"""Create or replace the PhysInOne moving-camera Level Sequence.

Run inside Unreal Engine while the target level is open. The script reads
BP_CameraTrajectory, creates CineCamera_Moving, adds all managed static cameras
to a sequence, and writes camera metadata under Rendered/Videos.

The post-processing tools intentionally never choose validation views and never
overwrite transforms_train.json, transforms_val.json, or transforms_test.json.
This script is the single authority for those split files.
"""

from __future__ import annotations

import argparse
import hashlib
import json
import math
from pathlib import Path
import random
import re
import sys

import numpy as np
import unreal


CONFIG_ACTOR_LABEL = "BP_CameraTrajectory"
MOVING_CAMERA_LABEL = "CineCamera_Moving"
STATIC_CAMERA_PATTERN = re.compile(r"^CineCamera_\d+$")
FPS_60_PHENOMENA = {
    "FixedPlanarRedirect",
    "FixedArrayRedirect",
    "FixedConcaveRedirect",
    "FixedConvexRedirect",
    "DynMirrorRedirect",
    "LaserBlock",
}


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Generate a PhysInOne camera sequence.")
    parser.add_argument("--focal", type=float, default=18.0, help="Focal length in mm.")
    parser.add_argument("--aperture", type=float, default=10.0)
    parser.add_argument("--radius", type=float, default=100.0, help="Base radius in cm.")
    parser.add_argument("--latitude-range", type=float, default=60.0)
    parser.add_argument(
        "--path-type",
        choices=("random", "arc", "sine", "loop"),
        default="random",
        help="Moving-camera path family.",
    )
    parser.add_argument(
        "--seed",
        type=int,
        default=None,
        help="Optional trajectory seed. The level name provides a stable seed by default.",
    )
    parser.add_argument(
        "--output-root",
        default=None,
        help="Metadata root. Default: <project>/Rendered/Videos.",
    )
    return parser.parse_known_args()[0]


def stable_seed(text: str) -> int:
    return int.from_bytes(hashlib.sha256(text.encode("utf-8")).digest()[:8], "big")


def current_level_parts() -> tuple[str, str, str, str]:
    world = unreal.EditorLevelLibrary.get_editor_world()
    object_path = world.get_path_name().replace("\\", "/")
    match = re.fullmatch(
        r"/Game/PhysInOne/Scenes/(Train|Val|Test)/"
        r"(SinglePhysics|DoublePhysics|TriplePhysics)/([^./]+)(?:\.([^./]+))?",
        object_path,
    )
    if not match:
        raise ValueError(
            "The open level must use /Game/PhysInOne/Scenes/<Split>/<Physics>/<Scene>."
        )
    split, physics, scene, object_name = match.groups()
    if object_name is not None and object_name != scene:
        raise ValueError(f"Level package and object names do not match: {object_path}")
    return split, physics, scene, object_path


def infer_fps(scene_name: str) -> int:
    prefix = scene_name.split("__", 1)[0]
    return 60 if any(name in prefix for name in FPS_60_PHENOMENA) else 30


def find_config_actor():
    for actor in unreal.EditorLevelLibrary.get_all_level_actors():
        if actor.get_actor_label() == CONFIG_ACTOR_LABEL:
            return actor
    return None


def validate_config(config_actor) -> None:
    scale = config_actor.get_actor_scale3d()
    rotation = config_actor.get_actor_rotation()
    tolerance = 1e-4
    if max(abs(rotation.roll), abs(rotation.pitch), abs(rotation.yaw)) > tolerance:
        raise ValueError("BP_CameraTrajectory rotation must be zero.")
    if max(abs(scale.x - scale.y), abs(scale.x - scale.z)) > tolerance:
        raise ValueError("BP_CameraTrajectory XYZ scale must be uniform.")
    if min(scale.x, scale.y, scale.z) <= 0:
        raise ValueError("BP_CameraTrajectory scale must be positive.")
    duration = float(config_actor.get_editor_property("Time"))
    if duration <= 0:
        raise ValueError("BP_CameraTrajectory.Time must be positive.")


