#!/usr/bin/env sh
# SPDX-License-Identifier: 0BSD
# SPDX-FileCopyrightText: 2026 Kris Lamoureux <kris@lamoureux.io>

# Allow local variable scoping, therefore not strictly POSIX
# shellcheck disable=SC3043

err() {
	printf '[ERROR]: %s\n' "$1" >&2
	exit 1
}

check_http() {
	case $1 in
	2[0-9][0-9]) return 0 ;;
	*) return 1 ;;
	esac
}

# Check for plausible looking PIA token
check_token() {
	printf '%s\n' "$1" | grep -q '^[0-9A-Fa-f]\{128\}$'
}

bao_curl() {
	local path
	local response
	local error
	local http_code
	local notfound
	notfound=0
	while getopts "n" opt; do
		case "$opt" in
		n) notfound=1 ;;
		*) err "bao_curl option '$opt' not found" ;;
		esac
	done
	shift $((OPTIND - 1))
	path="$1"
	shift
	error="Failed request to '$BAO_ADDR/v1/$path'"
	if ! response=$(curl -sS --connect-timeout 5 \
		--max-time 20 --retry 5 --retry-delay 2 \
		-H 'Content-Type: application/json' \
		-H "X-Vault-Token: $bao_token" \
		-w '\n%{http_code}' \
		"$@" "$BAO_ADDR/v1/$path"); then
		err "$error"
	fi
	http_code="$(printf '%s' "$response" | tail -1)"
	if [ "$http_code" = "404" ]; then
		[ "$notfound" -eq 1 ] && return 4
		err "$error (404)"
	fi
	check_http "$http_code" || err "$error"
	printf '%s' "$response" | sed '$d'
}

opn_curl() {
	local path
	local error
	local response
	local http_code
	path="$1"
	shift
	error="Failed request to '$opn_endpoint/$path'"
	if ! response="$(curl -sS --connect-timeout 5 \
		--max-time 20 --retry 5 --retry-delay 2 \
		-H 'Content-Type: application/json' \
		-u "$opn_key:$opn_secret" \
		-w '\n%{http_code}' \
		"$@" "$opn_endpoint/$path")"; then
		err "$error"
	fi
	http_code="$(printf '%s' "$response" | tail -1)"
	check_http "$http_code" || err "$error"
	printf '%s' "$response" | sed '$d'
}

pia_addkey() {
	local response
	local key
	local port
	local peer_ip
	local updates
	# Add pubkey via PIA API and get connection details
	if ! response=$(
		curl -sS -G --connect-timeout 5 \
			--max-time 20 --retry 5 --retry-delay 2 \
			--resolve "$server_cn:$server_port:$server_ip" \
			--cacert ./ca.rsa.4096.crt \
			--data-urlencode "pt=$pia_token" \
			--data-urlencode "pubkey=$piawg_pubkey" \
			"https://$server_cn:1337/addKey"
	); then
		err "Failed connect to $server_cn to addKey"
	fi
	[ "$(printf '%s' "$response" | jq -r '.status')" != "OK" ] &&
		err "Failed to addKey to $server_cn"

	# Update Wireguard config on OPNsense
	updates='{}'
	if [ "$server_ip" != "$piawgsrv_srvaddr" ]; then
		updates="$(printf '%s' "$updates" |
			jq --arg a "$server_ip" '.serveraddress = $a')"
	fi
	key="$(printf '%s' "$response" | jq -r '.server_key')"
	if [ "$key" != "$piawgsrv_pubkey" ]; then
		updates="$(printf '%s' "$updates" | jq --arg k "$key" '.pubkey = $k')"
	fi
	port="$(printf '%s' "$response" | jq -r '.server_port')"
	if [ "$port" != "$piawgsrv_srvport" ]; then
		updates="$(printf '%s' "$updates" |
			jq --arg p "$port" '.serverport = $p')"
	fi
	if [ "$updates" != '{}' ]; then
		updates="$(printf '%s' "$updates" |
			jq --arg s "$piawg_uuid" '.servers = $s')"
		if [ "$(opn_curl "wireguard/client/setClient/$piawgsrv_uuid" \
			-d "$(printf '%s' "$updates" | jq '{client: .}')" |
			jq -r '.result')" != "saved" ]; then
			err "Failed to update $OPN_PEER pubkey/port"
		fi
	fi
	peer_ip="$(printf '%s' "$response" | jq -r '.peer_ip')"
	if [ "$peer_ip" != "$piawg_tunaddr" ]; then
		if [ "$(opn_curl "wireguard/server/setServer/$piawg_uuid" \
			-d "$(jq -n --arg ip "$peer_ip/32" \
				'{server: {tunneladdress: $ip}}')" |
			jq -r '.result')" != "saved" ]; then
			err "Failed to update $OPN_WG tunnel address to $peer_ip"
		fi
	fi
	opn_curl 'wireguard/service/reconfigure' -d '{}'

