from __future__ import annotations

from datetime import datetime
from decimal import Decimal

from sqlalchemy import DateTime, ForeignKey, Index, Numeric, String
from sqlalchemy.orm import Mapped, mapped_column

from app.models.base import Base, TimestampMixin


class CreditRecordAllocation(Base, TimestampMixin):
    __tablename__ = "credit_record_allocations"
    __table_args__ = (
        Index("ix_credit_record_allocations_record", "credit_record_id", "id"),
        Index("ix_credit_record_allocations_balance", "credit_balance_id", "created_at"),
        Index("ix_credit_record_allocations_user_time", "user_id", "created_at"),
        Index("ix_credit_record_allocations_source_allocation", "source_allocation_id"),
    )

    id: Mapped[str] = mapped_column(String(32), primary_key=True)
    credit_record_id: Mapped[str] = mapped_column(
        String(32), ForeignKey("credit_records.id", ondelete="CASCADE"), nullable=False
    )
    credit_balance_id: Mapped[str] = mapped_column(
        String(32), ForeignKey("user_credit_balances.id", ondelete="RESTRICT"), nullable=False
    )
    user_id: Mapped[str] = mapped_column(
        String(32), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    source_allocation_id: Mapped[str | None] = mapped_column(
        String(32), ForeignKey("credit_record_allocations.id", ondelete="SET NULL"), nullable=True
    )
    allocation_action: Mapped[str] = mapped_column(String(48), nullable=False, index=True)
    amount: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False)
    request_time: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)

    credit_level_snapshot: Mapped[str] = mapped_column(String(32), nullable=False)
    source_type_snapshot: Mapped[str] = mapped_column(String(48), nullable=False)
    source_id_snapshot: Mapped[str | None] = mapped_column(String(64), nullable=True)
    valid_from_snapshot: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    expires_at_snapshot: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)

    unspent_before: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False)
    unspent_after: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False)
    consumed_before: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False)
    consumed_after: Mapped[Decimal] = mapped_column(Numeric(20, 2), nullable=False)