"""
Embedding model — stores CLIP/SigLIP image embeddings via pgvector.

Composite PK (photo_id, model) allows re-embedding with newer models
without clobbering old vectors.

Vector dimension is 768 to support SigLIP2 ViT-B/16 (the default).
OpenCLIP ViT-B/32 (512-d) embeddings are zero-padded on insert so
both models coexist in the same column. The padding is invisible to
cosine similarity (zeros don't affect the angle).
"""
from sqlalchemy import Column, String, ForeignKey, DateTime, func
from pgvector.sqlalchemy import Vector

from app.database import Base


class Embedding(Base):
    __tablename__ = 'embeddings'

    photo_id = Column(String, ForeignKey('photos.id', ondelete='CASCADE'), primary_key=True)
    model = Column(String(64), primary_key=True)  # e.g. 'siglip2_vitb16'
    vector = Column(Vector(768))                   # SigLIP2 ViT-B/16 → 768-d
    created_at = Column(DateTime(timezone=True), server_default=func.now())