const express = require('express');

const path = require('path');

const fs = require('fs');

const url = require('url');

const packageJson = require('../package');

const {

__DEV__,

frontendSrcPath,

frontendBuildPath,

} = require('../environment');

const app = express();

if (__DEV__) {

const webpack = require('webpack');

const webpackDev = require('webpack-dev-middleware');

const webpackHot = require('webpack-hot-middleware');

const webpackConfig = require('../webpack.frontend.config.js');

const compiler = webpack(webpackConfig);

app.use(express.static(path.resolve(frontendSrcPath, 'static')));

app.use(webpackDev(compiler, {

stats: {

cached: false,

colors: true,

},

serverSideRender: true,

index: false,

}));

app.use(webpackHot(compiler));

app.use((req, res, next) => {

const { fs } = res.locals;

const outputPath = res.locals.webpackStats.toJson().outputPath;

const filePath = path.resolve(outputPath, 'index.html');

fs.readFile(filePath, 'utf8', (err, data) => {

if (err) return next(err);

res.indexFile = data;

next();

});

});

} else {

app.use(express.static(frontendBuildPath, { index: false }));

app.use((req, res, next) => {

const filePath = path.resolve(frontendBuildPath, 'index.html');

fs.readFile(filePath, 'utf8', (err, data) => {

if (err) return next(err);

res.indexFile = data;

next();

});

});

}

app.use((req, res) => {

const backend = require('./backend');

const hierarchy = backend.getHierarchy();

const [, categoryKey, algorithmKey] = url.parse(req.originalUrl).pathname.split('/');

let { title, description } = packageJson;

let algorithm = undefined;

if (categoryKey && categoryKey !== 'scratch-paper') {

algorithm = hierarchy.find(categoryKey, algorithmKey) || null;

if (algorithm) {

title = [algorithm.categoryName, algorithm.algorithmName].join(' - ');

description = algorithm.description;

} else {

res.status(404);

}

}

const indexFile = res.indexFile

.replace(/\$TITLE/g, title)

.replace(/\$DESCRIPTION/g, description)

.replace(/\$ALGORITHM/g, algorithm === undefined ? 'undefined' :

JSON.stringify(algorithm).replace(/</g, '\\u003c'));

res.send(indexFile);

});

module.exports = app;