#!/usr/bin/env bash
set -euo pipefail
config="$HOME/.config/git/identities"
input="${1:-}"
usage="Usage
	git identity [<name>|help|-]
	git-identity --help
"
[ -z "$input" ] \
	&& echo "$usage"\
	&& echo -e "$config/current.conf … current identity:" \
	&& cat "$config/current.conf" \
	&& exit 0
[ "$input" = --help ] \
	&& input="help"
[ "$input" = help ] \
	&& echo "$usage"\
	&& echo '- _empty_: shows usage and current identity' \
	&& echo '- <name>: set identity' \
	&& echo '- -: show path to identities directory' \
	&& echo '- help: shows this help' \
	&& echo -e '\n\nExamples' \
	&& echo '- git identity' \
	&& echo '- git identity user' \
	&& echo '- ls $(git identity -)' \
	&& echo -e '\n\nGit config' \
	&& echo "- git config --global include.path '$config/current.conf'" \
	&& exit 0
[ "$input" = - ] \
	&& echo "$config" \
	&& exit 0

identity="$config/$input.conf"
[ ! -e "$identity" ] \
	&& echo "No such identity: $input" >&2 \
	&& echo "$identity" >&2 \
	&& exit 1

ln --verbose --force "$identity" "$config/current.conf"