class_name MovementMotor
extends Node

const GRAVITY := 1200.0
const KNOCKBACK_FRICTION := 480.0
const ActionRuleResolverScript := preload("res://scripts/resolvers/action_rule_resolver.gd")

@onready var actor: CharacterBody2D = get_parent() as CharacterBody2D
@onready var state_machine: Node = get_node_or_null("../StateMachine")
@onready var effect_container: Node = get_node_or_null("../EffectContainer")

# 击退的水平残速还没衰减完；期间 set_heading 不得改写朝向（受击不转身）。
var _knockback_stray_active := false


func handle_input() -> void:
	if actor == null or not can_move_freely():
		return
	# 自主移动接管 velocity.x，击退残速语义随之结束。
	_knockback_stray_active = false
	var direction := get_horizontal_axis()
	actor.velocity.x = direction * float(actor.get("speed")) * _move_speed_multiplier()
	if direction < 0.0:
		actor.set("heading", Vector2.LEFT)
	elif direction > 0.0:
		actor.set("heading", Vector2.RIGHT)


func handle_air_time(delta: float) -> void:
	if actor == null:
		return
	_decay_stray_velocity(delta)
	if _presentation_state() != Character.PRESENTATION_JUMP and _ground_state() != &"Airborne":
		return
	var height := float(actor.get("height"))
	var height_speed := float(actor.get("height_speed"))
	height += height_speed * delta
	if height <= 0.0 and height_speed < 0.0:
		actor.set("height", 0.0)
		actor.set("height_speed", 0.0)
		actor.set("state", Character.PRESENTATION_LAND)
		actor.velocity.y = 0.0
		_set_ground_state(&"Grounded")
		_reset_air_actions()
		_dispatch_effect_event(&"on_landed")
	else:
		actor.set("height", height)
		actor.set("height_speed", height_speed - GRAVITY * delta)
		_set_ground_state(&"Airborne")


func _decay_stray_velocity(delta: float) -> void:
	var state := _presentation_state()
	if state == Character.PRESENTATION_ATTACK or state == Character.PRESENTATION_AIR_ATTACK:
		return
	actor.velocity.x = move_toward(actor.velocity.x, 0.0, KNOCKBACK_FRICTION * delta)
	actor.velocity.y = 0.0
	if actor.velocity.x == 0.0:
		_knockback_stray_active = false


func handle_movement() -> void:
	if actor == null:
		return
	var state := _presentation_state()
	if state == Character.PRESENTATION_JUMP or state == Character.PRESENTATION_ATTACK or state == Character.PRESENTATION_AIR_ATTACK:
		return
	if _ground_state() == &"Airborne" or float(actor.get("height")) > 0.0 or not is_zero_approx(float(actor.get("height_speed"))):
		_set_ground_state(&"Airborne")
		return
	if state == Character.PRESENTATION_LAND:
		actor.set("state", Character.PRESENTATION_IDLE)
	elif absf(actor.velocity.x) > 0.0:
		actor.set("state", Character.PRESENTATION_WALK)
	else:
		actor.set("state", Character.PRESENTATION_IDLE)
	_set_ground_state(&"Grounded")


func set_heading() -> void:
	if actor == null:
		return
	# 受击不转身（2026-07-05 定案）：Hitstun/击退残速期间保持受击前朝向。
	if _knockback_stray_active or _life_state() != &"Alive":
		return
	if actor.velocity.x > 0.0:
		actor.set("heading", Vector2.RIGHT)
	elif actor.velocity.x < 0.0:
		actor.set("heading", Vector2.LEFT)


func start_jump() -> bool:
	if actor == null or not can_jump():
		return false
	actor.set("state", Character.PRESENTATION_JUMP)
	actor.set("height_speed", float(actor.get("jump_intensity")))
	_set_ground_state(&"Airborne")
	return true


func can_jump() -> bool:
	if actor == null:
		return false
	var state := _presentation_state()
	return state == Character.PRESENTATION_IDLE or state == Character.PRESENTATION_WALK


