#!/usr/bin/env node --no-warnings
// ©2023 Ruben Verborgh – MIT License

import assert from 'node:assert';
import { resolve } from 'node:path';
import { promisify } from 'node:util';
import * as childProcess from 'node:child_process';
import { lstat, readdir, readFile, writeFile } from 'node:fs/promises';

const execFile = promisify(childProcess.execFile);

const expectedArgs = {
  'nss/config.json': 'path to the NSS configuration file',
  'css/data': 'path to the CSS data folder',
  'https://css.pod/': 'URL to the running CSS server instance',
  'xxx@users.css.pod': 'e-mail pattern to generate CSS usernames',
};

const passwordHashStart = '$2a$10$';

main(...process.argv).catch(console.error);

// Starts migration with the command-line arguments
async function main(bin, script, ...args) {
  if (args.length !== Object.keys(expectedArgs).length) {
    process.stderr.write(`usage: ${script.replace(/.*\//, '')} ${
      Object.keys(expectedArgs).join(' ')}\n${
      Object.entries(expectedArgs).map(([example, description]) =>
        `    ${example}:\t${description}`).join('\n')}\n`);
    process.exit(1);
  }
  return copyNssPodsToCSS(...args);
}

// Copies the pods and accounts from NSS disk storage
// to a CSS instance and associated disk storage
async function copyNssPodsToCSS(nssConfigPath, cssDataPath, cssUrl, emailPattern) {
  print('1️⃣  NSS: Read pod configurations from disk');
  const nss = await readNssConfig(nssConfigPath);
  const userFiles = (await readdir(nss.usersPath)).map(f => resolve(nss.usersPath, f));
  const pods = await asyncMap(readPodConfig, userFiles);

  print(`2️⃣  CSS: Create ${pods.length} accounts with pods via HTTP`);
  const { account: { create } } = await getAccountControls(cssUrl);
  const emailDomain = emailPattern.replace(/.*@+/, '');
  const accounts = await asyncMap(createAccount, pods, create, emailDomain);

  print(`3️⃣  CSS: Update ${accounts.length} accounts on disk`);
  await asyncMap(updateAccount, accounts, resolve(cssDataPath, 'www/.internal'));

  print(`4️⃣  CSS: Copy ${accounts.length} pod contents on disk`);
  await asyncMap(copyPodFiles, accounts, nss.hostname, nss.dataPath, cssDataPath);

  print(`5️⃣  CSS: Check ${accounts.length} pods for known resources`);
  await asyncMap(testPod, accounts, cssUrl);
}

// Reads the configuration of an NSS instance
async function readNssConfig(configPath) {
  assert.match(configPath, /config\.json$/, 'Invalid NSS config.json');
  const configFolder = resolve(configPath, '../');
  const config = await readJson(configPath);
  return {
    hostname: new URL(config.serverUri).hostname,
    dataPath: resolve(configFolder, config.root),
    usersPath: resolve(configFolder, config.dbPath, 'oidc/users/users/'),
  };
}

// Reads the configuration of a single pod from the NSS database
async function readPodConfig(configFile) {
  const pod = await readJson(configFile);
  const checks = {
    username: !!pod.username,
    password: (pod.hashedPassword || '').startsWith(passwordHashStart),
    webId: !!pod.webId,
  };
  assert(printChecks(pod.username, checks), 'Invalid pod config');
  return pod;
}

// Creates a CSS account with a login and pod
async function createAccount(pod, creationUrl, emailDomain) {
  const { username, webId, hashedPassword } = pod;
  const checks = { account: false, login: false, pod: false };

  try {
    // Create and obtain a new empty account
    const { authorization } = await cssApiPost(creationUrl);
    const { controls } = await cssApiGet(creationUrl, authorization);
    const [, id] = /\/account\/([^/]+)\//.exec(controls.account.webId);
    checks.account = true;

    // Create a login to the account with a temporary password
    const password = generateRandomPassword();
    // We have to generate a new e-mail address per pod,
    // since NSS does not perform e-mail validation on sign-up.
    // As such, there exists a security risk in which
    // an attacker registers a bogus pod with someone else's e-mail,
    // in an attempt to gain access to all pods under that e-mail.
    const email = `${username}@${emailDomain}`;
    await cssApiPost(controls.password.create, { email, password }, authorization);
    checks.login = true;

    // Create a pod under the account
    await cssApiPost(controls.account.pod, { name: username }, authorization);
    checks.pod = true;

    return { id, username, email, webId, hashedPassword };
  }
  finally {
    assert(printChecks(username, checks), 'Could not create account');
  }
}

// Updates the password and WebID in the account file
async function updateAccount(account, internalPath) {
  const checks = { read: false, password: false, webId: false, write: false };
  try {
    // Read the account file from disk
    const accountFile = resolve(internalPath, `accounts/data/${account.id}$.json`);
    const accountConfig = await readJson(accountFile);
    checks.read = true;

    // Update the password section
    const passwordSections = Object.values(accountConfig['**password**']);
    assert.equal(passwordSections.length, 1);
    assert(account.hashedPassword.startsWith(passwordHashStart));
    assert(passwordSections[0].password.startsWith(passwordHashStart));
    passwordSections[0].password = account.hashedPassword;
    checks.password = true;

    // Update the WebID section
    if (account.webId) {
      const webIdSections = Object.values(accountConfig['**webIdLink**']);
      assert.equal(webIdSections.length, 1);
      assert(webIdSections[0].webId.startsWith('http'));
      assert(account.webId.startsWith('http'));
      webIdSections[0].webId = account.webId;
    }
    checks.webId = true;

    // Write the updated account configuration
    await writeJson(accountFile, accountConfig);
    checks.write = true;
  }
  finally {
    assert(printChecks(account.username, checks), 'Password update failed');
  }
}

// Copies the contents of the NSS pod to CSS via disk
async function copyPodFiles({ username }, hostname, nssDataPath, cssDataPath) {
  const checks = { clear: false, copy: false };
  const source = resolve(nssDataPath, `${username}.${hostname}`);
  const destination = resolve(cssDataPath, username);
  try {
    // Check that source and destination are folders
    assert((await lstat(source)).isDirectory(), 'Invalid source');
    assert((await lstat(destination)).isDirectory(), 'Invalid destination');

    // Remove existing pod contents from the destination
    await execFile('rm', ['-r', '--', destination]);
    checks.clear = true;

    // Copy new contents from the source to the destination
    await execFile('cp', ['-a', '--', source, destination]);
    checks.copy = true;
  }
  finally {
    assert(printChecks(username, checks), 'Pod copy failed');
  }
}

// Tests the given pod by trying to access typical resources
async function testPod({ username }, cssUrl) {
  const checks = { publicProfile: false, privateInbox: false };

  // Create URL for pod
  const podUrl = new URL(cssUrl);
  podUrl.hostname = `${username}.${podUrl.hostname}`;

  try {
    // Check presence of resources available in typical NSS pods
    const profile = await localFetch(new URL('/profile/card', podUrl));
    checks.publicProfile = profile.status === 200;
    const inbox = await localFetch(new URL('/inbox/', podUrl));
    checks.privateInbox = inbox.status === 401;
  }
  finally {
    assert(printChecks(username, checks), 'Pod test failed');
  }
}

// Retrieves the CSS hypermedia controls for the account API
async function getAccountControls(cssUrl) {
  try {
    const body = await cssApiGet(new URL('.account/', cssUrl));
    assert.equal(body.version, '0.5', 'Unsupported CSS account API');
    return body.controls;
  }
  catch (cause) {
    throw new Error(`Could not access CSS configuration at ${cssUrl}`, { cause });
  }
}

// Performs an HTTP GET on an authenticated CSS API
async function cssApiGet(url, authorization = '') {
  return cssApiFetch(url, {}, authorization);
}

// Performs an HTTP POST on an authenticated CSS API
async function cssApiPost(url, body = {}, authorization = '') {
  return cssApiFetch(url, {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify(body),
  }, authorization);
}

// Performs an HTTP request on an authenticated CSS API
async function cssApiFetch(url, options = {}, authorization = '') {
  const response = await fetch(url, {
    ...options,
    headers: {
      ...options.headers,
      accept: 'application/json',
      authorization: `CSS-Account-Cookie ${authorization}`,
    },
  });
  const json = await response.json();
  if (response.status !== 200)
    throw new Error(json.message);
  return json;
}

// Fetches the resource with special DNS resolution for local names
function localFetch(url, init = {}) {
  url = new URL(url);

  // The `pod.localhost` pattern is common within NSS and CSS,
  // but Node.js does not resolve this well by default
  const host = url.host;
  if (url.hostname.endsWith('.localhost'))
    url.hostname = 'localhost';

  return fetch(url, { ...init, headers: { host } });
}

// Generates a random password
function generateRandomPassword(length = 32) {
  return new Array(length).fill(0).map(() =>
    String.fromCharCode(65 + Math.floor(58 * Math.random()))).join('');
}

// Fail-safe async version of map that ignores failures
async function asyncMap(func, items, ...params) {
  const results = [];
  for (const item of items) {
    try {
      results.push(await func(item, ...params));
    }
    catch { /* Ignore unsuccessful executions */ }
  }
  return results;
}

// Prints a message to the console
function print(message) {
  process.stdout.write(`${message}\n`);
}

// Prints a list of key/value checks to the console,
// returning whether all checks passed
function printChecks(name, checks) {
  const success = Object.values(checks).every(c => c);
  print(`\t${check(success)} ${name}\t ${
    Object.entries(checks).map(([key, value]) =>
      `${check(value)} ${key}`).join('\t')
  }`);
  return success;
}

// Returns a symbol for success or failure
function check(value) {
  return value ? '✅' : '❌';
}

// Reads and parses a JSON file from disk
async function readJson(path) {
  return JSON.parse(await readFile(path, 'utf-8'));
}

// Writes a JSON file to disk
async function writeJson(path, contents = {}) {
  await writeFile(path, JSON.stringify(contents));
}