From 61419c032a7fd6ef851a21b195c46d8d81b24495 Mon Sep 17 00:00:00 2001
From: Chris Keller <xylo04@gmail.com>
Date: Sun, 1 Nov 2020 16:41:18 -0700
Subject: [PATCH] Add sending Replay

Part of #2
---
 cmd/main.go     |  5 +++++
 encoder.go      |  7 +++++++
 encoder_test.go | 32 ++++++++++++++++++++++++++++++++
 messages.go     | 17 +++++++++++++++++
 server.go       |  7 +++++++
 5 files changed, 68 insertions(+)

diff --git a/cmd/main.go b/cmd/main.go
index 529638b..9c3b2ba 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -90,6 +90,11 @@ func handleCommand(command string, wsjtxServer wsjtx.Server) {
 	case "close":
 		fmt.Println("Sending Close")
 		err = wsjtxServer.Close(wsjtx.CloseMessage{Id: "WSJT-X"})
+
+	case "replay":
+		fmt.Println("Sending Replay")
+		err = wsjtxServer.Replay(wsjtx.ReplayMessage{Id: "WSJT-X"})
+
 	}
 	if err != nil {
 		fmt.Println(err)
diff --git a/encoder.go b/encoder.go
index ff4cf47..abd5c38 100644
--- a/encoder.go
+++ b/encoder.go
@@ -46,6 +46,13 @@ func encodeClose(msg CloseMessage) ([]byte, error) {
 	return e.finish()
 }
 
+func encodeReplay(msg ReplayMessage) ([]byte, error) {
+	e := newEncoder()
+	e.encodeUint32(replayNum)
+	e.encodeUtf8(msg.Id)
+	return e.finish()
+}
+
 type encoder struct {
 	buf *bytes.Buffer
 }
diff --git a/encoder_test.go b/encoder_test.go
index c138d6e..073df59 100644
--- a/encoder_test.go
+++ b/encoder_test.go
@@ -147,3 +147,35 @@ func Test_encodeClose(t *testing.T) {
 		})
 	}
 }
+
+func Test_encodeReplay(t *testing.T) {
+	type args struct {
+		msg ReplayMessage
+	}
+	wantBin, _ := hex.DecodeString("adbccbda00000002000000070000000657534a542d58")
+	tests := []struct {
+		name    string
+		args    args
+		want    []byte
+		wantErr bool
+	}{
+		{
+			name:    "encodeReplay",
+			args:    args{msg: ReplayMessage{"WSJT-X"}},
+			want:    wantBin,
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := encodeReplay(tt.args.msg)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("encodeReplay() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("encodeReplay() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/messages.go b/messages.go
index 84947cd..b3654bf 100644
--- a/messages.go
+++ b/messages.go
@@ -177,6 +177,23 @@ type CloseMessage struct {
 
 const closeNum = 6
 
+/*
+When a server starts it may  be useful for it to determine the
+state  of preexisting  clients. Sending  this message  to each
+client as it is discovered  will cause that client (WSJT-X) to
+send a "Decode" message for each decode currently in its "Band
+activity"  window.
+
+In only.
+
+https://sourceforge.net/p/wsjt/wsjtx/ci/8f99fcce/tree/Network/NetworkMessage.hpp#l326
+*/
+type ReplayMessage struct {
+	Id string `json:"id"`
+}
+
+const replayNum = 7
+
 /*
 The decode message is sent when  a new decode is completed, in
 this case the 'New' field is true.
diff --git a/server.go b/server.go
index cdc4398..bd4b97e 100644
--- a/server.go
+++ b/server.go
@@ -71,6 +71,13 @@ func (s *Server) Close(msg CloseMessage) error {
 	return err
 }
 
+// Send a message to WSJT-X to replay QSOs in the Band Activity window.
+func (s *Server) Replay(msg ReplayMessage) error {
+	msgBytes, _ := encodeReplay(msg)
+	_, err := s.conn.WriteTo(msgBytes, s.remoteAddr)
+	return err
+}
+
 func check(err error) {
 	if err != nil {
 		panic(err)