	# Update firewall rule alias
	piawg_ip_alias="$(opn_curl 'firewall/alias/searchItem' -d '{}' |
		jq -r '.rows[] | select(.name == "PIAwg_IP") | .uuid')"
	opn_curl "firewall/alias/setItem/$piawg_ip_alias" \
		-d "$(jq -n --arg ip "$peer_ip" '{alias: {content: $ip}}')"
	opn_curl 'firewall/alias/reconfigure' -d '{}'
}

# Get a new PIA API token and store
renew_token() {
	local login_response
	local token_response
	local pia_user
	local pia_pass
	local pia_token

	login_response="$(bao_curl "$BAO_KV_MOUNT/data/$BAO_PATH_PIA")"
	pia_user="$(printf '%s' "$login_response" | jq -r '.data.data.username')"
	pia_pass="$(printf '%s' "$login_response" | jq -r '.data.data.password')"
	unset login_response
	if ! token_response="$(curl -s -X POST "$PIA_API" \
		-F "username=$pia_user" \
		-F "password=$pia_pass")"; then
		err "Failed to get a new PIA token"
	fi
	unset pia_pass
	unset pia_user
	pia_token="$(echo "$token_response" | jq -r .token)"
	unset token_response
	check_token "$pia_token" || err "Invalid PIA token during renewal attempt"
	bao_curl "$BAO_KV_MOUNT/data/$BAO_PATH_TOKEN" -X POST \
		-d "$(jq -n --arg t "$pia_token" '{data:{token:$t}}')"
	unset pia_token
}

# Check for required external commands
for rbin in curl jq openssl; do
	command -v "$rbin" >/dev/null 2>&1 ||
		err "Required binary '$rbin' not found"
done

# Setup config structure
: "${PIAWG_CONF_DIR:=$HOME/.config/piawg}"
: "${PIAWG_CONF:=$PIAWG_CONF_DIR/config}"
[ -d "$HOME/.config" ] || install -d -m 0755 "$HOME/.config"
[ -d "$PIAWG_CONF_DIR" ] || install -d -m 0700 "$PIAWG_CONF_DIR"
if [ ! -f "$PIAWG_CONF" ]; then
	install -m 0600 /dev/null "$PIAWG_CONF"
	cat <<-'EOF' >"$PIAWG_CONF"
		# piawg configuration
		#BAO_ADDR=
		#BAO_ROLE=
		#BAO_SECRET=
	EOF
fi

# Source config
if [ -r "$PIAWG_CONF" ]; then
	# shellcheck source=/dev/null
	. "$PIAWG_CONF"
else
	err "Can't find config at '$PIAWG_CONF'"
fi

# Must set these in PIAWG_CONF
: "${BAO_ADDR:?[ERROR]: BAO_ADDR is not set}"
: "${BAO_ROLE:?[ERROR]: BAO_ROLE is not set}"
: "${BAO_SECRET:?[ERROR]: BAO_SECRET is not set}"

# Overridable defaults
_fingerprint=1fd25658456eab3041fba77ccd398ab8124edcc1b8b2fc1d55fdf6b1bbfc9d70
: "${PIA_API:=https://www.privateinternetaccess.com/api/client/v2/token}"
: "${PIA_CRT:=https://www.privateinternetaccess.com/openvpn/ca.rsa.4096.crt}"
: "${PIA_HASH:=$_fingerprint}"
: "${BAO_AUTH_PATH:=approle}"
: "${BAO_KV_MOUNT:=kv}"
: "${BAO_PATH_CONFIG:=piawg/config/wireguard}"
: "${BAO_PATH_OPNSENSE:=piawg/creds/opnsense}"
: "${BAO_PATH_PIA:=piawg/creds/pia}"
: "${BAO_PATH_TOKEN:=piawg/session/token}"
: "${OPN_IF:=PIAwg}"
: "${OPN_PEER:=PIAwg_srv}"

# Get ephemeral session token from AppRole login
if ! bao_token_reply=$(curl -sS \
	--connect-timeout 5 \
	--max-time 20 \
	--retry 5 \
	--retry-delay 2 \
	-H 'Content-Type: application/json' \
	-d "{\"role_id\":\"$BAO_ROLE\",\"secret_id\":\"$BAO_SECRET\"}" \
	"$BAO_ADDR/v1/auth/$BAO_AUTH_PATH/login"); then
	err "Failed to login to '$BAO_ADDR'"
fi
bao_token=$(printf '%s' "$bao_token_reply" | jq -er '.auth.client_token')
unset bao_token_reply
[ -n "$bao_token" ] || err "Failed to get token from '$BAO_ADDR'"

