Check if newer version exists in Github (#128)

* Check if newer version exists in Github

cli/mizu/versionCheck.go

@@ -1,15 +1,19 @@
 package mizu
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
+	"github.com/google/go-github/v37/github"
+	"github.com/romana/rlog"
 	"github.com/up9inc/mizu/shared"
 	"github.com/up9inc/mizu/shared/semver"
+	"io/ioutil"
 	"net/http"
 	"net/url"
+	"time"
 )
 
-
 func getApiVersion(port uint16) (string, error) {
 	versionUrl, _ := url.Parse(fmt.Sprintf("http://localhost:%d/mizu/metadata/version", port))
 	req := &http.Request{
@@ -44,3 +48,45 @@ func CheckVersionCompatibility(port uint16) (bool, error) {
 	fmt.Printf(Red, fmt.Sprintf("cli version (%s) is not compatible with api version (%s)\n", SemVer, apiSemVer))
 	return false, nil
 }
+
+func CheckNewerVersion() {
+	rlog.Debugf("Checking for newer version...")
+	start := time.Now()
+	client := github.NewClient(nil)
+	latestRelease, _, err := client.Repositories.GetLatestRelease(context.Background(), "up9inc", "mizu")
+	if err != nil {
+		rlog.Debugf("Failed to get latest release")
+		return
+	}
+
+	versionFileUrl := ""
+	for _, asset := range latestRelease.Assets {
+		if *asset.Name == "version.txt" {
+			versionFileUrl = *asset.BrowserDownloadURL
+			break
+		}
+	}
+	if versionFileUrl == "" {
+		rlog.Debugf("Version file not found in the latest release")
+		return
+	}
+
+	res, err := http.Get(versionFileUrl)
+	if err != nil {
+		rlog.Debugf("http.Get version asset -> %v", err)
+		return
+	}
+
+	data, err := ioutil.ReadAll(res.Body)
+	res.Body.Close()
+	if err != nil {
+		rlog.Debugf("ioutil.ReadAll -> %v", err)
+		return
+	}
+	gitHubVersion := string(data)
+	gitHubVersion = gitHubVersion[:len(gitHubVersion)-1]
+	rlog.Debugf("Finished version validation, took %v", time.Since(start))
+	if SemVer < gitHubVersion {
+		fmt.Printf(Yellow, fmt.Sprintf("Update available! %v -> %v (%v)\n", SemVer, gitHubVersion, *latestRelease.HTMLURL))
+	}
+}