feat: complete login

backend/providers/wechat/funcs.go

@@ -0,0 +1,14 @@
+package wechat
+
+import "math/rand"
+
+// RandomString generate random size string
+func randomString(size int) (string, error) {
+	// generate size string [0-9a-zA-Z]
+	const chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	b := make([]byte, size)
+	for i := range b {
+		b[i] = chars[rand.Intn(len(chars))]
+	}
+	return string(b), nil
+}