import { clientStore, config, datastore, editor, index } from "@silverbulletmd/silverbullet/syscalls";
import { convertIcsCalendar } from "https://esm.sh/ts-ics@2.4.0";

const VERSION = "0.3.16";
const CACHE_KEY = "icalendar:lastSync";

const TIMEZONE_OFFSETS: Record<string, number> = {
  "GMT Standard Time": 0,
  "W. Europe Standard Time": 1,
  "Central Europe Standard Time": 1,
  "Romance Standard Time": 1,
  "Central European Standard Time": 1,
  "Eastern Standard Time": -5,
  "Central Standard Time": -6,
  "Mountain Standard Time": -7,
  "Pacific Standard Time": -8,
  "UTC": 0,
  "None": 0
};

async function getSources(): Promise<{ sources: any[], tzShift: number }> {
  try {
    const rawConfig = await config.get("icalendar", { sources: [] });
    const sources = rawConfig.sources || [];
    const tzShift = rawConfig.tzShift || 0;
    return { sources, tzShift };
  } catch (e) {
    return { sources: [], tzShift: 0 };
  }
}

async function fetchAndParseCalendar(source: any, hourShift = 0): Promise<any[]> {
  const response = await fetch(source.url);
  if (!response.ok) return [];
  const text = await response.text();
  const calendar = convertIcsCalendar(undefined, text);
  if (!calendar.events) return [];
  
  const events: any[] = [];
  for (const icsEvent of calendar.events) {
    const obj = icsEvent.start;
    let wallTimeStr = "";
    if (obj.local && typeof obj.local.date === "string") wallTimeStr = obj.local.date;
    else if (typeof obj.date === "string") wallTimeStr = obj.date;
    if (!wallTimeStr) continue;

    const baseDate = new Date(wallTimeStr.replace("Z", "") + "Z");
    const tzName = obj.local?.timezone || obj.timezone || "UTC";
    const sourceOffset = TIMEZONE_OFFSETS[tzName] ?? 0;
    const utcMillis = baseDate.getTime() - (sourceOffset * 3600000);
    const finalDate = new Date(utcMillis + (hourShift * 3600000));
    
    const pad = (n: number) => String(n).padStart(2, "0");
    const localIso = finalDate.getFullYear() + "-" + pad(finalDate.getMonth() + 1) + "-" + pad(finalDate.getDate()) + "T" + pad(finalDate.getHours()) + ":" + pad(finalDate.getMinutes()) + ":" + pad(finalDate.getSeconds());

    events.push({
      ...icsEvent,
      start: localIso,
      tag: "ical-event",
      sourceName: source.name
    });
  }
  return events;
}

export async function syncCalendars() {
  try {
    const { sources, tzShift } = await getSources();
    if (sources.length === 0) return;
    await editor.flashNotification("Syncing calendars...", "info");
    const allEvents: any[] = [];
    for (const source of sources) {
      try {
        const events = await fetchAndParseCalendar(source, tzShift);
        allEvents.push(...events);
      } catch (err) {
        console.error(`Failed to sync ${source.name}:`, err);
      }
    }
    await index.indexObjects("$icalendar", allEvents);
    await editor.flashNotification(`Synced ${allEvents.length} events`, "info");
  } catch (err) {
    console.error("Sync failed:", err);
  }
}

export async function forceSync() {
  await clientStore.del(CACHE_KEY);
  await syncCalendars();
}

export async function clearCache() {
  if (!await editor.confirm("Clear all calendar events?")) return;
  const pageKeys = await datastore.query({ prefix: ["ridx", "$icalendar"] });
  const allKeys: any[] = [];
  for (const { key } of pageKeys) {
    allKeys.push(key);
    allKeys.push(["idx", ...key.slice(2), "$icalendar"]);
  }
  if (allKeys.length > 0) await datastore.batchDel(allKeys);
  await clientStore.del(CACHE_KEY);
  await editor.flashNotification("Calendar index cleared", "info");
}

export async function showVersion() {
  await editor.flashNotification(`iCalendar Plug ${VERSION}`, "info");
}