import db from "../../db.server";

const MAX_BYTES = 5 * 1024 * 1024; // 5 MB cap
const STALE_AFTER_MS = 24 * 60 * 60 * 1000; // re-fetch once a day at most

/**
 * Sentinel value stored in `ShopSettings.logoUrl` when the logo was uploaded
 * directly through the settings UI (rather than fetched from a remote URL).
 * The actual bytes live in `LogoCache` for that shop.
 */
export const STORED_LOGO_SENTINEL = "stored://shop-logo";

/**
 * Returns a `data:` URL for the shop's logo bytes, fetching from the
 * configured URL on first use (or when stale) and persisting to the
 * `LogoCache` table for subsequent renders.
 */
export async function getLogoDataUrl(
  shopDomain: string,
  logoUrl: string,
): Promise<string | undefined> {
  if (!logoUrl) return undefined;

  const cached = await db.logoCache.findUnique({ where: { shopDomain } });

  // Locally uploaded logo: bytes live in LogoCache, no HTTP fetch.
  if (logoUrl === STORED_LOGO_SENTINEL) {
    return cached ? toDataUrl(cached.bytes, cached.contentType) : undefined;
  }

  const isFresh =
    cached &&
    cached.sourceUrl === logoUrl &&
    Date.now() - cached.fetchedAt.getTime() < STALE_AFTER_MS;

  if (isFresh && cached) {
    return toDataUrl(cached.bytes, cached.contentType);
  }

  let response: Response;
  try {
    response = await fetch(logoUrl);
  } catch (err) {
    console.warn(`Logo fetch failed for ${shopDomain}:`, err);
    return cached ? toDataUrl(cached.bytes, cached.contentType) : undefined;
  }
  if (!response.ok) {
    console.warn(`Logo fetch HTTP ${response.status} for ${shopDomain}`);
    return cached ? toDataUrl(cached.bytes, cached.contentType) : undefined;
  }

  const arrayBuf = await response.arrayBuffer();
  if (arrayBuf.byteLength > MAX_BYTES) {
    console.warn(`Logo too large (${arrayBuf.byteLength} bytes) — skipping cache.`);
    return undefined;
  }
  const bytes = Buffer.from(arrayBuf);
  const contentType = response.headers.get("content-type") || guessContentType(logoUrl);
  const etag = response.headers.get("etag") || "";

  await db.logoCache.upsert({
    where: { shopDomain },
    create: { shopDomain, sourceUrl: logoUrl, bytes, contentType, etag },
    update: { sourceUrl: logoUrl, bytes, contentType, etag, fetchedAt: new Date() },
  });

  return toDataUrl(bytes, contentType);
}

function toDataUrl(bytes: Buffer | Uint8Array, contentType: string): string {
  const buf = Buffer.isBuffer(bytes) ? bytes : Buffer.from(bytes);
  return `data:${contentType};base64,${buf.toString("base64")}`;
}

function guessContentType(url: string): string {
  const lower = url.toLowerCase();
  if (lower.endsWith(".jpg") || lower.endsWith(".jpeg")) return "image/jpeg";
  if (lower.endsWith(".webp")) return "image/webp";
  return "image/png";
}

const ALLOWED_LOGO_MIME = new Set(["image/png", "image/jpeg", "image/webp", "image/gif"]);

export interface StoreUploadedLogoResult {
  ok: boolean;
  error?: string;
  contentType?: string;
  byteLength?: number;
}

/**
 * Persists an uploaded logo file directly into `LogoCache`. Caller is
 * responsible for setting `ShopSettings.logoUrl = STORED_LOGO_SENTINEL`.
 */
export async function storeUploadedLogo(
  shopDomain: string,
  bytes: Buffer,
  contentType: string,
): Promise<StoreUploadedLogoResult> {
  const ct = (contentType || "").toLowerCase();
  if (!ALLOWED_LOGO_MIME.has(ct)) {
    return { ok: false, error: `Unsupported image type "${contentType || "unknown"}". Use PNG, JPEG, WebP or GIF.` };
  }
  if (bytes.byteLength === 0) {
    return { ok: false, error: "Uploaded file is empty." };
  }
  if (bytes.byteLength > MAX_BYTES) {
    return { ok: false, error: `File too large (${(bytes.byteLength / 1024 / 1024).toFixed(2)} MB). Max is ${MAX_BYTES / 1024 / 1024} MB.` };
  }

  const bytesU8 = new Uint8Array(bytes);
  await db.logoCache.upsert({
    where: { shopDomain },
    create: { shopDomain, sourceUrl: STORED_LOGO_SENTINEL, bytes: bytesU8, contentType: ct, etag: "" },
    update: { sourceUrl: STORED_LOGO_SENTINEL, bytes: bytesU8, contentType: ct, etag: "", fetchedAt: new Date() },
  });

  return { ok: true, contentType: ct, byteLength: bytes.byteLength };
}

export async function deleteStoredLogo(shopDomain: string): Promise<void> {
  await db.logoCache.deleteMany({ where: { shopDomain } });
}