class_name PlayableMetrics
extends RefCounted

## STB-01 §9.1 帧间隔与长帧指标（纯数据，时钟可注入）。
##
## - frame() 每帧调用一次，记录与上一帧的 monotonic 间隔；首个调用只起表。
## - 所有存储都有固定上限：当前窗口的样本在 capacity 大小的环形缓冲里，
##   已关闭窗口 / 长帧事件 / 标记 / 分段表各有上限，超出只计丢弃数，
##   测试自身不会因为长跑而无限增长内存。
## - 窗口按注入时钟（墙钟期限）关闭，或在分段标签变化时关闭；不按帧数。
##   窗口样本超过 capacity 时分位数只来自最近 capacity 个样本并标 truncated，
##   max 与 >50ms / >100ms 计数始终精确。
## - 分段标签只取 map / phase / actor_count / gpu_skin；actor_count 请用 actor_bucket() 分桶。
## - 默认不逐帧打印，只保留长帧事件（>50ms），附带本帧和上一帧内的标记用于归因。
## - GPU 内存拿不到时写 null + "unavailable"，从不写 0。

const TAG_KEYS := ["map", "phase", "actor_count", "gpu_skin"]
const LONG_MS := 50.0
const SEVERE_MS := 100.0
## 9.3 标记：同步模型 build、动作 reload、GR2 解析、材质初次使用、实体批量生成、缓存命中等。
const MARKER_DETAIL_KEYS := ["race", "count", "ms", "state", "map", "hits", "misses", "size", "round", "kind"]
const MAX_PENDING_MARKERS := 16
const MAX_MARKER_KIND_LENGTH := 32

var capacity := 4096
var window_us := 60_000_000
var max_windows := 512
var max_long_frames := 512
var max_markers := 1024
var max_segments := 64
var print_frames := false
var clock_us: Callable = func() -> int: return Time.get_ticks_usec()

var _ring := PackedFloat32Array()
var _ring_head := 0
var _ring_len := 0
var _window_count := 0
var _window_over_long := 0
var _window_over_severe := 0
var _window_max := 0.0
var _window_start_us := -1
var _origin_us := -1
var _last_frame_us := -1
var _tags := {}
var _tag_key := ""
var _frames := 0
var _windows: Array = []
var _windows_dropped := 0
var _segments := {}
var _unsegmented_frames := 0
var _severe_by_phase := {}
var _long_unattributed_by_phase := {}
var _long_frames: Array = []
var _long_frames_dropped := 0
var _markers: Array = []
var _markers_dropped := 0
var _pending_markers: Array[String] = []
var _previous_markers: Array[String] = []

func _init() -> void:
	_ring.resize(capacity)

func configure(options: Dictionary) -> void:
	capacity = maxi(1, int(options.get("capacity", capacity)))
	window_us = maxi(1, int(float(options.get("window_seconds", window_us / 1_000_000.0)) * 1_000_000.0))
	max_windows = maxi(1, int(options.get("max_windows", max_windows)))
	max_long_frames = maxi(1, int(options.get("max_long_frames", max_long_frames)))
	max_markers = maxi(1, int(options.get("max_markers", max_markers)))
	max_segments = maxi(1, int(options.get("max_segments", max_segments)))
	print_frames = bool(options.get("print_frames", false))
	_ring.resize(capacity)
	_ring_head = 0
	_ring_len = 0

## Switches the segment. A different tag set closes the current window first.
func set_tags(tags: Dictionary) -> void:
	var normalized := {}
	for key in TAG_KEYS:
		if tags.has(key):
			normalized[key] = String(str(tags[key])).left(80)
	var key := JSON.stringify(normalized)
	if key == _tag_key:
		return
	if _window_count > 0:
		close_window()
	_tags = normalized
	_tag_key = key

func tags() -> Dictionary:
	return _tags.duplicate()

## Call once per rendered frame. The first call only arms the clock.
func frame(now_us := -1) -> void:
	var now := now_us if now_us >= 0 else int(clock_us.call())
	if _last_frame_us >= 0:
		add_interval_us(now - _last_frame_us, now)
	else:
		_arm(now)
	_last_frame_us = now

