adding session management with login and logout capabilities

executors/message_manager.go

@@ -0,0 +1,6 @@
+package executors
+
+// SendText sends the provided text message to the receipient.
+func SendText(text, reciever string) error {
+	return nil
+}

executors/session_manager.go

@@ -0,0 +1,85 @@
+package executors
+
+import (
+	"encoding/gob"
+	"fmt"
+	"os"
+	"time"
+
+	qrcodeTerminal "github.com/Baozisoftware/qrcode-terminal-go"
+	"github.com/Rhymen/go-whatsapp"
+)
+
+// Login logs in the user. It ries to see if a session already exists. If not, tries to create a
+// new one using qr scanned on the terminal.
+func Login() error {
+	wac, err := whatsapp.NewConn(5 * time.Second)
+	if err != nil {
+		return fmt.Errorf("error while logging in %v\n", err)
+	}
+	//load saved session
+	session, err := readSession()
+	if err == nil {
+		//restore session
+		session, err = wac.RestoreWithSession(session)
+		if err != nil {
+			return fmt.Errorf("restoring failed: %v\n", err)
+		}
+	} else {
+		//no saved session -> regular login
+		qr := make(chan string)
+		go func() {
+			terminal := qrcodeTerminal.New()
+			terminal.Get(<-qr).Print()
+		}()
+		session, err = wac.Login(qr)
+		if err != nil {
+			return fmt.Errorf("error during login: %v\n", err)
+		}
+	}
+
+	//save session
+	err = writeSession(session)
+	if err != nil {
+		return fmt.Errorf("error saving session: %v\n", err)
+	}
+	return nil
+}
+
+// Logout logs out the user.
+func Logout() error {
+	return removeSession()
+}
+
+func readSession() (whatsapp.Session, error) {
+	session := whatsapp.Session{}
+	file, err := os.Open(os.TempDir() + "/whatsappCLISession.gob")
+	if err != nil {
+		return session, err
+	}
+	defer file.Close()
+	decoder := gob.NewDecoder(file)
+	err = decoder.Decode(&session)
+	if err != nil {
+		return session, err
+	}
+	return session, nil
+}
+
+func writeSession(session whatsapp.Session) error {
+	file, err := os.Create(os.TempDir() + "/whatsappCLISession.gob")
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	encoder := gob.NewEncoder(file)
+	err = encoder.Encode(session)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func removeSession() error {
+	return os.Remove(os.TempDir() + "/whatsappCLISession.gob")
+}

main.go

@@ -2,27 +2,58 @@ package main
 
 import (
 	"fmt"
-	"github.com/Baozisoftware/qrcode-terminal-go"
-	"github.com/Rhymen/go-whatsapp"
+	"flag"
 	"os"
-	"time"
+
+	"github.com/abansal4032/go-whatsapp-cli/executors"
+	"github.com/abansal4032/go-whatsapp-cli/utils"
 )
 
-func main() {
-	wac, err := whatsapp.NewConn(5 * time.Second)
+func commandUsage(err error) {
+	// TODO : graceful error handling here
 	if err != nil {
-		panic(err)
+		fmt.Println("correct command usage is described below:")
+		flag.PrintDefaults()
 	}
+}
 
-	qr := make(chan string)
-	go func() {
-		terminal := qrcodeTerminal.New()
-		terminal.Get(<-qr).Print()
+func main() {
+	sendTextCmd := flag.NewFlagSet("sendText", flag.ExitOnError)
+	var err error
+	defer func() {
+		commandUsage(err)
 	}()
 
-	session, err := wac.Login(qr)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "error during login: %v\n", err)
+	switch os.Args[1] {
+
+	case "login":
+		if err = executors.Login(); err != nil {
+			fmt.Println(err)
+			return
+		}
+
+	case "logout":
+		if err = executors.Logout(); err != nil {
+			fmt.Println(err)
+			return
+		}
+
+	case "sendText":
+		//var args *utils.SendArgs
+		_, err = utils.ParseSendArgs(sendTextCmd, os.Args[2:])
+		if err != nil {
+			fmt.Println(err)
+			return
+		}
+		/*if err = executors.SendText(args); err != nil {
+			fmt.Println(err)
+			return
+		}*/
+
+	default:
+		fmt.Println("wrong command provided. please see below for the list of permitted actions")
+		flag.PrintDefaults()
+		return
+
 	}
-	fmt.Printf("login successful, session: %v\n", session)
-}
+}

utils/models.go

@@ -0,0 +1,25 @@
+package utils
+
+import (
+	"flag"
+	"fmt"
+)
+
+type SendArgs struct {
+	to	string
+}
+
+func ParseSendArgs(f *flag.FlagSet, args []string) (*SendArgs, error) {
+	to := f.String("to", "", "the receipient of the message.")
+	if err := f.Parse(args); err != nil {
+		return nil, err
+	}
+	// checks for mandatory fields
+	if *to == "" {
+		return nil, fmt.Errorf("wrong arguments provided")
+	}
+	sendArgs := &SendArgs{
+		to: *to,
+	}
+	return sendArgs, nil
+}