--rebas|--rebase)
		rebase=true
		;;
	--no-r|--no-re|--no-reb|--no-reba|--no-rebas|--no-rebase)
		rebase=false
		;;
	--recurse-submodules)
		recurse_submodules=--recurse-submodules
		;;
	--no-recurse-submodules)
		recurse_submodules=--no-recurse-submodules
		;;
	--d|--dr|--dry|--dry-|--dry-r|--dry-ru|--dry-run)
		dry_run=--dry-run
		;;
	-h|--h|--he|--hel|--help)
		usage
		;;
	*)
		# Pass thru anything that may be meant for fetch.
		break
		;;
	esac
	shift
done

error_on_no_merge_candidates () {
	exec >&2
	for opt
	do
		case "$opt" in
		-t|--t|--ta|--tag|--tags)
			echo "Fetching tags only, you probably meant:"
			echo "  git fetch --tags"
			exit 1
		esac
	done

	if test true = "$rebase"
	then
		op_type=rebase
		op_prep=against
	else
		op_type=merge
		op_prep=with
	fi

	curr_branch=${curr_branch#refs/heads/}
	upstream=$(git config "branch.$curr_branch.merge")
	remote=$(git config "branch.$curr_branch.remote")

	if [ $# -gt 1 ]; then
		if [ "$rebase" = true ]; then
			printf "There is no candidate for rebasing against "
		else
			printf "There are no candidates for merging "
		fi
		echo "among the refs that you just fetched."
		echo "Generally this means that you provided a wildcard refspec which had no"
		echo "matches on the remote end."
	elif [ $# -gt 0 ] && [ "$1" != "$remote" ]; then
		echo "You asked to pull from the remote '$1', but did not specify"
		echo "a branch. Because this is not the default configured remote"
		echo "for your current branch, you must specify a branch on the command line."
	elif [ -z "$curr_branch" ]; then
		echo "You are not currently on a branch, so I cannot use any"
		echo "'branch.<branchname>.merge' in your configuration file."
		echo "Please specify which remote branch you want to use on the command"
		echo "line and try again (e.g. 'git pull <repository> <refspec>')."
		echo "See git-pull(1) for details."
	elif [ -z "$upstream" ]; then
		echo "You asked me to pull without telling me which branch you"
		echo "want to $op_type $op_prep, and 'branch.${curr_branch}.merge' in"
		echo "your configuration file does not tell me, either. Please"
		echo "specify which branch you want to use on the command line and"
		echo "try again (e.g. 'git pull <repository> <refspec>')."
		echo "See git-pull(1) for details."
		echo
		echo "If you often $op_type $op_prep the same branch, you may want to"
		echo "use something like the following in your configuration file:"
		echo
		echo "    [branch \"${curr_branch}\"]"
		echo "    remote = <nickname>"
		echo "    merge = <remote-ref>"
		test rebase = "$op_type" &&
			echo "    rebase = true"
		echo
		echo "    [remote \"<nickname>\"]"
		echo "    url = <url>"
		echo "    fetch = <refspec>"
		echo
		echo "See git-config(1) for details."
	else
		echo "Your configuration specifies to $op_type $op_prep the ref '${upstream#refs/heads/}'"
		echo "from the remote, but no such ref was fetched."
	fi
	exit 1
}

test true = "$rebase" && {
	if ! git rev-parse -q --verify HEAD >/dev/null
	then
		# On an unborn branch
		if test -f "$GIT_DIR/index"
		then
			die "updating an unborn branch with changes added to the index"
		fi
	else
		require_clean_work_tree "pull with rebase" "Please commit or stash them."
	fi
	oldremoteref= &&
	. git-parse-remote &&
	remoteref="$(get_remote_merge_branch "$@" 2>/dev/null)" &&
	oldremoteref="$(git rev-parse -q --verify "$remoteref")" &&
	for reflog in $(git rev-list -g $remoteref 2>/dev/null)
	do
		if test "$reflog" = "$(git merge-base $reflog $curr_branch)"
		then
			oldremoteref="$reflog"
			break
		fi
	done
}
orig_head=$(git rev-parse -q --verify HEAD)
git fetch $verbosity $progress $dry_run $recurse_submodules --update-head-ok "$@" || exit 1
test -z "$dry_run" || exit 0

curr_head=$(git rev-parse -q --verify HEAD)
if test -n "$orig_head" && test "$curr_head" != "$orig_head"
then
	# The fetch involved updating the current branch.

	# The working tree and the index file is still based on the
	# $orig_head commit, but we are merging into $curr_head.
	# First update the working tree to match $curr_head.

	echo >&2 "Warning: fetch updated the current branch head."
	echo >&2 "Warning: fast-forwarding your working tree from"
	echo >&2 "Warning: commit $orig_head."
	git update-index -q --refresh
	git read-tree -u -m "$orig_head" "$curr_head" ||
		die 'Cannot fast-forward your working tree.
After making sure that you saved anything precious from
$ git diff '$orig_head'
output, run
$ git reset --hard
to recover.'

fi

merge_head=$(sed -e '/	not-for-merge	/d' \
	-e 's/	.*//' "$GIT_DIR"/FETCH_HEAD | \
	tr '\012' ' ')

case "$merge_head" in
'')
	error_on_no_merge_candidates "$@"
	;;
?*' '?*)
	if test -z "$orig_head"
	then
		die "Cannot merge multiple branches into empty head"
	fi
	if test true = "$rebase"
	then
		die "Cannot rebase onto multiple branches"
	fi
	;;
esac

if test -z "$orig_head"
then
	git update-ref -m "initial pull" HEAD $merge_head "$curr_head" &&
	git read-tree --reset -u HEAD || exit 1
	exit
fi

if test true = "$rebase"
then
	o=$(git show-branch --merge-base $curr_branch $merge_head $oldremoteref)
	if test "$oldremoteref" = "$o"
	then
		unset oldremoteref
	fi
fi

merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
case "$rebase" in
true)
	eval="git-rebase $diffstat $strategy_args $merge_args"
	eval="$eval --onto $merge_head ${oldremoteref:-$merge_head}"
	;;
*)
	eval="git-merge $diffstat $no_commit $squash $no_ff $ff_only"
	eval="$eval  $log_arg $strategy_args $merge_args"
	eval="$eval \"\$merge_name\" HEAD $merge_head $verbosity"
	;;
esac
eval "exec $eval"