class_name Movement
extends RefCounted
## Pure movement helpers. These run on the server (authoritative) and on the
## client (prediction). They must stay side-effect free so a client can replay
## them over a history of inputs and land on the same result as the server.

## Clamp a raw analogue/keyboard vector to a unit disc.
static func sanitize_move(raw: Vector2) -> Vector2:
	if raw.length_squared() > 1.0:
		return raw.normalized()
	return raw


## One tick of player locomotion. Returns the new position.
static func step_player(pos: Vector2, move: Vector2, speed: float, bounds: Vector2) -> Vector2:
	var next := pos + sanitize_move(move) * speed * SimConfig.TICK_DELTA
	next.x = clampf(next.x, -bounds.x, bounds.x)
	next.y = clampf(next.y, -bounds.y, bounds.y)
	return next


## Circle-vs-circle overlap test used for every hit in the game.
static func circles_overlap(a: Vector2, ar: float, b: Vector2, br: float) -> bool:
	var r := ar + br
	return a.distance_squared_to(b) <= r * r


## True when a point has drifted outside the arena plus the cull margin.
static func outside_arena(p: Vector2, margin: float = SimConfig.BULLET_CULL_MARGIN) -> bool:
	return absf(p.x) > SimConfig.ARENA_HALF.x + margin \
		or absf(p.y) > SimConfig.ARENA_HALF.y + margin