extends Node

signal question_loaded(question: Dictionary)
signal question_failed(message: String)
signal pass_completed(summary: Dictionary)
signal attempt_synced(question_id: String, is_correct: bool, pending_count: int)

const EndpointConfig := preload("res://scripts/autoload/api_endpoint_config.gd")
const DEFAULT_API_URL := "https://us3q.ranaze.com/api/review-queue"
const OUTBOX_PATH := "user://pending_review_attempts.json"

var api_url := DEFAULT_API_URL
var next_request: HTTPRequest
var attempt_request: HTTPRequest
var retry_timer: Timer
var loading := false
var submitting := false
var request_token := ""
var excluded_question_ids: Array = []
var current_cycle := 0
var pending_count := 0
var reviewed_count := 0
var cleared_count := 0
var retained_count := 0
var outbox: Array = []
var active_account_key := ""
var step3_system := ""


func _ready() -> void:
	api_url = EndpointConfig.resolve(
		str(ProjectSettings.get_setting("step3/review_queue_api_url", DEFAULT_API_URL)),
		"/api/review-queue")
	next_request = HTTPRequest.new()
	next_request.timeout = 25.0
	next_request.request_completed.connect(_on_next_completed)
	add_child(next_request)
	attempt_request = HTTPRequest.new()
	attempt_request.timeout = 25.0
	attempt_request.request_completed.connect(_on_attempt_completed)
	add_child(attempt_request)
	retry_timer = Timer.new()
	retry_timer.one_shot = true
	retry_timer.wait_time = 5.0
	retry_timer.timeout.connect(_process_outbox)
	add_child(retry_timer)
	_load_outbox()
	AuthState.auth_changed.connect(_on_auth_changed)
	_on_auth_changed()


func start_pass(requested_step3_system: String = "") -> void:
	step3_system = requested_step3_system
	excluded_question_ids.clear()
	reviewed_count = 0
	cleared_count = 0
	retained_count = 0
	load_next()


func load_next() -> void:
	if loading:
		return
	if not AuthState.can_send_authenticated_request():
		question_failed.emit("Login is required to load the review queue.")
		return
	loading = true
	request_token = AuthState.access_token
	var payload := {
		"excludeExternalIds": excluded_question_ids,
		"supportsChoicePools": true
	}
	if not step3_system.is_empty():
		payload["step3System"] = step3_system
	var error := next_request.request(
		"%s/next" % api_url,
		_headers(),
		HTTPClient.METHOD_POST,
		JSON.stringify(payload))
	if error != OK:
		loading = false
		question_failed.emit("The review queue could not be loaded. Check your connection and try again.")


func record_first_submission(question: Dictionary, choice_id: String, presented_choice_ids: Array, duration_seconds: int) -> void:
	var question_id := str(question.get("id", ""))
	if question_id == "" or choice_id == "" or current_cycle < 1:
		return
	var is_correct := choice_id == str(question.get("correct_choice_id", ""))
	reviewed_count += 1
	if is_correct:
		cleared_count += 1
		pending_count = maxi(0, pending_count - 1)
	else:
		retained_count += 1
	var payload := {
		"clientAttemptId": _new_uuid(),
		"questionExternalId": question_id,
		"cycle": current_cycle,
		"choiceId": choice_id,
		"presentedChoiceIds": presented_choice_ids.duplicate(),
		"durationSeconds": clampi(duration_seconds, 0, 86400)
	}
	outbox.append({"account": _account_key(), "payload": payload, "retry_count": 0})
	_save_outbox()
	_process_outbox()


func get_summary() -> Dictionary:
	return {
		"reviewed": reviewed_count,
		"cleared": cleared_count,
		"remaining": maxi(0, pending_count),
		"needs_review": retained_count
	}


func has_pending_submissions() -> bool:
	return _next_account_item_index() >= 0


func _on_next_completed(result: int, response_code: int, _headers_value: PackedStringArray, body: PackedByteArray) -> void:
	loading = false
	if response_code == 401:
		AuthState.handle_unauthorized(request_token)
		return
	if result != HTTPRequest.RESULT_SUCCESS or response_code < 200 or response_code >= 300:
		question_failed.emit("The review queue could not be loaded. Check your connection and try again.")
		return
	var parsed: Variant = JSON.parse_string(body.get_string_from_utf8())
	if typeof(parsed) != TYPE_DICTIONARY:
		question_failed.emit("The review service returned an invalid response.")
		return
	pending_count = int(parsed.get("pendingCount", parsed.get("pending_count", pending_count)))
	var raw_question: Variant = parsed.get("question", {})
	if typeof(raw_question) != TYPE_DICTIONARY or raw_question.is_empty():
		pass_completed.emit(get_summary())
		return
	var question := QuestionBankService.normalize_api_question(raw_question)
	if question.is_empty() or str(question.get("id", "")) == "":
		question_failed.emit("The review service returned an invalid question.")
		return
	current_cycle = int(parsed.get("cycle", 0))
	question["review_cycle"] = current_cycle
	var question_id := str(question.get("id", ""))
	if not excluded_question_ids.has(question_id):
		excluded_question_ids.append(question_id)
	question_loaded.emit(question)


