extends RefCounted

## A07 Mana warp: every completed warp is linked to every other warp by one
## path connector, so crossing is a single instant step. Connectors are derived
## from construction state; their operational state follows the reserve and the
## warps' own power. Fares are charged by the Runtime when an actor steps.
const PathType := preload("res://scripts/world/path_service.gd")
const DEFINITION_ID := &"mana_warp"
const PREFIX := "warp.connector:"
const MANA_PER_TRIP := 3
const PATH_COST := 400


static func is_warp_connector(connector_id: StringName) -> bool:
	return String(connector_id).begins_with(PREFIX)


## Completed warps sorted by instance id: [{instance_id, origin}].
static func warps_from_facilities(facilities: Array) -> Array[Dictionary]:
	var warps: Array[Dictionary] = []
	for value: Variant in facilities:
		if not value is Dictionary:
			continue
		var facility: Dictionary = value
		if StringName(str(facility.get(&"definition_id", ""))) != DEFINITION_ID:
			continue
		var origin: Variant = facility.get(&"origin")
		if not origin is Vector3i:
			continue
		warps.append({&"instance_id": StringName(str(facility.get(&"instance_id", ""))), &"origin": origin})
	warps.sort_custom(func(a: Dictionary, b: Dictionary) -> bool:
		return String(a[&"instance_id"]) < String(b[&"instance_id"]))
	return warps


static func expected_connectors(facilities: Array) -> Array[Dictionary]:
	var warps := warps_from_facilities(facilities)
	var result: Array[Dictionary] = []
	for i: int in warps.size():
		for j: int in range(i + 1, warps.size()):
			result.append({
				&"id": StringName("%s%s|%s" % [PREFIX, warps[i][&"instance_id"], warps[j][&"instance_id"]]),
				&"from": warps[i][&"origin"],
				&"to": warps[j][&"origin"],
				&"endpoints": [warps[i][&"instance_id"], warps[j][&"instance_id"]],
			})
	return result


## Rebuilds warp connectors from construction state and applies availability.
## available: instance_id -> bool. Atomic: on failure the path is restored. The
## rollback snapshot is taken only when a change is actually needed.
static func synchronize(path: PathService, facilities: Array, available: Dictionary, fare_affordable: bool) -> Dictionary:
	var expected := expected_connectors(facilities)
	var expected_ids: Dictionary = {}
	for connector: Dictionary in expected:
		expected_ids[connector[&"id"]] = true
	var before: Variant = null
	for connector_id: StringName in path.get_connector_ids_with_prefix(PREFIX):
		if expected_ids.has(connector_id):
			continue
		if before == null:
			before = path.create_snapshot()
		if not path.remove_connector(connector_id):
			path.restore_snapshot(before)
			return {&"ok": false, &"code": &"WARP_CONNECTOR_REMOVE_FAILED", &"reason": path.last_error}
	for connector: Dictionary in expected:
		var connector_id: StringName = connector[&"id"]
		var existing := path.get_connector(connector_id)
		var endpoints: Array = connector[&"endpoints"]
		var usable := fare_affordable and bool(available.get(endpoints[0], false)) and bool(available.get(endpoints[1], false))
		var state := PathType.CONNECTOR_OPERATIONAL if usable else PathType.CONNECTOR_OUTAGE
		if not existing.is_empty() and existing[&"from"] == connector[&"from"] and existing[&"to"] == connector[&"to"] \
				and existing[&"operational_state"] == state:
			continue
		if before == null:
			before = path.create_snapshot()
		if existing.is_empty() or existing[&"from"] != connector[&"from"] or existing[&"to"] != connector[&"to"]:
			if not existing.is_empty():
				path.remove_connector(connector_id)
			if not path.configure_connector(connector_id, connector[&"from"], connector[&"to"], PATH_COST, true, &"", true,
					{&"movement_type": PathType.MOVEMENT_CONNECTOR}):
				path.restore_snapshot(before)
				return {&"ok": false, &"code": &"WARP_CONNECTOR_CONFIGURE_FAILED", &"reason": path.last_error}
		if not path.set_connector_operational_state(connector_id, state):
			path.restore_snapshot(before)
			return {&"ok": false, &"code": &"WARP_CONNECTOR_STATE_FAILED", &"reason": path.last_error}
	return {&"ok": true, &"connector_count": expected.size()}


## Saved paths must hold exactly the derived warp connectors.
static func connectors_match(path: PathService, facilities: Array) -> bool:
	var expected := expected_connectors(facilities)
	var ids := path.get_connector_ids_with_prefix(PREFIX)
	if ids.size() != expected.size():
		return false
	for connector: Dictionary in expected:
		var existing := path.get_connector(connector[&"id"])
		if existing.is_empty() or existing[&"from"] != connector[&"from"] or existing[&"to"] != connector[&"to"] \
				or int(existing[&"cost"]) != PATH_COST or StringName(existing[&"access_id"]) != &"" \
				or existing[&"movement_type"] != PathType.MOVEMENT_CONNECTOR:
			return false
	return true