class_name DefinitionRegistry
extends RefCounted

## Loads, validates, and indexes immutable game definitions.
##
## Invalid definitions are reported but never exposed through lookup/query APIs.
## All returned definition and issue lists use a deterministic ID-first order.

const DEFAULT_FACILITY_DIRECTORY := "res://data/facilities"
const FACILITY_FILE_EXTENSION := "tres"

const SEVERITY_ERROR := &"error"
const SEVERITY_WARNING := &"warning"

var _facilities_by_id: Dictionary = {}
var _ordered_facility_ids: Array[StringName] = []
var _errors: Array[Dictionary] = []
var _warnings: Array[Dictionary] = []
var _source_count := 0


## Scans the default facility directory and rebuilds the registry.
func rebuild(directory_path: String = DEFAULT_FACILITY_DIRECTORY) -> Dictionary:
	_reset()
	var paths := _discover_facility_paths(directory_path)
	if not _errors.is_empty():
		_finish_rebuild()
		return get_report()
	_load_and_index(paths)
	_finish_rebuild()
	return get_report()


## Rebuilds from an explicit path list. Primarily useful for content packs and tests.
func rebuild_from_paths(paths: Array[String]) -> Dictionary:
	_reset()
	var ordered_paths := paths.duplicate()
	ordered_paths.sort()
	_load_and_index(ordered_paths)
	_finish_rebuild()
	return get_report()


func is_valid() -> bool:
	return _errors.is_empty()


func has_fatal_errors() -> bool:
	return not _errors.is_empty()


func facility_count() -> int:
	return _ordered_facility_ids.size()


func source_count() -> int:
	return _source_count


func has_facility(facility_id: StringName) -> bool:
	return _facilities_by_id.has(facility_id)


func get_facility(facility_id: StringName) -> FacilityDefinition:
	return _facilities_by_id.get(facility_id) as FacilityDefinition


func get_facility_ids() -> Array[StringName]:
	return _ordered_facility_ids.duplicate()


func get_all_facilities() -> Array[FacilityDefinition]:
	var result: Array[FacilityDefinition] = []
	for facility_id in _ordered_facility_ids:
		result.append(_facilities_by_id[facility_id] as FacilityDefinition)
	return result


func query_facilities_by_tag(tag: StringName) -> Array[FacilityDefinition]:
	var result: Array[FacilityDefinition] = []
	for facility_id in _ordered_facility_ids:
		var definition := _facilities_by_id[facility_id] as FacilityDefinition
		if tag in definition.tags:
			result.append(definition)
	return result


func query_facilities_by_zone(zone: int) -> Array[FacilityDefinition]:
	var result: Array[FacilityDefinition] = []
	for facility_id in _ordered_facility_ids:
		var definition := _facilities_by_id[facility_id] as FacilityDefinition
		if definition.zone == zone:
			result.append(definition)
	return result


func query_facilities_by_layer(layer: int) -> Array[FacilityDefinition]:
	var result: Array[FacilityDefinition] = []
	for facility_id in _ordered_facility_ids:
		var definition := _facilities_by_id[facility_id] as FacilityDefinition
		if definition.layer == layer:
			result.append(definition)
	return result


func get_fatal_errors() -> Array[Dictionary]:
	return _errors.duplicate(true)


func get_warnings() -> Array[Dictionary]:
	return _warnings.duplicate(true)


func get_report() -> Dictionary:
	return {
		&"valid": is_valid(),
		&"source_count": _source_count,
		&"definition_count": facility_count(),
		&"error_count": _errors.size(),
		&"warning_count": _warnings.size(),
		&"errors": get_fatal_errors(),
		&"warnings": get_warnings(),
	}


func _reset() -> void:
	_facilities_by_id.clear()
	_ordered_facility_ids.clear()
	_errors.clear()
	_warnings.clear()
	_source_count = 0


func _discover_facility_paths(directory_path: String) -> Array[String]:
	var result: Array[String] = []
	var directory := DirAccess.open(directory_path)
	if directory == null:
		_add_error(
			&"directory_unreadable",
			&"",
			directory_path,
			&"resource_path",
			"Facility definition directory cannot be opened."
		)
		return result

