class_name AdaptiveInputDepthController
extends RefCounted

# Client-only policy for choosing whether the server's input jitter buffer may
# run at depth zero. It deliberately does not change server buffering, action
# encoding, or bot behavior; NetworkedMatch pins --test-bot clients at depth 1.

const TARGET_DEPTH_SAFE := 1
const TARGET_DEPTH_LOW_LATENCY := 0
const CLEAN_JITTER_MS := 3.0
const EXIT_JITTER_MS := 5.0
const REQUIRED_STABLE_TICKS := 240
const REENTRY_COOLDOWN_TICKS := 120

var target_depth := TARGET_DEPTH_SAFE
var stable_low_jitter_ticks := 0
var cooldown_ticks := 0


func update(rtt_ms: float, jitter_ms: float, advertised_depth: int) -> int:
	if cooldown_ticks > 0:
		cooldown_ticks -= 1
	# -2 is a genuine server starvation sentinel. -1 means no header yet and
	# must not be mistaken for starvation.
	if advertised_depth < -1 or jitter_ms > EXIT_JITTER_MS:
		target_depth = TARGET_DEPTH_SAFE
		stable_low_jitter_ticks = 0
		cooldown_ticks = REENTRY_COOLDOWN_TICKS
		return target_depth
	if rtt_ms >= 0.0 and jitter_ms < CLEAN_JITTER_MS:
		stable_low_jitter_ticks += 1
		if stable_low_jitter_ticks >= REQUIRED_STABLE_TICKS and cooldown_ticks == 0:
			target_depth = TARGET_DEPTH_LOW_LATENCY
	else:
		stable_low_jitter_ticks = 0
		target_depth = TARGET_DEPTH_SAFE
	return target_depth