Split into multiple packages and improve error handling

domain/domain.go

@@ -0,0 +1,50 @@
+package domain
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+)
+
+type Domain struct {
+	domains map[string]bool
+}
+
+func NewDomain() (*Domain, error) {
+	var err error
+
+	domainsJsonFile, err := os.Open("domains.json")
+
+	if err != nil {
+		return nil, fmt.Errorf("an error occurred while opening the domains file: %v", err)
+	}
+
+	byteValue, err := ioutil.ReadAll(domainsJsonFile)
+
+	if err != nil {
+		return nil, fmt.Errorf("an error occurred while reading the domains file: %v", err)
+	}
+
+	var domainsSlice []string
+
+	err = json.Unmarshal(byteValue, &domainsSlice)
+
+	if err != nil {
+		return nil, fmt.Errorf("an error occurred while parsing the domains file: %v", err)
+	}
+
+	domains := make(map[string]bool)
+
+	for _, domain := range domainsSlice {
+		domains[domain] = true
+	}
+
+	return &Domain{
+		domains: domains,
+	}, nil
+}
+
+func (d *Domain) GetIsDisposable(emailOrDomain string) bool {
+	return d.domains[emailOrDomain]
+}

http/server.go

@@ -0,0 +1,69 @@
+package http
+
+import (
+	"encoding/json"
+	"github.com/julienschmidt/httprouter"
+	"log"
+	"net/http"
+	"strings"
+)
+
+type domain interface {
+	GetIsDisposable(string) bool
+}
+
+type Server struct {
+	domain domain
+}
+
+type ErrorResponse struct {
+	Detail string `json:"detail"`
+}
+
+type Response struct {
+	IsDisposable bool `json:"isDisposable"`
+}
+
+func NewServer(d domain) Server {
+	return Server{
+		domain: d,
+	}
+}
+
+func (s *Server) index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
+	queryParams := r.URL.Query()
+	email := queryParams.Get("email")
+
+	w.Header().Set("Content-Type", "application/json")
+
+	if email == "" {
+		errorResponse, _ := json.Marshal(ErrorResponse{
+			Detail: "email query parameter should be set.",
+		})
+
+		w.WriteHeader(400)
+		w.Write(errorResponse)
+
+		return
+	}
+
+	parts := strings.Split(email, "@")
+	emailDomain := parts[len(parts)-1]
+
+	isDisposable := s.domain.GetIsDisposable(emailDomain)
+
+	jsonBytes, _ := json.Marshal(Response{
+		IsDisposable: isDisposable,
+	})
+
+	w.Write(jsonBytes)
+}
+
+func (s *Server) Run() {
+	router := httprouter.New()
+
+	router.GET("/", s.index)
+
+	log.Println("Starting to listen on 0.0.0.0:80...")
+	log.Fatal(http.ListenAndServe(":80", router))
+}

main.go

@@ -1,76 +1,19 @@
 package main
 
 import (
-	"encoding/json"
-	"github.com/julienschmidt/httprouter"
-	"io/ioutil"
+	"github.com/th0th/is-email-disposable/domain"
+	"github.com/th0th/is-email-disposable/http"
 	"log"
-	"net/http"
-	"os"
-	"strings"
 )
 
-type ErrorResponse struct {
-	Detail string `json:"detail"`
-}
-
-type Response struct {
-	IsDisposable bool `json:"isDisposable"`
-}
-
-var domains []string
-
-func handler(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
-	queryParams := r.URL.Query()
-
-	email := queryParams.Get("email")
-
-	w.Header().Set("Content-Type", "application/json")
-
-	if email == "" {
-		errorResponse, _ := json.Marshal(ErrorResponse{
-			Detail: "email query parameter should be set.",
-		})
-
-		w.WriteHeader(400)
-		w.Write(errorResponse)
-
-		return
-	}
-
-	parts := strings.Split(email, "@")
-	domain := parts[len(parts)-1]
-
-	isDisposable := Find(domains, domain)
-
-	jsonBytes, _ := json.Marshal(Response{
-		IsDisposable: isDisposable,
-	})
-
-	w.Write(jsonBytes)
-}
-
 func main() {
-	domainsJsonFile, _ := os.Open("domains.json")
-
-	byteValue, _ := ioutil.ReadAll(domainsJsonFile)
+	d, err := domain.NewDomain()
 
-	_ = json.Unmarshal(byteValue, &domains)
-
-	router := httprouter.New()
-
-	router.GET("/", handler)
-
-	log.Println("Starting to listen on 0.0.0.0:80...")
-	log.Fatal(http.ListenAndServe(":80", router))
-}
-
-func Find(slice []string, val string) bool {
-	for _, item := range slice {
-		if item == val {
-			return true
-		}
+	if err != nil {
+		log.Panic(err)
 	}
 
-	return false
+	server := http.NewServer(d)
+
+	server.Run()
 }