diff --git a/internal/leetcode/base.go b/internal/leetcode/base.go
index 05886ed10..1f5e6d9bb 100644
--- a/internal/leetcode/base.go
+++ b/internal/leetcode/base.go
@@ -3,6 +3,8 @@ package leetcode
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
+	"fmt"
 	"io/ioutil"
 	"net/http"
 	"net/http/cookiejar"
@@ -12,18 +14,24 @@ import (
 	"path"
 )
 
-func checkErr(err error) {
-	if err != nil {
-		panic(err)
+var err error
+
+func init() {
+	http.DefaultClient.Jar, err = cookiejar.New(nil)
+	checkErr(err)
+	http.DefaultClient.CheckRedirect = func(req *http.Request, via []*http.Request) error {
+		req.Header.Set("Referer", req.URL.String())
+		fmt.Println(req.URL.String())
+		if len(via) >= 3 {
+			return errors.New("stopped after 3 redirects")
+		}
+		return nil
 	}
 }
 
-func client() *http.Client {
-	jar, err := cookiejar.New(nil)
-	// jar.SetCookies()
-	checkErr(err)
-	return &http.Client{
-		Jar: jar,
+func checkErr(err error) {
+	if err != nil {
+		panic(err)
 	}
 }
 
@@ -36,29 +44,45 @@ func getCsrfToken(cookies []*http.Cookie) string {
 	return ""
 }
 
-func getPath(f string) string {
-	dir := os.TempDir()
+func getCachePath(f string) string {
+	dir, err := os.UserCacheDir()
+	checkErr(err)
 	u, err := user.Current()
 	if err == nil && u.HomeDir != "" {
 		dir = path.Join(u.HomeDir, ".leetcode")
 	}
-	err = os.MkdirAll(dir, 0755)
-	checkErr(err)
 	return path.Join(dir, f)
 }
 
-func saveCookies(cookies []*http.Cookie) {
-	data, err := json.Marshal(cookies)
+func getFilePath(filename string) string {
+	if dir := path.Dir(filename); dir != "" {
+		if err := os.MkdirAll(dir, 0755); err != nil {
+			checkErr(err)
+		}
+	}
+	return filename
+}
+
+func filePutContents(filename string, data []byte) {
+	filename = getFilePath(filename)
+	err = ioutil.WriteFile(filename, data, 0644)
+	checkErr(err)
+}
+
+func jsonEncode(v interface{}) []byte {
+	data, err := json.Marshal(v)
 	checkErr(err)
 	dst := bytes.Buffer{}
 	err = json.Indent(&dst, data, "", "\t")
 	checkErr(err)
-	err = ioutil.WriteFile(getPath(cookiesFile), dst.Bytes(), 0755)
-	checkErr(err)
+	return dst.Bytes()
+}
+func saveCookies(cookies []*http.Cookie) {
+	filePutContents(getCachePath(cookiesFile), jsonEncode(cookies))
 }
 
 func getCookies() (cookies []*http.Cookie) {
-	b, err := ioutil.ReadFile(getPath(cookiesFile))
+	b, err := ioutil.ReadFile(getCachePath(cookiesFile))
 	checkErr(err)
 	err = json.Unmarshal(b, &cookies)
 	checkErr(err)
@@ -66,7 +90,13 @@ func getCookies() (cookies []*http.Cookie) {
 }
 
 func saveCredential(data url.Values) {
-	u := url.UserPassword(data.Get("login"), data.Get("password"))
-	err := ioutil.WriteFile(getPath(credentialsFile), []byte(u.String()), 0755)
+	filePutContents(getCachePath(credentialsFile), jsonEncode(data))
+}
+
+func getCredential() (data url.Values) {
+	b, err := ioutil.ReadFile(getCachePath(credentialsFile))
+	checkErr(err)
+	err = json.Unmarshal(b, &data)
 	checkErr(err)
+	return
 }
diff --git a/internal/leetcode/config.go b/internal/leetcode/config.go
index 0e20f0a91..69703c68d 100644
--- a/internal/leetcode/config.go
+++ b/internal/leetcode/config.go
@@ -11,6 +11,6 @@ const (
 
 const cookiesFile = "cookies.json"
 
-const credentialsFile = "credentials"
+const credentialsFile = "credentials.json"
 
 const problemsAllFile = "problems_all.json"
diff --git a/internal/leetcode/login.go b/internal/leetcode/login.go
index f1286407e..451f40da9 100644
--- a/internal/leetcode/login.go
+++ b/internal/leetcode/login.go
@@ -1,36 +1,41 @@
 package leetcode
 
 import (
+	"fmt"
 	"net/http"
 	"net/url"
-	"strings"
 )
 
 func AccountsLogin(username, password string) (*http.Response, error) {
 	resp, err := http.Head(AccountsLoginUrl)
 	checkErr(err)
 	defer resp.Body.Close()
-	cookies := resp.Cookies()
-	saveCookies(cookies)
-	csrftoken := getCsrfToken(cookies)
+	saveCookies(resp.Cookies())
+	csrftoken := getCsrfToken(resp.Cookies())
 	data := url.Values{
 		"login":               {username},
 		"password":            {password},
 		"csrfmiddlewaretoken": {csrftoken},
 	}
-	req, err := http.NewRequest("POST", AccountsLoginUrl, strings.NewReader(data.Encode()))
-	checkErr(err)
-	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-	req.Header.Set("Referer", AccountsLoginUrl)
-	for _, cookie := range cookies {
-		req.AddCookie(cookie)
-	}
-	resp, err = http.DefaultClient.Do(req)
+	http.PostForm(AccountsLoginUrl, data)
 	checkErr(err)
 	defer resp.Body.Close()
 	saveCookies(resp.Cookies())
 	if resp.StatusCode == 200 {
 		saveCredential(data)
+	} else {
+		fmt.Println("login error: ", resp.Status)
 	}
 	return resp, err
 }
+
+func AutoLogin() (*http.Response, error) {
+	data := getCredential()
+	if data.Get("login") == "" {
+		fmt.Println("can't get username")
+	}
+	if data.Get("password") == "" {
+		fmt.Println("can't get password")
+	}
+	return AccountsLogin(data.Get("login"), data.Get("password"))
+}
diff --git a/internal/leetcode/problem.go b/internal/leetcode/problem.go
index d83677d3e..4e87727df 100644
--- a/internal/leetcode/problem.go
+++ b/internal/leetcode/problem.go
@@ -70,8 +70,7 @@ func ProblemsAll() (pa ProblemsAllType) {
 	dst := bytes.Buffer{}
 	err = json.Indent(&dst, body, "", "\t")
 	checkErr(err)
-	err = ioutil.WriteFile(getPath(problemsAllFile), dst.Bytes(), 0755)
-	checkErr(err)
+	filePutContents(getCachePath(problemsAllFile), dst.Bytes())
 	err = json.Unmarshal(body, &pa)
 	checkErr(err)
 	return