extends CharacterBody2D
## Untagged grunt — the Act-1 learning-language enemy. Walks at the
## mech, deals contact damage on a tick. Untagged = neutral hue, no
## tag behavior of its own; heat is a status OTHERS put on it.
##
## Heat: accumulates, glows, detonates at threshold (HEAT's signature).
## The threshold check runs in physics so detonations resolve when time
## flows — stack heat while frozen, release, pop. Detonation is damage
## only, zero knockback: moving things is KINETIC's verb, not HEAT's
## (tag purity keeps the chemistry legible).

signal died

@export var speed := 70.0
@export var hp := 3.0
@export var contact_damage := 5.0
@export var contact_interval := 0.5
@export var knockback_decay := 5.0

@export_group("Heat status")
@export var heat_threshold := 3.0
@export var detonation_damage := 1.5
@export var detonation_radius := 56.0

const FX_RING := preload("res://scripts/fx_ring.gd")

var heat := 0.0
var _knockback := Vector2.ZERO
var _contact_cd := 0.0
var _flash := 0.0
var _dead := false
var _mech: Node2D


func _ready() -> void:
	add_to_group("enemies")
	_mech = get_tree().get_first_node_in_group("mech")


func _physics_process(delta: float) -> void:
	if heat >= heat_threshold:
		_detonate()
		return

	_contact_cd -= delta
	var seek := Vector2.ZERO
	if is_instance_valid(_mech):
		seek = (_mech.global_position - global_position).normalized() * speed
	_knockback = _knockback.lerp(Vector2.ZERO, 1.0 - exp(-knockback_decay * delta))
	velocity = seek + _knockback
	move_and_slide()

	for i in get_slide_collision_count():
		var collider := get_slide_collision(i).get_collider()
		if collider == _mech and _contact_cd <= 0.0:
			_mech.take_damage(contact_damage)
			_contact_cd = contact_interval

	if _flash > 0.0:
		_flash -= delta
		queue_redraw()


func hit(damage: float, kb: Vector2) -> void:
	if _dead:
		return
	hp -= damage
	_knockback += kb
	_flash = 0.12
	queue_redraw()
	if hp <= 0.0:
		_die()


func add_heat(amount: float) -> void:
	if _dead:
		return
	heat += amount
	queue_redraw()


func _detonate() -> void:
	if _dead:
		return
	for e in get_tree().get_nodes_in_group("enemies"):
		if e == self:
			continue
		if global_position.distance_to(e.global_position) <= detonation_radius:
			e.hit(detonation_damage, Vector2.ZERO)
	var ring: Node2D = FX_RING.new()
	ring.position = global_position
	ring.max_radius = detonation_radius
	get_parent().add_child(ring)
	_die()


func _die() -> void:
	if _dead:
		return
	_dead = true
	died.emit()
	queue_free()


func _draw() -> void:
	var body := Color(0.45, 0.47, 0.4)
	var heat_k := clampf(heat / heat_threshold, 0.0, 1.0)
	if heat_k > 0.0:
		body = body.lerp(Color(0.95, 0.5, 0.15), heat_k * 0.8)
	if _flash > 0.0:
		body = Color(0.95, 0.95, 0.95)
	draw_circle(Vector2.ZERO, 8.0, body)
	if heat_k > 0.0:
		draw_arc(Vector2.ZERO, 10.0, 0.0, TAU, 24, Color(0.95, 0.55, 0.2, 0.4 + heat_k * 0.5), 1.5)