	directory.list_dir_begin()
	var file_name := directory.get_next()
	while not file_name.is_empty():
		if not directory.current_is_dir() and file_name.get_extension().to_lower() == FACILITY_FILE_EXTENSION:
			result.append(directory_path.path_join(file_name))
		file_name = directory.get_next()
	directory.list_dir_end()
	result.sort()

	if result.is_empty():
		_add_warning(
			&"no_definitions_found",
			&"",
			directory_path,
			&"resource_path",
			"No facility definitions were found."
		)
	return result


func _load_and_index(paths: Array[String]) -> void:
	var candidates: Array[Dictionary] = []
	var seen_paths: Dictionary = {}

	for path in paths:
		_source_count += 1
		if seen_paths.has(path):
			_add_warning(
				&"duplicate_source_path",
				&"",
				path,
				&"resource_path",
				"The same source path was supplied more than once."
			)
		seen_paths[path] = true

		if not _validate_requested_path(path):
			continue
		var resource := ResourceLoader.load(path)
		if resource == null:
			_add_error(
				&"resource_load_failed",
				&"",
				path,
				&"resource_path",
				"The resource could not be loaded."
			)
			continue
		if not resource is FacilityDefinition:
			_add_error(
				&"wrong_resource_type",
				&"",
				path,
				&"resource",
				"Expected FacilityDefinition, got %s." % resource.get_class()
			)
			continue

		var definition := resource as FacilityDefinition
		candidates.append({
			&"definition": definition,
			&"path": path,
			&"valid": _validate_facility(definition, path),
		})

	candidates.sort_custom(_candidate_less)
	var counts_by_id: Dictionary = {}
	var paths_by_id: Dictionary = {}
	for candidate in candidates:
		var definition := candidate[&"definition"] as FacilityDefinition
		if definition.id.is_empty():
			continue
		counts_by_id[definition.id] = int(counts_by_id.get(definition.id, 0)) + 1
		if not paths_by_id.has(definition.id):
			paths_by_id[definition.id] = []
		var id_paths := paths_by_id[definition.id] as Array
		id_paths.append(String(candidate[&"path"]))

	for candidate in candidates:
		var definition := candidate[&"definition"] as FacilityDefinition
		var path := String(candidate[&"path"])
		if definition.id.is_empty():
			continue
		if int(counts_by_id[definition.id]) > 1:
			var duplicate_paths := paths_by_id[definition.id] as Array
			_add_error(
				&"duplicate_id",
				definition.id,
				path,
				&"id",
				"Facility ID is duplicated by: %s." % ", ".join(duplicate_paths)
			)
			continue
		if not bool(candidate[&"valid"]):
			continue
		_facilities_by_id[definition.id] = definition
		_ordered_facility_ids.append(definition.id)


func _validate_requested_path(path: String) -> bool:
	var valid := true
	if path.is_empty():
		_add_error(&"empty_resource_path", &"", path, &"resource_path", "Resource path is empty.")
		return false
	if not path.begins_with("res://"):
		_add_error(
			&"non_project_resource_path",
			&"",
			path,
			&"resource_path",
			"Facility definitions must use a res:// project path."
		)
		valid = false
	if path.get_extension().to_lower() != FACILITY_FILE_EXTENSION:
		_add_error(
			&"wrong_resource_extension",
			&"",
			path,
			&"resource_path",
			"Facility definitions must use the .tres extension."
		)
		valid = false
	# Exported .tres resources are remapped to binary .res files. Physical
	# FileAccess checks incorrectly reject them when no source checkout exists.
	if not ResourceLoader.exists(path):
		_add_error(
			&"resource_not_found",
			&"",
			path,
			&"resource_path",
			"Facility definition file does not exist."
		)
		valid = false
	return valid


func _validate_facility(definition: FacilityDefinition, requested_path: String) -> bool:
	var valid := true
	var facility_id := definition.id
	var actual_path := definition.resource_path