def choose_hemisphere(config_actor, rng: random.Random) -> bool | None:
    if bool(config_actor.get_editor_property("RandomHemisphere")):
        return rng.choice([True, False])
    return bool(config_actor.get_editor_property("UpperHemisphere"))


def generate_path(
    frame_count: int,
    longitude_range: float,
    latitude_range: float,
    clockwise: bool,
    upper_hemisphere: bool | None,
    path_type: str,
    rng: random.Random,
) -> tuple[list[float], list[float], list[float], str]:
    if frame_count < 2:
        raise ValueError("The sequence must contain at least two frames.")
    selected_type = rng.choice(["arc", "sine", "loop"]) if path_type == "random" else path_type
    direction = 1.0 if clockwise else -1.0
    start_longitude = rng.uniform(0.0, 360.0)

    if upper_hemisphere is True:
        low_latitude, high_latitude = 0.0, latitude_range
    elif upper_hemisphere is False:
        low_latitude, high_latitude = -latitude_range, 0.0
    else:
        low_latitude, high_latitude = -latitude_range, latitude_range

    start_latitude = rng.uniform(low_latitude, high_latitude)
    end_latitude = rng.uniform(low_latitude, high_latitude)
    longitudes: list[float] = []
    latitudes: list[float] = []
    radius_factors: list[float] = []

    for index in range(frame_count):
        t = index / (frame_count - 1)
        if selected_type == "arc":
            smooth_t = t * t * (3.0 - 2.0 * t)
            longitude = start_longitude + direction * longitude_range * smooth_t
            latitude = (1.0 - smooth_t) * start_latitude + smooth_t * end_latitude
            radius_factor = 1.0
        elif selected_type == "sine":
            longitude = start_longitude + direction * longitude_range * t
            latitude = start_latitude + (end_latitude - start_latitude) * math.sin(math.pi * t)
            radius_factor = 1.0 - 0.3 * abs(math.sin(2.0 * math.pi * t))
        else:
            loop_radius = min(40.0, max(10.0, longitude_range / 4.0))
            phase = 2.0 * math.pi * t * direction
            center_latitude = (low_latitude + high_latitude) / 2.0
            longitude = start_longitude + loop_radius * math.cos(phase)
            latitude = center_latitude + min(loop_radius, latitude_range / 2.0) * math.sin(phase)
            radius_factor = 1.0

        longitudes.append(longitude % 360.0)
        latitudes.append(max(-90.0, min(90.0, latitude)))
        radius_factors.append(radius_factor)

    return longitudes, latitudes, radius_factors, selected_type


def spherical_position(radius, longitude, latitude, scale, center):
    lon = math.radians(longitude)
    lat = math.radians(latitude)
    return unreal.Vector(
        center.x + radius * math.cos(lat) * math.cos(lon) * scale.x,
        center.y + radius * math.cos(lat) * math.sin(lon) * scale.y,
        center.z + radius * math.sin(lat) * scale.z,
    )


def look_at(camera_position, target_position):
    direction = unreal.MathLibrary.normal(target_position - camera_position)
    rotation = unreal.MathLibrary.make_rot_from_x(direction)
    rotation.roll = 0.0
    return rotation


def configure_camera(camera_actor, focal: float, aperture: float) -> None:
    component = camera_actor.get_cine_camera_component()
    component.set_editor_property("current_focal_length", focal)
    component.set_editor_property("current_aperture", aperture)
    filmback = component.get_editor_property("filmback")
    filmback.sensor_width = 23.76
    filmback.sensor_height = 23.76
    component.set_editor_property("filmback", filmback)
    focus = component.get_editor_property("focus_settings")
    focus.focus_method = unreal.CameraFocusMethod.MANUAL
    focus.manual_focus_distance = 10000.0
    component.set_editor_property("focus_settings", focus)


def replace_sequence_asset(sequence_object_path: str):
    package_path, object_name = sequence_object_path.rsplit("/", 1)
    sequence_name = object_name.split(".", 1)[0]
    full_object_path = f"{package_path}/{sequence_name}.{sequence_name}"
    registry = unreal.AssetRegistryHelpers.get_asset_registry()
    asset_data = registry.get_asset_by_object_path(full_object_path)
    if asset_data.is_valid():
        try:
            unreal.LevelSequenceEditorBlueprintLibrary.close_level_sequence()
        except Exception:
            pass
        unreal.SystemLibrary.collect_garbage()
        if not unreal.EditorAssetLibrary.delete_asset(full_object_path):
            raise RuntimeError(f"Could not replace existing sequence: {full_object_path}")

    if not unreal.EditorAssetLibrary.does_directory_exist(package_path):
        unreal.EditorAssetLibrary.make_directory(package_path)
    sequence = unreal.AssetToolsHelpers.get_asset_tools().create_asset(
        sequence_name,
        package_path,
        unreal.LevelSequence,
        unreal.LevelSequenceFactoryNew(),
    )
    if sequence is None:
        raise RuntimeError(f"Could not create sequence: {full_object_path}")
    return sequence


def remove_moving_camera() -> None:
    for actor in unreal.EditorLevelLibrary.get_all_level_actors():
        if (
            isinstance(actor, unreal.CineCameraActor)
            and actor.get_actor_label() == MOVING_CAMERA_LABEL
        ):
            unreal.EditorLevelLibrary.destroy_actor(actor)