## Forget the previous frame time (e.g. before a deliberately unmeasured pause).
func reset_frame_clock() -> void:
	_last_frame_us = -1

func add_interval_us(interval_us: int, now_us: int) -> void:
	if _origin_us < 0:
		_arm(now_us - interval_us)
	if _window_start_us < 0:
		_window_start_us = now_us - interval_us
	var ms := float(interval_us) / 1000.0
	_ring[_ring_head] = ms
	_ring_head = (_ring_head + 1) % capacity
	_ring_len = mini(_ring_len + 1, capacity)
	_window_count += 1
	_frames += 1
	_window_max = maxf(_window_max, ms)
	var segment := _segment()
	if not segment.is_empty():
		segment.frames = int(segment.frames) + 1
		segment.max_ms = maxf(float(segment.max_ms), ms)
	var attribution: Array[String] = []
	for kind in _previous_markers + _pending_markers:
		if not (kind in attribution):
			attribution.append(kind)
	_previous_markers = _pending_markers
	_pending_markers = []
	if ms > LONG_MS:
		_window_over_long += 1
		if not segment.is_empty():
			segment.over_50ms = int(segment.over_50ms) + 1
		_push_bounded(_long_frames, {"t_ms": _t_ms(now_us), "ms": ms, "tags": _tags.duplicate(),
			"markers": attribution}, max_long_frames, "_long_frames_dropped")
		if attribution.is_empty():
			var long_phase := String(_tags.get("phase", ""))
			if _long_unattributed_by_phase.has(long_phase) or _long_unattributed_by_phase.size() < max_segments:
				_long_unattributed_by_phase[long_phase] = int(_long_unattributed_by_phase.get(long_phase, 0)) + 1
	if ms > SEVERE_MS:
		_window_over_severe += 1
		if not segment.is_empty():
			segment.over_100ms = int(segment.over_100ms) + 1
		var phase := String(_tags.get("phase", ""))
		if _severe_by_phase.has(phase) or _severe_by_phase.size() < max_segments:
			_severe_by_phase[phase] = int(_severe_by_phase.get(phase, 0)) + 1
	if print_frames:
		print("FRAME ms=%.3f tags=%s" % [ms, _tag_key])
	if now_us - _window_start_us >= window_us:
		close_window(now_us)

## Attribution marker (model build, motion reload, GR2 parse, material first use, entity batch, ...).
func mark(kind: String, detail := {}) -> void:
	var name := kind.left(MAX_MARKER_KIND_LENGTH)
	var clean := {}
	for key in detail:
		if String(key) in MARKER_DETAIL_KEYS:
			var value: Variant = detail[key]
			clean[String(key)] = value if (value is int or value is float or value is bool) else String(str(value)).left(80)
	var now := int(clock_us.call())
	_push_bounded(_markers, {"t_ms": _t_ms(now), "kind": name, "tags": _tags.duplicate(), "detail": clean},
		max_markers, "_markers_dropped")
	if _pending_markers.size() < MAX_PENDING_MARKERS and not (name in _pending_markers):
		_pending_markers.append(name)

func close_window(now_us := -1) -> void:
	if _window_count == 0:
		return
	var end := now_us if now_us >= 0 else maxi(_last_frame_us, _window_start_us)
	var sorted := PackedFloat32Array()
	sorted.resize(_ring_len)
	for i in _ring_len:
		sorted[i] = _ring[(_ring_head - _ring_len + i + capacity) % capacity]
	sorted.sort()
	var window := {"tags": _tags.duplicate(), "start_ms": _t_ms(_window_start_us), "end_ms": _t_ms(end),
		"count": _window_count, "sampled": _ring_len, "truncated": _window_count > _ring_len,
		"p50_ms": percentile(sorted, 0.50), "p95_ms": percentile(sorted, 0.95), "p99_ms": percentile(sorted, 0.99),
		"max_ms": _window_max, "over_50ms": _window_over_long, "over_100ms": _window_over_severe}
	_push_bounded(_windows, window, max_windows, "_windows_dropped")
	var segment: Dictionary = _segments.get(_tag_key, {})
	if not segment.is_empty():
		segment.windows = int(segment.windows) + 1
		segment.worst_p99_ms = maxf(float(segment.worst_p99_ms), float(window.p99_ms))
	_ring_head = 0
	_ring_len = 0
	_window_count = 0
	_window_over_long = 0
	_window_over_severe = 0
	_window_max = 0.0
	_window_start_us = end

func summary() -> Dictionary:
	close_window()
	var segments: Array = []
	for key in _segments:
		segments.append(_segments[key].duplicate(true))
	return {"schema_version": 1, "capacity": capacity, "window_seconds": window_us / 1_000_000.0,
		"thresholds_ms": [LONG_MS, SEVERE_MS], "print_frames": print_frames, "frames": _frames,
		"segments": segments, "unsegmented_frames": _unsegmented_frames,
		"windows": _windows.duplicate(true), "windows_dropped": _windows_dropped,
		"long_frames": _long_frames.duplicate(true), "long_frames_dropped": _long_frames_dropped,
		"markers": _markers.duplicate(true), "markers_dropped": _markers_dropped,
		"severe_by_phase": _severe_by_phase.duplicate(),
		"long_unattributed_by_phase": _long_unattributed_by_phase.duplicate()}

func stored_sample_count() -> int:
	return _ring_len

## Cumulative >100ms counts per phase tag; diff two snapshots to judge one repetition.
func severe_by_phase() -> Dictionary:
	return _severe_by_phase.duplicate()

