Bring back usage of API v8

This reverts commit 5700060.
Discord have now moved API v6 to deprecated status. We should use v8 soon so that the tool doesn't stop working unexpectedly.

client/api.go

@@ -10,7 +10,7 @@ import (
 	"time"
 )
 
-const api = "https://discord.com/api/v6"
+const api = "https://discord.com/api/v8"
 const messageLimit = 25
 
 var endpoints = map[string]string{
@@ -290,14 +290,15 @@ func (c *Client) request(method string, endpoint string, reqData interface{}, re
 		if err != nil {
 			return errors.Wrap(err, "Error decoding response")
 		}
-		log.Infof("Server asked us to sleep for %v milliseconds", data.RetryAfter)
-		time.Sleep(time.Duration(data.RetryAfter) * time.Millisecond)
+		millis := time.Duration(data.RetryAfter*1000) * time.Millisecond
+		log.Infof("Server asked us to sleep for %v", millis)
+		time.Sleep(millis)
 		// Try again once we've waited for the period that the server has asked us to.
 		return c.request(method, endpoint, reqData, resData)
 	case status == http.StatusForbidden:
 		break
 	case status == http.StatusUnauthorized:
-		return errors.New(fmt.Sprintf("Bad status code %v, is your token correct?", http.StatusText(res.StatusCode)))
+		return errors.New(fmt.Sprintf("Bad status code %v, log out and log back in to Discord or verify your token is correct", http.StatusText(res.StatusCode)))
 	case status == http.StatusBadRequest:
 		return errors.New(fmt.Sprintf("Bad status code %v", http.StatusText(res.StatusCode)))
 	case status == http.StatusNoContent:
@@ -357,5 +358,5 @@ type Messages struct {
 }
 
 type ServerWait struct {
-	RetryAfter int `json:"retry_after"`
+	RetryAfter float32 `json:"retry_after"`
 }