def add_component_tracks(sequence, actor_binding, camera_actor) -> None:
    component_binding = sequence.add_possessable(camera_actor.get_cine_camera_component())
    component_binding.set_parent(actor_binding)
    component_binding.set_display_name("CameraComponent")
    for display_name, property_path in (
        ("Current Focal Length", "CurrentFocalLength"),
        ("Current Aperture", "CurrentAperture"),
        ("Manual Focus Distance", "FocusSettings.ManualFocusDistance"),
    ):
        track = component_binding.add_track(unreal.MovieSceneFloatTrack)
        track.set_property_name_and_path(display_name, property_path)
        section = track.add_section()
        section.set_start_frame_bounded(0)
        section.set_end_frame_bounded(0)


def add_moving_camera(sequence, positions, rotations, focal, aperture, frame_count):
    camera = unreal.EditorLevelLibrary.spawn_actor_from_class(
        unreal.CineCameraActor, positions[0], rotations[0]
    )
    camera.set_actor_label(MOVING_CAMERA_LABEL)
    configure_camera(camera, focal, aperture)
    binding = sequence.add_possessable(camera)
    binding.set_display_name(MOVING_CAMERA_LABEL)
    track = binding.add_track(unreal.MovieScene3DTransformTrack)
    section = track.add_section()
    section.set_range(0, frame_count)
    channels = section.get_all_channels()
    for index, (position, rotation) in enumerate(zip(positions, rotations)):
        frame = unreal.FrameNumber(index)
        for channel, value in zip(
            channels[:6],
            (position.x, position.y, position.z, rotation.roll, rotation.pitch, rotation.yaw),
        ):
            channel.add_key(frame, value)
    add_component_tracks(sequence, binding, camera)
    return binding


def add_static_camera(sequence, camera, frame_count):
    parent = camera.get_attach_parent_actor()
    location = camera.get_actor_location()
    rotation = camera.get_actor_rotation()
    scale = camera.get_actor_scale3d()
    if parent:
        camera.detach_from_actor(
            location_rule=unreal.DetachmentRule.KEEP_WORLD,
            rotation_rule=unreal.DetachmentRule.KEEP_WORLD,
            scale_rule=unreal.DetachmentRule.KEEP_WORLD,
        )
    binding = sequence.add_possessable(camera)
    binding.set_display_name(camera.get_actor_label())
    track = binding.add_track(unreal.MovieScene3DTransformTrack)
    section = track.add_section()
    section.set_range(0, frame_count)
    channels = section.get_all_channels()
    frame = unreal.FrameNumber(0)
    for channel, value in zip(
        channels[:9],
        (
            location.x,
            location.y,
            location.z,
            rotation.roll,
            rotation.pitch,
            rotation.yaw,
            scale.x,
            scale.y,
            scale.z,
        ),
    ):
        channel.add_key(frame, value)
    add_component_tracks(sequence, binding, camera)


def rotation_matrix(roll: float, pitch: float, yaw: float) -> np.ndarray:
    roll, pitch, yaw = map(math.radians, (roll, pitch, yaw))
    rx = np.array(
        [[1, 0, 0], [0, math.cos(roll), math.sin(roll)], [0, -math.sin(roll), math.cos(roll)]]
    )
    ry = np.array(
        [[math.cos(pitch), 0, -math.sin(pitch)], [0, 1, 0], [math.sin(pitch), 0, math.cos(pitch)]]
    )
    rz = np.array(
        [[math.cos(yaw), -math.sin(yaw), 0], [math.sin(yaw), math.cos(yaw), 0], [0, 0, 1]]
    )
    return rz @ ry @ rx


def camera_json(camera_name, positions, rotations, frame_count, fov, fps, convention):
    frames = []
    for index in range(frame_count):
        position_m = np.asarray(positions[index], dtype=float).reshape(3, 1) / 100.0
        ue_rotation = rotation_matrix(*rotations[index])
        if convention == "ue":
            matrix = np.vstack((np.hstack((ue_rotation, position_m)), [0, 0, 0, 1]))
        else:
            world_conversion = np.diag([1, -1, 1])
            camera_conversion = np.array([[0, 0, -1], [1, 0, 0], [0, 1, 0]])
            matrix = np.eye(4)
            matrix[:3, :3] = world_conversion @ ue_rotation @ camera_conversion
            matrix[:3, 3] = (world_conversion @ position_m).ravel()
        frames.append(
            {
                "frame": index,
                "transform_matrix": matrix.tolist(),
                "file_path": f"{camera_name}/rgb/{index:04d}",
                "time": index / (frame_count - 1) if frame_count > 1 else 0.0,
                "time_abs": index / float(fps),
            }
        )
    return {
        "camera_angle_x": fov,
        "img_h": 1120,
        "img_w": 1120,
        "total_frames": frame_count,
        "fps": fps,
        "frames": frames,
    }


