From 9a8cf96e08ab929dcadf7bfcb76545f9b271a171 Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Mon, 7 Nov 2022 11:01:00 -0800
Subject: [PATCH 1/3] refactor simple TCP server into pkg

---
 cmd/primetime/main.go | 23 +++++++++++++++++++++++
 cmd/smoketest/main.go | 26 ++++----------------------
 pkg/conn/conn.go      | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 22 deletions(-)
 create mode 100644 cmd/primetime/main.go
 create mode 100644 pkg/conn/conn.go

diff --git a/cmd/primetime/main.go b/cmd/primetime/main.go
new file mode 100644
index 0000000..f2ecded
--- /dev/null
+++ b/cmd/primetime/main.go
@@ -0,0 +1,23 @@
+package main
+
+import (
+	"log"
+	"net"
+
+	"protohackers/pkg/conn"
+)
+
+type data struct {
+	Method string `json:"method"`
+	Number int    `json:"number"`
+}
+
+func main() {
+	err := conn.StartSimple(primetime)
+	if err != nil {
+		log.Fatalln(err)
+	}
+}
+
+func primetime(c net.Conn) {
+}
diff --git a/cmd/smoketest/main.go b/cmd/smoketest/main.go
index 10f924b..f90bcf8 100644
--- a/cmd/smoketest/main.go
+++ b/cmd/smoketest/main.go
@@ -1,40 +1,22 @@
 package main
 
 import (
-	"fmt"
 	"io"
 	"log"
 	"net"
-	"os"
-)
 
-const (
-	connPort = "3030"
-	connType = "tcp4"
+	"protohackers/pkg/conn"
 )
 
 func main() {
-	l, err := net.Listen(connType, ":"+connPort)
+	err := conn.StartSimple(smoketest)
 	if err != nil {
 		log.Fatalln(err)
-		os.Exit(1)
-	}
-	defer l.Close()
-
-	fmt.Println(fmt.Sprintf("Listening on port %s", connPort))
-
-	for {
-		conn, err := l.Accept()
-		if err != nil {
-			log.Fatalln(err)
-		}
-		go handleRequest(conn)
 	}
 }
 
-func handleRequest(conn net.Conn) {
-	defer conn.Close()
-	if _, err := io.Copy(conn, conn); err != nil {
+func smoketest(c net.Conn) {
+	if _, err := io.Copy(c, c); err != nil {
 		log.Fatalln(err)
 	}
 }
diff --git a/pkg/conn/conn.go b/pkg/conn/conn.go
new file mode 100644
index 0000000..3d928ba
--- /dev/null
+++ b/pkg/conn/conn.go
@@ -0,0 +1,33 @@
+package conn
+
+import (
+	"fmt"
+	"net"
+)
+
+const (
+	Port = ":3030"
+	Type = "tcp4"
+)
+
+func StartSimple(handler func(conn net.Conn)) error {
+	l, err := net.Listen(Type, Port)
+	if err != nil {
+		return err
+	}
+	defer l.Close()
+
+	fmt.Println(fmt.Sprintf("Listening on port %s", Port))
+
+	for {
+		c, err := l.Accept()
+		if err != nil {
+			return err
+		}
+		go handler(c)
+		err = c.Close()
+		if err != nil {
+			return err
+		}
+	}
+}

From 71179f50992d95b93d60fa65c227ed73f80b1ce7 Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Mon, 7 Nov 2022 11:06:30 -0800
Subject: [PATCH 2/3] fix close bug

---
 cmd/primetime/main.go | 1 +
 cmd/smoketest/main.go | 1 +
 pkg/conn/conn.go      | 1 -
 3 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/cmd/primetime/main.go b/cmd/primetime/main.go
index f2ecded..7ad3841 100644
--- a/cmd/primetime/main.go
+++ b/cmd/primetime/main.go
@@ -20,4 +20,5 @@ func main() {
 }
 
 func primetime(c net.Conn) {
+	defer c.Close()
 }
diff --git a/cmd/smoketest/main.go b/cmd/smoketest/main.go
index f90bcf8..717bb7b 100644
--- a/cmd/smoketest/main.go
+++ b/cmd/smoketest/main.go
@@ -16,6 +16,7 @@ func main() {
 }
 
 func smoketest(c net.Conn) {
+	defer c.Close()
 	if _, err := io.Copy(c, c); err != nil {
 		log.Fatalln(err)
 	}
diff --git a/pkg/conn/conn.go b/pkg/conn/conn.go
index 3d928ba..9d266e9 100644
--- a/pkg/conn/conn.go
+++ b/pkg/conn/conn.go
@@ -25,7 +25,6 @@ func StartSimple(handler func(conn net.Conn)) error {
 			return err
 		}
 		go handler(c)
-		err = c.Close()
 		if err != nil {
 			return err
 		}

From 594f17547277c575663f807c73af882d2d9306e6 Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Mon, 7 Nov 2022 11:24:46 -0800
Subject: [PATCH 3/3] implement primetime

---
 cmd/primetime/main.go | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/cmd/primetime/main.go b/cmd/primetime/main.go
index 7ad3841..5921b0e 100644
--- a/cmd/primetime/main.go
+++ b/cmd/primetime/main.go
@@ -1,15 +1,24 @@
 package main
 
 import (
+	"bufio"
+	"encoding/json"
 	"log"
+	"math/big"
 	"net"
 
 	"protohackers/pkg/conn"
 )
 
+var (
+	malformedResponse = []byte("malformed\n")
+	trueResponse      = []byte(`{"method":"isPrime","prime":true}` + "\n")
+	falseResponse     = []byte(`{"method":"isPrime","prime":false}` + "\n")
+)
+
 type data struct {
-	Method string `json:"method"`
-	Number int    `json:"number"`
+	Method string   `json:"method"`
+	Number *float64 `json:"number"`
 }
 
 func main() {
@@ -21,4 +30,23 @@ func main() {
 
 func primetime(c net.Conn) {
 	defer c.Close()
+	sc := bufio.NewScanner(c)
+	for sc.Scan() {
+		response := process(sc.Bytes())
+		c.Write(response)
+	}
+	if err := sc.Err(); err != nil {
+		log.Fatalln(err)
+	}
+}
+
+func process(buf []byte) []byte {
+	var in data
+	err := json.Unmarshal(buf, &in)
+	if err != nil || in.Method != "isPrime" || in.Number == nil {
+		return malformedResponse
+	} else if big.NewInt(int64(*in.Number)).ProbablyPrime(0) {
+		return trueResponse
+	}
+	return falseResponse
 }