self-reload-json/lib/index.js

Self reloading JSON handler

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _walkthroughtree = require('./walkthroughtree');

Object.keys(_walkthroughtree).forEach(function (key) {
  if (key === "default" || key === "__esModule") return;
  Object.defineProperty(exports, key, {
    enumerable: true,
    get: function () {
      return _walkthroughtree[key];
    }
  });
});

var _fs = require('fs');

var _fs2 = _interopRequireDefault(_fs);

var _path = require('path');

var _path2 = _interopRequireDefault(_path);

var _events = require('events');

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

const getOwnPropertyHashes = typeof Reflect === 'object' && Reflect.ownKeys || (Object.getOwnPropertySymbols ? function getOwnPropertyHashes(obj) {
  return Array.prototype.concat(Object.getOwnPropertyNames(obj), Object.getOwnPropertySymbols(obj));
} : Object.getOwnPropertyNames);

const privateProps = typeof Symbol === 'function' ? Symbol('internals') : '__internals';

function isObject(o) {
  if (!o) return false;
  var type = typeof o;
  return type === 'object' || type === 'function';
}

function getAllProperties(obj, output = []) {
  if (!obj) return output;
  Array.prototype.push.apply(output, getOwnPropertyHashes(obj));
  return getAllProperties(Object.getPrototypeOf(obj), output);
}

function fileChanged(a, b, deferred) {
  const internals = this[privateProps],
        { options } = internals;
  if (options.delay) {
    if (internals.fileChangeTimeout) {
      clearTimeout(internals.fileChangeTimeout);
      delete internals.fileChangeTimeout;
    }
    if (!deferred && !internals.updateFileLock) {
      internals.fileChangeTimeout = setTimeout(internals.fileChanged, options.delay, a, b, true);
      return;
    }
  }
  if (internals.updateFileLock) return;
  try {
    if (a instanceof _fs2.default.Stats ? a.mtime === b.mtime : b !== internals.fileName) return;
    this.forceUpdate();
  } catch (err) {
    console.log(err.stack || err);
  }
}

function deepPatchLayer(srcObject, srcDescriptor, patchDescriptor, key, depth, options) {
  // Pass the patched value if source / patch is not patchable, or already patched.
  if (!depth || !srcDescriptor) return Object.defineProperty(srcObject, key, patchDescriptor);

  const srcValue = srcDescriptor.value;
  const patchValue = patchDescriptor.value;
  if (srcValue === patchValue || !isObject(srcValue) || !isObject(patchValue)) return Object.defineProperty(srcObject, key, patchDescriptor);

  const { ignoreProperties, keepNonExists } = options;

  // Fetch all keys from patcher object.
  const patchKeys = getOwnPropertyHashes(patchValue);
  for (const key of patchKeys) {
    if (ignoreProperties && ignoreProperties.includes(key)) continue;

    const srcDescriptor = Object.getOwnPropertyDescriptor(srcValue, key);
    if (srcDescriptor && !srcDescriptor.configurable) continue;

    const patchDescriptor = Object.getOwnPropertyDescriptor(patchValue, key);
    if (!srcDescriptor || !srcDescriptor.get && !patchDescriptor.get) this.next(srcValue, srcDescriptor, patchDescriptor, key, depth - 1, options);
  }

  // Take away properties that does not available in patcher (Pending to be deleted)
  if (!keepNonExists) for (const key of getOwnPropertyHashes(srcValue)) {
    if (patchKeys.includes(key) || ignoreProperties && ignoreProperties.includes(key)) continue;

    const srcDescriptor = Object.getOwnPropertyDescriptor(srcValue, key);
    if (!srcDescriptor.configurable) continue;

    delete srcValue[key];
  }

  return srcObject;
}

class SelfReloadJSON extends _events.EventEmitter {
  constructor(options) {
    super();

    switch (typeof options) {
      case 'string':
        options = { fileName: options };break;
      case 'object':case 'undefined':
        break;
      default:
        throw new Error('Invalid options type.');
    }

