// OPFS-backed SD card store — the source of truth for /sdcard contents.
// It persists across page reloads, so "edit files, then reboot to apply" works
// by reloading the page: edits survive in OPFS and are seeded into the guest's
// MEMFS /sdcard on the next boot. Guest-side writes remain ephemeral.

const SD_DIR = 'sdcard';

async function sdRoot() {
  const root = await navigator.storage.getDirectory();
  return root.getDirectoryHandle(SD_DIR, { create: true });
}

async function resolveParent(path, create) {
  const parts = path.split('/').filter(Boolean);
  const filename = parts.pop();
  let dir = await sdRoot();
  for (const part of parts) {
    dir = await dir.getDirectoryHandle(part, { create });
  }
  return [dir, filename];
}

export async function listSdFiles() {
  const entries = [];
  const walk = async (dir, prefix) => {
    for await (const [name, handle] of dir.entries()) {
      const path = prefix ? `${prefix}/${name}` : name;
      if (handle.kind === 'directory') {
        entries.push({ path: `${path}/`, directory: true });
        await walk(handle, path);
      } else {
        entries.push({ path, size: (await handle.getFile()).size });
      }
    }
  };
  await walk(await sdRoot(), '');
  entries.sort((a, b) => a.path.localeCompare(b.path));
  return entries;
}

export async function readSdFile(path) {
  const [dir, name] = await resolveParent(path, false);
  const handle = await dir.getFileHandle(name);
  return new Uint8Array(await (await handle.getFile()).arrayBuffer());
}

export async function writeSdFile(path, data) {
  const bytes = typeof data === 'string' ? new TextEncoder().encode(data) : data;
  const [dir, name] = await resolveParent(path, true);
  const handle = await dir.getFileHandle(name, { create: true });
  const writable = await handle.createWritable();
  await writable.write(bytes);
  await writable.close();
}

// ponytail: empty dirs live only in OPFS; readAllSdFiles skips them, so they vanish on reboot. Add a placeholder file if guest-side empty dirs ever matter.
export async function mkdirSd(path) {
  let dir = await sdRoot();
  for (const part of path.split('/').filter(Boolean)) {
    dir = await dir.getDirectoryHandle(part, { create: true });
  }
}

export async function deleteSdFile(path) {
  const [dir, name] = await resolveParent(path, false);
  await dir.removeEntry(name, { recursive: true });
}

export async function clearSdFiles() {
  const root = await navigator.storage.getDirectory();
  await root.removeEntry(SD_DIR, { recursive: true });
}

// Flatten to [{ path, bytes }] for seeding the guest's MEMFS /sdcard at boot.
export async function readAllSdFiles() {
  const out = [];
  for (const entry of await listSdFiles()) {
    if (!entry.directory) {
      out.push({ path: entry.path, bytes: await readSdFile(entry.path) });
    }
  }
  return out;
}