const express = require('express');
const app = express();
const path = require('path');
const PORT = process.env.PORT || 3000;
const fs = require("fs");
const { default: axios } = require('axios');
const { btoa } = require('buffer');
//const indexPath = path.resolve(__dirname, '..', 'build', 'index.html');
const indexPath = path.resolve(process.env.ROOT_PATH, 'index.html');
const iconPath = path.resolve(process.env.ROOT_PATH, 'favicon.ico');
const staticPath = path.resolve(process.env.ROOT_PATH, "static");

app.enable('trust proxy');

// static resources should just be served as they are
app.use("/static", express.static(
    staticPath,
    { maxAge: '30d' },
));

const fetchMetaTags = async (url) => {
    const encoded = btoa(url);
    const resp = await axios.get(`${process.env.API_URL}meta?path=${encoded}`);
    console.log(resp.data)
    return resp.data;
}

const fillMetaTags = async (request, htmlData) => {
    const url = request.originalUrl;

    let title = process.env.DEFAULT_TITLE;
    let description = process.env.DEFAULT_DESCRIPTION;
    let image = "";
    let icon = "/favicon.ico"

    try {
        const resp = await fetchMetaTags(url);
        title = resp.title ? resp.title : title;
        description = resp.description ? resp.description : description;
        image = resp.image ? resp.image : image;
        icon = resp.icon ? resp.icon : icon;
    } catch (e) {
        console.error(e.message)
        console.log("ERROR FETCHING TAGS");
    }

    htmlData = htmlData.replace(
        "<title></title>",
        `<title>${title}</title>`
    )
        .replace(/__META_FAVICON__/g, icon)
        .replace(/__META_OG_TITLE__/g, title)
        .replace(/__META_OG_DESCRIPTION__/g, description)
        .replace(/__META_DESCRIPTION__/g, description)
        .replace(/__META_OG_IMAGE__/g, image)

    //console.log(htmlData);
    return htmlData;

}

app.get('/favicon.ico', (req, res, next) => {
    return res.sendFile(iconPath)
})

app.get('/*', (req, res, next) => {
    fs.readFile(indexPath, 'utf8', async (err, htmlData) => {
        if (err) {
            console.error('Error during file reading', err);
            return res.status(404).end()
        }
        // inject meta tags
        htmlData = await fillMetaTags(req, htmlData);
        return res.send(htmlData);
    });
});
app.listen(PORT, "0.0.0.0", (error) => {
    if (error) {
        return console.log('Error during app startup', error);
    }
    console.log("Listening for requests...");
});