	if facility_id.is_empty():
		_add_error(&"missing_required_value", facility_id, requested_path, &"id", "Facility ID is required.")
		valid = false
	elif not _is_snake_case_id(String(facility_id)):
		_add_error(
			&"invalid_id_format",
			facility_id,
			requested_path,
			&"id",
			"Facility ID must be lowercase ASCII snake_case and begin with a letter."
		)
		valid = false

	if definition.display_name.strip_edges().is_empty():
		_add_error(
			&"missing_required_value",
			facility_id,
			requested_path,
			&"display_name",
			"Display name is required."
		)
		valid = false
	if definition.description.strip_edges().is_empty():
		_add_warning(
			&"empty_description",
			facility_id,
			requested_path,
			&"description",
			"Description is empty."
		)

	if actual_path.is_empty():
		_add_error(
			&"missing_resource_path",
			facility_id,
			requested_path,
			&"resource_path",
			"Loaded FacilityDefinition has no resource_path."
		)
		valid = false
	elif actual_path != requested_path:
		_add_error(
			&"resource_path_mismatch",
			facility_id,
			requested_path,
			&"resource_path",
			"Loaded resource_path '%s' does not match its requested path." % actual_path
		)
		valid = false

	if definition.zone < FacilityDefinition.MapZone.ANY \
			or definition.zone > FacilityDefinition.MapZone.UNDERGROUND:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"zone", "Zone enum value is out of range.")
		valid = false
	if definition.layer < FacilityDefinition.ViewLayer.FRONT \
			or definition.layer > FacilityDefinition.ViewLayer.BACK:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"layer", "Layer enum value is out of range.")
		valid = false
	if definition.footprint.x <= 0 or definition.footprint.y <= 0:
		_add_error(
			&"value_out_of_range",
			facility_id,
			requested_path,
			&"footprint",
			"Footprint dimensions must both be greater than zero."
		)
		valid = false
	if definition.build_minutes <= 0:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"build_minutes", "Build time must be greater than zero.")
		valid = false
	if definition.weight_per_cell not in [1, 2, 3]:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"weight_per_cell", "Structural weight must be 1, 2, or 3.")
		valid = false
	if definition.allowed_rotations.is_empty():
		_add_error(&"missing_required_value", facility_id, requested_path, &"allowed_rotations", "At least one rotation is required.")
		valid = false
	else:
		var seen_rotations := {}
		for rotation in definition.allowed_rotations:
			if rotation not in [0, 90, 180, 270] or seen_rotations.has(rotation):
				_add_error(&"invalid_rotation", facility_id, requested_path, &"allowed_rotations", "Rotations must be unique quarter turns.")
				valid = false
			seen_rotations[rotation] = true
	if definition.staff_min < 0 or definition.staff_max < definition.staff_min:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"staff_min", "Staff limits are inconsistent.")
		valid = false
	if definition.capacity < 0 or definition.queue_capacity < 0:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"capacity", "Service and queue capacities cannot be negative.")
		valid = false
	if definition.base_service_minutes <= 0 or definition.base_price < 0:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"base_service_minutes", "Service duration must be positive and price cannot be negative.")
		valid = false
	for item_id: Variant in definition.inventory_inputs:
		if StringName(item_id).is_empty() or int(definition.inventory_inputs[item_id]) <= 0:
			_add_error(&"invalid_inventory_requirement", facility_id, requested_path, &"inventory_inputs", "Inventory input ids and quantities must be positive.")
			valid = false
	for item_id: Variant in definition.inventory_outputs:
		if StringName(item_id).is_empty() or int(definition.inventory_outputs[item_id]) <= 0:
			_add_error(&"invalid_inventory_output", facility_id, requested_path, &"inventory_outputs", "Inventory output ids and quantities must be positive.")
			valid = false

