from __future__ import annotations

import uuid
from datetime import timedelta
from typing import Any

from syncgames.errors import LeaseHeldError
from syncgames.store import Meta, ObjectStore, parse_expires, utc_now


def lease_active(lease: dict[str, Any] | None) -> bool:
    if not lease:
        return False
    exp = parse_expires(lease.get("expires_at"))
    if exp is None:
        return False
    return exp > utc_now()


def acquire_lease(
    store: ObjectStore,
    game_id: str,
    device_id: str,
    *,
    ttl_hours: int,
    versions_to_keep: int,
    break_other: bool = False,
) -> Meta:
    meta = store.get_meta(game_id)
    if meta is None:
        from syncgames.store import empty_meta

        meta = empty_meta(game_id, versions_to_keep)

    lease = meta.lease
    if lease_active(lease) and lease and lease.get("holder") != device_id:
        if not break_other:
            raise LeaseHeldError(
                f"Lease held by {lease.get('holder')} until {lease.get('expires_at')}"
            )

    session_id = str(uuid.uuid4())
    expires = utc_now() + timedelta(hours=ttl_hours)
    meta.raw["lease"] = {
        "holder": device_id,
        "expires_at": expires.strftime("%Y-%m-%dT%H:%M:%SZ"),
        "session_id": session_id,
    }
    meta.raw["versions_to_keep"] = versions_to_keep
    store.put_meta(game_id, meta)
    # Re-read to reduce lost-update window (optimistic)
    again = store.get_meta(game_id)
    if again is None or not again.lease or again.lease.get("holder") != device_id:
        raise LeaseHeldError("Lost lease race — another device acquired the lease")
    return again


def release_lease(store: ObjectStore, game_id: str, device_id: str, meta: Meta | None = None) -> Meta:
    meta = meta or store.get_meta(game_id)
    if meta is None:
        from syncgames.store import empty_meta

        meta = empty_meta(game_id)
    lease = meta.lease
    if lease and lease.get("holder") not in (None, device_id):
        if lease_active(lease):
            raise LeaseHeldError(f"Cannot release lease owned by {lease.get('holder')}")
    meta.raw["lease"] = None
    store.put_meta(game_id, meta)
    return meta


def break_lease(store: ObjectStore, game_id: str) -> Meta:
    from syncgames.store import empty_meta

    meta = store.get_meta(game_id) or empty_meta(game_id)
    meta.raw["lease"] = None
    store.put_meta(game_id, meta)
    return meta