athandle

#!/bin/sh

dig2at() {
	for q in "$@"; do
		shift
		set -- "$@" "_atproto.$q"
	done
	dig +noall +answer TXT "$@" | sed -E 's/^_atproto\.([^[:space:]]*)\.[[:space:]][^[:space:]]*[[:space:]]IN[[:space:]]TXT[[:space:]]"did=([^"]*)".*$/\1\t\2/'
	# The status code here is not relevant since the final status code will be determined after
	# falling back on the well-known URI.
}

wellknown() {
	printf '%s\t' "$1"
	ret=0
	# The extra `echo` ensures that the output ends with a line feed
	result="$(curl -qfLs --compressed "https://$1/.well-known/atproto-did")" || ret=$?
	echo "$result"
	return "$ret"
}

main() {
	status=0
	dig2at "$@" | {
		read -r resolved
		for q in "$@"; do
			shift
			case "$resolved" in
			"$q$(printf '\t')"*)
				echo "$resolved"
				read -r resolved
				;;
			*)
				wellknown "$q" || status=$?
				;;
			esac
		done
		return "$status"
	}
}

main "$@"