botbuilder-dialogs-adaptive/src/templates/textTemplate.ts

Rule system for the Microsoft BotBuilder dialog system.

/**
 * @module botbuilder-dialogs-adaptive
 */
/**
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License.
 */

import { Converter, ConverterFactory, Configurable, DialogContext, TemplateInterface } from 'botbuilder-dialogs';
import { TemplateEngineLanguageGenerator } from '../generators/templateEngineLanguageGenerator';
import { LanguageGenerator } from '../languageGenerator';
import { languageGeneratorKey } from '../languageGeneratorExtensions';

export interface TextTemplateConfiguration {
    template?: string;
}

/**
 * Defines a text template where the template expression is local aka "inline"
 * and processed through registered language generator.
 */
export class TextTemplate<D = Record<string, unknown>>
    implements TemplateInterface<string, D>, TextTemplateConfiguration, Configurable
{
    static $kind = 'Microsoft.TextTemplate';

    /**
     * Initialize a new instance of TextTemplate class.
     *
     * @param template The template to evaluate to create text.
     */
    constructor(template?: string) {
        this.template = template;
    }

    /**
     * Gets or sets the template to evaluate to create the text.
     */
    template: string;

    /**
     * @param _property The key of the conditional selector configuration.
     * @returns The converter for the selector configuration.
     */
    getConverter(_property: keyof TextTemplateConfiguration): Converter | ConverterFactory {
        return undefined;
    }

    /**
     * @param config The configuration.
     * @returns A object with the given configuration.
     */
    configure(config: TextTemplateConfiguration): this {
        const { template } = config;
        this.template = template;
        return this;
    }

    /**
     * Bind data to template.
     *
     * @param dialogContext DialogContext.
     * @param data Data to bind to.
     * @returns A promise representing the asynchronous operation.
     */
    async bind(dialogContext: DialogContext, data: D): Promise<string> {
        if (!this.template) {
            throw new Error(`ArgumentNullException: ${this.template}`);
        }

        let languageGenerator = dialogContext.services.get(languageGeneratorKey) as LanguageGenerator<string, unknown>;
        languageGenerator ??= new TemplateEngineLanguageGenerator();

        const lgResult = await languageGenerator.generate(dialogContext, this.template, data);
        return lgResult ? lgResult.toString() : '';
    }

    toString = (): string => {
        return `TextTemplate(${this.template})`;
    };
}