class_name HostBanStore
extends Node

signal bans_changed

const FORMAT_VERSION := 1
const STORE_PATH := "user://host_bans.json"
const TEMP_PATH := STORE_PATH + ".tmp"
const MAX_BANS := 500

var _namespaces: Dictionary = {}
var _loaded := false
var _write_blocked := false


func is_banned(host_fingerprint: String, target_fingerprint: String) -> bool:
	_ensure_loaded()
	return Dictionary(_namespaces.get(host_fingerprint, {})).has(target_fingerprint)


func ban(host_fingerprint: String, target_fingerprint: String, name: String) -> bool:
	if (
		not NetworkIdentityCrypto.valid_fingerprint(host_fingerprint)
		or not NetworkIdentityCrypto.valid_fingerprint(target_fingerprint)
		or not NetworkProfilePreferences.is_valid_display_name(name)
	):
		return false
	_ensure_loaded()
	if _write_blocked:
		return false
	var previous_namespace: Dictionary = Dictionary(
		_namespaces.get(host_fingerprint, {})
	).duplicate(true)
	var records: Dictionary = _namespaces.get(host_fingerprint, {})
	records[target_fingerprint] = {
		"host_fingerprint": host_fingerprint,
		"target_fingerprint": target_fingerprint,
		"last_known_display_name": name,
		"banned_unix": int(Time.get_unix_time_from_system()),
		"reason": "host_ban",
	}
	while records.size() > MAX_BANS:
		records.erase(records.keys().front())
	_namespaces[host_fingerprint] = records
	if not _save():
		_namespaces[host_fingerprint] = previous_namespace
		return false
	bans_changed.emit()
	return true


func unban(host_fingerprint: String, target_fingerprint: String) -> bool:
	_ensure_loaded()
	if _write_blocked:
		return false
	var previous_namespace: Dictionary = Dictionary(
		_namespaces.get(host_fingerprint, {})
	).duplicate(true)
	var records: Dictionary = _namespaces.get(host_fingerprint, {})
	records.erase(target_fingerprint)
	_namespaces[host_fingerprint] = records
	if not _save():
		_namespaces[host_fingerprint] = previous_namespace
		return false
	bans_changed.emit()
	return true


func get_bans(host_fingerprint: String) -> Array[Dictionary]:
	_ensure_loaded()
	var result: Array[Dictionary] = []
	for value: Dictionary in Dictionary(_namespaces.get(host_fingerprint, {})).values():
		result.append(value.duplicate(true))
	result.sort_custom(func(a: Dictionary, b: Dictionary) -> bool:
		return str(a["last_known_display_name"]).naturalnocasecmp_to(
			str(b["last_known_display_name"])
		) < 0
	)
	return result


func _ensure_loaded() -> void:
	if _loaded:
		return
	_loaded = true
	if not FileAccess.file_exists(STORE_PATH):
		return
	var file := FileAccess.open(STORE_PATH, FileAccess.READ)
	if file == null:
		return
	var json := JSON.new()
	if json.parse(file.get_as_text()) != OK or typeof(json.data) != TYPE_DICTIONARY:
		return
	var data: Dictionary = json.data
	if data.get("format_version") != FORMAT_VERSION:
		_write_blocked = true
		return
	for value: Variant in data.get("records", []):
		if typeof(value) != TYPE_DICTIONARY:
			continue
		var record: Dictionary = value
		var host := str(record.get("host_fingerprint", ""))
		var target := str(record.get("target_fingerprint", ""))
		if not NetworkIdentityCrypto.valid_fingerprint(host) or not NetworkIdentityCrypto.valid_fingerprint(target):
			continue
		var records: Dictionary = _namespaces.get(host, {})
		records[target] = record.duplicate(true)
		_namespaces[host] = records


func _save() -> bool:
	var values: Array = []
	for records: Dictionary in _namespaces.values():
		values.append_array(records.values())
	var file := FileAccess.open(TEMP_PATH, FileAccess.WRITE)
	if file == null:
		return false
	file.store_string(JSON.stringify({
		"format_version": FORMAT_VERSION,
		"records": values,
	}, "\t"))
	file.flush()
	var ok := file.get_error() == OK
	file.close()
	if not ok:
		return false
	if FileAccess.file_exists(STORE_PATH):
		DirAccess.remove_absolute(ProjectSettings.globalize_path(STORE_PATH))
	return DirAccess.rename_absolute(
		ProjectSettings.globalize_path(TEMP_PATH),
		ProjectSettings.globalize_path(STORE_PATH),
	) == OK