	if not _validate_construction_cost(definition.construction_cost, facility_id, requested_path):
		valid = false
	if definition.maintenance_mana < 0:
		_add_error(
			&"value_out_of_range",
			facility_id,
			requested_path,
			&"maintenance_mana",
			"Maintenance mana cannot be negative."
		)
		valid = false
	if definition.staff_min < 0:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"staff_min", "Minimum staff cannot be negative.")
		valid = false
	if definition.staff_max < 0:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"staff_max", "Maximum staff cannot be negative.")
		valid = false
	if definition.staff_max < definition.staff_min:
		_add_error(
			&"invalid_value_relation",
			facility_id,
			requested_path,
			&"staff_max",
			"Maximum staff must be greater than or equal to minimum staff."
		)
		valid = false
	if definition.capacity < 0:
		_add_error(&"value_out_of_range", facility_id, requested_path, &"capacity", "Capacity cannot be negative.")
		valid = false

	if not _validate_tags(definition.tags, facility_id, requested_path):
		valid = false
	if not _validate_detailed_profile(definition, requested_path):
		valid = false
	if not facility_id.is_empty() and requested_path.get_file().get_basename() != String(facility_id):
		_add_warning(
			&"id_filename_mismatch",
			facility_id,
			requested_path,
			&"id",
			"Facility ID does not match the resource filename."
		)
	return valid


func _validate_detailed_profile(definition: FacilityDefinition, path: String) -> bool:
	var facility_id := definition.id
	if definition.definition_schema_version == FacilityDefinition.LEGACY_SCHEMA_VERSION:
		return true
	if definition.definition_schema_version != FacilityDefinition.DETAILED_SCHEMA_VERSION:
		_add_error(&"unsupported_definition_schema", facility_id, path, &"definition_schema_version", "Facility definition schema is unsupported.")
		return false
	var valid := true
	if definition.category.is_empty() or not _is_snake_case_id(String(definition.category)):
		_add_error(&"invalid_category", facility_id, path, &"category", "Detailed facilities require one snake_case category.")
		valid = false
	if not _validate_service_profiles(definition, path):
		valid = false
	for field_row: Array in [
		[&"service_types", definition.service_types, true],
		[&"required_connection_tags", definition.required_connection_tags, false],
		[&"preferred_adjacency_tags", definition.preferred_adjacency_tags, false],
		[&"forbidden_adjacency_tags", definition.forbidden_adjacency_tags, false],
		[&"allowed_guest_tags", definition.allowed_guest_tags, false],
		[&"forbidden_guest_tags", definition.forbidden_guest_tags, false],
		[&"research_requirements", definition.research_requirements, false],
		[&"statistics_keys", definition.statistics_keys, true],
	]:
		if not _validate_name_list(field_row[1], bool(field_row[2]), facility_id, path, field_row[0]):
			valid = false
	if not _validate_access_offsets(definition, definition.guest_access_offsets, &"guest_access_offsets", path):
		valid = false
	if not _validate_access_offsets(definition, definition.staff_access_offsets, &"staff_access_offsets", path):
		valid = false
	if not definition.pass_through and definition.guest_access_offsets.is_empty() and definition.staff_access_offsets.is_empty():
		_add_error(&"missing_access_point", facility_id, path, &"guest_access_offsets", "A non-route detailed facility requires a guest or staff access point.")
		valid = false
	if definition.max_level < 1 or definition.max_level > 5 or definition.upgrade_costs.size() != definition.max_level - 1:
		_add_error(&"invalid_upgrade_ladder", facility_id, path, &"upgrade_costs", "Upgrade costs must contain exactly max_level - 1 entries.")
		valid = false
	for index: int in definition.upgrade_costs.size():
		if not _validate_construction_cost(definition.upgrade_costs[index], facility_id, path):
			valid = false
	if definition.demolition_refund_percent < 0 or definition.demolition_refund_percent > 100:
		_add_error(&"value_out_of_range", facility_id, path, &"demolition_refund_percent", "Demolition refund percent must be from 0 through 100.")
		valid = false
	if definition.unlock_rank < 1 or definition.unlock_rank > 7:
		_add_error(&"value_out_of_range", facility_id, path, &"unlock_rank", "Unlock rank must be from 1 through 7.")
		valid = false
	var expected_schedule_keys: Array[StringName] = [&"morning", &"day", &"night"]
	if definition.opening_schedule.size() != expected_schedule_keys.size() \
			or not definition.opening_schedule.has(&"morning") \
			or not definition.opening_schedule.has(&"day") \
			or not definition.opening_schedule.has(&"night"):
		_add_error(&"invalid_opening_schedule", facility_id, path, &"opening_schedule", "Opening schedule must contain exactly morning, day, and night.")
		valid = false
	else:
		for time_band: StringName in expected_schedule_keys:
			if not definition.opening_schedule[time_band] is bool:
				_add_error(&"wrong_value_type", facility_id, path, &"opening_schedule", "Opening schedule values must be booleans.")
				valid = false
	if not _validate_nonnegative_int_map(definition.incident_weights, facility_id, path, &"incident_weights"):
		valid = false
	if not _validate_policy_schema(definition.policy_schema, facility_id, path):
		valid = false
	if definition.adult_content and (not definition.tags.has(&"adult_only") or definition.content_replacement_id.is_empty()):
		_add_error(&"unsafe_adult_content_profile", facility_id, path, &"adult_content", "Adult content requires adult_only and a safe content replacement ID.")
		valid = false
	if not definition.adult_content and not definition.content_replacement_id.is_empty():
		_add_warning(&"unused_content_replacement", facility_id, path, &"content_replacement_id", "A non-adult facility does not use a content replacement.")
	return valid


