const mime = require('mime-types');
const path = require('path');
const fs = require('fs');
const CONFIG = require('./config.js');

function RouterUtils(app) {
    this.app = app;
}

RouterUtils.prototype.httpResponse = function(res, code, response) {
    res.writeHead(code);
    res.end(response);
    return true;
}

RouterUtils.prototype.redirect = function(res, url) {
    res.writeHead(302, { Location: url });
    res.end();
}

RouterUtils.prototype.apiError = function(res) {
    res.writeHead(400, { "Content-Type": "application/json"});
    res.end();
}

RouterUtils.prototype.jsonResponse = function(res, data) {
    res.writeHead(200, { "Content-Type": "application/json"});
    if (typeof data !== 'string')
        data = JSON.stringify(data);
    res.end(data);
}

RouterUtils.prototype.onPageNotFound = function(res) {
    return this.httpResponse(res, 404, "Page not found...");
}

RouterUtils.prototype.staticServe = async function(res, filePath) {
    return new Promise((ok, ko) => {
        const stream = fs.createReadStream(filePath);
        const fileSize = fs.statSync(filePath)?.size || undefined;
        if (!stream || !fileSize) {
            console.error("RouterUtils::staticGet", url, err);
            this.httpResponse(res, 500, "Internal Server Error");
            return ko(err);
        }
        res.writeHead(200, {
            "Content-Type": mime.contentType(path.basename(filePath)),
            "Content-Length": fileSize
        });
        stream.pipe(res);
        stream.once('end', () => ok());
    });
}

RouterUtils.prototype.staticGet = function(app, url, staticResources) {
    app.router.get(url, (req, res) => {
        app.routerUtils.staticServe(res, staticResources);
    });
}

RouterUtils.prototype.commonRenderInfos = function(endpointName) {
    let context = {
        page_title: CONFIG.sitename,
        endpoints: [],
        currentEndpoint: endpointName
    };
    for (let endpoint in CONFIG.endpoints)
        context.endpoints.push({
            name: endpoint,
            address: '/dashboard/'+this.encodeUrlComponent(endpoint),
            selected: endpoint === endpointName,
            icon: CONFIG.endpoints[endpoint].icon
        });
    return context;
}

module.exports = { RouterUtils: RouterUtils, encodeUrlComponent: RouterUtils.encodeUrlComponent, decodeUrlComponent: RouterUtils.decodeUrlComponent };