class_name CatalogInteractionService
extends InteractionService

const CAPABILITY_PRIORITY_ATTRIBUTE := &"offer_priority"
const PARAM_CAPABILITY_ATTRIBUTES := &"capability_attributes"
const PARAM_DECISION_PARAMETERS := &"decision_parameters"
const PARAM_REASON_CODE := &"reason_code"
const PARAM_REASON_TRACE := &"reason_trace"

const REASON_SERVICE_INVALID := &"interaction_service_invalid"
const REASON_ACTOR_INVALID := &"interaction_actor_invalid"
const REASON_TARGET_STALE := &"interaction_target_stale"
const REASON_TARGET_INVALID := &"interaction_target_invalid"
const REASON_DECISION_INVALID := &"availability_decision_invalid"

var _registry: WorldTargetRegistry
var _catalog: ContentCatalog
var _availability_evaluator: Callable
var _last_query_reason_trace: Array[StringName] = []


func _init(
	registry: WorldTargetRegistry = null,
	catalog: ContentCatalog = null,
	availability_evaluator: Callable = Callable()
) -> void:
	_registry = registry
	_catalog = catalog
	_availability_evaluator = availability_evaluator


func is_configured() -> bool:
	return _registry != null and _catalog != null and _catalog.is_valid()


func get_last_query_reason_trace() -> Array[StringName]:
	return _last_query_reason_trace.duplicate()


# The optional evaluator is advisory and pure. It receives isolated copies of
# actor, target descriptor, action definition, and target capability, and must
# return an InteractionAvailabilityDecision. This service never receives an
# authority mutation callback.
func get_offers(actor: WorldEntityRef, target: WorldTargetHandle) -> Array[ActionOffer]:
	_last_query_reason_trace.clear()
	if not is_configured():
		_last_query_reason_trace.append(REASON_SERVICE_INVALID)
		return []
	if not _actor_is_supported(actor):
		_last_query_reason_trace.append(REASON_ACTOR_INVALID)
		return []
	if not _registry.is_handle_valid(target):
		_last_query_reason_trace.append(REASON_TARGET_STALE)
		return []
	var descriptor := _registry.resolve_handle(target)
	if descriptor == null or not descriptor.is_valid():
		_last_query_reason_trace.append(REASON_TARGET_INVALID)
		return []

	var offers: Array[ActionOffer] = []
	for capability_id in descriptor.get_capability_ids():
		var definition := _catalog.get_action(capability_id)
		if definition == null or not definition.validate().is_empty():
			continue
		var capability := descriptor.get_capability(capability_id)
		if capability == null or not capability.is_valid():
			continue
		var priority_result := _offer_priority(capability)
		var decision := _evaluate_availability(actor, descriptor, definition, capability)
		var reason_trace: Array[StringName] = [
			&"target_handle_live", &"target_capability_matched", &"action_definition_authored"
		]
		reason_trace.append_array(priority_result["reason_trace"])
		reason_trace.append_array(decision.get_reason_trace())
		var parameters := {
			String(PARAM_CAPABILITY_ATTRIBUTES): capability.get_attributes(),
			String(PARAM_DECISION_PARAMETERS): decision.get_parameters(),
			String(PARAM_REASON_CODE): String(decision.get_reason_code()),
			String(PARAM_REASON_TRACE): reason_trace,
		}
		var offer := ActionOffer.new(
			_offer_id(target, capability_id),
			capability_id,
			_copy_handle(target),
			definition.display_name,
			decision.is_enabled(),
			decision.get_reason_message() if not decision.is_enabled() else "",
			parameters,
			float(priority_result["priority"])
		)
		if offer.is_valid():
			offers.append(offer)
	offers.sort_custom(_offer_less)
	_last_query_reason_trace = [&"offers_projected", &"stable_priority_action_order"]
	return offers


func _evaluate_availability(
	actor: WorldEntityRef,
	descriptor: WorldTargetDescriptor,
	definition: ActionDefinition,
	capability: WorldTargetCapability
) -> InteractionAvailabilityDecision:
	if not _availability_evaluator.is_valid():
		return InteractionAvailabilityDecision.allowed([&"availability_default_allowed"])
	var definition_copy := definition.duplicate(true) as ActionDefinition
	var result: Variant = _availability_evaluator.call(
		actor.duplicate_ref(), descriptor.copy(), definition_copy, capability.copy()
	)
	var decision := result as InteractionAvailabilityDecision
	if decision != null and decision.is_valid():
		return decision
	return (
		InteractionAvailabilityDecision
		. denied(
			REASON_DECISION_INVALID,
			"Availability policy returned an invalid decision",
			[&"availability_callback_invalid"],
		)
	)


func _offer_priority(capability: WorldTargetCapability) -> Dictionary:
	var raw_priority: Variant = capability.get_attribute(CAPABILITY_PRIORITY_ATTRIBUTE, 0.0)
	if raw_priority is int or raw_priority is float:
		var priority := float(raw_priority)
		if is_finite(priority):
			return {"priority": priority, "reason_trace": [&"offer_priority_authored"]}
	return {"priority": 0.0, "reason_trace": [&"offer_priority_defaulted"]}


func _offer_id(target: WorldTargetHandle, action_id: StringName) -> StringName:
	var stable_source := (
		"%s|%s|%s|%d|%s"
		% [
			target.get_context_id(),
			target.get_target_kind(),
			target.get_target_id(),
			target.get_generation(),
			action_id,
		]
	)
	return StringName("offer_" + stable_source.sha256_text().substr(0, 24))


func _copy_handle(source: WorldTargetHandle) -> WorldTargetHandle:
	return WorldTargetHandle.new(
		source.get_registry_instance_id(),
		source.get_context_id(),
		source.get_target_id(),
		source.get_target_kind(),
		source.get_generation()
	)


static func _actor_is_supported(actor: WorldEntityRef) -> bool:
	return (
		actor != null
		and actor.is_valid()
		and actor.get_entity_type() in [SimulationIds.ENTITY_PLAYER, SimulationIds.ENTITY_PERSON]
	)


static func _offer_less(first: ActionOffer, second: ActionOffer) -> bool:
	if first.get_priority() != second.get_priority():
		return first.get_priority() > second.get_priority()
	return String(first.get_action_id()) < String(second.get_action_id())