import math

import unreal


def look_at(actor, target):
    actor.set_actor_rotation(unreal.MathLibrary.find_look_at_rotation(
        actor.get_actor_location(), unreal.Vector(*target)), False)


def create(scene, location=(450, -550, 300), target=(0, 0, 100), fov=43.6):
    """Create a camera with a horizontal field of view in degrees (0 < fov < 180)."""
    fov = float(fov)
    if not 0 < fov < 180:
        raise ValueError("fov must be between 0 and 180 degrees (exclusive)")
    sensor_width = 36.0
    focal_length = sensor_width / (2 * math.tan(math.radians(fov) / 2))
    actor = scene.spawn(unreal.CineCameraActor, "Camera", location)
    component = actor.get_cine_camera_component()
    filmback = component.get_editor_property("filmback")
    filmback.set_editor_property("sensor_width", sensor_width)
    filmback.set_editor_property("sensor_height", 20.25)
    component.set_editor_property("filmback", filmback)
    component.set_editor_property("current_focal_length", float(focal_length))
    focus = component.get_editor_property("focus_settings")
    focus.set_editor_property("focus_method", unreal.CameraFocusMethod.DISABLE)
    component.set_editor_property("focus_settings", focus)
    settings = component.get_editor_property("post_process_settings")
    settings.set_editor_property("override_auto_exposure_bias", True)
    settings.set_editor_property("auto_exposure_bias", 0.0)
    settings.set_editor_property("override_auto_exposure_min_brightness", True)
    settings.set_editor_property("override_auto_exposure_max_brightness", True)
    # Extended luminance range interprets these as EV100, not linear brightness.
    settings.set_editor_property("auto_exposure_min_brightness", 8.0)
    settings.set_editor_property("auto_exposure_max_brightness", 8.0)
    component.set_editor_property("post_process_settings", settings)
    look_at(actor, target)
    return actor