/**
 * React Static Boilerplate
 * https://github.com/kriasoft/react-static-boilerplate
 *
 * Copyright © 2015-present Kriasoft, LLC. All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE.txt file in the root directory of this source tree.
 */

const toRegExp = require("path-to-regexp");

function escape(text) {
  return text.replace("'", "\\'").replace("\\", "\\\\");
}

/**
 * Converts application routes from JSON to JavaScript. For example, a route like
 *
 *   {
 *     "path": "/about",
 *     "page": "./pages/about"
 *   }
 *
 * becomes
 *
 *   {
 *     path: '/about',
 *     pattern: /^\\/about(?:\/(?=$))?$/i,
 *     keys: [],
 *     page: './pages/about',
 *     load: function () { return new Promise(resolve => require(['./pages/about'], resolve)); }
 *   }
 */
module.exports = function routesLoader(source) {
  this.cacheable();

  const output = ["[\n"];
  const routes = JSON.parse(source);

  for (const route of routes) {
    const keys = [];
    const pattern = toRegExp(route.path, keys);
    const required =
      route.chunk && route.chunk === "main"
        ? (module) => `Promise.resolve(require('${escape(module)}').default)`
        : (module) => `new Promise(function (resolve, reject) {
        try {
          require.ensure(['${escape(module)}'], function (require) {
            resolve(require('${escape(module)}').default);
          }${typeof route.chunk === "string" ? `, '${escape(route.chunk)}'` : ""});
        } catch (err) {
          reject(err);
        }
      })`;
    output.push("  {\n");
    output.push(`    path: '${escape(route.path)}',\n`);
    output.push(`    pattern: ${pattern.toString()},\n`);
    output.push(`    keys: ${JSON.stringify(keys)},\n`);
    output.push(`    page: '${escape(route.page)}',\n`);
    if (route.data) {
      output.push(`    data: ${JSON.stringify(route.data)},\n`);
    }
    output.push(`    load() {\n      return ${required(route.page)};\n    },\n`);
    output.push("  },\n");
  }

  output.push("]");

  return `module.exports = ${output.join("")};`;
};