"""History persistence for the 年假计算器.

Each invocation of the calculator writes one row capturing the full
computation graph: inputs, per-segment breakdown (formula + raw +
rounded), pre-cap totals, post-cap final values, used / carryover
balances, and the resulting unused balances. Used both for audit
defensibility (HR responds to employee questions with the exact numbers
they computed) and for spot-checking rule-engine regressions over time.
"""
from __future__ import annotations

import uuid
from datetime import date as date_type
from datetime import datetime
from decimal import Decimal

from sqlalchemy import CHAR, JSON, Boolean, Date, DateTime, Numeric, String, Text
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.sql import func

from app.core.database import Base


class HrToolsAnnualLeaveCalculation(Base):
    __tablename__ = "hr_tools_annual_leave_calculations"

    id: Mapped[str] = mapped_column(
        CHAR(36), primary_key=True, default=lambda: str(uuid.uuid4()),
    )

    # Subject of calculation
    person_id: Mapped[str | None] = mapped_column(CHAR(36), index=True)
    employee_no: Mapped[str | None] = mapped_column(String(64))
    employee_name: Mapped[str | None] = mapped_column(String(128))

    # Inputs
    work_start_date: Mapped[date_type] = mapped_column(Date, nullable=False)
    hire_date: Mapped[date_type] = mapped_column(Date, nullable=False)
    termination_date: Mapped[date_type] = mapped_column(Date, nullable=False)
    fiscal_year_start: Mapped[date_type] = mapped_column(Date, nullable=False)
    fiscal_year_end: Mapped[date_type] = mapped_column(Date, nullable=False)
    carry_legal_days: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    carry_welfare_days: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    used_legal_days: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    used_welfare_days: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)

    # Full-year entitlement (assumes employed all 365 days). One JSON
    # column per block — each segment carries both legal_basis and
    # welfare_basis, so a separate legal/welfare segment list would be
    # the same data twice. raw uses Numeric(8,4) so a future rule that
    # raises max combined entitlement past 99.99 days doesn't silently
    # overflow.
    full_year_segments: Mapped[list] = mapped_column(JSON, nullable=False)
    full_year_legal_raw: Mapped[Decimal] = mapped_column(Numeric(8, 4), nullable=False)
    full_year_welfare_raw: Mapped[Decimal] = mapped_column(Numeric(8, 4), nullable=False)
    full_year_legal_rounded: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    full_year_welfare_rounded: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    full_year_legal_capped: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    full_year_welfare_capped: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)

    # Prorated by actual employed days (settlement)
    settlement_segments: Mapped[list] = mapped_column(JSON, nullable=False)
    settlement_legal_raw: Mapped[Decimal] = mapped_column(Numeric(8, 4), nullable=False)
    settlement_welfare_raw: Mapped[Decimal] = mapped_column(Numeric(8, 4), nullable=False)
    settlement_legal_rounded: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    settlement_welfare_rounded: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    settlement_legal_capped: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    settlement_welfare_capped: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)

    # Final balance (capped settlement + carry - used)
    balance_legal_days: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)
    balance_welfare_days: Mapped[Decimal] = mapped_column(Numeric(4, 1), nullable=False)

    cap_applied_full_year: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
    cap_applied_settlement: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)

    # 基数 cap (2026-08-26) — the prorated result was pulled back to the
    # employee's own annual-leave basis. Kept SEPARATE from the 15-day
    # combined cap above because the two produce different explanations
    # to an employee disputing a settlement. Backfilled False on
    # existing rows, which is the truth: no row written before this
    # rule shipped ever had a 基数 cap applied to it.
    basis_cap_applied_full_year: Mapped[bool] = mapped_column(
        Boolean, nullable=False, default=False,
    )
    basis_cap_applied_settlement: Mapped[bool] = mapped_column(
        Boolean, nullable=False, default=False,
    )

    # Audit
    calculated_by_user_id: Mapped[str] = mapped_column(CHAR(36), nullable=False, index=True)
    calculated_by_name: Mapped[str] = mapped_column(String(128), nullable=False)
    notes: Mapped[str | None] = mapped_column(Text)
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now(),
    )