bin/vcs: Add initial version of VCS compatibility utility

1 files changed, 96 insertions, 0 deletions

diff --git a/bin/vcs b/bin/vcs
new file mode 100755
index 0000000..3cd8ed0
--- /dev/null
+++ b/bin/vcs
@@ -0,0 +1,96 @@
+#!/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"