class_name Toil extends RefCounted
## A single atomic step within a Job — walk, wait, idle, etc.
##
## Save/load contract: every value in `data` MUST be JSON-safe.
## Vector2i is NOT JSON-safe in Godot 4 — tile coordinates are stored as
## "to_x"/"to_y" integer keys, never as Vector2i. get_walk_destination()
## reconstructs Vector2i on demand.
##
## Round-trip invariant:
##   var t2 := Toil.from_dict(t.to_dict())
##   assert(t2.kind == t.kind and t2.done == t.done and t2.data == t.data)

const KIND_WALK: StringName = &"walk"
const KIND_WAIT: StringName = &"wait"
const KIND_IDLE: StringName = &"idle"

var kind: StringName = KIND_IDLE
## Toil-specific params — all values must be int, float, bool, String, Dict, or Array.
var data: Dictionary = {}
## Set by JobRunner when this toil is complete.
var done: bool = false


# ── factories ────────────────────────────────────────────────────────────────

## Walk to the given tile. Stores coords as separate ints for JSON safety.
static func walk_to(tile: Vector2i) -> Toil:
	var t := Toil.new()
	t.kind = KIND_WALK
	t.data = {
		"to_x": tile.x,
		"to_y": tile.y,
		"started": false,
	}
	return t


## Pause for `n` sim ticks.
static func wait_ticks(n: int) -> Toil:
	var t := Toil.new()
	t.kind = KIND_WAIT
	t.data = {"ticks_remaining": n}
	return t


## Stand idle — never completes on its own; JobRunner must cancel or replace.
static func idle() -> Toil:
	var t := Toil.new()
	t.kind = KIND_IDLE
	t.data = {}
	return t


# ── save / load ──────────────────────────────────────────────────────────────

func to_dict() -> Dictionary:
	return {
		"kind": str(kind),
		"data": data.duplicate(true),
		"done": done,
	}


static func from_dict(d: Dictionary) -> Toil:
	var t := Toil.new()
	t.kind = StringName(d.get("kind", str(KIND_IDLE)))
	t.data = (d.get("data", {}) as Dictionary).duplicate(true)
	t.done = d.get("done", false)
	return t


# ── convenience ──────────────────────────────────────────────────────────────

## Rebuild Vector2i from the JSON-safe int fields. Only valid for KIND_WALK.
func get_walk_destination() -> Vector2i:
	return Vector2i(data.get("to_x", 0), data.get("to_y", 0))