from __future__ import annotations

from datetime import date, datetime, timezone

from sqlalchemy import BigInteger, Boolean, Date, DateTime, ForeignKey, Integer, String, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column

from app.core.db.common import CommonBase


def _utcnow() -> datetime:
    return datetime.now(timezone.utc)


class AccountingMirrorRegistry(CommonBase):
    """Authoritative link between one ERP client/FY and its active local .act mirror."""

    __tablename__ = "accounting_mirror_registry"
    __table_args__ = (
        UniqueConstraint(
            "tenant_id",
            "client_id",
            "financial_year",
            "version_no",
            name="uq_accounting_mirror_registry_client_fy_version",
        ),
    )

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    tenant_id: Mapped[int] = mapped_column(ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False, index=True)
    client_id: Mapped[int] = mapped_column(ForeignKey("clients.id", ondelete="CASCADE"), nullable=False, index=True)
    storage_node_id: Mapped[int | None] = mapped_column(ForeignKey("branch_storage_nodes.id", ondelete="SET NULL"), nullable=True, index=True)

    financial_year: Mapped[str] = mapped_column(String(7), nullable=False, index=True)
    accounting_relative_dir: Mapped[str] = mapped_column(String(1000), nullable=False)
    mirror_file_name: Mapped[str] = mapped_column(String(255), nullable=False)

    company_name: Mapped[str] = mapped_column(String(255), nullable=False, default="")
    company_guid: Mapped[str] = mapped_column(String(160), nullable=False, default="")
    voucher_from_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    voucher_to_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    file_size_bytes: Mapped[int] = mapped_column(BigInteger, nullable=False, default=0)

    version_no: Mapped[int] = mapped_column(Integer, nullable=False, default=1, index=True)
    is_current: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, index=True)
    status: Mapped[str] = mapped_column(String(30), nullable=False, default="active", index=True)
    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, index=True)
    replacement_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    supersedes_mirror_id: Mapped[int | None] = mapped_column(
        ForeignKey("accounting_mirror_registry.id", ondelete="SET NULL"), nullable=True, index=True
    )

    created_by_user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True)
    last_synced_by_user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True)
    created_at_utc: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, default=_utcnow)
    last_synced_at_utc: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    updated_at_utc: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, default=_utcnow, onupdate=_utcnow)