from __future__ import annotations

from dataclasses import dataclass, field, replace
from datetime import datetime, timedelta

from sources import Item
from state import AlertRecord


@dataclass(frozen=True)
class Notice:
    kind: str
    title: str
    detail: str
    path: str | None
    urgent: bool


@dataclass
class Plan:
    notices: list[Notice] = field(default_factory=list)
    records: list[AlertRecord] = field(default_factory=list)


def _reminder_due(item: Item, now: datetime) -> bool:
    return (
        item.opened_at is not None
        and item.reminder_after is not None
        and item.opened_at + item.reminder_after <= now
    )


def decide(
    now: datetime,
    seen: dict[str, tuple[str, Item]],
    known: dict[str, AlertRecord],
    checked_sources: set[str],
    realert: timedelta | None,
    notify_cleared: bool,
) -> Plan:
    plan = Plan()

    for key, (source, item) in seen.items():
        record = known.get(key)

        if record is None or not record.open:
            overdue = _reminder_due(item, now)
            plan.notices.append(Notice("new", item.title, item.detail, item.path, item.urgent))
            plan.records.append(AlertRecord(key, source, item.title, now, now, overdue, True))
            continue

        if not record.reminded and _reminder_due(item, now):
            opened = item.opened_at.strftime("%Y-%m-%d %H:%M UTC") if item.opened_at else "unknown"
            detail = f"{item.detail}\nOpen since {opened}"
            plan.notices.append(Notice("reminder", item.title, detail, item.path, item.urgent))
            plan.records.append(replace(record, last_alerted=now, reminded=True))
        elif realert is not None and now - record.last_alerted >= realert:
            plan.notices.append(Notice("repeat", item.title, item.detail, item.path, item.urgent))
            plan.records.append(replace(record, last_alerted=now))

    for key, record in known.items():
        if not record.open or key in seen or record.source not in checked_sources:
            continue
        plan.records.append(replace(record, open=False))
        if notify_cleared:
            plan.notices.append(Notice("cleared", record.title, "No longer open in the admin UI.", None, False))

    return plan