#!/bin/bash
set -euo pipefail
IFS=$'\n'

error() {
	printf 'Error: %s\n' "$1" >&2
	exit 1
}

arguments() {
	if [ "$1" -ne "$2" ]; then
		error "expected $1 argument(s), got $2"
	fi
}

valid_repo_name() {
	# If you modify this, make sure that "git-shell-commands" cannot be accessed.
	# Currently this is ensured by forbidding / and enforcing a .git suffix.
	case "$1" in
		*" "*) error "name may not contain spaces"; ;;
		*"*"*) error "name may not contain asterisks (*)"; ;;
		*'\'*) error 'name may not contain backslashes (\)'; ;;
		 *'/'*) error "name may not contain slashes (/)"; ;;
		*\'*) error "name may not contain apostrophes (')"; ;;
		*\"*) error 'name may not contain quotes (")'; ;;
		*$'\t'*) error "name may not contain tabs"; ;;
		*$'\n'*) error "name may not contain newlines"; ;;
		.*) error "name may not start with a dot"; ;;
		.git|"") error "name may not be empty"; ;;
		*.git) printf '%s' "$1"; ;;
		*) printf '%s' "$1.git"; ;;
	esac
}

repo_name_new() {
	# Do not remove the extra `|| exit 1`!
	# Due to bash weirdness, `exit 1` does not propagate through more than one $(…) even with set -e
	local repo_name="$(valid_repo_name "$1")" || exit 1
	# `test` dereferences symlinks, so explicit -L is necessary
	if [ -e "$repo_name" -o -L "$repo_name" ]; then
		error "'$repo_name' already exists."
	fi
	printf '%s' "$repo_name"
}

repo_name_existing() {
	# Do not remove the extra `|| exit 1`!
	# Due to bash weirdness, `exit 1` does not propagate through more than one $(…) even with set -e
	local repo_name="$(valid_repo_name "$1")" || exit 1
	# `test` dereferences symlinks, so explicit -L is necessary
	if ! [ -e "$repo_name" -o -L "$repo_name" ]; then
		error "'$repo_name' does not exist."
	fi
	printf '%s' "$repo_name"
}