Go routine it

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

command/checkForUpdate.go

@@ -0,0 +1,59 @@
+package command
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+
+	"github.com/github/gh-cli/utils"
+	"github.com/mattn/go-isatty"
+)
+
+const nwo = "github/homebrew-gh"
+
+func CheckForUpdate(handleUpdate chan func()) {
+	if !isatty.IsTerminal(os.Stdout.Fd()) {
+		handleUpdate <- nil
+	}
+
+	latestVersion, err := getLastestVersion()
+	if err != nil {
+		handleUpdate <- nil
+	}
+
+	updateAvailable := latestVersion != Version
+
+	if updateAvailable {
+		handleUpdate <- func() {
+			fmt.Printf(utils.Cyan(`
+A new version of gh is available! %s → %s
+Changelog: https://github.com/%s/releases/tag/%[2]s
+Run 'brew upgrade github/gh/gh' to update!`)+"\n\n", Version, latestVersion, nwo)
+		}
+	} else {
+		handleUpdate <- nil
+	}
+}
+
+func getLastestVersion() (string, error) {
+	url := fmt.Sprintf("https://api.github.com/repos/%s/releases/latest", nwo)
+	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
+}