import { NextResponse } from "next/server";
import { fetchServerForecast } from "@/lib/server-forecast";
import { fetchMeteoWarnings } from "@/lib/server-warnings";
import {
  getPushSubscriptions,
  hasSentMorningBrief,
  markMorningBriefSent,
  removePushSubscription,
} from "@/lib/push-store";
import { isWebPushConfigured, sendMorningBriefNotification } from "@/lib/push-service";
import { buildWeatherBrief } from "@/lib/weather-brief";
import { DEFAULT_TEMPERATURE_UNIT, DEFAULT_WIND_SPEED_UNIT } from "@/lib/weather-utils";

export const runtime = "nodejs";

function isCronAuthorized(request: Request) {
  const secret = process.env.NOTIFICATIONS_CRON_SECRET;
  if (!secret) return process.env.NODE_ENV !== "production";
  const authHeader = request.headers.get("authorization");
  const secretHeader = request.headers.get("x-cron-secret");
  return authHeader === `Bearer ${secret}` || secretHeader === secret;
}

const DEFAULT_MORNING_BRIEF_TIME = "07:00";

function normalizeTime(value: string | undefined, fallback: string) {
  return value && /^\d{2}:\d{2}$/.test(value) ? value : fallback;
}

function getLocalDateParts(timeZone: string | null, date = new Date()) {
  const parts = new Intl.DateTimeFormat("en-CA", {
    timeZone: timeZone || "Europe/Warsaw",
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
    hour: "2-digit",
    minute: "2-digit",
    hourCycle: "h23",
  }).formatToParts(date);
  const part = (type: Intl.DateTimeFormatPartTypes) => parts.find((entry) => entry.type === type)?.value ?? "";
  return {
    dateKey: `${part("year")}-${part("month")}-${part("day")}`,
    time: `${part("hour")}:${part("minute")}`,
  };
}

export async function GET(request: Request) {
  if (!isCronAuthorized(request)) {
    return NextResponse.json({ error: "Unauthorized." }, { status: 401 });
  }
  if (!isWebPushConfigured()) {
    return NextResponse.json({ error: "Web Push is not configured." }, { status: 503 });
  }

  const now = new Date();
  const briefTime = normalizeTime(process.env.NOTIFICATIONS_MORNING_BRIEF_TIME, DEFAULT_MORNING_BRIEF_TIME);
  const subscriptions = getPushSubscriptions().filter(
    (subscription) =>
      subscription.morningBriefEnabled &&
      Number.isFinite(subscription.latitude) &&
      Number.isFinite(subscription.longitude),
  );
  let warningsUnavailable = false;
  const hasPolishSubscriptions = subscriptions.some((subscription) => subscription.region === "PL");
  const warnings = hasPolishSubscriptions
    ? await fetchMeteoWarnings(AbortSignal.timeout(12_000)).catch(() => {
        warningsUnavailable = true;
        return [];
      })
    : [];
  let sent = 0;
  let skipped = 0;
  let failed = 0;

  for (const subscription of subscriptions) {
    const localTime = getLocalDateParts(subscription.timezone, now);
    if (localTime.time < briefTime) {
      skipped += 1;
      continue;
    }
    const dateKey = localTime.dateKey;
    if (hasSentMorningBrief(subscription.endpoint, dateKey)) {
      skipped += 1;
      continue;
    }

    try {
      const forecast = await fetchServerForecast(
        subscription.latitude as number,
        subscription.longitude as number,
        subscription.region,
      );
      const brief = buildWeatherBrief({
        forecast,
        warnings: subscription.region === "PL" ? warnings : [],
        province: subscription.province,
        countyTeryt: subscription.region === "PL" ? subscription.countyTeryt : null,
        locationName: subscription.locationName ?? "wtr.",
        language: subscription.language,
        temperatureUnit: subscription.temperatureUnit ?? DEFAULT_TEMPERATURE_UNIT,
        windSpeedUnit: subscription.windSpeedUnit ?? DEFAULT_WIND_SPEED_UNIT,
        now,
      });
      if (!brief) {
        skipped += 1;
        continue;
      }
      await sendMorningBriefNotification(subscription, brief);
      markMorningBriefSent(subscription.endpoint, dateKey);
      sent += 1;
    } catch (error) {
      failed += 1;
      const statusCode =
        typeof error === "object" && error !== null && "statusCode" in error ? Number(error.statusCode) : null;
      if (statusCode === 404 || statusCode === 410) removePushSubscription(subscription.endpoint);
    }
  }

  return NextResponse.json({
    ok: true,
    time: briefTime,
    subscriptions: subscriptions.length,
    warningsUnavailable,
    sent,
    skipped,
    failed,
  });
}