    // Prevent removal of internal handlers
    this[privateProps] = null;

    this[privateProps] = {
      keys: [],
      fileName: '',
      watcher: null,
      content: null,
      fileChanged: (a, b, deferred) => fileChanged.call(this, a, b, deferred),
      forceUpdate: () => this.forceUpdate(),
      omitKeys: getAllProperties(this),
      options: Object.assign({
        fileName: '',
        encoding: 'utf8',
        additive: false,
        method: 'native',
        interval: 5000,
        reviver: null,
        replacer: null,
        delay: 0,
        depth: -1
      }, options)
    };

    // Convert all internal values to non-enumerable,
    // prevents those values exposed by save function.
    for (let key in this) {
      const value = this[key];
      delete this[key];
      Object.defineProperty(this, key, {
        value,
        enumerable: false,
        configurable: true,
        writable: true
      });
    }

    this.resume();
  }

  stop() {
    const internals = this[privateProps];
    if (!internals.watcher) return;
    if (typeof internals.watcher === 'string') _fs2.default.unwatchFile(internals.watcher, internals.fileChanged);else internals.watcher.close();
    internals.watcher = null;
  }

  resume() {
    this.stop();
    const internals = this[privateProps],
          { options } = internals;

    options.fileName = _path2.default.resolve(options.fileName);
    internals.fileName = _path2.default.basename(options.fileName);

    switch (options.method) {
      case 'native':
        internals.watcher = _fs2.default.watch(options.fileName, { encoding: options.encoding }, internals.fileChanged);
        break;

      case 'polling':
        internals.watcher = options.fileName;
        _fs2.default.watchFile(options.fileName, { interval: options.interval }, internals.fileChanged);
        break;
    }
    this.forceUpdate();
  }

  save(options) {
    const internals = this[privateProps];
    options = Object.assign({ space: null }, internals.options, options);
    internals.updateFileLock = true;
    try {
      const json = JSON.stringify(this, options.replacer, options.space);
      _fs2.default.writeFileSync(internals.options.fileName, json, options);
      internals.raw = json;
    } finally {
      internals.updateFileLock = false;
    }
  }

  forceUpdate() {
    const internals = this[privateProps],
          { options } = internals;
    if (internals.updateFileLock) return;
    internals.updateFileLock = true;

    if (internals.retryTimer) {
      clearTimeout(internals.retryTimer);
      delete internals.retryTimer;
    }

    if (internals.fileChangeTimeout) {
      clearTimeout(internals.fileChangeTimeout);
      delete internals.fileChangeTimeout;
    }

    try {
      const rawContent = _fs2.default.readFileSync(options.fileName, { encoding: options.encoding });
      if (internals.raw === rawContent) return;
      internals.raw = rawContent;

      let newContent = JSON.parse(rawContent, options.reviver);
      if (typeof newContent !== 'object') newContent = { value: newContent };

      SelfReloadJSON.deepPatch(this, newContent, {
        keepNonExists: options.additive,
        ignoreProperties: internals.omitKeys,
        depth: options.depth
      });

      internals.newContent = SelfReloadJSON.deepPatch(internals.newContent || {}, newContent, {
        keepNonExists: options.additive,
        depth: options.depth
      });
    } catch (err) {
      switch (err && err.code) {
        case 'EBUSY':
        case 'EAGAIN':
          internals.retryTimer = setTimeout(internals.forceUpdate, options.delay);
          return;
      }

      this.emit('error', err);
      return;
    } finally {
      internals.updateFileLock = false;
    }

    this.emit('updated', internals.newContent);
  }

  static deepPatch(source, patch, options = {}) {
    if (!isObject(source) || !isObject(patch)) return patch;
    const dummy = { value: source };
    return (0, _walkthroughtree.walkThroughTree)(deepPatchLayer, {
      firstResult: true
    }, dummy, dummy, {
      value: patch,
      configurable: true,
      enumerable: true,
      writable: true
    }, 'value', 'depth' in options ? options.depth : -1, options).value;
  }
}

exports.default = SelfReloadJSON;
module.exports = exports['default'];