import { readFile } from 'graceful-fs';
import * as Handlebars from 'handlebars';
import { Observable, Observer } from 'rxjs';
import { shareReplay } from 'rxjs/operators';

const jsStringEscape = require('js-string-escape');
const helpers = require('handlebars-helpers')({ handlebars: Handlebars });

// add custom helpers
Handlebars.registerHelper('jsEscape', jsStringEscape);

function _compile(aFile: string): Observable<HandlebarsTemplateDelegate> {

    return Observable.create((observer: Observer<HandlebarsTemplateDelegate>) => {

        // read the file
        readFile(aFile, 'utf-8', (err, data) => {
            if (err) {
                observer.error(err);
            } else {
                try {
                    observer.next(Handlebars.compile(data));
                    observer.complete();
                } catch (error) {
                    observer.error(error);
                }
            }
        });
    }).pipe(shareReplay())
}


export {
    _compile as hbsCompile
}