bottender-compose/lib/utils.js

An utility library for bottender and higher-order handlers

"use strict";

const get = require('lodash/get');

const replace = require('lodash/replace');

const warning = require('warning');

const TEMPLATE_WHITELIST_KEYS = ['context', 'session', 'user', 'event', 'state', 'param', 'props'];
const contextKeyPrefixResolveMap = {
  context: '',
  session: 'session.',
  user: 'session.user.',
  event: 'event.',
  state: 'state.'
};
const JOINED_KEYS = `(${TEMPLATE_WHITELIST_KEYS.join('|')})((\\.[\u4e00-\u9fa5_a-zA-Z0-9]+)+)`; // support Chinese words

exports.isValidTemplate = str => {
  const templateRegExp = new RegExp(`{{\\s*${JOINED_KEYS}\\s*}}`, 'g');
  return templateRegExp.test(str);
};

exports.compileTemplate = tpl => (context, props) => {
  let compiledResult = tpl;
  const templateRegExp = new RegExp(`{{\\s*${JOINED_KEYS}\\s*}}`, 'g');
  const matchStrings = tpl.match(templateRegExp);

  for (const matchString of matchStrings) {
    const [targetString, firstWhitelistKey, ...otherResults] = templateRegExp.exec(matchString);
    let value;
    let properties;
    warning(firstWhitelistKey !== 'params', '`param` is deprecated. Use `props` instead.');

    if (['param', 'props'].includes(firstWhitelistKey)) {
      properties = otherResults[0].slice(1);
      value = get(props, properties);
    } else {
      properties = `${contextKeyPrefixResolveMap[firstWhitelistKey]}${otherResults[0].slice(1)}`;
      value = get(context, properties);
    }

    warning(value && typeof value === 'string', `Properties accessors (${firstWhitelistKey}.${properties}) in template is invalid -- expected return a non-empty string but got: ${typeof value}`);
    compiledResult = replace(compiledResult, targetString, value || '');
    templateRegExp.lastIndex = 0;
  }

  return compiledResult;
};