From 15bb7c34e5b41d2b9886316508a211ae2c49af22 Mon Sep 17 00:00:00 2001
From: Chris Sexton <chris.sexton@gmail.com>
Date: Mon, 18 Feb 2019 18:45:23 -0500
Subject: [PATCH] slackApp: add dedupe

---
 connectors/slackapp/slackApp.go      | 33 ++++++++++++++++
 connectors/slackapp/slackApp_test.go | 58 ++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 connectors/slackapp/slackApp_test.go

diff --git a/connectors/slackapp/slackApp.go b/connectors/slackapp/slackApp.go
index a252037..45d3b0d 100644
--- a/connectors/slackapp/slackApp.go
+++ b/connectors/slackapp/slackApp.go
@@ -2,6 +2,7 @@ package slackapp
 
 import (
 	"bytes"
+	"container/ring"
 	"encoding/json"
 	"fmt"
 	"html"
@@ -23,6 +24,8 @@ import (
 	"github.com/velour/catbase/config"
 )
 
+const DEFAULT_RING = 5
+
 type SlackApp struct {
 	bot    bot.Bot
 	config *config.Config
@@ -40,6 +43,8 @@ type SlackApp struct {
 	emoji   map[string]string
 
 	event bot.Callback
+
+	msgIDBuffer *ring.Ring
 }
 
 func New(c *config.Config) *SlackApp {
@@ -50,6 +55,12 @@ func New(c *config.Config) *SlackApp {
 
 	api := slack.New(token, slack.OptionDebug(false))
 
+	idBuf := ring.New(c.GetInt("ringSize", DEFAULT_RING))
+	for i := 0; i < idBuf.Len(); i++ {
+		idBuf.Value = ""
+		idBuf = idBuf.Next()
+	}
+
 	return &SlackApp{
 		api:          api,
 		config:       c,
@@ -60,6 +71,7 @@ func New(c *config.Config) *SlackApp {
 		lastRecieved: time.Now(),
 		users:        make(map[string]string),
 		emoji:        make(map[string]string),
+		msgIDBuffer:  idBuf,
 	}
 }
 
@@ -106,7 +118,28 @@ func (s *SlackApp) Serve() error {
 	return nil
 }
 
+// checkRingOrAdd returns true if it finds the ts value
+// or false if the ts isn't yet in the ring (and adds it)
+func (s *SlackApp) checkRingOrAdd(ts string) bool {
+	found := false
+	s.msgIDBuffer.Do(func(p interface{}) {
+		if p.(string) == ts {
+			found = true
+		}
+	})
+	if found {
+		return true
+	}
+	s.msgIDBuffer.Value = ts
+	s.msgIDBuffer = s.msgIDBuffer.Next()
+	return false
+}
+
 func (s *SlackApp) msgReceivd(msg *slackevents.MessageEvent) {
+	if s.checkRingOrAdd(msg.TimeStamp) {
+		log.Printf("Got a duplicate message from server: %s", msg.TimeStamp)
+		return
+	}
 	isItMe := msg.BotID != "" && msg.BotID == s.myBotID
 	if !isItMe && msg.ThreadTimeStamp == "" {
 		m := s.buildMessage(msg)
diff --git a/connectors/slackapp/slackApp_test.go b/connectors/slackapp/slackApp_test.go
new file mode 100644
index 0000000..939f1fa
--- /dev/null
+++ b/connectors/slackapp/slackApp_test.go
@@ -0,0 +1,58 @@
+package slackapp
+
+import (
+	"container/ring"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDedupeNoDupes(t *testing.T) {
+	buf := ring.New(3)
+	for i := 0; i < 3; i++ {
+		buf.Value = ""
+		buf = buf.Next()
+	}
+	s := SlackApp{msgIDBuffer: buf}
+	expected := []bool{
+		false,
+		false,
+		false,
+		false,
+		false,
+	}
+
+	actuals := []bool{}
+	actuals = append(actuals, s.checkRingOrAdd("a"))
+	actuals = append(actuals, s.checkRingOrAdd("b"))
+	actuals = append(actuals, s.checkRingOrAdd("c"))
+	actuals = append(actuals, s.checkRingOrAdd("d"))
+	actuals = append(actuals, s.checkRingOrAdd("e"))
+
+	assert.ElementsMatch(t, expected, actuals)
+}
+
+func TestDedupeWithDupes(t *testing.T) {
+	buf := ring.New(3)
+	for i := 0; i < 3; i++ {
+		buf.Value = ""
+		buf = buf.Next()
+	}
+	s := SlackApp{msgIDBuffer: buf}
+	expected := []bool{
+		false,
+		false,
+		true,
+		false,
+		true,
+	}
+
+	actuals := []bool{}
+	actuals = append(actuals, s.checkRingOrAdd("a"))
+	actuals = append(actuals, s.checkRingOrAdd("b"))
+	actuals = append(actuals, s.checkRingOrAdd("a"))
+	actuals = append(actuals, s.checkRingOrAdd("d"))
+	actuals = append(actuals, s.checkRingOrAdd("d"))
+
+	assert.ElementsMatch(t, expected, actuals)
+}