#!/bin/sh
set -eu


usage() {
	cat <<-'EOF'
		Usage:
		  vcs TYPE ACTION
		  vcs -h
	EOF
}

help() {
	cat <<-'EOF'


		Options:
		  -h, --help    show this message

		  TYPE          the type of the underlying VCS:
		                - git
		                - darcs
		                - mercurial
		                - fossil
		                - cvs
		  ACTION        the action to be performed on the repository:
		                - fetch
	EOF
}


for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		*)
			;;
	esac
done

while getopts 'h' flag; do
	case "$flag" in
		h)
			usage
			help
			exit
			;;
		*)
			usage >&2
			exit 2
	esac
done
shift $((OPTIND - 1))


git_fetch() {
	git fetch
}

darcs_fetch() {
	darcs fetch
}

mercurial_fetch() {
	hg pull
}

fossil_fetch() {
	fossil pull
}

cvs_fetch() {
	cvs update
}


VCS="${1:-}"
ACTION="${2:-}"

eval "$(assert-arg "$VCS"    'VCS')"
eval "$(assert-arg "$ACTION" 'ACTION')"


CMD="$VCS"_"$ACTION"
if ! command -v "$CMD" >/dev/null; then
	printf 'Invalid VCS/action combination: %s %s.\n' "$VCS" "$ACTION" >&2
	exit 2
fi

"$CMD"