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

class LicenseStatus(str, enum.Enum):
    active = "active"
    expired = "expired"
    revoked = "revoked"
    trial = "trial"

def generate_license_key() -> str:
    alphabet = string.ascii_uppercase + string.digits
    segments = ["TTUB"] + [
        "".join(secrets.choice(alphabet) for _ in range(5))
        for _ in range(3)
    ]
    return "-".join(segments)

class License(Base):
    __tablename__ = "licenses"

    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)
    key: Mapped[str] = mapped_column(String(50), unique=True, nullable=False, default=generate_license_key, index=True)
    status: Mapped[LicenseStatus] = mapped_column(SAEnum(LicenseStatus), default=LicenseStatus.trial, nullable=False)
    tier: Mapped[str] = mapped_column(String(20), default="standard", nullable=False)
    issued_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc))
    expires_at: Mapped[date | None] = mapped_column(Date, nullable=True)
    last_validated_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
    last_seen_ip: Mapped[str | None] = mapped_column(String(45), nullable=True)
    hardware_fingerprint: Mapped[str | None] = mapped_column(String(255), nullable=True)
    max_students: Mapped[int] = mapped_column(Integer, default=500, nullable=False)
    notes: Mapped[str | None] = mapped_column(Text, nullable=True)

    school: Mapped["School"] = relationship("School", back_populates="license")