// reminders.js — native OS notifications for upcoming appointments.
// Checks once a minute; fires once per appointment when it enters the lead window
// (default 30 min before start_time, configurable via the "reminderLeadMinutes" setting).
"use strict";

const { Notification, BrowserWindow } = require("electron");
const db = require("./db");

const CHECK_INTERVAL_MS = 60 * 1000;
const DEFAULT_LEAD_MINUTES = 30;

const notified = new Set(); // appointment ids already notified

function pad(n) {
  return String(n).padStart(2, "0");
}
function isoToday() {
  const d = new Date();
  return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())}`;
}

function leadMinutes() {
  const raw = db.getSetting("reminderLeadMinutes");
  const n = raw ? Number(raw) : NaN;
  return Number.isFinite(n) && n > 0 ? n : DEFAULT_LEAD_MINUTES;
}

function checkNow() {
  if (!Notification.isSupported()) return;
  let appointments;
  try {
    appointments = db.listAppointments(isoToday(), isoToday());
  } catch {
    return; // db not ready yet
  }
  const lead = leadMinutes();
  const now = new Date();
  for (const appt of appointments) {
    if (!appt.start_time || notified.has(appt.id)) continue;
    const [h, m] = appt.start_time.split(":").map(Number);
    if (Number.isNaN(h) || Number.isNaN(m)) continue;
    const start = new Date();
    start.setHours(h, m, 0, 0);
    const minutesUntil = (start - now) / 60000;
    // Fire once the appointment enters the lead window, and up to 2 min after its
    // start (covers the case where the app was closed/asleep right at the moment).
    if (minutesUntil <= lead && minutesUntil >= -2) {
      notified.add(appt.id);
      const who = appt.animalName ? ` – ${appt.animalName}${appt.ownerName ? " (" + appt.ownerName + ")" : ""}` : "";
      const title = minutesUntil > 1 ? `Termin in ${Math.round(minutesUntil)} Min.` : "Termin jetzt";
      const n = new Notification({
        title,
        body: `${appt.title}${who}${appt.location ? "\n" + appt.location : ""}`,
      });
      n.on("click", () => {
        const win = BrowserWindow.getAllWindows()[0];
        if (win) {
          win.show();
          win.focus();
        }
      });
      n.show();
    }
  }
}

let timer = null;
function start() {
  if (timer) return;
  checkNow();
  timer = setInterval(checkNow, CHECK_INTERVAL_MS);
}
function stop() {
  if (timer) clearInterval(timer);
  timer = null;
}

module.exports = { start, stop };