func _validate_service_profiles(definition: FacilityDefinition, path: String) -> bool:
	var valid := true
	if definition.default_service_type.is_empty() or not definition.service_types.has(definition.default_service_type):
		_add_error(&"invalid_default_service", definition.id, path, &"default_service_type", "Default service must reference one declared service type.")
		valid = false
	if definition.service_profiles.size() != definition.service_types.size():
		_add_error(&"service_profile_mismatch", definition.id, path, &"service_profiles", "Every declared service type requires exactly one profile.")
		valid = false
	for service_type: StringName in definition.service_types:
		if not definition.service_profiles.has(service_type) or not definition.service_profiles[service_type] is Dictionary:
			_add_error(&"missing_service_profile", definition.id, path, &"service_profiles", "Service '%s' requires a Dictionary profile." % service_type)
			valid = false
			continue
		var profile := definition.service_profiles[service_type] as Dictionary
		for required_key: StringName in [&"duration_minutes", &"base_quality", &"base_price", &"capacity_units", &"need_effects"]:
			if not profile.has(required_key):
				_add_error(&"missing_service_profile_field", definition.id, path, &"service_profiles", "Service '%s' is missing '%s'." % [service_type, required_key])
				valid = false
		if profile.has(&"duration_minutes") and (not profile[&"duration_minutes"] is int or int(profile[&"duration_minutes"]) <= 0):
			_add_error(&"invalid_service_profile_value", definition.id, path, &"service_profiles", "Service '%s' duration_minutes must be a positive integer." % service_type)
			valid = false
		if profile.has(&"base_quality") and (not profile[&"base_quality"] is int or int(profile[&"base_quality"]) < 0 or int(profile[&"base_quality"]) > 100):
			_add_error(&"invalid_service_profile_value", definition.id, path, &"service_profiles", "Service '%s' base_quality must be an integer from 0 through 100." % service_type)
			valid = false
		if profile.has(&"base_price") and (not profile[&"base_price"] is int or int(profile[&"base_price"]) < 0):
			_add_error(&"invalid_service_profile_value", definition.id, path, &"service_profiles", "Service '%s' base_price must be a non-negative integer." % service_type)
			valid = false
		if profile.has(&"capacity_units") and (not profile[&"capacity_units"] is int or int(profile[&"capacity_units"]) <= 0):
			_add_error(&"invalid_service_profile_value", definition.id, path, &"service_profiles", "Service '%s' capacity_units must be a positive integer." % service_type)
			valid = false
		if not profile.has(&"need_effects"):
			pass # The missing-field issue was emitted above.
		elif not profile[&"need_effects"] is Dictionary:
			_add_error(&"invalid_service_profile_value", definition.id, path, &"service_profiles", "Service '%s' need_effects must be a Dictionary." % service_type)
			valid = false
		elif not _validate_signed_int_map(profile[&"need_effects"], -100, 100, definition.id, path, &"service_profiles"):
			valid = false
	return valid


