package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"net/smtp"
	"os"
	"os/exec"
	"path"
	"time"

	"github.com/BurntSushi/toml"
	homedir "github.com/mitchellh/go-homedir"
	"github.com/domodwyer/mailyak"
)

type Config struct {
	MailHost, Username, Password string
	MailPort int
	Len int64
}

var conf Config
var confFile string

func getConf() Config {
	confDir := path.Dir(confFile)

	if _, err := os.Stat(confDir); os.IsNotExist(err) {
		log.Printf("Creating config directory")
		err = os.MkdirAll(confDir, 0777)
		if err != nil {
			log.Fatal("Cannot create config directory: ", err)
		}
	}
	if _, err := os.Stat(confFile); os.IsNotExist(err) {
		log.Printf("Creating config file")
		f, err := os.Create(confFile)
		if err != nil {
			log.Fatal("Cannot create config file: ", err)
		}
		err = f.Close()
		if err != nil {
			log.Fatal("Error closing config file: ", err)
		}
	}
	if _, err := toml.DecodeFile(confFile, &conf); err != nil {
		log.Fatal("Error reading config file: ", err)
	}
	of, err := os.Create(path.Join(confDir, "c.R"))
	if err != nil {
		log.Fatal("Error creating R source file: ", err)
	}
	_, err = of.WriteString(rCode())
	if err != nil {
		log.Fatal("Error writing R source code: ", err)
	}
	return conf
}

func save() {
	of, err := os.Create(confFile)
	if err != nil {
		log.Fatal("Cannot open config file: ", err)
	}
	var buf bytes.Buffer
	w := bufio.NewWriter(&buf)
	enc := toml.NewEncoder(w)
	enc.Encode(conf)
	io.Copy(of, &buf)
	err = of.Close()
	if err != nil {
		log.Fatal("Error closing config file: ", err)
	}
}

func fetch() {
	url := "https://health.data.ny.gov/api/views/xdss-u53e/rows.csv?accessType=DOWNLOAD"

	resp, err := http.Get(url)
	if err != nil {
		log.Printf("HTTP error: ", err)
		return
	}
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Printf("Read error: ", err)
		return
	}
	if int64(len(body)) == conf.Len {
		log.Printf("Equal length, returning")
		return
	}
	log.Printf("Length differs: body = %d", len(body))
	conf.Len = int64(len(body))
	save()

	of, err := os.Create(path.Join(path.Dir(confFile), "rows.csv"))
	if err != nil {
		log.Fatal("Cannot create rows.csv: ", err)
	}
	_, err = of.Write(body)
	if err != nil {
		log.Fatal("Error writing rows.csv: ", err)
	}

	confDir := path.Dir(confFile)
	cmd := exec.Command("R", "--no-save", "-f", path.Join(confDir, "c.R"))
	log.Printf("Running R")
	err = cmd.Run()
	if err != nil {
		log.Fatal("Error running R: ", err)
	}
	log.Printf("R completed")
	if conf.MailHost == "" {
		log.Print("No mail host set, returning")
		return
	}
	f, err := os.Open("Rplots.pdf")
	if err != nil {
		log.Fatal("Error opening Rplots.pdf: ", err)
	}
	defer f.Close()
	email := mailyak.New(fmt.Sprintf("%s:%d", conf.MailHost, conf.MailPort),
		smtp.PlainAuth("", conf.Username, conf.Password, conf.MailHost))
	email.To("gmp@wow.st")
	email.From("covid@wow.st")
	msg := "Covid dashboard update for " + time.Now().Format("Monday, January 2 2006")
	email.Subject(msg)
	email.Plain().Set(msg)
	email.Attach("dashboard.pdf", f)
	err = email.Send()
	if err != nil {
		log.Print("Error sending email: ", err)
	}
}

func main() {
	log.Printf("starting")
	homeDir, err := homedir.Dir()
	if err != nil {
		log.Fatal("Cannot locate user's home directory")
	}
	confFile = path.Join(homeDir, ".config", "cget", "cget.conf")
	os.Chdir(path.Dir(confFile))
	getConf()

	for {
		fetch()
		time.Sleep(time.Minute * 30)
	}
	log.Printf("done")
}