import fs from "node:fs/promises";
import path from "node:path";
import { isJpeg } from "./magic";

export class StorageError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "StorageError";
  }
}

export function pageFileName(n: number): string {
  return `page-${String(n).padStart(3, "0")}.jpg`;
}

export function catalogDir(storageDir: string, id: string): string {
  return path.join(storageDir, "catalogs", id);
}

export async function saveCatalogPages(
  storageDir: string,
  id: string,
  pages: Buffer[],
): Promise<void> {
  const dir = catalogDir(storageDir, id);
  await fs.mkdir(dir, { recursive: true });
  let i = 1;
  for (const page of pages) {
    if (!isJpeg(page)) {
      await fs.rm(dir, { recursive: true, force: true });
      throw new StorageError("نوع فایل پشتیبانی نمی‌شود");
    }
    await fs.writeFile(path.join(dir, pageFileName(i)), page);
    i += 1;
  }
}

export async function saveQr(
  storageDir: string,
  id: string,
  png: Buffer,
): Promise<void> {
  const dir = catalogDir(storageDir, id);
  await fs.mkdir(dir, { recursive: true });
  await fs.writeFile(path.join(dir, "qr.png"), png);
}

export async function readPage(
  storageDir: string,
  id: string,
  n: number,
): Promise<Buffer> {
  const file = path.join(catalogDir(storageDir, id), pageFileName(n));
  try {
    return await fs.readFile(file);
  } catch {
    throw new StorageError("کاتالوگ پیدا نشد");
  }
}

export async function readQr(storageDir: string, id: string): Promise<Buffer> {
  const file = path.join(catalogDir(storageDir, id), "qr.png");
  try {
    return await fs.readFile(file);
  } catch {
    throw new StorageError("کاتالوگ پیدا نشد");
  }
}

export async function deleteCatalogFiles(
  storageDir: string,
  id: string,
): Promise<void> {
  await fs.rm(catalogDir(storageDir, id), { recursive: true, force: true });
}