## Exact per-phase count of >50ms frames without a marker (not limited by max_long_frames).
func long_unattributed_by_phase() -> Dictionary:
	return _long_unattributed_by_phase.duplicate()

## Retained long frames that have no marker in their frame or the one before. They
## need manual attribution (§9.3); the automated gate never explains them away.
func unattributed_long_frames() -> Array:
	return _long_frames.filter(func(item: Dictionary) -> bool: return item.markers.is_empty())

## Nearest-rank percentile of an ascending array.
static func percentile(sorted: PackedFloat32Array, q: float) -> float:
	if sorted.is_empty():
		return 0.0
	var index := clampi(int(ceil(q * sorted.size())) - 1, 0, sorted.size() - 1)
	return sorted[index]

static func actor_bucket(count: int) -> String:
	if count <= 0:
		return "0"
	for limit in [8, 16, 32, 64]:
		if count <= limit:
			return "%d-%d" % [limit / 2 + 1 if limit > 8 else 1, limit]
	return "65+"

## §9.3: an interaction repeated at least 3 times where 2 of any 3 consecutive
## repetitions contained a >100ms frame. history: interaction -> Array[bool].
static func repeated_severe(history: Dictionary) -> Array[String]:
	var out: Array[String] = []
	for key in history:
		var runs: Array = history[key]
		for i in range(0, runs.size() - 2):
			var hits := int(bool(runs[i])) + int(bool(runs[i + 1])) + int(bool(runs[i + 2]))
			if hits >= 2:
				out.append(String(key))
				break
	return out

## MEMORY_STATIC is Godot's own allocator counter, not process RSS (the runner
## samples RSS externally). GPU memory has no reliable source here.
static func memory_snapshot() -> Dictionary:
	var video := int(Performance.get_monitor(Performance.RENDER_VIDEO_MEM_USED))
	return {"memory_static_kib": int(Performance.get_monitor(Performance.MEMORY_STATIC)) / 1024,
		"memory_static_max_kib": int(Performance.get_monitor(Performance.MEMORY_STATIC_MAX)) / 1024,
		"gpu_memory_kib": null, "gpu_memory_status": "unavailable",
		"godot_video_mem_kib": video / 1024 if video > 0 else null,
		"godot_video_mem_note": "Godot RenderingDevice allocation counter; not system GPU memory"}

## Cost of one sample on this machine; compare with the frame budget in reports.
static func measure_overhead(iterations := 20000) -> Dictionary:
	var probe := new()
	probe.configure({"capacity": 4096, "window_seconds": 3600})
	probe.set_tags({"map": "overhead", "phase": "probe", "actor_count": "1-8", "gpu_skin": false})
	var started := Time.get_ticks_usec()
	for i in iterations:
		probe.add_interval_us(16_000 + (i % 7) * 1000, (i + 1) * 16_000)
	var elapsed := Time.get_ticks_usec() - started
	return {"iterations": iterations, "total_us": elapsed, "per_sample_us": float(elapsed) / maxf(1.0, iterations)}

func _arm(now_us: int) -> void:
	if _origin_us < 0:
		_origin_us = now_us
	if _window_start_us < 0:
		_window_start_us = now_us

func _t_ms(us: int) -> float:
	return float(us - maxi(_origin_us, 0)) / 1000.0

func _segment() -> Dictionary:
	if _segments.has(_tag_key):
		return _segments[_tag_key]
	if _segments.size() >= max_segments:
		_unsegmented_frames += 1
		return {}
	var row := {"tags": _tags.duplicate(), "frames": 0, "windows": 0, "max_ms": 0.0, "worst_p99_ms": 0.0,
		"over_50ms": 0, "over_100ms": 0}
	_segments[_tag_key] = row
	return row

func _push_bounded(list: Array, item: Dictionary, limit: int, dropped_field: String) -> void:
	if list.size() >= limit:
		list.pop_front()
		set(dropped_field, int(get(dropped_field)) + 1)
	list.append(item)