func can_move_freely() -> bool:
	if not _free_movement_inputs_bound():
		return false
	if _movement_blocked_by_effect():
		return false
	var context := _movement_context()
	if bool(ActionRuleResolverScript.can_move_freely(context)):
		return true
	return _charging_movement_allowed_by_effect()


func get_horizontal_axis() -> float:
	var axis := 0.0
	if Input.is_action_pressed(&"move_left"):
		axis -= 1.0
	if Input.is_action_pressed(&"move_right"):
		axis += 1.0
	return axis


func apply_knockback(knockback: Vector2) -> void:
	if actor == null:
		return
	actor.velocity.x = knockback.x
	_knockback_stray_active = knockback.x != 0.0
	if knockback.y > 0.0:
		actor.set("height", maxf(float(actor.get("height")), 0.1))
		actor.set("height_speed", knockback.y)
		_set_ground_state(&"Airborne")
	elif knockback.y < 0.0:
		actor.set("height_speed", knockback.y)
	else:
		actor.velocity.y = 0.0


## 供覆写了 handle_movement 的宿主（Boss/小怪 AI）查询：击退残速未衰减完时
## 不得清零 velocity.x，否则击退位移活不过一帧。
func has_knockback_stray() -> bool:
	return _knockback_stray_active


## 强制结束击退滑行语义（Boss 受击链强制撤退等"压倒击退"的路径专用）。
func clear_knockback_stray() -> void:
	_knockback_stray_active = false


func _ground_state() -> StringName:
	if state_machine != null and state_machine.has_method("build_context"):
		return StringName(str(state_machine.call("build_context").get("ground_state", &"Grounded")))
	return &"Grounded"


func _movement_context() -> Dictionary:
	var context := {
		"life_state": &"Alive",
		"action_phase": &"Neutral",
		"ground_state": &"Grounded",
	}
	if state_machine != null and state_machine.has_method("build_context"):
		context = state_machine.call("build_context")
	context["effect_container"] = effect_container
	return context


func _presentation_state() -> StringName:
	if actor == null:
		return Character.PRESENTATION_IDLE
	return StringName(str(actor.get("state")))


func _action_phase() -> StringName:
	if state_machine != null and state_machine.has_method("build_context"):
		return StringName(str(state_machine.call("build_context").get("action_phase", &"Neutral")))
	return &"Neutral"


func _life_state() -> StringName:
	if state_machine != null and state_machine.has_method("build_context"):
		return StringName(str(state_machine.call("build_context").get("life_state", &"Alive")))
	return &"Alive"


func _charging_movement_allowed_by_effect() -> bool:
	if _action_phase() != &"Charging":
		return false
	if effect_container == null or not effect_container.has_method("action_rule_modifiers"):
		return false
	for modifier: Resource in effect_container.call("action_rule_modifiers"):
		if bool(modifier.get("allow_movement_while_charging")):
			return true
	return false


func _movement_blocked_by_effect() -> bool:
	if effect_container == null or not effect_container.has_method("action_rule_modifiers"):
		return false
	for modifier: Resource in effect_container.call("action_rule_modifiers"):
		if bool(modifier.get("block_movement")):
			return true
	return false


func _move_speed_multiplier() -> float:
	if effect_container == null or not effect_container.has_method("stat_multiplier"):
		return 1.0
	return float(effect_container.call("stat_multiplier", &"move_speed", null))


func _free_movement_inputs_bound() -> bool:
	for action_name: StringName in [&"move_left", &"move_right"]:
		if InputMap.has_action(action_name) and not InputMap.action_get_events(action_name).is_empty():
			return true
	return false


func _set_ground_state(next_state: StringName) -> void:
	if state_machine != null and state_machine.has_method("set_ground_state"):
		state_machine.call("set_ground_state", next_state)


func _reset_air_actions() -> void:
	if state_machine != null and "air_action_count" in state_machine:
		state_machine.set("air_action_count", 0)


func _dispatch_effect_event(event_name: StringName) -> void:
	if effect_container == null:
		effect_container = get_node_or_null("../EffectContainer")
	if effect_container != null and effect_container.has_method("dispatch_event"):
		effect_container.call("dispatch_event", event_name, {"actor": actor})