class_name PickupBehaviorController extends Area2D

## Controls visual movement (bob, shake) and drift of a pickup.
## Attach to the root Area2D node of your pickup scene.

@export var behavior: PickupBehavior
@export var drift_behavior: PickupDriftBehavior


var _icon_node: TextureRect
var _spawn_position: Vector2 = Vector2.ZERO


func _ready() -> void:
    # Find the runtime-added icon node.
    for child in get_children():
        if child is TextureRect:
            _icon_node = child as TextureRect
            break
    # Capture the initial spawn position.
    _spawn_position = global_position

    if behavior != null:
        behavior.start()


func _process(delta: float) -> void:
    if behavior == null or drift_behavior == null:
        return

    var alpha: float = behavior.process(delta)

    if _icon_node != null:
        _icon_node.visible = alpha > 0.01
        if behavior != null and behavior.fade_in_duration > 0 and _icon_node is CanvasItem:
            _icon_node.modulate.a = alpha

    var offset := _compute_animation_offset()
    var drift_offset := _compute_drift_offset()

    position = _spawn_position + Vector2(drift_offset.x, drift_offset.y)

    if _icon_node != null:
        _icon_node.position = offset


func _compute_animation_offset() -> Vector2:
    # Returns the bob + shake offset applied to the icon node.
    var result := Vector2.ZERO

    if behavior == null:
        return result

    # Bob (vertical oscillation).
    if behavior.bob_enabled:
        var bob_angle := _elapsed_time() * TAU * behavior.bob_frequency
        result.y += sin(bob_angle) * behavior.bob_amplitude

    # Shake (subtle jitter).
    if behavior.shake_enabled:
        var shake_angle := _elapsed_time() * TAU * behavior.shake_frequency
        result.x += sin(shake_angle) * behavior.shake_amplitude

    return result


func _compute_drift_offset() -> Vector2:
    # Returns the global drift position offset from initial spawn position.
    if drift_behavior == null:
        return Vector2.ZERO

    match drift_behavior.drift_type:
        PickupDriftBehavior.DriftType.STATIONARY:
            return Vector2.ZERO

        PickupDriftBehavior.DriftType.SINE_WAVE:
            var t := _elapsed_time() * drift_behavior.wave_frequency
            var travel_speed: float = drift_behavior.drift_speed
            if drift_behavior.reverse_direction:
                travel_speed *= -1.0

            var offset := Vector2.ZERO
            if drift_behavior.drift_along_x:
                # Travels along X; waves on Y.
                offset.x = travel_speed * _elapsed_time()
                offset.y = sin(t + drift_behavior.phase_offset) * drift_behavior.wave_amplitude
            else:
                # Travels along Y; waves on X.
                offset.y = travel_speed * _elapsed_time()
                offset.x = sin(t + drift_behavior.phase_offset) * drift_behavior.wave_amplitude
            return offset

        PickupDriftBehavior.DriftType.LEAF_FALL:
            var leaf_t := _elapsed_time() * drift_behavior.wave_frequency
            var travel_speed: float = drift_behavior.fall_speed
            if drift_behavior.reverse_direction:
                travel_speed *= -1.0

            var offset := Vector2.ZERO
            if drift_behavior.drift_along_x:
                # Travels along X; waves on Y.
                offset.x = travel_speed * _elapsed_time()
                offset.y = sin(leaf_t + drift_behavior.phase_offset) * drift_behavior.wave_amplitude
            else:
                # Travels along Y; waves on X.
                offset.y = travel_speed * _elapsed_time()
                offset.x = sin(leaf_t + drift_behavior.phase_offset) * drift_behavior.wave_amplitude
            return offset

        PickupDriftBehavior.DriftType.DIAGONAL:
            var dir: float = 1.0 if drift_behavior.diagonal_forward else -1.0
            if drift_behavior.reverse_direction:
                dir *= -1.0

            var offset := Vector2.ZERO
            if drift_behavior.drift_along_x:
                # Travels along X; secondary on Y.
                offset.x = dir * drift_behavior.drift_speed * _elapsed_time()
                offset.y = dir * (drift_behavior.drift_speed * 0.5) * _elapsed_time()
            else:
                # Travels along Y; secondary on X.
                offset.y = dir * drift_behavior.drift_speed * _elapsed_time()
                offset.x = dir * (drift_behavior.drift_speed * 0.5) * _elapsed_time()
            return offset

    return Vector2.ZERO


func _elapsed_time() -> float:
    if behavior == null:
        return 0.0
    return behavior._elapsed