"""
KPI 表單 Model
"""
from datetime import datetime
from decimal import Decimal
from typing import Optional, List, TYPE_CHECKING

from sqlalchemy import String, Integer, DateTime, Text, Numeric, ForeignKey
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.core.database import Base

if TYPE_CHECKING:
    from app.models.employee import Employee
    from app.models.kpi_period import KPIPeriod
    from app.models.department import Department
    from app.models.kpi_item import KPIItem
    from app.models.kpi_review_log import KPIReviewLog


# KPI 表單狀態
class KPISheetStatus:
    DRAFT = "draft"              # 草稿
    PENDING = "pending"          # 待審核
    APPROVED = "approved"        # 已核准
    SELF_EVAL = "self_eval"      # 自評中
    MANAGER_EVAL = "manager_eval"  # 主管評核中
    COMPLETED = "completed"      # 已完成
    SETTLED = "settled"          # 已結算


# 狀態轉換規則
VALID_STATUS_TRANSITIONS = {
    KPISheetStatus.DRAFT: [KPISheetStatus.PENDING],
    KPISheetStatus.PENDING: [KPISheetStatus.APPROVED, KPISheetStatus.DRAFT],
    KPISheetStatus.APPROVED: [KPISheetStatus.SELF_EVAL],
    KPISheetStatus.SELF_EVAL: [KPISheetStatus.MANAGER_EVAL],
    KPISheetStatus.MANAGER_EVAL: [KPISheetStatus.COMPLETED],
    KPISheetStatus.COMPLETED: [KPISheetStatus.SETTLED],
    KPISheetStatus.SETTLED: [],
}


class KPISheet(Base):
    """KPI 表單"""

    __tablename__ = "KPI_D_sheets"

    id: Mapped[int] = mapped_column(primary_key=True)
    employee_id: Mapped[int] = mapped_column(ForeignKey("KPI_D_employees.id"), nullable=False)
    period_id: Mapped[int] = mapped_column(ForeignKey("KPI_D_periods.id"), nullable=False)
    department_id: Mapped[int] = mapped_column(ForeignKey("KPI_D_departments.id"), nullable=False)
    status: Mapped[str] = mapped_column(String(20), default=KPISheetStatus.DRAFT)

    # 提交資訊
    submitted_at: Mapped[Optional[datetime]] = mapped_column(DateTime)

    # 審核資訊
    approved_by: Mapped[Optional[int]] = mapped_column(ForeignKey("KPI_D_employees.id"))
    approved_at: Mapped[Optional[datetime]] = mapped_column(DateTime)
    approve_comment: Mapped[Optional[str]] = mapped_column(Text)

    # 退回資訊
    rejected_by: Mapped[Optional[int]] = mapped_column(ForeignKey("KPI_D_employees.id"))
    rejected_at: Mapped[Optional[datetime]] = mapped_column(DateTime)
    reject_reason: Mapped[Optional[str]] = mapped_column(Text)

    # 自評資訊
    self_eval_at: Mapped[Optional[datetime]] = mapped_column(DateTime)

    # 主管評核資訊
    manager_eval_by: Mapped[Optional[int]] = mapped_column(ForeignKey("KPI_D_employees.id"))
    manager_eval_at: Mapped[Optional[datetime]] = mapped_column(DateTime)
    manager_eval_comment: Mapped[Optional[str]] = mapped_column(Text)

    # 分數
    total_score: Mapped[Optional[Decimal]] = mapped_column(Numeric(5, 4))

    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    # Relationships
    employee: Mapped["Employee"] = relationship(
        "Employee", back_populates="kpi_sheets", foreign_keys=[employee_id]
    )
    period: Mapped["KPIPeriod"] = relationship("KPIPeriod", back_populates="kpi_sheets")
    department: Mapped["Department"] = relationship("Department")
    items: Mapped[List["KPIItem"]] = relationship(
        "KPIItem", back_populates="sheet", cascade="all, delete-orphan"
    )
    review_logs: Mapped[List["KPIReviewLog"]] = relationship(
        "KPIReviewLog", back_populates="sheet", cascade="all, delete-orphan"
    )
    approver: Mapped[Optional["Employee"]] = relationship("Employee", foreign_keys=[approved_by])
    rejecter: Mapped[Optional["Employee"]] = relationship("Employee", foreign_keys=[rejected_by])
    manager_evaluator: Mapped[Optional["Employee"]] = relationship("Employee", foreign_keys=[manager_eval_by])

    def can_transition_to(self, new_status: str) -> bool:
        """檢查是否可以轉換到指定狀態"""
        return new_status in VALID_STATUS_TRANSITIONS.get(self.status, [])

    def __repr__(self) -> str:
        return f"<KPISheet id={self.id} employee={self.employee_id} period={self.period_id} status={self.status}>"