"""Multi-agent registry.

Holds multiple Agent instances keyed by name. The first registered
agent is the default (used by scheduler and as fallback).
"""

from __future__ import annotations

import logging
from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from .agent import Agent

log = logging.getLogger(__name__)


class AgentRegistry:
    """Registry of named Agent instances."""

    def __init__(self):
        self._agents: dict[str, Agent] = {}
        self._default_name: str | None = None

    def register(self, name: str, agent: Agent, is_default: bool = False):
        """Register an agent by name."""
        self._agents[name] = agent
        if is_default or self._default_name is None:
            self._default_name = name
        log.info("Registered agent: %s (default=%s)", name, name == self._default_name)

    def get(self, name: str) -> Agent | None:
        return self._agents.get(name)

    def list_agents(self) -> list[str]:
        return list(self._agents.keys())

    @property
    def default(self) -> Agent | None:
        if self._default_name:
            return self._agents.get(self._default_name)
        return None

    @property
    def default_name(self) -> str:
        return self._default_name or "default"

    def __len__(self) -> int:
        return len(self._agents)