# Get latest PIA token
get_token_reply="$(
	bao_curl -n "$BAO_KV_MOUNT/data/$BAO_PATH_TOKEN"
)" && rc=0 || rc=$?
if [ "$rc" -eq 4 ]; then
	renew_token
	get_token_reply="$(bao_curl "$BAO_KV_MOUNT/data/$BAO_PATH_TOKEN")"
fi
pia_token="$(printf '%s' "$get_token_reply" | jq -r .data.data.token)"
unset get_token_reply
check_token "$pia_token" || err "Failed to get valid PIA token"

# Download PIA RSA CA certificate
if [ ! -f ./ca.rsa.4096.crt ]; then
	[ -f ./.ca.rsa.4096.crt ] && rm ./.ca.rsa.4096.crt
	curl -sS --connect-timeout 5 --max-time 20 --retry 5 --retry-delay 2 \
		-o ./.ca.rsa.4096.crt "$PIA_CRT"
	pia_file_hash="$(openssl x509 -in ./.ca.rsa.4096.crt -outform DER |
		openssl dgst -sha256 -r | awk '{print $1}')"
	[ "$pia_file_hash" != "$PIA_HASH" ] && err "PIA CA fingerprint mismatch"
	mv ./.ca.rsa.4096.crt ./ca.rsa.4096.crt
fi

# Get OPNsense login details
bao_opn_login="$(bao_curl "$BAO_KV_MOUNT/data/$BAO_PATH_OPNSENSE")"
opn_key="$(printf '%s' "$bao_opn_login" | jq -r .data.data.key)"
opn_secret="$(printf '%s' "$bao_opn_login" | jq -r .data.data.secret)"
opn_endpoint="$(printf '%s' "$bao_opn_login" | jq -r .data.data.endpoint)"
opn_endpoint="${opn_endpoint%/}"

# Get OPNsense Wireguard config
opn_if_reply="$(opn_curl 'wireguard/server/searchServer' -d '{}' |
	jq ".rows[] | select(.name == \"$OPN_IF\")")"
piawg_uuid="$(printf '%s' "$opn_if_reply" | jq -r .uuid)"
piawg_pubkey="$(printf '%s' "$opn_if_reply" | jq -r .pubkey)"
piawg_tunaddr="$(printf '%s' "$opn_if_reply" | jq -r .tunneladdress)"
echo "$opn_if_reply" | jq .
unset opn_if_reply

opn_peer_reply="$(opn_curl 'wireguard/client/searchClient' -d '{}' |
	jq ".rows[] | select(.name == \"$OPN_PEER\")")"
piawgsrv_uuid="$(printf '%s' "$opn_peer_reply" | jq -r .uuid)"
piawgsrv_pubkey="$(printf '%s' "$opn_peer_reply" | jq -r .pubkey)"
piawgsrv_srvaddr="$(printf '%s' "$opn_peer_reply" | jq -r .serveraddress)"
piawgsrv_srvport="$(printf '%s' "$opn_peer_reply" | jq -r .serverport)"
echo "$opn_peer_reply" | jq .
unset opn_peer_reply

# Get target server IP, common name, and OPNsense WG pubkey
wg_reply="$(bao_curl "$BAO_KV_MOUNT/data/$BAO_PATH_CONFIG")"
server_ip="$(printf '%s' "$wg_reply" | jq -r .data.data.server_ip)"
server_cn="$(printf '%s' "$wg_reply" | jq -r .data.data.server_cn)"
server_port="$(printf '%s' "$wg_reply" | jq -r .data.data.server_port)"
echo "$wg_reply" | jq .
unset wg_reply

# Update to reflect desired state
[ "$server_ip" != "$piawgsrv_srvaddr" ] && pia_addkey

# Check tunnel
piawg_tunaddr="$(opn_curl 'wireguard/server/searchServer' -d '{}' |
	jq -r ".rows[] | select(.name == \"$OPN_IF\") | .tunneladdress")"
wg_status_reply="$(opn_curl 'wireguard/service/show' -d '{}' |
	jq ".rows[] | select(.name == \"$OPN_PEER\")")"
echo "$wg_status_reply" | jq .
wg_status="$(printf '%s' "$wg_status_reply" | jq -r '."peer-status"')"
[ ! "$wg_status" = "online" ] && err "$OPN_PEER is offline"
if ! ping -c1 -W3 -S "${piawg_tunaddr%/32}" 1.1.1.1 >/dev/null 2>&1; then
	if ! ping -c1 -W3 -S "${piawg_tunaddr%/32}" 8.8.8.8 >/dev/null 2>&1; then
		err "$OPN_PEER failed to ping internet"
	fi
fi