const express = require("express");
const fs = require("fs");
const ics = require("ics");
const marked = require("marked");

// Define defaults of HTTP port/host, can be redefined by environment variables.
const HTTP_PORT = process.env.HTTP_PORT || 8080;
const HTTP_HOST = process.env.HTTP_HOST || "localhost";
const README_FILE = "README.md";

// Init the Express application instance.
const app = express();

// Just show `README.md` file as a main page.
app.get("/", (req, res) => {
  fs.readFile(README_FILE, { encoding: "utf8" }, (error, file) => {
    if (error) {
      console.error(error);
      process.exit(1);
      return;
    }
    const html = marked.marked(file);
    res.send(html);
  });
});

// Generate ICS-file example tuned with URL query parameters.
app.get("/generate-event", function (req, res) {
  // Load event template from the file.
  const eventTemplate = require("./eventTemplate");
  let event = JSON.parse(JSON.stringify(eventTemplate.eventTemplate));
  event.description = req.query.description;
  ics.createEvent(event, (error, iCalEventText) => {
    if (error) {
      console.error(error);
      return;
    }

    // Response as a file if required.
    if (req.query.output === "file") {
      res.set({
        "Content-Type": "text/calendar",
        "Content-Disposition": "inline;filename=calendar.ics",
      });
    } else {
      res.set({
        "Content-Type": "text/plain",
      });
    }
    res.send(iCalEventText);
  });
});

// Starting a HTTP server.
console.log(`Server is running on http://${HTTP_HOST}:${HTTP_PORT}...`);
app.listen(HTTP_PORT);