From 5006304edfbad67a8a1e93fbf4a2cda8dc3fe3cf Mon Sep 17 00:00:00 2001
From: Harrison Shoebridge <harrison@theshoebridges.com>
Date: Wed, 13 Apr 2016 16:14:23 +1000
Subject: [PATCH] Add handling receiving messages

---
 .gitignore      |  3 +++
 actions.go      |  8 ++++++
 cmd/bot/main.go |  6 +++++
 message.go      | 10 ++++++++
 messenger.go    | 65 +++++++++++++++++++++++++++++++++++++++++++++++--
 receiving.go    | 33 +++++++++++++++++++++++++
 6 files changed, 123 insertions(+), 2 deletions(-)
 create mode 100644 actions.go
 create mode 100644 message.go
 create mode 100644 receiving.go

diff --git a/.gitignore b/.gitignore
index daf913b..ac5a2b7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,6 @@ _testmain.go
 *.exe
 *.test
 *.prof
+
+# Configuration
+cmd/bot/config.json
diff --git a/actions.go b/actions.go
new file mode 100644
index 0000000..e535d71
--- /dev/null
+++ b/actions.go
@@ -0,0 +1,8 @@
+package messenger
+
+type Action int
+
+const (
+	UnknownAction Action = iota - 1
+	TextAction
+)
diff --git a/cmd/bot/main.go b/cmd/bot/main.go
index 4a17639..4535ed0 100644
--- a/cmd/bot/main.go
+++ b/cmd/bot/main.go
@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"net/http"
+	"time"
 
 	"github.com/paked/configure"
 	"github.com/paked/messenger"
@@ -26,6 +27,11 @@ func main() {
 		VerifyToken: *verifyToken,
 	})
 
+	m.Handle(messenger.TextAction, func(m messenger.Message) {
+		fmt.Printf("%v (Sent, %v)\n", m.Text, m.Time.Format(time.UnixDate))
+	})
+
 	fmt.Println("Serving messenger bot on localhost:8080")
+
 	http.ListenAndServe("localhost:8080", m.Handler())
 }
diff --git a/message.go b/message.go
new file mode 100644
index 0000000..28228fb
--- /dev/null
+++ b/message.go
@@ -0,0 +1,10 @@
+package messenger
+
+import "time"
+
+type Message struct {
+	Sender    int64
+	Recipient int64
+	Time      time.Time
+	Text      string
+}
diff --git a/messenger.go b/messenger.go
index 0bca0ea..88ca5ae 100644
--- a/messenger.go
+++ b/messenger.go
@@ -1,8 +1,10 @@
 package messenger
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/http"
+	"time"
 )
 
 const (
@@ -14,26 +16,85 @@ type MessengerOptions struct {
 	VerifyToken string
 }
 
+type MessageHandler func(Message)
+
 type Messenger struct {
-	mux *http.ServeMux
+	mux      *http.ServeMux
+	handlers map[Action]MessageHandler
 }
 
 func New(mo MessengerOptions) *Messenger {
 	m := &Messenger{
-		mux: http.NewServeMux(),
+		mux:      http.NewServeMux(),
+		handlers: make(map[Action]MessageHandler),
 	}
 
 	if mo.Verify {
 		m.mux.HandleFunc(WebhookURL, newVerifyHandler(mo.VerifyToken))
+	} else {
+		m.mux.HandleFunc(WebhookURL, m.handle)
 	}
 
 	return m
 }
 
+func (m *Messenger) Handle(a Action, f MessageHandler) {
+	m.handlers[a] = f
+}
+
 func (m *Messenger) Handler() http.Handler {
 	return m.mux
 }
 
+func (m *Messenger) handle(w http.ResponseWriter, r *http.Request) {
+	var rec Receive
+
+	err := json.NewDecoder(r.Body).Decode(&rec)
+	if err != nil {
+		fmt.Println(err)
+
+		fmt.Fprintln(w, `{status: 'not ok'}`)
+		return
+	}
+
+	if rec.Object != "page" {
+		fmt.Println("Object is not page, undefined behaviour. Got", rec.Object)
+	}
+
+	m.dispatch(rec)
+
+	fmt.Fprintln(w, `{status: 'ok'}`)
+}
+
+func (m *Messenger) dispatch(r Receive) {
+	for _, entry := range r.Entry {
+		for _, info := range entry.Messaging {
+			a := m.classify(info, entry)
+			if a == UnknownAction {
+				fmt.Println("Unknown action:", info)
+				continue
+			}
+
+			if f := m.handlers[a]; f != nil {
+				f(Message{
+					Sender:    info.Sender.ID,
+					Recipient: info.Recipient.ID,
+					Time:      time.Unix(info.Timestamp, 0),
+					Text:      info.Message.Text,
+				})
+			}
+		}
+	}
+}
+
+func (m *Messenger) classify(info MessageInfo, e Entry) Action {
+	if info.Message != nil {
+		return TextAction
+	}
+
+	return UnknownAction
+}
+
 func newVerifyHandler(token string) func(w http.ResponseWriter, r *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if r.FormValue("hub.verify_token") == token {
diff --git a/receiving.go b/receiving.go
new file mode 100644
index 0000000..2548488
--- /dev/null
+++ b/receiving.go
@@ -0,0 +1,33 @@
+package messenger
+
+type Receive struct {
+	Object string  `json:"object"`
+	Entry  []Entry `json:"entry"`
+}
+
+type Entry struct {
+	ID        int64         `json:"id"`
+	Time      int64         `json:"time"`
+	Messaging []MessageInfo `json:"messaging"`
+}
+
+type MessageInfo struct {
+	Sender    Sender           `json:"sender"`
+	Recipient Recipient        `json:"recipient"`
+	Timestamp int64            `json:"timestamp"`
+	Message   *MessageCallback `json:"message"`
+}
+
+type Sender struct {
+	ID int64 `json:"id"`
+}
+
+type Recipient struct {
+	ID int64 `json:"id"`
+}
+
+type MessageCallback struct {
+	Mid  string `json:"mid"`
+	Seq  int    `json:"seq"`
+	Text string `json:"text"`
+}