func _validate_name_list(values: Array[StringName], required: bool, facility_id: StringName, path: String, field: StringName) -> bool:
	if required and values.is_empty():
		_add_error(&"missing_required_value", facility_id, path, field, "%s requires at least one ID." % field)
		return false
	var valid := true
	var seen: Dictionary = {}
	for value: StringName in values:
		if value.is_empty() or not _is_snake_case_id(String(value)) or seen.has(value):
			_add_error(&"invalid_id_list", facility_id, path, field, "%s must contain unique snake_case IDs." % field)
			valid = false
		seen[value] = true
	return valid


func _validate_access_offsets(definition: FacilityDefinition, offsets: Array[Vector2i], field: StringName, path: String) -> bool:
	var valid := true
	var seen: Dictionary = {}
	for offset: Vector2i in offsets:
		if offset.x < 0 or offset.y < 0 or offset.x >= definition.footprint.x or offset.y >= definition.footprint.y or seen.has(offset):
			_add_error(&"invalid_access_offset", definition.id, path, field, "Access points must be unique cells inside the unrotated footprint.")
			valid = false
		seen[offset] = true
	return valid


func _validate_nonnegative_int_map(values: Dictionary, facility_id: StringName, path: String, field: StringName) -> bool:
	var valid := true
	for raw_key: Variant in values:
		var key := StringName(raw_key)
		if key.is_empty() or not _is_snake_case_id(String(key)) or not values[raw_key] is int or int(values[raw_key]) < 0:
			_add_error(&"invalid_weight_map", facility_id, path, field, "%s requires snake_case IDs and non-negative integer weights." % field)
			valid = false
	return valid


func _validate_signed_int_map(values: Dictionary, minimum: int, maximum: int, facility_id: StringName, path: String, field: StringName) -> bool:
	var valid := true
	for raw_key: Variant in values:
		var key := StringName(raw_key)
		if key.is_empty() or not _is_snake_case_id(String(key)) or not values[raw_key] is int or int(values[raw_key]) < minimum or int(values[raw_key]) > maximum:
			_add_error(&"invalid_signed_value_map", facility_id, path, field, "%s requires snake_case IDs and integer values from %d through %d." % [field, minimum, maximum])
			valid = false
	return valid


func _validate_policy_schema(values: Dictionary, facility_id: StringName, path: String) -> bool:
	var valid := true
	for raw_key: Variant in values:
		var key := StringName(raw_key)
		var row: Variant = values[raw_key]
		if key.is_empty() or not _is_snake_case_id(String(key)) or not row is Dictionary:
			_add_error(&"invalid_policy_schema", facility_id, path, &"policy_schema", "Policy entries require snake_case IDs and Dictionary schemas.")
			valid = false
			continue
		var schema := row as Dictionary
		if not schema.has(&"type") or not schema.has(&"default") or StringName(schema[&"type"]) not in [&"bool", &"enum", &"int"]:
			_add_error(&"invalid_policy_schema", facility_id, path, &"policy_schema", "Every policy requires type and default; type must be bool, enum, or int.")
			valid = false
	return valid


func _validate_construction_cost(cost: Dictionary, facility_id: StringName, path: String) -> bool:
	var valid := true
	for required_key in [&"gold", &"materials"]:
		if not cost.has(required_key):
			_add_error(
				&"missing_required_key",
				facility_id,
				path,
				&"construction_cost",
				"Construction cost is missing '%s'." % required_key
			)
			valid = false
			continue
		var value: Variant = cost[required_key]
		if not value is int:
			_add_error(
				&"wrong_value_type",
				facility_id,
				path,
				&"construction_cost",
				"Construction cost '%s' must be an integer." % required_key
			)
			valid = false
		elif int(value) < 0:
			_add_error(
				&"value_out_of_range",
				facility_id,
				path,
				&"construction_cost",
				"Construction cost '%s' cannot be negative." % required_key
			)
			valid = false

