from abc import ABC, abstractmethod
from typing import Union
from ..motion import MotionClip
PersonSelector = Union[str, int]

class PoseBackend(ABC):
    """MotionBackend kind: video -> MotionClip (own skeleton); goes through resample+retarget+bake."""
    name: str
    kind: str = "motion"
    @abstractmethod
    def infer(self, video_path: str, fps=None, person: PersonSelector = "auto") -> MotionClip: ...

class DirectRetargetBackend(ABC):
    """Direct kind: (video, target rig + reference frame) -> rotations already on the target skeleton.
    Returns a retarget.TargetAnimation; the pipeline sends it straight to bake (no MotionClip)."""
    name: str
    kind: str = "direct"
    @abstractmethod
    def infer(self, video_path: str, target_rig_glb: str, reference_frame=None,
              fps=None, person: PersonSelector = "auto"):  # -> retarget.retarget.TargetAnimation
        ...