implement primetime

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"`
+	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
 }