from __future__ import annotations

from datetime import datetime, timezone

from sqlalchemy import Boolean, DateTime, Float, ForeignKey, Integer, String, Text, UniqueConstraint
from sqlalchemy.orm import Mapped, mapped_column

from app.core.db.common import CommonBase


class AccountingLedgerLearningRule(CommonBase):
    """Client-scoped learned evidence used to rank accounting natures.

    Rules are intentionally contextual.  A supplier rule learned for one client
    never becomes a universal rule for another client.
    """

    __tablename__ = "accounting_ledger_learning_rules"
    __table_args__ = (
        UniqueConstraint(
            "tenant_id", "client_id", "tally_guid", "rule_type", "rule_key", "nature_id", "ledger_name",
            name="uq_accounting_ledger_learning_rule",
        ),
    )

    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)
    tally_guid: Mapped[str] = mapped_column(String(120), nullable=False, default="", index=True)

    rule_type: Mapped[str] = mapped_column(String(40), nullable=False, index=True)
    rule_key: Mapped[str] = mapped_column(String(500), nullable=False, index=True)
    display_value: Mapped[str] = mapped_column(String(500), nullable=False, default="")

    nature_id: Mapped[int] = mapped_column(ForeignKey("accounting_natures.id", ondelete="RESTRICT"), nullable=False, index=True)
    ledger_name: Mapped[str] = mapped_column(String(240), nullable=False, default="")

    confirmation_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    rejection_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    confidence_percent: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, index=True)

    last_confirmed_by_user_id: Mapped[int | None] = mapped_column(ForeignKey("users.id", ondelete="SET NULL"), nullable=True)
    last_confirmed_at_utc: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    created_at_utc: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc), nullable=False)
    updated_at_utc: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        default=lambda: datetime.now(timezone.utc),
        onupdate=lambda: datetime.now(timezone.utc),
        nullable=False,
    )


class AccountingLedgerLearningEvent(CommonBase):
    """Immutable review feedback used to audit and improve ledger selection."""

    __tablename__ = "accounting_ledger_learning_events"

    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)
    tally_guid: Mapped[str] = mapped_column(String(120), nullable=False, default="", index=True)

    source_type: Mapped[str] = mapped_column(String(40), nullable=False, default="manual_review", index=True)
    supplier_name: Mapped[str] = mapped_column(String(240), nullable=False, default="", index=True)
    supplier_gstin: Mapped[str] = mapped_column(String(20), nullable=False, default="", index=True)
    hsn_code: Mapped[str] = mapped_column(String(20), nullable=False, default="", index=True)
    description_text: Mapped[str | None] = mapped_column(Text, nullable=True)
    amount: Mapped[float | None] = mapped_column(Float, nullable=True)

    suggested_nature_id: Mapped[int | None] = mapped_column(ForeignKey("accounting_natures.id", ondelete="SET NULL"), nullable=True, index=True)
    suggested_ledger_name: Mapped[str] = mapped_column(String(240), nullable=False, default="")
    suggested_confidence: Mapped[int] = mapped_column(Integer, nullable=False, default=0)

    final_nature_id: Mapped[int] = mapped_column(ForeignKey("accounting_natures.id", ondelete="RESTRICT"), nullable=False, index=True)
    final_ledger_name: Mapped[str] = mapped_column(String(240), nullable=False, default="")
    accepted_suggestion: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False, index=True)

    explanation_json: Mapped[str | None] = mapped_column(Text, nullable=True)
    business_profile_snapshot_json: Mapped[str | None] = mapped_column(Text, nullable=True)

    reviewed_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), default=lambda: datetime.now(timezone.utc), nullable=False, index=True)