Add support for logging in using tdesktop session data (TDATA) (#58)

* Added TDATA session support

* Added example to authenticate with TDATA

examples/auth-using-tdata/main.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/celestix/gotgproto"
+	"github.com/celestix/gotgproto/sessionMaker"
+	"github.com/gotd/td/session/tdesktop"
+)
+
+func main() {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		log.Fatalln(err)
+	}
+	telegramDir := filepath.Join(home, ".local/share/TelegramDesktop")
+	accounts, err := tdesktop.Read(telegramDir, nil)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	// Type of client to login to, can be of 2 types:
+	// 1.) Bot  (Fill BotToken in this case)
+	// 2.) User (Fill Phone in this case)
+	clientType := gotgproto.ClientType{
+		Phone: "PHONE_NUMBER_HERE",
+	}
+
+	client, err := gotgproto.NewClient(
+		// Get AppID from https://my.telegram.org/apps
+		123456,
+		// Get ApiHash from https://my.telegram.org/apps
+		"API_HASH_HERE",
+		// ClientType, as we defined above
+		clientType,
+		// Optional parameters of client
+		&gotgproto.ClientOpts{
+			// There can be up to 3 tdesktop.Account, we consider here there is
+			// at least a single on, you can loop through them with
+			// for _, account := range accounts {// your code}
+			Session: sessionMaker.TdataSession(accounts[0]).Name("tdata"),
+		},
+	)
+	if err != nil {
+		log.Fatalln("failed to start client:", err)
+	}
+
+	fmt.Printf("client (@%s) has been started...\n", client.Self.Username)
+
+	client.Idle()
+}

sessionMaker/sessionConstructor.go

@@ -1,12 +1,14 @@
 package sessionMaker
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 
 	"github.com/celestix/gotgproto/functions"
 	"github.com/celestix/gotgproto/storage"
 	"github.com/gotd/td/session"
+	"github.com/gotd/td/session/tdesktop"
 )
 
 type SessionConstructor interface {
@@ -111,3 +113,38 @@ func (s *StringSessionConstructor) loadSession() (string, []byte, error) {
 	}
 	return s.name, sd.Data, err
 }
+
+type TdataSessionConstructor struct {
+	Account tdesktop.Account
+	name    string
+}
+
+func TdataSession(account tdesktop.Account) *TdataSessionConstructor {
+	return &TdataSessionConstructor{Account: account}
+}
+
+func (s *TdataSessionConstructor) Name(name string) *TdataSessionConstructor {
+	s.name = name
+	return s
+}
+
+func (s *TdataSessionConstructor) loadSession() (string, []byte, error) {
+	sd, err := session.TDesktopSession(s.Account)
+	if err != nil {
+		return s.name, nil, err
+	}
+	ctx := context.Background()
+	var (
+		gotdstorage = new(session.StorageMemory)
+		loader      = session.Loader{Storage: gotdstorage}
+	)
+	// Save decoded Telegram Desktop session as gotd session.
+	if err := loader.Save(ctx, sd); err != nil {
+		return s.name, nil, err
+	}
+	data, err := json.Marshal(jsonData{
+		Version: storage.LatestVersion,
+		Data:    *sd,
+	})
+	return s.name, data, err
+}