/**
 * archidekt.ts
 * ---------------------------------------------------------------------------
 * Server-side helper for pulling Greg's public MTG decks from Archidekt into
 * the TCGs page. The site is SSR (output: 'server'), so this runs on the
 * server — no CORS or API key required (Archidekt's decks list endpoint is
 * public JSON).
 *
 * Endpoint: GET https://archidekt.com/api/decks/v3/?ownerUsername=<username>
 *   -> { count, results: [{ id, name, featured, colors, size, deckFormat,
 *        updatedAt, private, unlisted, theorycrafted, ... }] }
 *
 * Decks are cached to a filesystem file for `CACHE_TTL_MS` (default 1 hour) so
 * repeat page loads are instant and we're gentle on Archidekt. The cache is
 * stale-while-revalidate: if a refresh fails, we serve the stale data rather
 * than erroring. Every failure path returns an empty list — the page renders a
 * fallback link and never breaks.
 */

/** Greg's Archidekt username. Change here to point at a different account. */
export const ARCHIDEKT_USERNAME = 'Patiun';

/** How long the cached deck list is considered fresh. Default: 1 hour. */
export const CACHE_TTL_MS = 60 * 60 * 1000;

const API_BASE = 'https://archidekt.com/api/decks/v3';
const USER_AGENT = 'GregKilmerProfileSite/1.0 (+https://gregkilmer.com)';

/** Known Archidekt deckFormat ids → labels. Add as needed. */
const FORMAT_LABELS: Record<number, string> = {
  1: 'Casual',
  2: 'Modern',
  3: 'Commander',
  5: 'Standard',
  7: 'Legacy',
  10: 'Pauper',
  14: 'Historic',
  16: 'Pioneer',
  37: 'Oathbreaker',
  45: 'Brawl',
};

export interface ArchidektDeck {
  id: number;
  name: string;
  /** Featured card art URL (may be empty). */
  featured: string;
  /** Mana color counts present in the deck. */
  colors: { W: number; U: number; B: number; R: number; G: number };
  /** Total card count. */
  size: number;
  /** Archidekt format id. */
  formatId: number;
  /** Human-readable format label (e.g. "Commander"). */
  formatLabel: string;
  /** ISO timestamp of last update. */
  updatedAt: string;
  /** Direct link to the deck on Archidekt. */
  href: string;
  theorycrafted: boolean;
}

export const formatLabel = (id: number): string => FORMAT_LABELS[id] ?? 'Custom';

interface RawDeck {
  id: number;
  name: string;
  featured?: string;
  customFeatured?: string;
  colors?: { W?: number; U?: number; B?: number; R?: number; G?: number };
  size?: number;
  deckFormat?: number;
  updatedAt?: string;
  private?: boolean;
  unlisted?: boolean;
  theorycrafted?: boolean;
}

const fileURL = (username: string): string =>
  // node_modules/.cache is gitignored and survives across dev reloads.
  new URL(
    `../node_modules/.cache/archidekt-${username}.json`,
    import.meta.url,
  ).href;

/**
 * Reads the cached decks for `username` if still fresh, else null.
 * Best-effort: any read/parse error returns null (treated as a miss).
 */
async function readCache(username: string): Promise<ArchidektDeck[] | null> {
  try {
    const { readFile } = await import('node:fs/promises');
    const raw = await readFile(fileURL(username), 'utf8');
    const data = JSON.parse(raw) as { fetchedAt: number; decks: ArchidektDeck[] };
    if (!data?.fetchedAt || !Array.isArray(data.decks)) return null;
    if (Date.now() - data.fetchedAt > CACHE_TTL_MS) return null;
    return data.decks;
  } catch {
    return null;
  }
}

/** Writes the cache. Failures are non-fatal (best-effort). */
async function writeCache(username: string, decks: ArchidektDeck[]): Promise<void> {
  try {
    const { mkdir, writeFile } = await import('node:fs/promises');
    const { dirname } = await import('node:path');
    const { fileURLToPath } = await import('node:url');
    const path = fileURLToPath(fileURL(username));
    await mkdir(dirname(path), { recursive: true });
    await writeFile(path, JSON.stringify({ fetchedAt: Date.now(), decks }, null, 2));
  } catch {
    /* cache write is best-effort */
  }
}

/** Reads stale cache regardless of TTL (used as a fallback on fetch failure). */
async function readStale(username: string): Promise<ArchidektDeck[] | null> {
  try {
    const { readFile } = await import('node:fs/promises');
    const raw = await readFile(fileURL(username), 'utf8');
    const data = JSON.parse(raw) as { fetchedAt: number; decks: ArchidektDeck[] };
    return Array.isArray(data?.decks) ? data.decks : null;
  } catch {
    return null;
  }
}

/**
 * Fetches Greg's public Archidekt decks, using a ~1h filesystem cache.
 * Never throws — on any failure returns an empty list (page shows a fallback).
 */
export async function getDecks(username = ARCHIDEKT_USERNAME): Promise<ArchidektDeck[]> {
  // 1. Fresh cache hit.
  const cached = await readCache(username);
  if (cached) return cached;

  // 2. Live fetch.
  const url = `${API_BASE}/?ownerUsername=${encodeURIComponent(username)}`;
  try {
    const res = await fetch(url, {
      headers: { 'User-Agent': USER_AGENT, Accept: 'application/json' },
      // Don't let a slow Archidekt hang the page render.
      signal: AbortSignal.timeout(8000),
    });
    if (!res.ok) throw new Error(`Archidekt responded ${res.status}`);
    const data = (await res.json()) as { results?: RawDeck[] };
    const decks: ArchidektDeck[] = (data.results ?? [])
      .filter((d) => !d.private && !d.unlisted)
      .map((d) => ({
        id: d.id,
        name: d.name,
        featured: d.customFeatured || d.featured || '',
        colors: {
          W: d.colors?.W ?? 0,
          U: d.colors?.U ?? 0,
          B: d.colors?.B ?? 0,
          R: d.colors?.R ?? 0,
          G: d.colors?.G ?? 0,
        },
        size: d.size ?? 0,
        formatId: d.deckFormat ?? 0,
        formatLabel: formatLabel(d.deckFormat ?? 0),
        updatedAt: d.updatedAt ?? '',
        href: `https://archidekt.com/decks/${d.id}`,
        theorycrafted: Boolean(d.theorycrafted),
      }));

    await writeCache(username, decks);
    return decks;
  } catch {
    // 3. Stale-while-revalidate fallback, else empty.
    return (await readStale(username)) ?? [];
  }
}

/** The Archidekt search-URL for the full decks list (used in fallback links). */
export const archidektSearchUrl = (username = ARCHIDEKT_USERNAME): string =>
  `https://archidekt.com/search/decks?ownerUsername=${encodeURIComponent(username)}`;