	var cost_keys := cost.keys()
	cost_keys.sort()
	for key in cost_keys:
		if key != &"gold" and key != &"materials":
			_add_warning(
				&"unknown_cost_key",
				facility_id,
				path,
				&"construction_cost",
				"Unknown construction cost key '%s' is ignored by the base game." % key
			)
	return valid


func _validate_tags(tags: Array[StringName], facility_id: StringName, path: String) -> bool:
	var valid := true
	var seen: Dictionary = {}
	for tag in tags:
		if tag.is_empty() or not _is_snake_case_id(String(tag)):
			_add_error(
				&"invalid_tag_format",
				facility_id,
				path,
				&"tags",
				"Tags must be non-empty lowercase ASCII snake_case identifiers."
			)
			valid = false
		if seen.has(tag):
			_add_warning(&"duplicate_tag", facility_id, path, &"tags", "Duplicate tag '%s'." % tag)
		seen[tag] = true
	return valid


func _is_snake_case_id(value: String) -> bool:
	if value.is_empty():
		return false
	var first := value.unicode_at(0)
	if first < 97 or first > 122:
		return false
	var previous_was_underscore := false
	for index in value.length():
		var character := value.unicode_at(index)
		var is_letter := character >= 97 and character <= 122
		var is_number := character >= 48 and character <= 57
		var is_underscore := character == 95
		if not is_letter and not is_number and not is_underscore:
			return false
		if is_underscore and previous_was_underscore:
			return false
		previous_was_underscore = is_underscore
	return not previous_was_underscore


func _finish_rebuild() -> void:
	_ordered_facility_ids.sort_custom(_id_less)
	_errors.sort_custom(_issue_less)
	_warnings.sort_custom(_issue_less)


func _add_error(
		code: StringName,
		definition_id: StringName,
		resource_path: String,
		field: StringName,
		message: String
) -> void:
	_errors.append(_make_issue(SEVERITY_ERROR, code, definition_id, resource_path, field, message))


func _add_warning(
		code: StringName,
		definition_id: StringName,
		resource_path: String,
		field: StringName,
		message: String
) -> void:
	_warnings.append(_make_issue(SEVERITY_WARNING, code, definition_id, resource_path, field, message))


func _make_issue(
		severity: StringName,
		code: StringName,
		definition_id: StringName,
		resource_path: String,
		field: StringName,
		message: String
) -> Dictionary:
	return {
		&"severity": severity,
		&"code": code,
		&"definition_id": definition_id,
		&"resource_path": resource_path,
		&"field": field,
		&"message": message,
	}


func _candidate_less(left: Dictionary, right: Dictionary) -> bool:
	var left_definition := left[&"definition"] as FacilityDefinition
	var right_definition := right[&"definition"] as FacilityDefinition
	var left_id := String(left_definition.id)
	var right_id := String(right_definition.id)
	if left_id != right_id:
		return left_id < right_id
	return String(left[&"path"]) < String(right[&"path"])


func _id_less(left: StringName, right: StringName) -> bool:
	return String(left) < String(right)


func _issue_less(left: Dictionary, right: Dictionary) -> bool:
	var left_id := String(left[&"definition_id"])
	var right_id := String(right[&"definition_id"])
	if left_id != right_id:
		return left_id < right_id
	var left_path := String(left[&"resource_path"])
	var right_path := String(right[&"resource_path"])
	if left_path != right_path:
		return left_path < right_path
	var left_field := String(left[&"field"])
	var right_field := String(right[&"field"])
	if left_field != right_field:
		return left_field < right_field
	var left_code := String(left[&"code"])
	var right_code := String(right[&"code"])
	if left_code != right_code:
		return left_code < right_code
	return String(left[&"message"]) < String(right[&"message"])