ckn.backend/view/CknHtmlViewEngineMiddleware.js

CKN Framework for Backend

import {ckn} from 'ckn.core';
import fs from 'fs';
import {ViewEngineMiddleware} from "./ViewEngineMiddleware.js";

class CknHtmlViewEngine {
    constructor() {
    }

    #cleanPage(page) {
        page = page.replaceAll("\n", "");
        page = page.replace(/  +/g, ' ');
        return page;
    }

    async render(page, model) {
        page = this.#cleanPage(page);
        let commands = [];
        let output = "";
        let print = str => {
            output += str;
        }
        for (let item of page.matchAll(/(((?!<%|%>).)*)(<%[^%]*%>)*/g)) {
            commands.push('output += `' + item[1] + '`;');
            if (item[3] != null) {
                commands.push(item[3].replaceAll("<%", "").replaceAll("%>", ""));
            }
        }
        try {
            return eval(commands.toText("") + "output;");
        } catch (err) {
            return err.message;
        }
    }
}

class CknHtmlViewEngineMiddleware extends ViewEngineMiddleware {

    async onInitialEngine(backend) {
        backend.server.engine('cknhtml', (filePath, options, callback) => { // define the template engine
            fs.readFile(filePath, async (err, content) => {
                if (err) return callback(err);
                let engine = new CknHtmlViewEngine();
                let rendered = await engine.render(content.toString(), options);
                return callback(null, rendered)
            })
        });
    }

}

export {CknHtmlViewEngineMiddleware}