extends Node3D
class_name Entity

## The thing in LEVEL 0.
##
## It borrows from three places, and the borrowings do different jobs:
##
##   SLENDERMAN — it does not move while you are looking at it. Look away and it has
##                closed the distance. Looking at it is also what builds the STATIC, so
##                the safe option (keep it in view) is the one that kills you slowly and
##                the fast option (run) is the one that lets it catch up. That's the
##                whole trap, and it's why Slender worked.
##
##   XENOMORPH  — it hunts by SOUND. And the thing you came to LEVEL 0 to do is smash
##                furniture, so the game's own objective feeds it. Every break and every
##                puff of the extinguisher drops a noise marker it walks toward.
##
##   BLAIR WITCH— it uses the loop. When the level wraps you round to the far side, it
##                gets to reposition, so "I've been here before" and "it's already here"
##                arrive together.
##
## It cannot be fought. Weapons pass through it. The only outs are distance, silence, and
## not looking at it — three things the rest of the game actively discourages.
##
## Godot 4.7 GDScript 2.0.

const MODEL := "res://assets/store/entity.glb"

enum S { DORMANT, STALKING, HUNTING, LUNGE }

## How far it can be seen from; beyond this it simply isn't rendered.
const SEE_DIST := 34.0
## Inside this, a lunge begins.
const LUNGE_DIST := 3.6
## Cone (dot product) within which the player counts as LOOKING at it.
const LOOK_DOT := 0.55

@export var stalk_speed := 2.5
@export var hunt_speed := 4.4
@export var lunge_speed := 9.5
## Static gained per second while it is on screen, scaled by how close it is.
@export var stare_static := 0.28
@export var static_decay := 0.22

var state: int = S.DORMANT
var static_level := 0.0            ## 0..1 — Slender's interference. At 1.0 it takes you.
var seen_now := false
var noise_at := Vector3.ZERO
var noise_heat := 0.0

var _player: Node3D
var _cam: Camera3D
var _bounds := 19.0
var _mesh: Node3D
var _cd := 0.0                     ## seconds until it may act again after a scare
var _think := 0.0
var _breath: AudioStreamPlayer3D
var _sting: AudioStreamPlayer

signal caught_you()                ## the jumpscare fires; Backrooms decides the cost

func setup(player: Node3D, cam: Camera3D, half_extent: float) -> void:
	_player = player
	_cam = cam
	_bounds = half_extent
	if ResourceLoader.exists(MODEL):
		var packed := load(MODEL) as PackedScene
		if packed != null:
			_mesh = packed.instantiate()
			add_child(_mesh)
	visible = false

	# it breathes, and you hear it before you see it
	_breath = AudioStreamPlayer3D.new()
	_breath.stream = _noise_wav(1.6, 70.0, 1.4, true)
	_breath.unit_size = 14.0
	_breath.max_db = -2.0
	_breath.autoplay = false
	add_child(_breath)

	_sting = AudioStreamPlayer.new()
	_sting.stream = _sting_wav()
	_sting.volume_db = 2.0
	add_child(_sting)

## Put it somewhere far from the player and switch it on.
func wake() -> void:
	state = S.STALKING
	static_level = 0.0
	_cd = 0.0
	visible = true
	_reposition(18.0)
	if _breath != null and not _breath.playing:
		_breath.play()

func sleep() -> void:
	state = S.DORMANT
	visible = false
	static_level = 0.0
	if _breath != null:
		_breath.stop()

func is_awake() -> bool:
	return state != S.DORMANT

## Something made a noise. The xenomorph half of it walks toward the last loud thing.
func hear(at: Vector3, loudness: float) -> void:
	if state == S.DORMANT:
		return
	if loudness >= noise_heat * 0.6:
		noise_at = at
		noise_heat = clampf(noise_heat + loudness, 0.0, 3.0)
	# A loud enough noise overrides the Slender freeze. Standing still and staring at it
	# is a valid answer to a stalker; it is not a valid answer to something that just
	# heard you put a sledgehammer through a filing cabinet. The escalation is the point:
	# the quiet rules protect you right up until you do the thing the game is about.
	if noise_heat > 1.2 and state == S.STALKING:
		state = S.HUNTING

## Teleport somewhere at least `min_dist` away, out of the player's current view if it
## can manage it — being *found* somewhere new is better than being *seen* moving there.
func _reposition(min_dist: float) -> void:
	if _player == null:
		return
	for attempt in 24:
		var p := Vector3(randf_range(-_bounds + 2.0, _bounds - 2.0), 0.0,
			randf_range(-_bounds + 2.0, _bounds - 2.0))
		if p.distance_to(_player.global_position) < min_dist:
			continue
		if attempt < 16 and _in_view(p):
			continue
		global_position = p
		return
	global_position = Vector3(randf_range(-_bounds, _bounds), 0.0,
		randf_range(-_bounds, _bounds))

## In the view cone AND actually visible. The line-of-sight test is not optional: this
## is a maze, so most of the time the cone contains a wall, and without the raycast the
## static built while you stared at plasterboard with the thing quietly behind it.
func _in_view(p: Vector3) -> bool:
	if _cam == null:
		return false
	var eye := _cam.global_position
	var to := p - eye
	if to.length() < 0.01:
		return true
	if to.normalized().dot(-_cam.global_transform.basis.z) <= LOOK_DOT:
		return false
	return _clear_line(eye, p + Vector3(0.0, 1.7, 0.0))

