/*
Serve is a very simple static file server in go
Usage:
	-p="8100": port to serve on
	-d=".":    the directory of static files to host
Navigating to http://localhost:8100 will display the index.html or directory
listing file.
*/
package main

import (
	"context"
	"io/ioutil"
	"local/args"
	"log"
	"net/http"
	"os"
	"path"
	"strings"
	"time"
)

func main() {
	fs := args.NewArgSet()
	fs.Append(args.STRING, "p", "port to serve", "8100")
	fs.Append(args.STRING, "d", "static path to serve", "./public")
	if err := fs.Parse(); err != nil {
		panic(err)
	}

	d := fs.Get("d").GetString()
	p := fs.Get("p").GetString()
	go serve(d, p)
	go poll(path.Join(d, "csv"), time.Minute)

	<-context.Background().Done()
}

func serve(directory, port string) {
	port = strings.TrimPrefix(port, ":")
	http.Handle("/", http.FileServer(http.Dir(directory)))
	log.Printf("Serving %s on HTTP port: %s\n", directory, port)
	log.Fatal(http.ListenAndServe(":"+port, nil))
}

func poll(path string, interval time.Duration) {
	for {
		select {
		case <-context.Background().Done():
		case <-time.After(interval):
			if err := refresh(path); err != nil {
				log.Println(err)
			}
		}
	}
}

func refresh(path string) error {
	url := "https://docs.google.com/spreadsheets/d/14F7zRrwGT6JkCeZqZLPM2r2GScrm9FLFxlPtDINbNWg/gviz/tq?tqx=out:csv"
	resp, err := http.Get(url)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	b, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	if err := ioutil.WriteFile(path, b, os.ModePerm); err != nil {
		return err
	}
	return nil
}