"""Session management for CLI."""

import json
import secrets
from dataclasses import asdict, dataclass
from datetime import datetime
from pathlib import Path
from typing import Any


@dataclass
class SessionData:
    """Local session data."""

    session_id: str
    name: str
    created_at: str
    last_active: str
    message_count: int = 0

    def to_dict(self) -> dict[str, Any]:
        """Convert to dictionary.

        Returns:
            dict: Session data as dictionary
        """
        return asdict(self)

    @classmethod
    def from_dict(cls, data: dict[str, Any]) -> "SessionData":
        """Create from dictionary.

        Args:
            data: Dictionary data

        Returns:
            SessionData: Session instance
        """
        return cls(**data)


class SessionManager:
    """Manages local CLI sessions."""

    def __init__(self, sessions_file: Path):
        """Initialize session manager.

        Args:
            sessions_file: Path to sessions file
        """
        self.sessions_file = sessions_file
        self.sessions: dict[str, SessionData] = {}
        self._load()

    def _load(self) -> None:
        """Load sessions from file."""
        if self.sessions_file.exists():
            try:
                with open(self.sessions_file, "r") as f:
                    data = json.load(f)

                self.sessions = {
                    name: SessionData.from_dict(session_data) for name, session_data in data.items()
                }
            except (json.JSONDecodeError, IOError) as e:
                print(f"Warning: Could not load sessions: {e}")
                self.sessions = {}

    def _save(self) -> None:
        """Save sessions to file."""
        self.sessions_file.parent.mkdir(parents=True, exist_ok=True)

        data = {name: session.to_dict() for name, session in self.sessions.items()}

        with open(self.sessions_file, "w") as f:
            json.dump(data, f, indent=2)

    def create_session(self, name: str = "default") -> SessionData:
        """Create or get a session.

        Args:
            name: Session name

        Returns:
            SessionData: Created or existing session
        """
        if name in self.sessions:
            return self.sessions[name]

        # Generate unique session ID
        session_id = f"cli_{name}_{secrets.token_hex(8)}"
        now = datetime.utcnow().isoformat()

        session = SessionData(
            session_id=session_id,
            name=name,
            created_at=now,
            last_active=now,
            message_count=0,
        )

        self.sessions[name] = session
        self._save()

        return session

    def get_session(self, name: str) -> SessionData | None:
        """Get a session by name.

        Args:
            name: Session name

        Returns:
            SessionData | None: Session or None if not found
        """
        return self.sessions.get(name)

    def get_or_create_session(self, name: str = "default") -> SessionData:
        """Get or create a session.

        Args:
            name: Session name

        Returns:
            SessionData: Session
        """
        session = self.get_session(name)
        if session:
            return session
        return self.create_session(name)

    def update_last_active(self, name: str) -> None:
        """Update session's last active time.

        Args:
            name: Session name
        """
        if name in self.sessions:
            self.sessions[name].last_active = datetime.utcnow().isoformat()
            self.sessions[name].message_count += 1
            self._save()

    def list_sessions(self) -> list[SessionData]:
        """List all sessions.

        Returns:
            list[SessionData]: All sessions
        """
        return sorted(self.sessions.values(), key=lambda s: s.last_active, reverse=True)

    def delete_session(self, name: str) -> bool:
        """Delete a session.

        Args:
            name: Session name

        Returns:
            bool: True if deleted, False if not found
        """
        if name in self.sessions:
            del self.sessions[name]
            self._save()
            return True
        return False