from __future__ import annotations

import uuid
from datetime import date, datetime
from decimal import Decimal
from typing import Any

from sqlalchemy import Date, DateTime, ForeignKey, Integer, Numeric, String, Text, func
from sqlalchemy.orm import Mapped, mapped_column, relationship
from sqlalchemy.types import JSON

from app.db.base_class import Base


class ExpenseClaim(Base):
    __tablename__ = "expense_claims"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    claim_no: Mapped[str] = mapped_column(String(50), unique=True, index=True)
    employee_id: Mapped[str | None] = mapped_column(
        ForeignKey("employees.id"), nullable=True, index=True
    )
    employee_name: Mapped[str] = mapped_column(String(100), index=True)
    department_id: Mapped[str | None] = mapped_column(
        ForeignKey("organization_units.id"), nullable=True, index=True
    )
    department_name: Mapped[str] = mapped_column(String(100), index=True)
    project_code: Mapped[str | None] = mapped_column(String(50), nullable=True)
    expense_type: Mapped[str] = mapped_column(String(50), index=True)
    reason: Mapped[str] = mapped_column(Text())
    location: Mapped[str] = mapped_column(String(100))
    amount: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    currency: Mapped[str] = mapped_column(String(10), default="CNY")
    invoice_count: Mapped[int] = mapped_column(Integer, default=0)
    occurred_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), index=True)
    submitted_at: Mapped[datetime | None] = mapped_column(
        DateTime(timezone=True), nullable=True, index=True
    )
    status: Mapped[str] = mapped_column(String(30), index=True)
    approval_stage: Mapped[str | None] = mapped_column(String(50), nullable=True)
    risk_flags_json: Mapped[list[Any]] = mapped_column(JSON, default=list)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
    )

    employee = relationship("Employee", foreign_keys=[employee_id])
    items = relationship(
        "ExpenseClaimItem",
        back_populates="claim",
        cascade="all, delete-orphan",
        order_by="asc(ExpenseClaimItem.item_date)",
    )

    @property
    def employee_position(self) -> str | None:
        return str(self.employee.position).strip() if self.employee is not None and self.employee.position else None

    @property
    def employee_grade(self) -> str | None:
        return str(self.employee.grade).strip() if self.employee is not None and self.employee.grade else None

    @property
    def manager_name(self) -> str | None:
        if self.employee is None:
            return None
        if self.employee.manager is not None and self.employee.manager.name:
            return str(self.employee.manager.name).strip() or None
        return None

    @property
    def role_labels(self) -> list[str]:
        if self.employee is None or not self.employee.roles:
            return []
        return [str(role.name).strip() for role in sorted(self.employee.roles, key=lambda item: item.name) if role.name]


class ExpenseClaimItem(Base):
    __tablename__ = "expense_claim_items"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    claim_id: Mapped[str] = mapped_column(ForeignKey("expense_claims.id"), index=True)
    item_date: Mapped[date] = mapped_column(Date(), index=True)
    item_type: Mapped[str] = mapped_column(String(50))
    item_reason: Mapped[str] = mapped_column(Text())
    item_location: Mapped[str] = mapped_column(String(100))
    item_amount: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    invoice_id: Mapped[str | None] = mapped_column(String(100), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
    )

    claim = relationship("ExpenseClaim", back_populates="items")

    @property
    def is_system_generated(self) -> bool:
        return str(self.item_type or "").strip().lower() in {"travel_allowance"}


class AccountsReceivableRecord(Base):
    __tablename__ = "accounts_receivable"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    receivable_no: Mapped[str] = mapped_column(String(50), unique=True, index=True)
    customer_id: Mapped[str] = mapped_column(String(64), index=True)
    customer_name: Mapped[str] = mapped_column(String(120), index=True)
    contract_no: Mapped[str | None] = mapped_column(String(100), nullable=True)
    invoice_no: Mapped[str | None] = mapped_column(String(100), nullable=True)
    amount_receivable: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    amount_received: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    amount_outstanding: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    currency: Mapped[str] = mapped_column(String(10), default="CNY")
    posting_date: Mapped[date] = mapped_column(Date(), index=True)
    due_date: Mapped[date] = mapped_column(Date(), index=True)
    aging_days: Mapped[int] = mapped_column(Integer, default=0)
    status: Mapped[str] = mapped_column(String(30), index=True)
    risk_flags_json: Mapped[list[Any]] = mapped_column(JSON, default=list)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
    )


class AccountsPayableRecord(Base):
    __tablename__ = "accounts_payable"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    payable_no: Mapped[str] = mapped_column(String(50), unique=True, index=True)
    vendor_id: Mapped[str] = mapped_column(String(64), index=True)
    vendor_name: Mapped[str] = mapped_column(String(120), index=True)
    invoice_no: Mapped[str | None] = mapped_column(String(100), nullable=True)
    amount_payable: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    amount_paid: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    amount_outstanding: Mapped[Decimal] = mapped_column(Numeric(12, 2))
    currency: Mapped[str] = mapped_column(String(10), default="CNY")
    posting_date: Mapped[date] = mapped_column(Date(), index=True)
    due_date: Mapped[date] = mapped_column(Date(), index=True)
    aging_days: Mapped[int] = mapped_column(Integer, default=0)
    status: Mapped[str] = mapped_column(String(30), index=True)
    risk_flags_json: Mapped[list[Any]] = mapped_column(JSON, default=list)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
    )