import fs from "fs";
import Handlebars from 'handlebars';
import i18next from "i18next";
import Backend from 'i18next-fs-backend';
import path from 'path';
import puppeteer from "puppeteer";
import { Runner } from './models/Runner';

/**
 * This class is responsible for all things pdf creation.
 * This uses the html templates from src/templates.
 */
export class PdfCreator {
    private templateDir = path.join(__dirname, '/templates');
    private browser;
    private static interpolations = { eventname: "Lauf für Kaya! 2021", sponsoring_receipt_minimum_amount: '10', currency_symbol: "€" }

    /**
     * Main constructor.
     * Initializes i18n(ext), Handlebars and puppeteer.
     */
    constructor() {
        i18next
            .use(Backend)
            .init({
                fallbackLng: 'en',
                lng: 'en',
                backend: {
                    loadPath: path.join(__dirname, '/locales/{{lng}}.json')
                }
            });
        Handlebars.registerHelper('__',
            function (str) {
                return i18next.t(str, PdfCreator.interpolations).toString();
            }
        );
        puppeteer.launch({ headless: true }).then(browser => {
            this.browser = browser;
        });
    }

    /**
     * Generate sponsoring contract pdfs.
     * @param runner The runner you want to generate the contracts for.
     * @param locale The locale used for the contracts (default:en)
     */
    public async generateSponsoringContract(runners: Runner[], locale: string = "en"): Promise<any> {
        i18next.changeLanguage(locale);
        const template_source = fs.readFileSync(`${this.templateDir}/sponsoring_contract.html`, 'utf8');
        const template = Handlebars.compile(template_source);
        const result = template({ runners })
        console.log(template)
        return await this.renderPdf(result, { format: "A5", landscape: true });
    }

    /**
     * This method manages the creation of pdfs via puppeteer.
     * @param html The HTML that should get rendered.
     * @param options Puppeteer PDF option (eg: {format: "A4"})
     */
    public async renderPdf(html: string, options): Promise<any> {
        const page = await this.browser.newPage();
        await page.setContent(html);
        const pdf = await page.pdf(options);
        await page.close();
        return pdf;
    }

}