Shooting Bullets

extends CharacterBody2D

## How fast the player moves.
@export var speed: float = 200.0
# The scene to copy for each bullet. It lives in this same folder.
const BULLET_SCENE: PackedScene = preload("bullet.tscn")

## How many seconds to wait between shots.
@export var fire_rate: float = 0.3optional

# True when the gun is loaded. Goes false the instant we fire.
var _can_shoot: bool = true

@onready var shoot_timer: Timer = %ShootTimer

# Muzzle is an empty node parked at the tip of the gun, so bullets start
# there instead of in the middle of the player.
@onready var muzzle: Marker2D = %Muzzle
@onready var sprite: Sprite2D = $Sprite2D

func _ready() -> void:optional
	shoot_timer.wait_time = fire_rate
	# When the timer runs out, "_on_shoot_timer_timeout" reloads the gun.
	shoot_timer.timeout.connect(_on_shoot_timer_timeout)

func _physics_process(_delta: float) -> void:
	# Move with WASD.
	var direction: Vector2 = Input.get_vector(
		"move_left", "move_right", "move_up", "move_down"
	)
	velocity = direction * speed
	move_and_slide()

	# Turn to face the mouse, the same as the Mouse Aiming lesson.
	look_at(get_global_mouse_position())

	# Aiming left would turn the picture upside down, so mirror it back.
	sprite.flip_v = abs(rotation) > PI / 2

	# "is_mouse_button_pressed" stays true the whole time you HOLD the left
	# mouse button, so you can hold it down to keep firing.
	if Input.is_mouse_button_pressed(MOUSE_BUTTON_LEFT):
		_shoot()

# Makes one bullet. The "_" in front means only this file uses it.
func _shoot() -> void:
	# Still reloading, so this press does nothing.
	if not _can_shoot:optional
		return
	# Lock the gun, then start the countdown that unlocks it again.
	_can_shoot = false
	shoot_timer.start()

	# "instantiate()" makes one real copy of bullet.tscn.
	var bullet: Node2D = BULLET_SCENE.instantiate()
	# Start it at the gun tip, pointed the way the player is facing.
	bullet.global_position = muzzle.global_position
	bullet.rotation = rotation
	# Add the bullet to the LEVEL, not to the player. If it were our child,
	# it would swing around with us every time we turned.
	get_tree().current_scene.add_child(bullet)

func _on_shoot_timer_timeout() -> void:optional
	_can_shoot = true

extends Area2D

## How fast the bullet flies.
@export var speed: float = 500.0
## How many seconds the bullet lives before erasing itself.
@export var lifetime: float = 2.0

func _ready() -> void:
	# Bullets that miss would fly on forever and slowly clog the game up.
	# "create_timer()" makes a one-time timer, and we hand it "queue_free"
	# so the bullet erases itself when the time is up.
	var timer: SceneTreeTimer = get_tree().create_timer(lifetime)
	timer.timeout.connect(queue_free)

	body_entered.connect(_on_body_entered)

func _physics_process(delta: float) -> void:
	# "Vector2.RIGHT" is an arrow pointing right. ".rotated(rotation)" turns
	# that arrow to match the way the bullet is facing. Multiplying by speed
	# and delta gives exactly how far to travel this frame.
	position += Vector2.RIGHT.rotated(rotation) * speed * delta

# "body" is whatever the bullet ran into.
func _on_body_entered(body: Node2D) -> void:
	if body is Enemy:
		# "body_entered" already handed us the target as "body", so we just
		# call a function on it. No signal needed.
		body.take_hit()
	# Erase the bullet no matter WHAT it hit, even a wall.
	# This line sits outside the "if" on purpose.
	queue_free()

class_name Enemy
extends StaticBody2D

## How many hits this target survives.
@export var health: int = 3

## Called BY bullet.gd, not by anything in this file.
func take_hit() -> void:
	health -= 1
	if health <= 0:
		queue_free()