From 971c162d33164d21b9881fa3f3882f904cd8d30c Mon Sep 17 00:00:00 2001
From: "diamondburned (Forefront)" <datutbrus@gmail.com>
Date: Fri, 17 Jan 2020 23:40:44 -0800
Subject: [PATCH] Fixed bug where reconnect would fail

---
 gateway/gateway.go          | 10 ++++++++--
 gateway/integration_test.go | 14 ++++++--------
 gateway/op.go               |  5 +++++
 gateway/pacemaker.go        |  8 +++++++-
 4 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/gateway/gateway.go b/gateway/gateway.go
index 42f6cc6..bb841b3 100644
--- a/gateway/gateway.go
+++ b/gateway/gateway.go
@@ -150,7 +150,10 @@ func (g *Gateway) Close() error {
 	g.Pacemaker.Stop()
 
 	// Stop the event handler
-	defer close(g.handler)
+	if g.handler != nil {
+		close(g.handler)
+		g.handler = nil
+	}
 
 	// Stop the Websocket
 	return g.WS.Close(nil)
@@ -190,7 +193,10 @@ func (g *Gateway) Open() error {
 			// If the connection is rate limited (documented behavior):
 			// https://discordapp.com/developers/docs/topics/gateway#rate-limiting
 			if err == ErrInvalidSession {
-				continue // retry
+				// Close the connection
+				g.Close()
+
+				continue // then retry
 			}
 
 			// Else, fatal
diff --git a/gateway/integration_test.go b/gateway/integration_test.go
index e814c25..d4973f2 100644
--- a/gateway/integration_test.go
+++ b/gateway/integration_test.go
@@ -32,9 +32,10 @@ func TestIntegration(t *testing.T) {
 		t.Fatal("Failed to authenticate with Discord:", err)
 	}
 
-	ready, ok := wait(t, gateway.Events).(*ReadyEvent)
+	ev := wait(t, gateway.Events)
+	ready, ok := ev.(*ReadyEvent)
 	if !ok {
-		t.Fatal("Event received is not of type Ready:", ready)
+		t.Fatal("Event received is not of type Ready:", ev)
 	}
 
 	if gateway.SessionID == "" {
@@ -48,18 +49,15 @@ func TestIntegration(t *testing.T) {
 		t.Fatal("Failed to reconnect:", err)
 	}
 
-	/* TODO: this isn't true, as Discord would keep sending Invalid Sessions.
+	/* TODO: We're not testing this, as Discord will replay events before it
+	 * sends the Resumed event.
+
 	resumed, ok := (<-gateway.Events).(*ResumedEvent)
 	if !ok {
 		t.Fatal("Event received is not of type Resumed:", resumed)
 	}
 	*/
 
-	ready, ok = wait(t, gateway.Events).(*ReadyEvent)
-	if !ok {
-		t.Fatal("Event received is not of type Ready:", ready)
-	}
-
 	if err := g.Close(); err != nil {
 		t.Fatal("Failed to close Gateway:", err)
 	}
diff --git a/gateway/op.go b/gateway/op.go
index 61e3198..89688c5 100644
--- a/gateway/op.go
+++ b/gateway/op.go
@@ -2,6 +2,8 @@ package gateway
 
 import (
 	"fmt"
+	"math/rand"
+	"time"
 
 	"github.com/diamondburned/arikawa/internal/json"
 	"github.com/diamondburned/arikawa/internal/wsutil"
@@ -122,6 +124,9 @@ func HandleOP(g *Gateway, op *OP) error {
 		return g.Reconnect()
 
 	case InvalidSessionOP:
+		// Discord expects us to sleep for no reason
+		time.Sleep(time.Duration(rand.Intn(5)+1) * time.Second)
+
 		// Invalid session, respond with Identify.
 		return g.Identify()
 
diff --git a/gateway/pacemaker.go b/gateway/pacemaker.go
index c8607e4..ee8d05e 100644
--- a/gateway/pacemaker.go
+++ b/gateway/pacemaker.go
@@ -39,7 +39,10 @@ func (p *Pacemaker) Dead() bool {
 }
 
 func (p *Pacemaker) Stop() {
-	close(p.stop)
+	if p.stop != nil {
+		close(p.stop)
+		p.stop = nil
+	}
 }
 
 // Start beats until it's dead.
@@ -57,10 +60,13 @@ func (p *Pacemaker) start(stop chan struct{}) error {
 	// Echo at least once
 	p.Echo()
 
+	// TODO: what happens if the heartbeat fails?
+
 	for {
 		select {
 		case <-stop:
 			return nil
+
 		case <-tick.C:
 			if err := p.Pace(); err != nil {
 				return err