parse-sitemap-and-send-email.go

// a small exmaple cli application for sending emails
//
// Expects a .env with the following configuration:
//
//	EMAIL_ADDRESS=<from address>
//	EMAIL_PASSWORD=<app password>
//	EMAIL_HOST=smtp.gmail.com
//	EMAIL_PORT=587
//	RECIPIENT=<optional>
//	SITEMAP=<optional>
package main

import (
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/smtp"
	"os"

	"github.com/disgoorg/log"
	"github.com/joho/godotenv"
	"github.com/jordan-wright/email"
	"github.com/spf13/cobra"
	"github.com/yterajima/go-sitemap"
)

var (
	sitemapUrl = ""
	recipient  = ""
	rootCmd    = &cobra.Command{
		Use:   "email",
		Short: "send an email with go",
		Run:   sendSitemap,
	}
)

func main() {
	err := godotenv.Load(".env")
	if err != nil {
		log.Fatal(err)
	}

	rootCmd.Flags().StringVarP(&sitemapUrl, "sitemap", "s", "", "The sitemap to crawl")
	rootCmd.Flags().StringVarP(&recipient, "recipient", "r", "", "The email recipient")

	if err := rootCmd.Execute(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

func sendSitemap(cmd *cobra.Command, args []string) {
	if sitemapUrl == "" {
		sitemapUrl = os.Getenv("SITEMAP")
	}
	if sitemapUrl == "" {
		log.Fatalf("no sitemap provided, exiting.")
	}

	if recipient == "" {
		recipient = os.Getenv("RECIPIENT")
	}
	if recipient == "" {
		log.Fatalf("no email recipient provided.\n%s", cmd.Usage())
	}

	sm, err := fetchSitemap(sitemapUrl)
	if err != nil {
		log.Fatal(err)
	}

	for _, v := range sm.URL {
		err = sendEmail(v.Loc)
		if err != nil {
			log.Errorf("error sending email for url %s - %v", v.Loc, err)
		}
	}
}
func sendEmail(url string) error {
	contents, err := fetchHTML(url)
	if err != nil {
		return err
	}

	tmp, err := ioutil.TempFile("./", "attachment.*.html")
	if err != nil {
		return err
	}

	_, err = tmp.Write([]byte(contents))
	if err != nil {
		log.Fatal(err)
	}

	defer tmp.Close()
	defer os.RemoveAll(tmp.Name())

	if err := sendWithAttachment(recipient, url+".html", contents, tmp.Name()); err != nil {
		return err
	}

	log.Infof("successfully sent %s to %s", url, recipient)

	return nil
}

func sendWithAttachment(to, subject, body, attachmentFile string) error {
	e := email.NewEmail()
	e.From = fmt.Sprintf("<%s>", os.Getenv("EMAIL_ADDRESS"))
	e.To = []string{os.Getenv("RECIPIENT")}
	e.Subject = subject
	e.HTML = []byte(body)
	_, err := e.AttachFile(attachmentFile)
	if err != nil {
		return err
	}
	return e.Send(fmt.Sprintf("%s:%s", os.Getenv("EMAIL_HOST"), os.Getenv("EMAIL_PORT")), smtp.PlainAuth("", os.Getenv("EMAIL_ADDRESS"), os.Getenv("EMAIL_PASSWORD"), os.Getenv("EMAIL_HOST")))
}

func fetchHTML(url string) (string, error) {
	resp, err := http.Get(url)
	if err != nil {
		return "", err
	}

	if resp.StatusCode > http.StatusUnsupportedMediaType {
		return "", errors.New("non successful response from server")
	}

	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}

	return string(body), nil
}

func fetchSitemap(url string) (*sitemap.Sitemap, error) {
	sm, err := sitemap.Get(url, nil)
	if err != nil {
		return nil, err
	}

	return &sm, nil
}