import uuid
from sqlalchemy import Column, String, Integer, Numeric, Date, DateTime, ForeignKey, Index, UniqueConstraint
from sqlalchemy.orm import relationship
from utils.utils import Base, utc_now


class Loancalculation(Base):
    __tablename__ = "loan_calculations"

    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    principal = Column(Numeric(15, 2), nullable=False)
    annual_interest_rate = Column(Numeric(5, 2), nullable=False)
    loan_term_months = Column(Integer, nullable=False)
    monthly_payment = Column(Numeric(15, 2), nullable=False)
    total_payment = Column(Numeric(15, 2), nullable=False)
    total_interest = Column(Numeric(15, 2), nullable=False)
    session_id = Column(String(255), nullable=False, index=True)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)
    updated_at = Column(DateTime(timezone=True), default=utc_now, onupdate=utc_now, nullable=False)

    amortization_schedule_entries = relationship("Amortizationscheduleentry", back_populates="loan_calculation", cascade="all, delete-orphan", passive_deletes=True)


class Amortizationscheduleentry(Base):
    __tablename__ = "amortization_schedule_entries"

    id = Column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    calculation_id = Column(String(36), ForeignKey("loan_calculations.id", ondelete="CASCADE"), nullable=False, index=True)
    payment_number = Column(Integer, nullable=False)
    payment_date = Column(Date, nullable=False)
    beginning_balance = Column(Numeric(15, 2), nullable=False)
    payment_amount = Column(Numeric(15, 2), nullable=False)
    principal_portion = Column(Numeric(15, 2), nullable=False)
    interest_portion = Column(Numeric(15, 2), nullable=False)
    ending_balance = Column(Numeric(15, 2), nullable=False)
    created_at = Column(DateTime(timezone=True), default=utc_now, nullable=False)
    updated_at = Column(DateTime(timezone=True), default=utc_now, onupdate=utc_now, nullable=False)

    loan_calculation = relationship("Loancalculation", back_populates="amortization_schedule_entries")

    __table_args__ = (
        UniqueConstraint("calculation_id", "payment_number", name="uq_calculation_payment"),
        Index("ix_schedule_calculation_payment", "calculation_id", "payment_number"),
    )