from datetime import datetime
from sqlalchemy import Column, Integer, String, Float, DateTime, ForeignKey, Enum, Text, JSON
from sqlalchemy.orm import relationship, DeclarativeBase
import enum


class Base(DeclarativeBase):
    pass


class UserRole(str, enum.Enum):
    USER = "user"
    ADMIN = "admin"


class UserStatus(str, enum.Enum):
    ACTIVE = "active"
    PENDING = "pending"
    DISABLED = "disabled"


class DebtStatus(str, enum.Enum):
    ACTIVE = "active"
    PAID = "paid"
    OVERDUE = "overdue"
    CLOSED = "closed"


class RateType(str, enum.Enum):
    ANNUAL = "annual"
    MONTHLY = "monthly"


class RepaymentMethod(str, enum.Enum):
    EQUAL_INSTALLMENT = "equal_installment"
    INTEREST_FIRST = "interest_first"
    LUMP_SUM = "lump_sum"


class PlanStatus(str, enum.Enum):
    PENDING = "pending"
    PAID = "paid"
    OVERDUE = "overdue"


class NotificationType(str, enum.Enum):
    REPAYMENT_DUE = "repayment_due"
    REPAYMENT_OVERDUE = "repayment_overdue"
    SYSTEM = "system"
    ACCOUNT = "account"


class Group(Base):
    __tablename__ = "groups"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String(100), nullable=False)
    description = Column(Text, default="")
    created_at = Column(DateTime, default=lambda: datetime.utcnow())

    members = relationship("User", back_populates="group")


class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True, index=True)
    email = Column(String(255), unique=True, index=True, nullable=False)
    real_email = Column(String(255), default="")
    password_hash = Column(String(255), nullable=False)
    nickname = Column(String(100), default="")
    role = Column(String(20), default=UserRole.USER.value)
    status = Column(String(20), default=UserStatus.ACTIVE.value)
    group_id = Column(Integer, ForeignKey("groups.id"), nullable=True)
    created_at = Column(DateTime, default=lambda: datetime.utcnow())

    group = relationship("Group", back_populates="members")
    debts = relationship("Debt", back_populates="user")
    audit_logs = relationship("AuditLog", back_populates="user")


class Debt(Base):
    __tablename__ = "debts"

    id = Column(Integer, primary_key=True, index=True)
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
    creditor_name = Column(String(255), nullable=False)
    amount = Column(Integer, nullable=False)
    borrow_date = Column(DateTime, nullable=False)
    interest_rate = Column(Float, nullable=False)
    rate_type = Column(String(20), default=RateType.ANNUAL.value)
    repayment_method = Column(String(30), nullable=False)
    period_count = Column(Integer, nullable=False)
    period_unit = Column(String(10), default="month")
    status = Column(String(20), default=DebtStatus.ACTIVE.value)
    purpose = Column(String(255), default="")
    notes = Column(Text, default="")
    created_at = Column(DateTime, default=lambda: datetime.utcnow())
    schedule_data = Column(JSON, default=list)
    paid_periods = Column(JSON, default=list)

    user = relationship("User", back_populates="debts")
    plans = relationship("RepaymentPlan", back_populates="debt", cascade="all, delete-orphan")
    records = relationship("RepaymentRecord", back_populates="debt", cascade="all, delete-orphan")


class RepaymentPlan(Base):
    __tablename__ = "repayment_plans"

    id = Column(Integer, primary_key=True, index=True)
    debt_id = Column(Integer, ForeignKey("debts.id"), nullable=False)
    due_date = Column(DateTime, nullable=False)
    principal_due = Column(Integer, nullable=False)
    interest_due = Column(Integer, nullable=False)
    total_due = Column(Integer, nullable=False)
    status = Column(String(20), default=PlanStatus.PENDING.value)

    debt = relationship("Debt", back_populates="plans")
    records = relationship("RepaymentRecord", back_populates="plan")


class RepaymentRecord(Base):
    __tablename__ = "repayment_records"

    id = Column(Integer, primary_key=True, index=True)
    debt_id = Column(Integer, ForeignKey("debts.id"), nullable=False)
    plan_id = Column(Integer, ForeignKey("repayment_plans.id"), nullable=True)
    amount = Column(Integer, nullable=False)
    paid_date = Column(DateTime, nullable=False)
    notes = Column(Text, default="")
    created_at = Column(DateTime, default=lambda: datetime.utcnow())

    debt = relationship("Debt", back_populates="records")
    plan = relationship("RepaymentPlan", back_populates="records")


class SystemSetting(Base):
    __tablename__ = "system_settings"

    key = Column(String(100), primary_key=True)
    value = Column(Text, nullable=False)


class AuditLog(Base):
    __tablename__ = "audit_logs"

    id = Column(Integer, primary_key=True, index=True)
    user_id = Column(Integer, ForeignKey("users.id"), nullable=True)
    action = Column(String(50), nullable=False)
    target_type = Column(String(50), default="")
    target_id = Column(Integer, nullable=True)
    details = Column(JSON, default=dict)
    created_at = Column(DateTime, default=lambda: datetime.utcnow())

    user = relationship("User", back_populates="audit_logs")


class Notification(Base):
    __tablename__ = "notifications"

    id = Column(Integer, primary_key=True, index=True)
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True)
    title = Column(String(255), nullable=False)
    message = Column(Text, nullable=False)
    type = Column(String(30), default=NotificationType.SYSTEM.value)
    is_read = Column(Integer, default=0)
    related_debt_id = Column(Integer, nullable=True)
    related_plan_id = Column(Integer, nullable=True)
    created_at = Column(DateTime, default=lambda: datetime.utcnow())

    user = relationship("User", backref="notifications")