def write_json(path: Path, data) -> None:
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("w", encoding="utf-8") as handle:
        json.dump(data, handle, indent=2)


def clean_camera_metadata(output_dir: Path) -> None:
    output_dir.mkdir(parents=True, exist_ok=True)
    names = {
        "camera_ue_data.json",
        "static_camera_list.txt",
        "transforms_train.json",
        "transforms_val.json",
        "transforms_test.json",
    }
    for path in output_dir.iterdir():
        if path.is_file() and (
            path.name in names
            or path.name.startswith("ue_CineCamera_")
            or path.name.startswith("blender_CineCamera_")
        ):
            path.unlink()


def choose_validation_cameras(static_cameras, center, seed: int) -> set[str]:
    if len(static_cameras) < 2:
        return {camera.get_actor_label() for camera in static_cameras}
    by_name = {camera.get_actor_label(): camera for camera in static_cameras}
    names = sorted(by_name)
    first = random.Random(seed).choice(names)
    first_location = by_name[first].get_actor_location() - center
    first_yaw = math.degrees(math.atan2(first_location.y, first_location.x)) % 360.0

    def diagonal_error(name: str) -> float:
        location = by_name[name].get_actor_location() - center
        yaw = math.degrees(math.atan2(location.y, location.x)) % 360.0
        difference = abs(yaw - first_yaw)
        difference = min(difference, 360.0 - difference)
        return abs(180.0 - difference)

    second = min((name for name in names if name != first), key=lambda name: (diagonal_error(name), name))
    return {first, second}


def combine_split(camera_documents, selected_names, first_half: bool):
    chosen = [camera_documents[name] for name in sorted(selected_names)]
    result = {"camera_angle_x": None, "img_h": None, "img_w": None, "frames": []}
    for document in chosen:
        if result["camera_angle_x"] is None:
            for key in ("camera_angle_x", "img_h", "img_w"):
                result[key] = document.get(key)
        for frame in document.get("frames", []):
            include = frame.get("time", 0.0) <= 0.5 if first_half else frame.get("time", 0.0) > 0.5
            if include:
                result["frames"].append(frame)
    return result


def generate(args: argparse.Namespace) -> Path:
    split, physics, scene_name, level_path = current_level_parts()
    fps = infer_fps(scene_name)
    config_actor = find_config_actor()
    if config_actor is None:
        raise RuntimeError(f"Actor {CONFIG_ACTOR_LABEL!r} was not found in the current level.")
    validate_config(config_actor)

    duration = float(config_actor.get_editor_property("Time"))
    frame_count = int(round(duration * fps))
    if frame_count < 2:
        raise ValueError("Time multiplied by FPS must produce at least two frames.")

    seed = args.seed if args.seed is not None else stable_seed(level_path)
    rng = random.Random(seed)
    clockwise = (
        rng.choice([True, False])
        if bool(config_actor.get_editor_property("RandomSampleDirection"))
        else bool(config_actor.get_editor_property("SampleClockwise"))
    )
    longitude_range = float(config_actor.get_editor_property("LongtitudeRange"))
    hemisphere = choose_hemisphere(config_actor, rng)
    longitudes, latitudes, radius_factors, path_type = generate_path(
        frame_count,
        longitude_range,
        args.latitude_range,
        clockwise,
        hemisphere,
        args.path_type,
        rng,
    )
    config_actor.set_editor_property("LongitudeAngles", longitudes)
    config_actor.set_editor_property("LatitudeAngles", latitudes)

    center = config_actor.get_actor_location()
    scale = config_actor.get_actor_scale3d()
    positions = [
        spherical_position(args.radius * factor, longitude, latitude, scale, center)
        for longitude, latitude, factor in zip(longitudes, latitudes, radius_factors)
    ]
    rotations = [look_at(position, center) for position in positions]

    sequence_name = f"{scene_name}_trajectory"
    sequence_object_path = (
        f"/Game/PhysInOne/Trajectories/{split}/{physics}/{sequence_name}.{sequence_name}"
    )
    remove_moving_camera()
    sequence = replace_sequence_asset(sequence_object_path)
    frame_rate = unreal.FrameRate(fps, 1)
    sequence.set_display_rate(frame_rate)
    sequence.set_tick_resolution(frame_rate)
    sequence.set_playback_start(0)
    sequence.set_playback_end(frame_count)
    moving_binding = add_moving_camera(
        sequence, positions, rotations, args.focal, args.aperture, frame_count
    )

