/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule SourceMapsUtils
 * @flow
 */

'use strict';

const Promise = require('Promise');
const NativeModules = require('NativeModules');
const SourceMapConsumer = require('SourceMap').SourceMapConsumer;
const SourceMapURL = require('./source-map-url');

const RCTSourceCode = NativeModules.SourceCode;
const RCTNetworking = NativeModules.Networking;

const SourceMapsUtils = {
  fetchMainSourceMap(): Promise {
    return SourceMapsUtils._getMainSourceMapURL().then(url =>
      SourceMapsUtils.fetchSourceMap(url)
    );
  },

  fetchSourceMap(sourceMappingURL: string): Promise {
    return fetch(sourceMappingURL)
      .then(response => response.text())
      .then(map => new SourceMapConsumer(map));
  },

  extractSourceMapURL(data: ({url?:string, text?:string, fullSourceMappingURL?:string})): ?string {
    const url = data.url;
    const text = data.text;
    const fullSourceMappingURL = data.fullSourceMappingURL;
    if (fullSourceMappingURL) {
      return fullSourceMappingURL;
    }
    const mapURL = SourceMapURL.getFrom(text);
    if (!mapURL) {
      return null;
    }
    if (!url) {
      return null;
    }
    const baseURLs = url.match(/(.+:\/\/.*?)\//);
    if (!baseURLs || baseURLs.length < 2) {
      return null;
    }
    return baseURLs[1] + mapURL;
  },

  _getMainSourceMapURL(): Promise {
    if (global.RAW_SOURCE_MAP) {
      return Promise.resolve(global.RAW_SOURCE_MAP);
    }

    if (!RCTSourceCode) {
      return Promise.reject(new Error('RCTSourceCode module is not available'));
    }

    if (!RCTNetworking) {
      // Used internally by fetch
      return Promise.reject(new Error('RCTNetworking module is not available'));
    }

    const scriptText = RCTSourceCode.getScriptText();
    if (scriptText) {
      return scriptText
        .then(SourceMapsUtils.extractSourceMapURL)
        .then((url) => {
          if (url === null) {
            return Promise.reject(new Error('No source map URL found. May be running from bundled file.'));
          }
          return Promise.resolve(url);
        });
    } else {
      // Running in mock-config mode
      return Promise.reject(new Error('Couldn\'t fetch script text'));
    }
  },
};

module.exports = SourceMapsUtils;