85 lines
3.6 KiB
TypeScript
85 lines
3.6 KiB
TypeScript
/**
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* Based on https://github.com/dwengovzw/Learning-Object-Repository/blob/main/app/processors/processing_proxy.js
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*/
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import BlockImageProcessor from "./image/block-image-processor.js";
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import InlineImageProcessor from "./image/inline-image-processor.js";
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import { MarkdownProcessor } from "./markdown/markdown-processor.js";
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import TextProcessor from "./text/text-processor.js";
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import AudioProcessor from "./audio/audio-processor.js";
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import PdfProcessor from "./pdf/pdf-processor.js";
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import ExternProcessor from "./extern/extern-processor.js";
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import GiftProcessor from "./gift/gift-processor.js";
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import {LearningObject} from "../../../entities/content/learning-object.entity";
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import Processor from "./processor";
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import {DwengoContentType} from "./content-type";
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import {LearningObjectIdentifier} from "../../../interfaces/learning-content";
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import {Language} from "../../../entities/content/language";
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import {replaceAsync} from "../../../util/async";
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const EMBEDDED_LEARNING_OBJECT_PLACEHOLDER = /<learning-object hruid="([^"]+)" language="([^"]+)" version="([^"]+)"\/>/g;
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const LEARNING_OBJECT_DOES_NOT_EXIST = "<div class='non-existing-learning-object' />";
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class ProcessingService {
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private processors!: Map<DwengoContentType, Processor<any>>;
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constructor() {
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const processors = [
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new InlineImageProcessor(),
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new BlockImageProcessor(),
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new MarkdownProcessor(),
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new TextProcessor(),
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new AudioProcessor(),
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new PdfProcessor(),
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new ExternProcessor(),
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new GiftProcessor()
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];
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this.processors = new Map(
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processors.map(processor => [processor.contentType, processor])
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)
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}
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/**
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* Render the given learning object.
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* @param learningObject The learning object to render
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* @param fetchEmbeddedLearningObjects A function which takes a learning object identifier as an argument and
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* returns the corresponding learning object. This is used to fetch learning
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* objects embedded into this one.
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* If this argument is omitted, embedded learning objects will be represented
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* by placeholders.
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* @returns Rendered HTML for this LearningObject as a string.
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*/
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async render(
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learningObject: LearningObject,
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fetchEmbeddedLearningObjects?: (loId: LearningObjectIdentifier) => Promise<LearningObject | null>
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): Promise<string> {
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const html = this.processors.get(learningObject.contentType)!.renderLearningObject(learningObject);
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if (fetchEmbeddedLearningObjects) {
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// Replace all embedded learning objects.
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return replaceAsync(
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html,
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EMBEDDED_LEARNING_OBJECT_PLACEHOLDER,
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async (_, hruid: string, language: string, version: string): Promise<string> => {
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// Fetch the embedded learning object...
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const learningObject = await fetchEmbeddedLearningObjects({
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hruid,
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language: language as Language,
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version: parseInt(version)
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});
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// If it does not exist, replace it by a placeholder.
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if (!learningObject) {
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return LEARNING_OBJECT_DOES_NOT_EXIST;
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}
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// ... and render it.
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return this.render(learningObject);
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}
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);
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}
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return html;
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}
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}
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export default new ProcessingService();
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