import uuid
import enum
from datetime import datetime, timezone, date
from sqlalchemy import String, Boolean, DateTime, Date, Enum as SAEnum, ForeignKey, Text, Numeric, Integer
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.database import Base

class InvoiceStatus(str, enum.Enum):
    draft = "draft"
    sent = "sent"
    paid = "paid"
    overdue = "overdue"
    cancelled = "cancelled"

class BillingCycle(str, enum.Enum):
    monthly = "monthly"
    annual = "annual"

class Invoice(Base):
    __tablename__ = "invoices"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    school_id: Mapped[str] = mapped_column(String(36), ForeignKey("schools.id", ondelete="CASCADE"), nullable=False, index=True)
    invoice_number: Mapped[str] = mapped_column(String(30), unique=True, nullable=False)
    status: Mapped[InvoiceStatus] = mapped_column(SAEnum(InvoiceStatus), default=InvoiceStatus.draft, nullable=False)
    billing_period_start: Mapped[date] = mapped_column(Date, nullable=False)
    billing_period_end: Mapped[date] = mapped_column(Date, nullable=False)
    subscription_amount: Mapped[float] = mapped_column(Numeric(12, 2), default=0.0, nullable=False)
    sms_credit_amount: Mapped[float] = mapped_column(Numeric(12, 2), default=0.0, nullable=False)
    other_amount: Mapped[float] = mapped_column(Numeric(12, 2), default=0.0, nullable=False)
    total_amount: Mapped[float] = mapped_column(Numeric(12, 2), nullable=False)
    currency: Mapped[str] = mapped_column(String(3), default="PHP", nullable=False)
    due_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    paid_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    payment_method: Mapped[str | None] = mapped_column(String(50), nullable=True)
    payment_reference: Mapped[str | None] = mapped_column(String(100), nullable=True)
    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
    pdf_path: Mapped[str | None] = mapped_column(String(255), nullable=True)
    email_sent_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc))

    school: Mapped["School"] = relationship("School", back_populates="invoices")
    line_items: Mapped[list["InvoiceLineItem"]] = relationship("InvoiceLineItem", back_populates="invoice", cascade="all, delete-orphan")

class InvoiceLineItem(Base):
    __tablename__ = "invoice_line_items"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    invoice_id: Mapped[str] = mapped_column(String(36), ForeignKey("invoices.id", ondelete="CASCADE"), nullable=False)
    description: Mapped[str] = mapped_column(String(255), nullable=False)
    quantity: Mapped[float] = mapped_column(Numeric(10, 2), default=1.0, nullable=False)
    unit_price: Mapped[float] = mapped_column(Numeric(12, 2), nullable=False)
    amount: Mapped[float] = mapped_column(Numeric(12, 2), nullable=False)

    invoice: Mapped[Invoice] = relationship("Invoice", back_populates="line_items")

class SchoolSubscription(Base):
    """Stores billing plan per school."""
    __tablename__ = "school_subscriptions"

    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
    school_id: Mapped[str] = mapped_column(String(36), ForeignKey("schools.id", ondelete="CASCADE"), unique=True, nullable=False)
    cycle: Mapped[BillingCycle] = mapped_column(SAEnum(BillingCycle), default=BillingCycle.monthly, nullable=False)
    monthly_fee: Mapped[float] = mapped_column(Numeric(12, 2), default=0.0, nullable=False)
    sms_cost_per_message: Mapped[float] = mapped_column(Numeric(8, 4), default=1.0, nullable=False)
    next_billing_date: Mapped[date | None] = mapped_column(Date, nullable=True)
    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc))