// s3d.yml read/write. Edits go through the yaml Document API so keys the GUI
// does not know about (and the operator's comments) survive a save.

import fs from 'node:fs';
import path from 'node:path';
import crypto from 'node:crypto';
import YAML from '../vendor/yaml/lib/index.js';
import { defaultDataDir } from './paths.js';

// Fields the settings form exposes, as dotted yaml paths. Anything else in the
// file is left untouched.
export const EDITABLE = [
  'apiAddress', 'apiHTTPSAddress', 'adminAddress', 'adminPassword', 'directory',
  'sia.diskUsageLimit', 'sia.uploadThreads', 'sia.dataShards', 'sia.parityShards',
  's3.hostBases',
  'log.stdout.enabled', 'log.stdout.level', 'log.file.enabled', 'log.file.level',
];

export const DEFAULTS = {
  apiAddress: '127.0.0.1:8000',
  adminAddress: '127.0.0.1:8001',
};

export function readConfig(file) {
  const exists = fs.existsSync(file);
  const doc = exists ? YAML.parseDocument(fs.readFileSync(file, 'utf8')) : new YAML.Document({});
  if (doc.errors.length) throw new Error(`${file}: ${doc.errors[0].message}`);
  const data = doc.toJS() || {};
  return {
    file,
    exists,
    data,
    // Effective values the daemon will use, for things the GUI needs to reach it.
    apiAddress: data.apiAddress || DEFAULTS.apiAddress,
    adminAddress: data.adminAddress || DEFAULTS.adminAddress,
    adminPassword: data.adminPassword || '',
    directory: process.env.S3D_DATA_DIR || data.directory || defaultDataDir(),
  };
}

// patch: { 'sia.uploadThreads': 8, 'apiHTTPSAddress': null, ... }; null/'' deletes the key.
export function writeConfig(file, patch) {
  const exists = fs.existsSync(file);
  const doc = exists ? YAML.parseDocument(fs.readFileSync(file, 'utf8')) : new YAML.Document({});
  if (doc.contents == null) doc.contents = doc.createNode({});
  for (const [key, value] of Object.entries(patch)) {
    if (!EDITABLE.includes(key)) throw new Error(`not an editable setting: ${key}`);
    const p = key.split('.');
    if (value === null || value === '' || (Array.isArray(value) && value.length === 0)) doc.deleteIn(p);
    else doc.setIn(p, value);
  }
  fs.mkdirSync(path.dirname(file), { recursive: true });
  const tmp = file + '.tmp';
  fs.writeFileSync(tmp, doc.toString(), { mode: 0o600 });
  fs.renameSync(tmp, file);
  return readConfig(file);
}

// A fresh config the daemon can start with: admin API on, random password.
export function ensureConfig(file) {
  if (fs.existsSync(file)) {
    const cfg = readConfig(file);
    if (cfg.data.adminAddress && cfg.data.adminPassword) return cfg;
    // s3d refuses to start without both, and the GUI needs them for stats.
    return writeConfig(file, {
      adminAddress: cfg.data.adminAddress || DEFAULTS.adminAddress,
      adminPassword: cfg.data.adminPassword || randomPassword(),
    });
  }
  return writeConfig(file, {
    apiAddress: DEFAULTS.apiAddress,
    adminAddress: DEFAULTS.adminAddress,
    adminPassword: randomPassword(),
  });
}

export function randomPassword() {
  return crypto.randomBytes(18).toString('base64url');
}