import json
import time
from dataclasses import asdict, dataclass
from pathlib import Path

from engine import runtime
from engine.stored import read_json, write_json

COUNTDOWN = 10.0
CHECK_EVERY = 0.25
STATE = "update-countdown.json"
STARTING_FOR = 120.0


def state(root: Path) -> Path:
    return runtime.folder(root) / STATE


def remaining(root: Path) -> dict:
    """The automatic update counting down, with the seconds it has left, or starting until its upgrade holds the mark; nothing when none is."""
    held = read_json(state(root), dict, {})
    version, until, now = held.get("version"), float(held.get("until", 0)), time.time()
    if not version:
        return {}
    if held.get("starting") and runtime.upgrading(root):
        cancel(root)
        return {}
    if held.get("starting"):
        return {} if now - until > STARTING_FOR else {"version": version, "seconds": 0, "starting": True}
    return {"version": version, "seconds": max(0, round(until - now))} if until - now > -1 else {}


@dataclass(frozen=True)
class UpdateState:
    """What a screen needs to know to cover itself: an upgrade under way and its step, the server still booting, an update counting down."""

    updating: bool
    ready: bool
    step: str
    countdown: dict


def update_state(root: Path) -> dict:
    return asdict(UpdateState(runtime.upgrading(root), not runtime.booting(root), runtime.upgrade_step(root) or runtime.boot_step(root), remaining(root)))


def cancel(root: Path) -> None:
    state(root).unlink(missing_ok=True)


def wait(root: Path, version: str, seconds: float = COUNTDOWN, every: float = CHECK_EVERY) -> bool:
    """Counts down before an automatic update and says whether it runs: false when it was cancelled meanwhile."""
    write_json(state(root), {"version": version, "until": time.time() + seconds})
    until = time.time() + seconds
    while time.time() < until:
        if read_json(state(root), dict, {}).get("version") != version:
            return False
        time.sleep(every)
    write_json(state(root), {"version": version, "until": until, "starting": True})
    return True