extwee/src/JSON/parse.js

A story compiler tool using Twine-compatible formats

import { Story } from '../Story.js';
import Passage from '../Passage.js';

/**
 * Parse JSON representation into Story.
 * @see {@link https://github.com/iftechfoundation/twine-specs/blob/master/twine-2-jsonoutput-doc.md Twine 2 JSON Specification}
 * @function parse
 * @param {string} jsonString - JSON string to convert to Story.
 * @throws {Error} - Invalid JSON!
 * @returns {Story} Story object.
 * @example
 * const jsonString = `{
 *  "name": "My Story",
 *  "start": "First Passage",
 *  "ifid": "A1B2C3D4-E5F6-G7H8-I9J0-K1L2M3N4O5P6",
 *  "format": "SugarCube",
 *  "formatVersion": "2.31.0",
 *  "creator": "Twine",
 *  "creatorVersion": "2.3.9",
 *  "zoom": 1,
 *  "passages": [
 *   {
 *    "name": "First Passage",
 *    "tags": "",
 *    "metadata": "",
 *    "text": "This is the first passage."
 *   },
 *  ]
 * }`;
 * const story = parse(jsonString);
 * console.log(story);
 * // => Story {
 * //      name: 'My Story',
 * //      start: 'First Passage',
 * //      IFID: 'A1B2C3D4-E5F6-G7H8-I9J0-K1L2M3N4O5P6',
 * //      format: 'SugarCube',
 * //      formatVersion: '2.31.0',
 * //      creator: 'Twine',
 * //      creatorVersion: '2.3.9',
 * //      zoom: 1,
 * //      tagColors: {},
 * //      metadata: {},
 * //      passages: [
 * //        Passage {
 * //          name: 'First Passage',
 * //          tags: '',
 * //          metadata: '',
 * //          text: 'This is the first passage.'
 * //        }
 * //      ]
 * //    }
 */
function parse (jsonString) {
  // Create future object.
  let result = {};

  // Create Story.
  const s = new Story();

  // Try to parse the string.
  try {
    result = JSON.parse(jsonString);
  } catch (error) {
    throw new Error(`Error: JSON could not be parsed! ${error.message}`);
  }

  // Name
  if (Object.prototype.hasOwnProperty.call(result, 'name')) {
    // Convert to String (if not String).
    s.name = String(result.name);
  }

  // Start Passage
  if (Object.prototype.hasOwnProperty.call(result, 'start')) {
    // Convert to String (if not String).
    s.start = String(result.start);
  }

  // IFID
  if (Object.prototype.hasOwnProperty.call(result, 'ifid')) {
    // Convert to String (if not String).
    // Enforce the uppercase rule of Twine 2 and Twee 3.
    s.IFID = String(result.ifid).toUpperCase();
  }

  // Format
  if (Object.prototype.hasOwnProperty.call(result, 'format')) {
    // Convert to String (if not String).
    s.format = String(result.format);
  }

  // Format Version
  if (Object.prototype.hasOwnProperty.call(result, 'formatVersion')) {
    // Convert to String (if not String).
    s.formatVersion = String(result.formatVersion);
  }

  // Creator
  if (Object.prototype.hasOwnProperty.call(result, 'creator')) {
    // Convert to String (if not String).
    s.creator = String(result.creator);
  }

  // Creator Version
  if (Object.prototype.hasOwnProperty.call(result, 'creatorVersion')) {
    // Convert to String (if not String).
    s.creatorVersion = String(result.creatorVersion);
  }

  // Zoom
  if (Object.prototype.hasOwnProperty.call(result, 'zoom')) {
    // Set Zoom.
    s.zoom = result.zoom;
  }

  // Tag Colors
  if (Object.prototype.hasOwnProperty.call(result, 'tagColors')) {
    // Set tagColors.
    s.tagColors = result.tagColors;
  }

  // Metadata
  if (Object.prototype.hasOwnProperty.call(result, 'metadata')) {
    // Set metadata.
    s.metadata = result.metadata;
  }

  // Passages
  if (Object.prototype.hasOwnProperty.call(result, 'passages')) {
    // Is s an array?
    if (Array.isArray(result.passages)) {
      // For each passage, convert into Passage objects.
      result.passages.forEach((p) => {
        // Create default passage.
        const newP = new Passage();

        // Does s have a name?
        if (Object.prototype.hasOwnProperty.call(p, 'name')) {
          // Set name.
          newP.name = p.name;
        }

        // Does s have tags?
        if (Object.prototype.hasOwnProperty.call(p, 'tags')) {
          // Set tags.
          newP.tags = p.tags;
        }

        // Does s have metadata?
        if (Object.prototype.hasOwnProperty.call(p, 'metadata')) {
          // Set metadata.
          newP.metadata = p.metadata;
        }

        // Does s have text?
        if (Object.prototype.hasOwnProperty.call(p, 'text')) {
          // Set text.
          newP.text = p.text;
        }

        // Add the new passage.
        s.addPassage(newP);
      });
    }
  }

  // Return Story.
  return s;
}

export { parse };