#!/bin/sh
#
# MQTT Bridge monitor daemon
# Scans configured USB adapters/presets and updates UCI with live metadata.

. /lib/functions.sh

UCI_NAMESPACE="mqtt-bridge"
LOGTAG="mqtt-bridge-monitor"
SCAN_INTERVAL=10
COMMIT_NEEDED=0

log_msg() {
	logger -t "$LOGTAG" "$*"
}

find_usb_device() {
	local vendor="$1"
	local product="$2"
	local dev

	for dev in /sys/bus/usb/devices/*; do
		[ -f "$dev/idVendor" ] || continue
		[ -f "$dev/idProduct" ] || continue
		local idVendor idProduct
		idVendor="$(cat "$dev/idVendor" 2>/dev/null)"
		idProduct="$(cat "$dev/idProduct" 2>/dev/null)"
		[ "$idVendor" = "$vendor" ] || continue
		[ "$idProduct" = "$product" ] || continue
		echo "$dev"
		return 0
	done

	return 1
}

find_usb_tty() {
	local base="$1"
	local path node
	for path in "$base" "$base"/* "$base"/*/*; do
		[ -d "$path/tty" ] || continue
		for node in "$path"/tty/*; do
			[ -e "$node" ] || continue
			local tty
			tty="$(basename "$node")"
			[ -e "/dev/$tty" ] && { echo "/dev/$tty"; return 0; }
		done
	done
	return 1
}

set_option_if_changed() {
	local section="$1"
	local key="$2"
	local value="$3"
	local current
	current="$(uci -q get ${UCI_NAMESPACE}.adapter.${section}.${key} 2>/dev/null)"
	[ "$current" = "$value" ] && return
	uci set ${UCI_NAMESPACE}.adapter.${section}.${key}="$value"
	COMMIT_NEEDED=1
}

clear_option_if_needed() {
	local section="$1"
	local key="$2"
	local current
	current="$(uci -q get ${UCI_NAMESPACE}.adapter.${section}.${key} 2>/dev/null)"
	[ -z "$current" ] && return
	uci delete ${UCI_NAMESPACE}.adapter.${section}.${key}
	COMMIT_NEEDED=1
}

update_adapter_section() {
	local section="$1"
	local enabled vendor product title preset

	config_get enabled "$section" enabled "1"
	config_get vendor "$section" vendor
	config_get product "$section" product
	config_get preset "$section" preset
	config_get title "$section" title

	if [ "$enabled" != "1" ]; then
		set_option_if_changed "$section" detected "0"
		set_option_if_changed "$section" health "disabled"
		return
	fi

	if [ -z "$vendor" ] || [ -z "$product" ]; then
		set_option_if_changed "$section" detected "0"
		set_option_if_changed "$section" health "unknown"
		return
	fi

	local dev_path
	dev_path="$(find_usb_device "$vendor" "$product")" || dev_path=""

	local prev_detected
	prev_detected="$(uci -q get ${UCI_NAMESPACE}.adapter.${section}.detected 2>/dev/null)"

	if [ -n "$dev_path" ]; then
		local bus devnum port ts
		bus="$(cat "$dev_path/busnum" 2>/dev/null)"
		devnum="$(cat "$dev_path/devnum" 2>/dev/null)"
		port="$(find_usb_tty "$dev_path")"
		ts="$(date -Iseconds)"

		set_option_if_changed "$section" detected "1"
		set_option_if_changed "$section" health "online"
		[ -n "$bus" ] && set_option_if_changed "$section" bus "$bus"
		[ -n "$devnum" ] && set_option_if_changed "$section" device "$devnum"
		if [ -n "$port" ]; then
			set_option_if_changed "$section" port "$port"
		else
			clear_option_if_needed "$section" port
		fi
		set_option_if_changed "$section" last_seen "$ts"

		if [ "$prev_detected" != "1" ]; then
			log_msg "Adapter $section ($title) detected on bus $bus dev $devnum $port"
		fi
	else
		set_option_if_changed "$section" detected "0"
		set_option_if_changed "$section" health "missing"
		clear_option_if_needed "$section" port
		clear_option_if_needed "$section" bus
		clear_option_if_needed "$section" device
		if [ "$prev_detected" = "1" ]; then
			log_msg "Adapter $section ($title) disconnected"
		fi
	fi
}

scan_loop() {
	while true; do
		COMMIT_NEEDED=0
		config_load "$UCI_NAMESPACE"
		local interval
		config_get interval monitor interval
		[ -n "$interval" ] && SCAN_INTERVAL="$interval"
		config_foreach update_adapter_section adapter
		if [ "$COMMIT_NEEDED" -eq 1 ]; then
			uci commit "$UCI_NAMESPACE"
		fi
		sleep "$SCAN_INTERVAL"
	done
}

scan_loop