"""Declarative base + shared mixins for all ORM models."""

from __future__ import annotations

import uuid
from datetime import UTC, datetime

from sqlalchemy import DateTime, MetaData, func
from sqlalchemy.dialects.postgresql import UUID as PG_UUID
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column

NAMING_CONVENTION = {
    "ix": "ix_%(column_0_label)s",
    "uq": "uq_%(table_name)s_%(column_0_name)s",
    "ck": "ck_%(table_name)s_%(constraint_name)s",
    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
    "pk": "pk_%(table_name)s",
}


class Base(DeclarativeBase):
    """Project-wide declarative base.

    UUID columns are declared explicitly on each model via `PG_UUID(as_uuid=True)`
    rather than through a `type_annotation_map` — Flask-SQLAlchemy injects its
    own registry which is incompatible with per-base annotation maps.
    """

    metadata = MetaData(naming_convention=NAMING_CONVENTION)


class UuidPkMixin:
    """Mixin: UUID v4 primary key generated client-side."""

    id: Mapped[uuid.UUID] = mapped_column(
        PG_UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
    )


def _utcnow() -> datetime:
    return datetime.now(tz=UTC)


class TimestampsMixin:
    """Mixin: `created_at` / `updated_at` columns, UTC timezone-aware."""

    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        onupdate=_utcnow,
        nullable=False,
    )