"""Send transport interface.

Pluggable Transport interface for the outbox send operation.
Default EchoTransport records the payload and marks as sent.
No real email in POC.
"""

from __future__ import annotations

from datetime import datetime, timezone
from typing import Any, Protocol


class Transport(Protocol):
    def send(self, payload: dict[str, Any]) -> dict[str, Any]:
        """Send a payload. Returns a result dict with at least 'success' bool."""
        ...


class EchoTransport:
    """Default transport: records payload, returns success.

    No real email is sent. Used for POC.
    """

    def __init__(self) -> None:
        self.sent: list[dict[str, Any]] = []

    def send(self, payload: dict[str, Any]) -> dict[str, Any]:
        self.sent.append(payload)
        return {
            "success": True,
            "sent_at": datetime.now(timezone.utc).isoformat(),
            "echo": payload,
        }


# Singleton instance
_default_transport: Transport | None = None


def get_transport() -> Transport:
    global _default_transport
    if _default_transport is None:
        _default_transport = EchoTransport()
    return _default_transport


def set_transport(t: Transport) -> None:
    global _default_transport
    _default_transport = t