import uuid
from datetime import UTC, datetime
from typing import Any

from sqlalchemy import DateTime, MetaData, TypeDecorator
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):
    metadata = MetaData(naming_convention=NAMING_CONVENTION)


class UTCDateTime(TypeDecorator):
    """Datetimes stored as naive UTC in the DB and exposed tz-aware (UTC) in Python."""

    impl = DateTime
    cache_ok = True

    def process_bind_param(self, value: Any, dialect: Any) -> Any:
        if value is not None:
            if value.tzinfo is None:
                value = value.replace(tzinfo=UTC)
            value = value.astimezone(UTC).replace(tzinfo=None)
        return value

    def process_result_value(self, value: Any, dialect: Any) -> Any:
        if value is not None:
            value = value.replace(tzinfo=UTC)
        return value


def utcnow() -> datetime:
    return datetime.now(UTC)


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


class TimestampMixin:
    created_at: Mapped[datetime] = mapped_column(UTCDateTime(), default=utcnow, nullable=False)
    updated_at: Mapped[datetime] = mapped_column(
        UTCDateTime(), default=utcnow, onupdate=utcnow, nullable=False
    )