import AsyncStorage from "@react-native-async-storage/async-storage";
import * as Notifications from "expo-notifications";
import { Platform } from "react-native";

const REMINDER_PREFIX = "invoice-send-reminder:";
const FIRED_PREFIX = "invoice-reminder-fired:";

export type InvoiceSendReminderSource = {
  id: string;
  status: string;
  invoiceNumber: string;
  invoicePrefix: string | null;
  sendReminderAt: Date | string | null | undefined;
  client?: { name: string } | null;
};

export function invoiceSendReminderNotificationId(invoiceId: string) {
  return `${REMINDER_PREFIX}${invoiceId}`;
}

Notifications.setNotificationHandler({
  handleNotification: async () => ({
    shouldShowAlert: true,
    shouldPlaySound: true,
    shouldSetBadge: false,
    shouldShowBanner: true,
    shouldShowList: true,
  }),
});

async function ensureAndroidChannel() {
  if (Platform.OS !== "android") return;
  await Notifications.setNotificationChannelAsync("invoice-reminders", {
    name: "Invoice reminders",
    importance: Notifications.AndroidImportance.HIGH,
    sound: "default",
    vibrationPattern: [0, 250, 250, 250],
  });
}

export async function ensureNotificationPermissions(): Promise<boolean> {
  if (Platform.OS === "web") return false;

  await ensureAndroidChannel();

  const { status: existing } = await Notifications.getPermissionsAsync();
  if (existing === "granted") return true;

  const { status } = await Notifications.requestPermissionsAsync({
    ios: {
      allowAlert: true,
      allowBadge: false,
      allowSound: true,
    },
  });

  return status === "granted";
}

function reminderContent(invoice: InvoiceSendReminderSource): Notifications.NotificationContentInput {
  const label = `${invoice.invoicePrefix ?? "#"}${invoice.invoiceNumber}`;
  const clientName = invoice.client?.name ?? "your client";

  return {
    title: "Time to send invoice",
    body: `${label} for ${clientName} is ready to send.`,
    data: {
      invoiceId: invoice.id,
      type: "invoice-send-reminder",
    },
    sound: true,
    ...(Platform.OS === "android" ? { channelId: "invoice-reminders" } : {}),
  };
}

export async function syncInvoiceSendReminders(invoices: InvoiceSendReminderSource[]) {
  if (Platform.OS === "web") return;

  const granted = await ensureNotificationPermissions();
  if (!granted) return;

  const scheduled = await Notifications.getAllScheduledNotificationsAsync();
  const ourScheduled = new Set(
    scheduled
      .map((entry) => entry.identifier)
      .filter((id): id is string => Boolean(id?.startsWith(REMINDER_PREFIX))),
  );

  const wanted = new Set<string>();
  const now = Date.now();

  for (const invoice of invoices) {
    if (invoice.status !== "draft" || !invoice.sendReminderAt) continue;

    const notificationId = invoiceSendReminderNotificationId(invoice.id);
    wanted.add(notificationId);

    const reminderAt = new Date(invoice.sendReminderAt);
    const reminderMs = reminderAt.getTime();
    if (Number.isNaN(reminderMs)) continue;

    const firedKey = `${FIRED_PREFIX}${invoice.id}`;
    const firedAt = await AsyncStorage.getItem(firedKey);
    const content = reminderContent(invoice);

    await Notifications.cancelScheduledNotificationAsync(notificationId).catch(() => {});

    if (reminderMs <= now) {
      const alreadyFiredForThisDate = firedAt === reminderAt.toISOString();
      if (alreadyFiredForThisDate) continue;

      await Notifications.scheduleNotificationAsync({
        identifier: notificationId,
        content,
        trigger: {
          type: Notifications.SchedulableTriggerInputTypes.TIME_INTERVAL,
          seconds: 2,
        },
      });
      await AsyncStorage.setItem(firedKey, reminderAt.toISOString());
      continue;
    }

    if (firedAt && firedAt !== reminderAt.toISOString()) {
      await AsyncStorage.removeItem(firedKey);
    }

    await Notifications.scheduleNotificationAsync({
      identifier: notificationId,
      content,
      trigger: {
        type: Notifications.SchedulableTriggerInputTypes.DATE,
        date: reminderAt,
      },
    });
  }

  for (const notificationId of ourScheduled) {
    if (wanted.has(notificationId)) continue;
    await Notifications.cancelScheduledNotificationAsync(notificationId).catch(() => {});
    const invoiceId = notificationId.slice(REMINDER_PREFIX.length);
    await AsyncStorage.removeItem(`${FIRED_PREFIX}${invoiceId}`);
  }
}

export async function cancelInvoiceSendReminder(invoiceId: string) {
  if (Platform.OS === "web") return;
  const notificationId = invoiceSendReminderNotificationId(invoiceId);
  await Notifications.cancelScheduledNotificationAsync(notificationId).catch(() => {});
  await AsyncStorage.removeItem(`${FIRED_PREFIX}${invoiceId}`);
}