extends Node
## Save/load — version field, file IO, save-between-ticks contract.
##
## Saves only happen between sim ticks (Sim owns the loop). JobRunner mid-toil
## state must round-trip from day one — see docs/architecture.md "Save format".
##
## Phase 3: pawn states (including mid-walk + JobRunner) round-trip via
## Pawn.to_dict() / Pawn.from_dict() — gated by has_method() so the pre-Phase-3
## Pawn (which lacked the methods) didn't break here.
## Phase 16 expands to tilemap data, storyteller state, items, furniture, etc.

const SAVE_VERSION: int = 1
const SAVE_PATH: String = "user://save_slot.json"


func write_save() -> bool:
	var pawn_dicts: Array = []
	for p in World.pawns:
		if p.has_method("to_dict"):
			pawn_dicts.append(p.to_dict())

	var payload := {
		"version": SAVE_VERSION,
		"sim_tick": Sim.tick,
		"game_state": GameState.save_dict(),
		"pawns": pawn_dicts,
	}
	var f := FileAccess.open(SAVE_PATH, FileAccess.WRITE)
	if f == null:
		push_error("SaveSystem.write_save: cannot open %s" % SAVE_PATH)
		return false
	f.store_string(JSON.stringify(payload))
	Audit.log("save", "wrote %d pawns at tick %d" % [pawn_dicts.size(), Sim.tick])
	return true


func read_save() -> Dictionary:
	if not FileAccess.file_exists(SAVE_PATH):
		return {}
	var f := FileAccess.open(SAVE_PATH, FileAccess.READ)
	if f == null:
		return {}
	var raw := f.get_as_text()
	var parsed: Variant = JSON.parse_string(raw)
	if typeof(parsed) != TYPE_DICTIONARY:
		push_error("SaveSystem.read_save: corrupt save")
		return {}
	if int(parsed.get("version", 0)) != SAVE_VERSION:
		push_warning(
			"SaveSystem.read_save: version mismatch (%s vs %s)" %
			[parsed.get("version", "?"), SAVE_VERSION]
		)
	return parsed


## Apply a previously-loaded save payload onto live world state.
## Pawn dicts are zipped against World.pawns by index — Phase 3 simplicity;
## Phase 16 will introduce stable pawn IDs.
func apply_save(payload: Dictionary) -> void:
	if payload.has("sim_tick"):
		Sim.tick = int(payload["sim_tick"])
	if payload.has("game_state"):
		GameState.apply_dict(payload["game_state"])

	var pawn_dicts: Array = payload.get("pawns", [])
	var n: int = min(pawn_dicts.size(), World.pawns.size())
	for i in n:
		var p = World.pawns[i]
		if p.has_method("from_dict"):
			p.from_dict(pawn_dicts[i])
	Audit.log("save", "applied %d pawns at tick %d" % [n, Sim.tick])