    static_cameras = sorted(
        (
            actor
            for actor in unreal.EditorLevelLibrary.get_all_level_actors()
            if isinstance(actor, unreal.CineCameraActor)
            and STATIC_CAMERA_PATTERN.fullmatch(actor.get_actor_label())
        ),
        key=lambda actor: int(actor.get_actor_label().rsplit("_", 1)[1]),
    )
    if not static_cameras:
        raise RuntimeError("No managed static cameras were found. Run generate_static_cameras.py first.")
    for camera in static_cameras:
        add_static_camera(sequence, camera, frame_count)

    cut_track = sequence.add_track(unreal.MovieSceneCameraCutTrack)
    cut_section = cut_track.add_section()
    cut_section.set_range(0, frame_count)
    cut_section.set_camera_binding_id(sequence.get_binding_id(moving_binding))

    if not unreal.EditorAssetLibrary.save_asset(sequence_object_path):
        raise RuntimeError(f"Failed to save sequence: {sequence_object_path}")

    output_root = (
        Path(args.output_root)
        if args.output_root
        else Path(unreal.Paths.project_dir()) / "Rendered" / "Videos"
    )
    output_dir = output_root / split / physics / sequence_name
    clean_camera_metadata(output_dir)
    fov = 2.0 * math.atan(23.76 / (2.0 * args.focal))

    ue_summary = {
        "Scene_Location_Info": {
            "center_location": {"x": center.x, "y": center.y, "z": center.z},
            "scale": scale.x,
        }
    }
    camera_documents = {}

    moving_positions = [(value.x, value.y, value.z) for value in positions]
    moving_rotations = [(value.roll, value.pitch, value.yaw) for value in rotations]
    for convention in ("ue", "blender"):
        document = camera_json(
            MOVING_CAMERA_LABEL,
            moving_positions,
            moving_rotations,
            frame_count,
            fov,
            fps,
            convention,
        )
        write_json(output_dir / f"{convention}_{MOVING_CAMERA_LABEL}.json", document)
    ue_summary[MOVING_CAMERA_LABEL] = {
        "type": "moving",
        "total_frames": frame_count,
        "frames": [
            {
                "frame": index,
                "location": {"x": position.x, "y": position.y, "z": position.z},
                "rotation": {"roll": rotation.roll, "pitch": rotation.pitch, "yaw": rotation.yaw},
            }
            for index, (position, rotation) in enumerate(zip(positions, rotations))
        ],
    }

    for camera in static_cameras:
        name = camera.get_actor_label()
        location = camera.get_actor_location()
        rotation = camera.get_actor_rotation()
        static_positions = [(location.x, location.y, location.z)] * frame_count
        static_rotations = [(rotation.roll, rotation.pitch, rotation.yaw)] * frame_count
        for convention in ("ue", "blender"):
            document = camera_json(
                name,
                static_positions,
                static_rotations,
                frame_count,
                fov,
                fps,
                convention,
            )
            write_json(output_dir / f"{convention}_{name}.json", document)
            if convention == "blender":
                camera_documents[name] = document
        ue_summary[name] = {
            "type": "static",
            "location": {"x": location.x, "y": location.y, "z": location.z},
            "rotation": {"roll": rotation.roll, "pitch": rotation.pitch, "yaw": rotation.yaw},
        }

    write_json(output_dir / "camera_ue_data.json", ue_summary)
    with (output_dir / "static_camera_list.txt").open("w", encoding="utf-8") as handle:
        handle.write("\n".join(camera.get_actor_label() for camera in static_cameras) + "\n")

    all_names = set(camera_documents)
    val_names = choose_validation_cameras(static_cameras, center, seed)
    train_names = all_names - val_names
    write_json(output_dir / "transforms_train.json", combine_split(camera_documents, train_names, True))
    write_json(output_dir / "transforms_val.json", combine_split(camera_documents, val_names, True))
    write_json(output_dir / "transforms_test.json", combine_split(camera_documents, all_names, False))

    unreal.log(
        f"Generated {sequence_object_path}: {frame_count} frames at {fps} FPS, "
        f"path={path_type}, seed={seed}, static_cameras={len(static_cameras)}."
    )
    unreal.log(f"Camera metadata: {output_dir}")
    return output_dir


if __name__ == "__main__":
    try:
        generate(parse_args())
    except Exception as exc:
        unreal.log_error(f"Camera sequence generation failed: {exc}")
        raise