from __future__ import annotations

from datetime import datetime, timezone

from sqlalchemy import DateTime, ForeignKey, Integer, Numeric, 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 AccountingFinancialLedgerMapping(CommonBase):
    """Client-specific reporting override for a mirrored Tally ledger.

    The default classifier remains Tally-group driven.  Rows in this table are
    only explicit overrides and therefore remain reusable across financial years.
    """

    __tablename__ = "accounting_financial_ledger_mappings"
    __table_args__ = (
        UniqueConstraint("tenant_id", "client_id", "ledger_name", name="uq_accounting_fs_mapping_client_ledger"),
    )

    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)
    ledger_name: Mapped[str] = mapped_column(String(255), nullable=False, index=True)
    statement_code: Mapped[str] = mapped_column(String(20), nullable=False, index=True)
    schedule_code: Mapped[str] = mapped_column(String(60), nullable=False, index=True)
    display_group: Mapped[str] = mapped_column(String(160), nullable=False, default="")
    updated_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)
    updated_at_utc: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, default=_utcnow, onupdate=_utcnow)


class AccountingPartnershipProfitShare(CommonBase):
    """Client/FY partner profit-sharing configuration used only for finalisation."""

    __tablename__ = "accounting_partnership_profit_shares"
    __table_args__ = (
        UniqueConstraint(
            "tenant_id", "client_id", "financial_year", "partner_name",
            name="uq_accounting_partner_share_client_fy_name",
        ),
    )

    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)
    financial_year: Mapped[str] = mapped_column(String(7), nullable=False, index=True)
    partner_name: Mapped[str] = mapped_column(String(200), nullable=False)
    profit_share_percent: Mapped[float] = mapped_column(Numeric(7, 4), nullable=False, default=0)
    target_ledger_name: Mapped[str] = mapped_column(String(255), nullable=False, default="")
    updated_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)
    updated_at_utc: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, default=_utcnow, onupdate=_utcnow)