add version check

main.go

@@ -22,6 +22,16 @@ const (
 )
 
 func main() {
+	outOfDate, err := needUpdate()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if outOfDate {
+		fmt.Println("There is a new version of epochcli, please update before running")
+		os.Exit(1)
+	}
+
 	var (
 		helpFlag       bool
 		updateOnlyFlag bool

version.go

@@ -1,3 +1,38 @@
 package main
 
-const version = "1.0.4"
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+)
+
+const (
+	version    = "1.0.4"
+	versionUrl = "https://git.burkey.co/eburk/epochcli/raw/branch/master/version.go"
+)
+
+func needUpdate() (bool, error) {
+	resp, err := http.Get(versionUrl)
+	if err != nil {
+		return false, fmt.Errorf("unable to get version file: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return false, fmt.Errorf("failed to download update, status code: %d", resp.StatusCode)
+	}
+
+	b, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return false, fmt.Errorf("unable to read response body: %v", err)
+	}
+
+	re := regexp.MustCompile(`const version = "([\d.]+)"`)
+	ver := re.FindStringSubmatch(string(b))
+	if len(ver) < 2 || ver[1] == "" {
+		return false, fmt.Errorf("unable to find version in response")
+	}
+
+	return ver[1] != version, nil
+}