Get latest version

Co-Authored-By: Josh Abernathy <joshaber@gmail.com>

command/checkUpdate.go

@@ -0,0 +1,47 @@
+package command
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+
+	"github.com/mattn/go-isatty"
+)
+
+func CheckForUpdate() error {
+	if !isatty.IsTerminal(os.Stdout.Fd()) {
+		return nil
+	}
+
+	latestVersion, err := getLastestVersion()
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("🌭 %+v %+v\n", latestVersion, Version)
+
+	return nil
+}
+
+func getLastestVersion() (string, error) {
+	url := "https://api.github.com/repos/github/homebrew-gh/releases/latest"
+	resp, err := http.Get(url)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	data, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+
+	var j struct {
+		LatestVersion string `json:"tag_name"`
+	}
+
+	json.Unmarshal(data, &j)
+	return j.LatestVersion, nil
+}

main.go

@@ -9,6 +9,8 @@ import (
 )
 
 func main() {
+	command.CheckForUpdate()
+
 	if cmd, err := command.RootCmd.ExecuteC(); err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		_, isFlagError := err.(command.FlagError)