## True if nothing static blocks the line. Only walls and fittings occlude — the loose
## furniture is chest-high and shouldn't hide a two-and-a-half metre figure.
func _clear_line(from: Vector3, to: Vector3) -> bool:
	var space := get_world_3d().direct_space_state
	if space == null:
		return true
	var q := PhysicsRayQueryParameters3D.create(from, to)
	q.collide_with_bodies = true
	q.collide_with_areas = false
	var hit := space.intersect_ray(q)
	if hit.is_empty():
		return true
	var col = hit.get("collider")
	return not (col is StaticBody3D)

# ---------------------------------------------------------------- per-frame
func _physics_process(dt: float) -> void:
	if state == S.DORMANT or _player == null or _cam == null:
		return
	_cd = maxf(0.0, _cd - dt)
	noise_heat = maxf(0.0, noise_heat - dt * 0.35)

	var to_player := _player.global_position - global_position
	var dist := to_player.length()
	seen_now = _in_view(global_position) and dist < SEE_DIST

	# always face you. It has no other business.
	var flat := Vector3(to_player.x, 0.0, to_player.z)
	if flat.length() > 0.05:
		var want := atan2(-flat.x, -flat.z)
		rotation.y = lerp_angle(rotation.y, want, clampf(dt * 6.0, 0.0, 1.0))

	# --- STATIC: looking at it is what hurts you ---
	if seen_now:
		var closeness := clampf(1.0 - dist / SEE_DIST, 0.0, 1.0)
		static_level = clampf(static_level + stare_static * (0.35 + closeness) * dt,
			0.0, 1.0)
	else:
		static_level = maxf(0.0, static_level - static_decay * dt)

	if static_level >= 1.0 and _cd <= 0.0:
		_catch()
		return

	match state:
		S.STALKING:
			_tick_stalk(dt, dist)
		S.HUNTING:
			_tick_hunt(dt, dist)
		S.LUNGE:
			_tick_lunge(dt, dist)

## Slender's rule: frozen while watched, and closer every time you look back.
func _tick_stalk(dt: float, dist: float) -> void:
	_think -= dt
	if seen_now:
		return                              # it does not move while you watch
	# closes ground, but toward the last noise if there was one — the two rules compose
	var goal := _player.global_position
	if noise_heat > 0.4:
		goal = noise_at
	_step_toward(goal, stalk_speed * dt)
	if dist < LUNGE_DIST * 2.2 or noise_heat > 1.6:
		state = S.HUNTING

func _tick_hunt(dt: float, dist: float) -> void:
	# hunting, it no longer respects being watched. That escalation is the point.
	var goal := _player.global_position
	if noise_heat > 1.2:
		goal = noise_at
	_step_toward(goal, hunt_speed * dt)
	if dist < LUNGE_DIST:
		state = S.LUNGE
	elif dist > SEE_DIST * 0.8 and noise_heat < 0.3:
		state = S.STALKING

func _tick_lunge(dt: float, dist: float) -> void:
	_step_toward(_player.global_position, lunge_speed * dt)
	if dist < 1.5 and _cd <= 0.0:
		_catch()

func _step_toward(goal: Vector3, amount: float) -> void:
	var d := goal - global_position
	d.y = 0.0
	if d.length() < 0.05:
		return
	global_position += d.normalized() * amount

func _catch() -> void:
	_cd = 3.0
	static_level = 0.0
	_sting.pitch_scale = randf_range(0.94, 1.06)
	_sting.play()
	caught_you.emit()
	state = S.STALKING
	_reposition(16.0)

# ---------------------------------------------------------------- audio
## A slow rasp for the breathing; `rough` doubles the noise and drops the tone.
func _noise_wav(dur: float, tone: float, decay: float, rough: bool) -> AudioStreamWAV:
	var rate := 22050
	var n := int(rate * dur)
	var out := PackedFloat32Array()
	out.resize(n)
	for i in n:
		var t := float(i) / float(rate)
		var env := exp(-fposmod(t, 0.8) * decay) * 0.8
		var s := sin(TAU * tone * t) * 0.4 * env
		if rough:
			s += (randf() * 2.0 - 1.0) * 0.35 * env
			s += sin(TAU * tone * 0.5 * t) * 0.25 * env
		out[i] = clampf(s, -1.0, 1.0)
	return _wav(out, rate, true)

## The jumpscare sting: a downward shriek over a hit of noise.
func _sting_wav() -> AudioStreamWAV:
	var rate := 22050
	var dur := 1.15
	var n := int(rate * dur)
	var out := PackedFloat32Array()
	out.resize(n)
	for i in n:
		var t := float(i) / float(rate)
		var env := exp(-t * 3.2)
		var f := 1800.0 - 1500.0 * clampf(t / dur, 0.0, 1.0)
		var s := sin(TAU * f * t) * 0.45 * env
		s += sin(TAU * f * 1.5 * t) * 0.20 * env
		s += (randf() * 2.0 - 1.0) * 0.55 * exp(-t * 11.0)
		s += sin(TAU * 46.0 * t) * 0.35 * exp(-t * 2.0)
		out[i] = clampf(s, -1.0, 1.0)
	return _wav(out, rate, false)

func _wav(samples: PackedFloat32Array, rate: int, loop: bool) -> AudioStreamWAV:
	var w := AudioStreamWAV.new()
	w.format = AudioStreamWAV.FORMAT_16_BITS
	w.mix_rate = rate
	w.stereo = false
	var b := PackedByteArray()
	b.resize(samples.size() * 2)
	for i in samples.size():
		b.encode_s16(i * 2, int(samples[i] * 32767.0))
	w.data = b
	if loop:
		w.loop_mode = AudioStreamWAV.LOOP_FORWARD
		w.loop_end = samples.size()
	return w