class SendJob(Base, TimestampMixin):
    __tablename__ = "send_jobs"
    id = Column(Integer, primary_key=True)
    campaign_id = Column(Integer, ForeignKey("campaigns.id", ondelete="CASCADE"), nullable=False, index=True)
    campaign_recipient_id = Column(Integer, ForeignKey("campaign_recipients.id", ondelete="CASCADE"), nullable=False, index=True)
    status = Column(String(30), default="queued")  # queued|processing|sent|failed|retrying|cancelled|dead
    attempts = Column(Integer, default=0)
    max_attempts = Column(Integer, default=3)
    retry_after = Column(DateTime(timezone=True))
    last_error = Column(Text, default="")
    locked_at = Column(DateTime(timezone=True))
    priority = Column(Integer, default=0)
    scheduled_at = Column(DateTime(timezone=True), default=utcnow, index=True)

    campaign = relationship("Campaign", back_populates="send_jobs")
    campaign_recipient = relationship("CampaignRecipient")


class SendAttempt(Base, TimestampMixin):
    __tablename__ = "send_attempts"
    id = Column(Integer, primary_key=True)
    send_job_id = Column(Integer, ForeignKey("send_jobs.id", ondelete="CASCADE"), nullable=False, index=True)
    campaign_id = Column(Integer, ForeignKey("campaigns.id", ondelete="CASCADE"), nullable=False, index=True)
    gmail_account_id = Column(Integer, ForeignKey("gmail_accounts.id", ondelete="SET NULL"))
    recipient_email = Column(String(320), nullable=False)
    subject = Column(String(500), default="")
    template_name = Column(String(250), default="")
    attachment_names = Column(JSON, default=list)
    method = Column(String(20), default="api")  # api|smtp
    outcome = Column(String(30), nullable=False)  # submitted|accepted|temp_failed|perm_failed|skipped
    provider_response = Column(Text, default="")   # sanitized provider response
    message_id = Column(String(200), default="")
    thread_id = Column(String(200), default="")
    retry_no = Column(Integer, default=0)
    failure_reason = Column(Text, default="")
    error_class = Column(String(60), default="")  # temporary|permanent|auth|quota|unknown

    send_job = relationship("SendJob")


class EmailEvent(Base, TimestampMixin):
    __tablename__ = "email_events"
    id = Column(Integer, primary_key=True)
    campaign_id = Column(Integer, ForeignKey("campaigns.id", ondelete="CASCADE"), index=True)
    campaign_recipient_id = Column(Integer, ForeignKey("campaign_recipients.id", ondelete="CASCADE"), index=True)
    gmail_account_id = Column(Integer, ForeignKey("gmail_accounts.id", ondelete="SET NULL"))
    event_type = Column(String(40), nullable=False)  # sent|failed|bounced|suppressed|unsubscribed|complained
    detail = Column(Text, default="")
    message_id = Column(String(200), default="")

    __table_args__ = (Index("ix_email_events_campaign", "campaign_id", "event_type"),)


class AuditLog(Base, TimestampMixin):