import secrets
from datetime import UTC, datetime, timedelta

from fastapi_oidc_op.models import MagicLink
from fastapi_oidc_op.store.protocols import MagicLinkRepository


class MagicLinkService:
    """Magic link token lifecycle management."""

    def __init__(self, repo: MagicLinkRepository, ttl: int = 86400) -> None:
        self._repo = repo
        self._ttl = ttl

    async def create(
        self,
        username: str,
        created_by: str | None = None,
        note: str | None = None,
    ) -> MagicLink:
        """Generate and store a new magic link for the given username."""
        token = secrets.token_urlsafe(32)
        expires_at = datetime.now(UTC) + timedelta(seconds=self._ttl)
        link = MagicLink(
            token=token,
            username=username,
            expires_at=expires_at,
            created_by=created_by,
            note=note,
        )
        return await self._repo.create(link)

    async def validate(self, token: str) -> MagicLink | None:
        """Validate a magic link token.

        Returns the MagicLink if it exists, is not used, and has not expired.
        Returns None otherwise.
        """
        link = await self._repo.get_by_token(token)
        if link is None or link.used:
            return None
        if link.expires_at < datetime.now(UTC):
            return None
        return link

    async def mark_used(self, token: str) -> bool:
        """Mark a magic link as used. Returns True if found and marked."""
        return await self._repo.mark_used(token)

    async def cleanup_expired(self) -> int:
        """Delete expired unused links. Returns count deleted."""
        return await self._repo.delete_expired()