"""
Model for terminal sessions - stores SSH terminal session metadata.
"""
from __future__ import annotations

from datetime import datetime
from typing import Optional

from sqlalchemy import DateTime, Index, Integer, String, text
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.sql import func

from .database import Base


# Session status constants
SESSION_STATUS_STARTING = "starting"
SESSION_STATUS_ACTIVE = "active"
SESSION_STATUS_CLOSING = "closing"
SESSION_STATUS_CLOSED = "closed"
SESSION_STATUS_EXPIRED = "expired"
SESSION_STATUS_ERROR = "error"

# Close reason constants
CLOSE_REASON_USER = "user_close"
CLOSE_REASON_TTL = "ttl"
CLOSE_REASON_IDLE = "idle"
CLOSE_REASON_QUOTA = "quota"
CLOSE_REASON_SERVER_SHUTDOWN = "server_shutdown"
CLOSE_REASON_CLIENT_LOST = "client_lost"
CLOSE_REASON_REUSED = "reused"


class TerminalSession(Base):
    """
    Represents an active or recent SSH terminal session.
    
    Sessions are created when a user opens a terminal to a host,
    and cleaned up after expiration or manual closure.
    
    Status lifecycle:
    - starting: Session being created, ttyd spawning
    - active: Session running, client connected
    - closing: Session being terminated
    - closed: Session terminated normally
    - expired: Session terminated due to TTL/idle timeout
    - error: Session terminated due to error
    """
    __tablename__ = "terminal_sessions"
    
    __table_args__ = (
        Index('ix_terminal_sessions_user_status', 'user_id', 'status'),
        Index('ix_terminal_sessions_last_seen', 'last_seen_at'),
    )

    id: Mapped[str] = mapped_column(String(64), primary_key=True)
    host_id: Mapped[str] = mapped_column(String, nullable=False, index=True)
    host_name: Mapped[str] = mapped_column(String, nullable=False)
    host_ip: Mapped[str] = mapped_column(String, nullable=False)
    user_id: Mapped[Optional[str]] = mapped_column(String, nullable=True)
    username: Mapped[Optional[str]] = mapped_column(String, nullable=True)
    
    # Token hash for session authentication (never store plain token)
    token_hash: Mapped[str] = mapped_column(String(128), nullable=False)
    
    # ttyd process management
    ttyd_port: Mapped[int] = mapped_column(Integer, nullable=False)
    ttyd_pid: Mapped[Optional[int]] = mapped_column(Integer, nullable=True)
    
    # Session mode: 'embedded' or 'popout'
    mode: Mapped[str] = mapped_column(String(20), nullable=False, server_default=text("'embedded'"))
    
    # Session status: 'starting', 'active', 'closing', 'closed', 'expired', 'error'
    status: Mapped[str] = mapped_column(String(20), nullable=False, server_default=text("'active'"))
    
    # Close reason: 'user_close', 'ttl', 'idle', 'quota', 'server_shutdown', 'client_lost', 'reused'
    reason_closed: Mapped[Optional[str]] = mapped_column(String(30), nullable=True)
    
    # Timestamps
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now()
    )
    last_seen_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now()
    )
    expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
    closed_at: Mapped[Optional[datetime]] = mapped_column(DateTime(timezone=True), nullable=True)

    def __repr__(self) -> str:
        return f"<TerminalSession id={self.id[:8]}... host={self.host_name} status={self.status}>"