class_name EventKnowledgeSystem
extends RefCounted

const WITNESS_RADIUS := 10.0

var known_events: Dictionary = {}


func observe_event(event: EconomicEventRecord, npcs: Array[SimNPC]) -> Array[KnownEventStateRecord]:
	var learned: Array[KnownEventStateRecord] = []
	if not _is_witnessable(event):
		return learned
	var actor := _find_npc(int(event.data["actor_id"]), npcs)
	if actor == null:
		return learned
	var event_id := int(event.data["event_id"])
	var actor_record := _remember(actor.id, event_id, SimulationIds.KNOWLEDGE_ACQUISITION_PERFORMED)
	if actor_record != null:
		learned.append(actor_record)
	var witness_radius_squared := WITNESS_RADIUS * WITNESS_RADIUS
	var event_position := event.get_world_position()
	for npc in npcs:
		if npc.id == actor.id or npc.is_dead:
			continue
		if npc.position.distance_squared_to(event_position) > witness_radius_squared:
			continue
		var witness_record := _remember(
			npc.id, event_id, SimulationIds.KNOWLEDGE_ACQUISITION_WITNESSED
		)
		if witness_record != null:
			learned.append(witness_record)
	learned.sort_custom(_sort_records)
	return learned


func communicate_event(
	event: EconomicEventRecord, speaker_id: int, listener_id: int
) -> KnownEventStateRecord:
	if (
		event == null
		or speaker_id == listener_id
		or listener_id == int(event.data["actor_id"])
		or not _is_witnessable(event)
	):
		return null
	var event_id := int(event.data["event_id"])
	var speaker_record := get_record(speaker_id, event_id)
	if speaker_record == null:
		return null
	if (
		speaker_record.get_acquisition_method()
		not in [
			SimulationIds.KNOWLEDGE_ACQUISITION_PERFORMED,
			SimulationIds.KNOWLEDGE_ACQUISITION_WITNESSED,
		]
	):
		return null
	return _remember(
		listener_id, event_id, SimulationIds.KNOWLEDGE_ACQUISITION_COMMUNICATED, speaker_id
	)


func knows_event(knower_id: int, event_id: int) -> bool:
	return known_events.has(_key(knower_id, event_id))


func get_record(knower_id: int, event_id: int) -> KnownEventStateRecord:
	return known_events.get(_key(knower_id, event_id)) as KnownEventStateRecord


func get_knowers(event_id: int) -> Array[int]:
	var knower_ids: Array[int] = []
	for record in known_events.values():
		if record.get_event_id() == event_id:
			knower_ids.append(record.get_knower_id())
	knower_ids.sort()
	return knower_ids


func get_known_event_ids(knower_id: int, max_count: int = 3) -> Array[int]:
	var event_ids: Array[int] = []
	for record in known_events.values():
		if record.get_knower_id() == knower_id:
			event_ids.append(record.get_event_id())
	event_ids.sort()
	if max_count <= 0 or event_ids.size() <= max_count:
		return event_ids
	var recent_ids: Array[int] = []
	for index in range(event_ids.size() - max_count, event_ids.size()):
		recent_ids.append(event_ids[index])
	return recent_ids


func get_all_sorted() -> Array[KnownEventStateRecord]:
	var records: Array[KnownEventStateRecord] = []
	for record in known_events.values():
		records.append(record)
	records.sort_custom(_sort_records)
	return records


func restore(records: Array[KnownEventStateRecord]) -> void:
	known_events.clear()
	for record in records:
		known_events[_key(record.get_knower_id(), record.get_event_id())] = record


func _remember(
	knower_id: int,
	event_id: int,
	acquisition_method: StringName,
	source_npc_id: int = KnownEventStateRecord.NO_SOURCE_NPC_ID
) -> KnownEventStateRecord:
	var key := _key(knower_id, event_id)
	if known_events.has(key):
		return null
	var record := KnownEventStateRecord.create(
		knower_id, event_id, acquisition_method, source_npc_id
	)
	known_events[key] = record
	return record


func _is_witnessable(event: EconomicEventRecord) -> bool:
	return (
		StringName(event.data["event_type"]) == SimulationIds.EVENT_STORAGE_DEPOSITED
		and StringName(event.data["item_id"]) == SimulationIds.RESOURCE_FOOD
		and float(event.data["amount"]) > 0.0
	)


static func _find_npc(npc_id: int, npcs: Array[SimNPC]) -> SimNPC:
	for npc in npcs:
		if npc.id == npc_id:
			return npc
	return null


static func _key(knower_id: int, event_id: int) -> String:
	return "%d:%d" % [knower_id, event_id]


static func _sort_records(first: KnownEventStateRecord, second: KnownEventStateRecord) -> bool:
	if first.get_knower_id() != second.get_knower_id():
		return first.get_knower_id() < second.get_knower_id()
	return first.get_event_id() < second.get_event_id()