extends KinematicBody

onready var util = get_node("/root/Util")

export var gravity: float = 6.0
# When falling, gravity is artificially increased
export var gravity_downwards_factor: float = 2
# Rate of gaining speed
export var velocity_acceleration_xz: float = 3
export var velocity_acceleration_y: float = 5
# Rate of losing speed when stopping
export var velocity_friction_xz: float = 15
export var velocity_friction_y: float = 1
export var jump_power: float = 50

# Controls the base speeds of walking and sprinting
export var sprint_factor: float = 1.5
export var walk_factor: float = 1.0

export var max_xz_speed: float = 2

"public" var velocity: Vector3 = Vector3.ZERO
# Value changed by code only to add slow down or speed up effects
var velocity_factor: Vector3 = Vector3.ONE
var target_velocity: Vector3 = Vector3.ZERO
var is_jumping: bool = false
var jump_permission: float = 1.0

func get_terminal_falling_velocity():
	return -gravity * .5

func is_falling_velocity_terminal():
	return velocity.y <= get_terminal_falling_velocity()


func process_velocity(delta: float):
	# Uses the input from MovementInput to compute and update this node's velocity
	# velocity_acceleration controls gradual speedup whereas velocity_friction
	# controls gradual slowdown
	
	# Gravity
	# You can buffer jumps by pressing releaseing the space bar and then pressing it again
	if not is_on_floor():
		var grav = -gravity
		target_velocity.y = grav 
		# Gravity is stronger when you're falling. Feels nicer
		target_velocity.y *= util.clamped_lerp(gravity_downwards_factor, 1.0, velocity.y/2, 0.0)
	else:
		velocity.y = max(0.0, velocity.y)
		target_velocity.y = max(0.0, max(target_velocity.y, jump_power * $"../MovementInput".jump_intent * jump_permission))
	if not is_jumping and $"../MovementInput".jump_intent != 0.0 and is_on_floor():
		jump_permission = 0.0
		is_jumping = true
	elif is_jumping and $"../MovementInput".jump_intent == 0.0:
		jump_permission = 1.0
		is_jumping = false
	
	
	var target_velocity_xz = $"../MovementInput".input_xz 
	target_velocity = util.vec2_xz_to_vec3(target_velocity_xz, target_velocity.y)
	var velocity_xz = util.vec3_xz(velocity)



	var xz_weight = velocity_acceleration_xz * delta
	if target_velocity_xz.length() < velocity_xz.length():
		xz_weight = velocity_friction_xz * delta

	var target_xz_length = util.clamped_lerp(velocity_xz.length(), target_velocity_xz.length(), xz_weight, 0.25)
	
	if target_velocity_xz != Vector2.ZERO:
		velocity_xz = target_velocity_xz.normalized() * target_xz_length
	elif velocity_xz != Vector2.ZERO:
		velocity_xz = velocity_xz.normalized() * target_xz_length
	
	var y_weight = velocity_acceleration_y * delta
	if target_velocity.y < velocity.y:
		y_weight = velocity_friction_y * delta
	
	var velocity_y = util.clamped_lerp(velocity.y, target_velocity.y, y_weight, 0.25)

	if $"../MovementInput".sprinting:
		velocity_xz *= sprint_factor
	else:
		velocity_xz *= walk_factor

	velocity = util.vec2_xz_to_vec3(velocity_xz, velocity_y) * velocity_factor

	velocity = util.vec2_xz_to_vec3(util.vec3_xz(velocity).limit_length(max_xz_speed), velocity.y)

func increase_velocity_factor(by: Vector3):
	velocity_factor *= by
	
func decrease_velocity_factor(by: Vector3):
	velocity_factor /= by

func _physics_process(delta):
	process_velocity(delta)
	velocity = move_and_slide(velocity, Vector3.UP)