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

const VERSION = "0.3.25";
const CACHE_KEY = "icalendar:lastSync";

console.log(`[iCalendar] Plug script executing at top level (Version ${VERSION})`);

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
};

// ============================================================================
// Utility Functions
// ============================================================================

/**
 * Creates a SHA-256 hash of a string (hex encoded)
 */
async function sha256Hash(str: string): Promise<string> {
  const encoder = new TextEncoder();
  const data = encoder.encode(str);
  const hashBuffer = await crypto.subtle.digest("SHA-256", data);
  const hashArray = Array.from(new Uint8Array(hashBuffer));
  return hashArray.map(b => b.toString(16).padStart(2, "0")).join("");
}

function localDateString(date: Date): string {
  const pad = (n: number) => String(n).padStart(2, "0");
  return date.getFullYear() + "-" + pad(date.getMonth() + 1) + "-" + pad(date.getDate()) + "T" + pad(date.getHours()) + ":" + pad(date.getMinutes()) + ":" + pad(date.getSeconds());
}

/**
 * Recursively converts all Date objects and ISO date strings to strings
 * Handles nested objects like {date: Date, local: {date: Date, timezone: string}}
 */
function convertDatesToStrings<T>(obj: T): any {
  if (obj === null || obj === undefined) {
    return obj;
  }

  if (obj instanceof Date) {
    return localDateString(obj);
  }
  
  if (typeof obj === 'object' && 'date' in obj && (obj as any).date instanceof Date) {
      return localDateString((obj as any).date);
  }

  if (typeof obj === 'string' && /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}/.test(obj)) {
    try {
        return localDateString(new Date(obj));
    } catch {
        return obj;
    }
  }

  if (Array.isArray(obj)) {
    return obj.map(item => convertDatesToStrings(item));
  }

  if (typeof obj === 'object') {
    const result: any = {};
    for (const key in obj) {
      if (Object.prototype.hasOwnProperty.call(obj, key)) {
        result[key] = convertDatesToStrings((obj as any)[key]);
      }
    }
    return result;
  }

  return obj;
}

// ============================================================================
// Configuration Functions
// ============================================================================

async function getSources(): Promise<{ sources: any[], tzShift: number }> {
  try {
    const rawConfig = await config.get("icalendar", { sources: [] });
    console.log("[iCalendar] Raw config retrieved:", JSON.stringify(rawConfig));
    
    let sources = rawConfig.sources || [];
    let tzShift = rawConfig.tzShift || 0;

    if (sources && typeof sources === "object" && !Array.isArray(sources)) {
        if (sources.tzShift !== undefined && tzShift === 0) {
            tzShift = sources.tzShift;
        }
        const sourceArray = [];
        for (const key in sources) {
            if (sources[key] && typeof sources[key].url === "string") {
                sourceArray.push(sources[key]);
            }
        }
        sources = sourceArray;
    }

    return { sources, tzShift };
  } catch (e) {
    console.error("[iCalendar] Error in getSources:", e);
    return { sources: [], tzShift: 0 };
  }
}

// ============================================================================
// Calendar Fetching & Parsing
// ============================================================================

async function fetchAndParseCalendar(source: any, hourShift = 0): Promise<any[]> {
  console.log(`[iCalendar] Fetching from: ${source.url}`);
  try {
    const response = await fetch(source.url);
    if (!response.ok) {
      console.error(`[iCalendar] Fetch failed for ${source.name}: ${response.status} ${response.statusText}`);
      return [];
    }
    const text = await response.text();
    const calendar = convertIcsCalendar(undefined, text);
    if (!calendar || !calendar.events) {
      return [];
    }
    
    const events: any[] = [];
    for (const icsEvent of calendar.events) {
      const obj = icsEvent.start;
      if (!obj) continue;

      let wallTimeStr = "";
      if (obj.local && obj.local.date) {
          wallTimeStr = typeof obj.local.date === "string" ? obj.local.date : (obj.local.date instanceof Date ? obj.local.date.toISOString() : String(obj.local.date));
      } else if (obj.date) {
          wallTimeStr = typeof obj.date === "string" ? obj.date : (obj.date instanceof Date ? obj.date.toISOString() : String(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 localIso = localDateString(finalDate);
      const uniqueKey = `${localIso}${icsEvent.uid || icsEvent.summary || ''}`;
      const ref = await sha256Hash(uniqueKey);

      events.push(convertDatesToStrings({
        ...icsEvent,
        name: icsEvent.summary || "Untitled Event",
        start: localIso,
        ref,
        tag: "ical-event",
        sourceName: source.name
      }));
    }
    return events;
  } catch (err) {
    console.error(`[iCalendar] Error fetching/parsing ${source.name}:`, err);
    return [];
  }
}

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) {
      const events = await fetchAndParseCalendar(source, tzShift);
      allEvents.push(...events);
    }
    await index.indexObjects("$icalendar", allEvents);
    await editor.flashNotification(`Synced ${allEvents.length} events`, "info");
  } catch (err) {
    console.error("[iCalendar] syncCalendars 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");
}