func _process_outbox() -> void:
	if submitting or outbox.is_empty() or not AuthState.can_send_authenticated_request():
		return
	var index := _next_account_item_index()
	if index < 0:
		return
	var item: Dictionary = outbox[index]
	item["active"] = true
	outbox[index] = item
	submitting = true
	request_token = AuthState.access_token
	var error := attempt_request.request(
		"%s/attempts" % api_url,
		_headers(),
		HTTPClient.METHOD_POST,
		JSON.stringify(item.get("payload", {})))
	if error != OK:
		submitting = false
		item.erase("active")
		item["retry_count"] = int(item.get("retry_count", 0)) + 1
		outbox[index] = item
		_save_outbox()
		retry_timer.start()


func _on_attempt_completed(result: int, response_code: int, _headers_value: PackedStringArray, body: PackedByteArray) -> void:
	submitting = false
	var index := _active_item_index()
	if index < 0:
		return
	var item: Dictionary = outbox[index]
	item.erase("active")
	if response_code == 401:
		outbox[index] = item
		_save_outbox()
		AuthState.handle_unauthorized(request_token)
		return
	if result == HTTPRequest.RESULT_SUCCESS and response_code >= 200 and response_code < 300:
		var parsed: Variant = JSON.parse_string(body.get_string_from_utf8())
		var synced_question_id := ""
		var synced_is_correct := false
		if typeof(parsed) == TYPE_DICTIONARY:
			pending_count = int(parsed.get("pendingCount", parsed.get("pending_count", pending_count)))
			synced_question_id = str(parsed.get("questionExternalId", parsed.get("question_external_id", "")))
			synced_is_correct = bool(parsed.get("isCorrect", parsed.get("is_correct", false)))
		outbox.remove_at(index)
		_save_outbox()
		attempt_synced.emit(synced_question_id, synced_is_correct, pending_count)
		_process_outbox()
		return
	if response_code >= 400 and response_code < 500 and response_code not in [408, 429]:
		outbox.remove_at(index)
		_save_outbox()
		_process_outbox()
		return
	item["retry_count"] = int(item.get("retry_count", 0)) + 1
	outbox[index] = item
	_save_outbox()
	retry_timer.start()


func _headers() -> PackedStringArray:
	return PackedStringArray([
		"Content-Type: application/json",
		"Authorization: Bearer %s" % AuthState.access_token
	])


func _on_auth_changed() -> void:
	active_account_key = _account_key()
	if AuthState.is_logged_in:
		_process_outbox()
	elif retry_timer != null:
		retry_timer.stop()


func _account_key() -> String:
	return AuthState.username.strip_edges().to_lower().sha256_text() if not AuthState.username.strip_edges().is_empty() else ""


func _next_account_item_index() -> int:
	for index in range(outbox.size()):
		if str(outbox[index].get("account", "")) == active_account_key:
			return index
	return -1


func _active_item_index() -> int:
	for index in range(outbox.size()):
		if bool(outbox[index].get("active", false)):
			return index
	return -1


func _load_outbox() -> void:
	outbox = []
	if not FileAccess.file_exists(OUTBOX_PATH):
		return
	var parsed: Variant = JSON.parse_string(FileAccess.get_file_as_string(OUTBOX_PATH))
	if typeof(parsed) != TYPE_ARRAY:
		return
	for item in parsed:
		if typeof(item) == TYPE_DICTIONARY and typeof(item.get("payload", {})) == TYPE_DICTIONARY:
			item.erase("active")
			outbox.append(item)


func _save_outbox() -> void:
	var stored := outbox.duplicate(true)
	for item in stored:
		item.erase("active")
	var file := FileAccess.open(OUTBOX_PATH, FileAccess.WRITE)
	if file != null:
		file.store_string(JSON.stringify(stored))


func _new_uuid() -> String:
	var bytes := Crypto.new().generate_random_bytes(16)
	bytes[6] = (bytes[6] & 0x0f) | 0x40
	bytes[8] = (bytes[8] & 0x3f) | 0x80
	var value := bytes.hex_encode()
	return "%s-%s-%s-%s-%s" % [value.substr(0, 8), value.substr(8, 4), value.substr(12, 4), value.substr(16, 4), value.substr(20, 12)]