From 4e0aeae7471302132cdb3b48a61410d9e74c4003 Mon Sep 17 00:00:00 2001
From: Trevor Slocum <trevor@rocket9labs.com>
Date: Wed, 20 Dec 2023 16:47:51 -0800
Subject: [PATCH] Add initial support for BEI protocol

---
 bei.go             | 131 +++++++++++++++++++++++++++++++++++++++++++++
 cmd/tabula/main.go |   7 +++
 go.mod             |   2 +
 go.sum             |   2 +
 4 files changed, 142 insertions(+)
 create mode 100644 bei.go

diff --git a/bei.go b/bei.go
new file mode 100644
index 0000000..a17a882
--- /dev/null
+++ b/bei.go
@@ -0,0 +1,131 @@
+package tabula
+
+import (
+	"bufio"
+	"bytes"
+	"log"
+	"net"
+	"strconv"
+
+	"code.rocket9labs.com/tslocum/bei"
+)
+
+type BEIServer struct {
+}
+
+func NewBEIServer() *BEIServer {
+	return &BEIServer{}
+}
+
+func (s *BEIServer) handleConnection(conn net.Conn) {
+	analysis := make([]*Analysis, 0, AnalysisBufferSize)
+	var beiCommand bool
+	scanner := bufio.NewScanner(conn)
+	for scanner.Scan() {
+		if scanner.Err() != nil {
+			log.Printf("error: failed to read from client: %s", scanner.Err())
+			conn.Close()
+			return
+		}
+		if !beiCommand && !bytes.Equal(scanner.Bytes(), []byte("bei")) {
+			log.Printf("error: failed to read from client: failed to receive bei command")
+			conn.Close()
+			return
+		}
+		switch {
+		case bytes.Equal(scanner.Bytes(), []byte("bei")):
+			buf, err := bei.EncodeEvent(&bei.EventOkBEI{
+				Version: 1,
+				ID: map[string]string{
+					"name": "tabula",
+				},
+			})
+			if err != nil {
+				log.Fatalf("error: failed to encode event: %s", err)
+			}
+			conn.Write(buf)
+			conn.Write([]byte("\n"))
+			beiCommand = true
+		case bytes.HasPrefix(scanner.Bytes(), []byte("move ")):
+			var stateInts []int
+			for _, v := range bytes.Split(scanner.Bytes()[5:], []byte(",")) {
+				i, err := strconv.Atoi(string(v))
+				if err != nil {
+					log.Printf("error: failed to read from client: failed to decode state: %s", err)
+					conn.Close()
+					return
+				}
+				stateInts = append(stateInts, i)
+			}
+			state, err := bei.DecodeState(stateInts)
+			if err != nil {
+				log.Printf("error: failed to read from client: failed to decode state: %s", err)
+				conn.Close()
+				return
+			}
+			b := Board{}
+			for i, v := range state.Board {
+				b[i] = int8(v)
+			}
+			b[SpaceRoll1] = int8(state.Roll1)
+			b[SpaceRoll2] = int8(state.Roll2)
+			if state.Roll1 == state.Roll2 {
+				b[SpaceRoll3], b[SpaceRoll4] = int8(state.Roll1), int8(state.Roll2)
+			}
+			// TODO entered, acey
+			b[SpaceEnteredPlayer] = 1
+			b[SpaceEnteredOpponent] = 1
+
+			available, _ := b.Available(1)
+			b.Analyze(available, &analysis)
+
+			if len(analysis) == 0 {
+				log.Printf("error: failed to read from client: zero moves returned for analysis")
+				conn.Close()
+				return
+			}
+
+			move := &bei.Move{}
+			for _, m := range analysis[0].Moves {
+				if m[0] == 0 && m[1] == 0 {
+					break
+				}
+				move.Play = append(move.Play, &bei.Play{From: int(m[0]), To: int(m[1])})
+			}
+			buf, err := bei.EncodeEvent(&bei.EventOkMove{
+				Moves: []*bei.Move{move},
+			})
+			if err != nil {
+				log.Fatalf("error: failed to encode event: %s", err)
+			}
+			conn.Write(buf)
+			conn.Write([]byte("\n"))
+		default:
+			log.Printf("error: received unexpected command from client: %s", scanner.Bytes())
+			conn.Close()
+			return
+		}
+	}
+	if scanner.Err() != nil {
+		log.Printf("error: failed to read from client: %s", scanner.Err())
+		conn.Close()
+		return
+	}
+}
+
+func (s *BEIServer) Listen(address string) {
+	listener, err := net.Listen("tcp", address)
+	if err != nil {
+		log.Fatalf("failed to listen on %s: %s", address, err)
+	}
+	log.Printf("Listening for connections on %s...", address)
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			log.Fatalf("failed to listen on %s: %s", address, err)
+		}
+
+		go s.handleConnection(conn)
+	}
+}
diff --git a/cmd/tabula/main.go b/cmd/tabula/main.go
index b906817..ede132a 100644
--- a/cmd/tabula/main.go
+++ b/cmd/tabula/main.go
@@ -10,7 +10,9 @@ import (
 )
 
 func main() {
+	var address string
 	var pips bool
+	flag.StringVar(&address, "address", "", "Listen for BEI connections on specified address (TCP)")
 	flag.BoolVar(&pips, "pips", false, "Print table of pseudopip values")
 	flag.Parse()
 
@@ -23,6 +25,11 @@ func main() {
 		return
 	}
 
+	if address != "" {
+		s := tabula.NewBEIServer()
+		s.Listen(address)
+	}
+
 	//b := tabula.Board{0, 0, 0, 0, 0, -1, 8, 0, 4, 0, 0, 0, 0, 0, -1, -1, 0, -1, -1, -1, 1, -2, -2, -3, -2, 0, 2, 0, 0, 0, 0, 4, 1, 1, 0}
 
 	b := tabula.Board{0, 0, -2, -2, -2, 4, 0, -1, 0, 0, -2, 4, 0, -2, -1, 0, -2, 4, 0, 2, 0, 0, 0, 0, -1, 0, 1, 0, 4, 1, 0, 0, 1, 1, 1}
diff --git a/go.mod b/go.mod
index ca756c9..7dd5e26 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module code.rocket9labs.com/tslocum/tabula
 
 go 1.17
+
+require code.rocket9labs.com/tslocum/bei v0.0.0-20231220232111-b1d4144d27bb
diff --git a/go.sum b/go.sum
index e69de29..5e20046 100644
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,2 @@
+code.rocket9labs.com/tslocum/bei v0.0.0-20231220232111-b1d4144d27bb h1:gU9+YXaDNq/7OyHJ4Mqu5qAyJFAxmCY++Ptk5T/B7w4=
+code.rocket9labs.com/tslocum/bei v0.0.0-20231220232111-b1d4144d27bb/go.mod h1:tS60/VNAJphKvDBkSLQhKALa15msIAuWWfEKNc4oFZc=