feat: add versioned simulation state records

simulation/SimulationManager.gd

@@ -309,4 +309,91 @@ func get_state_snapshot() -> Dictionary:
 	}
 
 func get_state_checksum() -> String:
-	return JSON.stringify(get_state_snapshot()).sha256_text()
+	return create_state_record().to_json().sha256_text()
+
+func create_state_record() -> SimulationStateRecord:
+	var record := SimulationStateRecord.new()
+	var wander_streams: Array[Dictionary] = []
+	var sorted_npc_ids: Array = wander_random_sources.keys()
+	sorted_npc_ids.sort()
+	for npc_id in sorted_npc_ids:
+		var source: RandomNumberGenerator = wander_random_sources[npc_id]
+		wander_streams.append({
+			"npc_id": int(npc_id),
+			"seed": str(source.seed),
+			"state": str(source.state)
+		})
+
+	record.simulation = {
+		"seed": simulation_seed,
+		"tick_interval": tick_interval,
+		"tick_count": tick_count,
+		"clock_accumulator": clock.accumulator,
+		"clock_elapsed_ticks": clock.elapsed_ticks,
+		"wander_random_streams": wander_streams
+	}
+	record.village = VillageStateRecord.capture(village)
+	for npc in npcs:
+		record.npcs.append(NPCStateRecord.capture(npc))
+
+	var resource_nodes := ResourceNode.get_all()
+	resource_nodes.sort_custom(
+		func(a: ResourceNode, b: ResourceNode) -> bool:
+			return String(a.node_id) < String(b.node_id)
+	)
+	var captured_resource_ids := {}
+	for node in resource_nodes:
+		if captured_resource_ids.has(node.node_id):
+			continue
+		captured_resource_ids[node.node_id] = true
+		record.resources.append(ResourceStateRecord.capture(node))
+	return record
+
+func serialize_state() -> String:
+	return create_state_record().to_json()
+
+func restore_state_from_json(json_text: String) -> bool:
+	var record := SimulationStateRecord.from_json(json_text)
+	if record == null:
+		push_error("SimulationManager: refused invalid or unsupported simulation state")
+		return false
+	return restore_state(record)
+
+func restore_state(record: SimulationStateRecord) -> bool:
+	if record == null:
+		return false
+
+	simulation_seed = int(record.simulation["seed"])
+	tick_interval = float(record.simulation["tick_interval"])
+	tick_count = int(record.simulation["tick_count"])
+	clock = SimulationClock.new(tick_interval)
+	clock.accumulator = float(record.simulation["clock_accumulator"])
+	clock.elapsed_ticks = int(record.simulation["clock_elapsed_ticks"])
+	village = record.village.restore(debug_logs)
+
+	npcs.clear()
+	for npc_record in record.npcs:
+		npcs.append(npc_record.restore(debug_logs))
+
+	wander_random_sources.clear()
+	var wander_streams: Array = record.simulation["wander_random_streams"]
+	for stream_data in wander_streams:
+		var source := RandomNumberGenerator.new()
+		source.seed = String(stream_data["seed"]).to_int()
+		source.state = String(stream_data["state"]).to_int()
+		wander_random_sources[int(stream_data["npc_id"])] = source
+
+	for resource_record in record.resources:
+		var node_id := StringName(resource_record.data["node_id"])
+		var node := ResourceNode.get_by_id(node_id)
+		if node == null:
+			push_warning(
+				"SimulationManager: resource state '%s' has no loaded presentation node"
+				% node_id
+			)
+			continue
+		if not resource_record.restore(node):
+			return false
+
+	village_changed.emit(village)
+	return true