extends Node
signal completed(id: int, ok: bool)
signal status_changed(message: String)
const URL := "http://127.0.0.1:8765"
var pending: Array[Dictionary] = []
var serial := 0
var busy := false
var device_feedback: Dictionary = {}
var feedback_received_ms: int = 0
var heartbeat: HTTPRequest

func _ready() -> void:
	process_mode = Node.PROCESS_MODE_ALWAYS
	heartbeat = HTTPRequest.new()
	heartbeat.timeout = 1.0
	add_child(heartbeat)
	heartbeat.request_completed.connect(_feedback_response)
	var timer := Timer.new()
	timer.wait_time = 1.0
	timer.timeout.connect(_heartbeat)
	add_child(timer)
	timer.start()

func _heartbeat() -> void:
	if heartbeat.get_http_client_status() == HTTPClient.STATUS_DISCONNECTED:
		heartbeat.request(URL + "/heartbeat", [], HTTPClient.METHOD_POST, "{}")

func send(payload: Dictionary) -> bool:
	if pending.size() >= 32:
		status_changed.emit("GPIO output queue is full")
		return false
	serial += 1
	var id := serial
	pending.append({"id": id, "payload": payload})
	_pump.call_deferred()
	while true:
		var result: Array = await completed
		if result[0] == id: return result[1]
	return false

func _pump() -> void:
	if busy or pending.is_empty(): return
	busy = true
	var item: Dictionary = pending[0]
	var request := HTTPRequest.new()
	request.timeout = 2.0
	add_child(request)
	var ok := false
	var message := "GPIO bridge unavailable — start pi_gpio_bridge.py on this Pi"
	var error := request.request(URL + "/output", ["Content-Type: application/json"], HTTPClient.METHOD_POST, JSON.stringify(item.payload))
	if error == OK:
		var response: Array = await request.request_completed
		var body = JSON.parse_string(response[3].get_string_from_utf8())
		ok = response[0] == HTTPRequest.RESULT_SUCCESS and response[1] == 200 and body is Dictionary and body.get("ok", false) == true
		if body is Dictionary and body.has("error"): message = str(body.error)
	request.queue_free()
	pending.pop_front()
	busy = false
	status_changed.emit("GPIO %s accepted by Pi bridge" % item.payload.pin if ok else message)
	completed.emit(item.id, ok)
	_pump.call_deferred()

func _feedback_response(result: int, code: int, _headers: PackedStringArray, body: PackedByteArray) -> void:
	if result != HTTPRequest.RESULT_SUCCESS or code != 200:
		return
	var data = JSON.parse_string(body.get_string_from_utf8())
	if data is Dictionary and data.get("feedback") is Dictionary:
		device_feedback = data.feedback
		feedback_received_ms = Time.get_ticks_msec()

func get_feedback() -> Dictionary:
	var result := device_feedback.duplicate(true)
	result["fresh"] = feedback_received_ms > 0 and Time.get_ticks_msec() - feedback_received_ms < 4000
	for device in result.get("devices", []):
		device["age_ms"] = int(device.get("age_ms", 999999)) + maxi(0, Time.get_ticks_msec() - feedback_received_ms)
	for entry in result.get("events", []):
		entry["age_ms"] = int(entry.get("age_ms", 999999)) + maxi(0, Time.get_ticks_msec() - feedback_received_ms)
	return result