build tx list message in controller, not in crud

bot/controller.go

@@ -209,15 +209,36 @@ func (bc *BotController) commandList(m *tb.Message) {
 		}
 		return
 	}
-	if tx == "" {
+	if tx == nil {
+		bc.Logf(ERROR, m, "Tx unexpectedly was nil")
+		return
+	}
+	SEP := "\n"
+	TG_MAX_MSG_CHAR_LEN := 4096
+	txMessages := []string{}
+	transactionsList := ""
+	for _, t := range tx {
+		if len(transactionsList)+len(t) >= TG_MAX_MSG_CHAR_LEN {
+			bc.Logf(TRACE, m, "Listed messages extend max message length. Splitting into multiple messages.")
+			txMessages = append(txMessages, transactionsList)
+			transactionsList = ""
+		}
+		transactionsList += t + SEP
+	}
+	if transactionsList != "" {
+		txMessages = append(txMessages, transactionsList)
+	}
+	if len(txMessages) == 0 {
 		_, err := bc.Bot.Send(m.Sender, fmt.Sprintf("Your transaction list is empty. Create some first. Check /%s for commands to create a transaction."+
 			"\nYou might also be looking for archived transactions using '/list archived'.", CMD_HELP), clearKeyboard())
 		if err != nil {
 			bc.Logf(ERROR, m, "Sending bot message failed: %s", err.Error())
 		}
 		return
 	}
-	_, err = bc.Bot.Send(m.Sender, tx, clearKeyboard())
+	for _, message := range txMessages {
+		_, err = bc.Bot.Send(m.Sender, message, clearKeyboard())
+	}
 	if err != nil {
 		bc.Logf(ERROR, m, "Sending bot message failed: %s", err.Error())
 	}

bot/controller_test.go

@@ -10,22 +10,28 @@ import (
 	tb "gopkg.in/tucnak/telebot.v2"
 
 	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/LucaBernstein/beancount-bot-tg/db/crud"
 	"github.com/LucaBernstein/beancount-bot-tg/helpers"
 )
 
 type MockBot struct {
-	LastSentWhat interface{}
+	LastSentWhat    interface{}
+	AllLastSentWhat []interface{}
 }
 
 func (b *MockBot) Start()                                           {}
 func (b *MockBot) Handle(endpoint interface{}, handler interface{}) {}
 func (b *MockBot) Send(to tb.Recipient, what interface{}, options ...interface{}) (*tb.Message, error) {
 	b.LastSentWhat = what
+	b.AllLastSentWhat = append(b.AllLastSentWhat, what)
 	return nil, nil
 }
 func (b *MockBot) Me() *tb.User {
 	return &tb.User{Username: "Test bot"}
 }
+func (b *MockBot) reset() {
+	b.AllLastSentWhat = nil
+}
 
 // GitHub-Issue #16: Panic if plain message without state arrives
 func TestTextHandlingWithoutPriorState(t *testing.T) {
@@ -108,3 +114,57 @@ func TestTransactionDeletion(t *testing.T) {
 		t.Errorf("there were unfulfilled expectations: %s", err)
 	}
 }
+
+func TestTransactionListMaxLength(t *testing.T) {
+	// create test dependencies
+	chat := &tb.Chat{ID: 12345}
+	db, mock, err := sqlmock.New()
+	crud.TEST_MODE = true
+	if err != nil {
+		log.Fatal(err)
+	}
+	mock.
+		ExpectQuery(`SELECT "value" FROM "bot::transaction"`).
+		WithArgs(chat.ID, false).
+		WillReturnRows(sqlmock.NewRows([]string{"value"}).AddRow(strings.Repeat("**********", 100)).AddRow(strings.Repeat("**********", 100))) // 1000 + 1000
+	mock.
+		ExpectQuery(`SELECT "value" FROM "bot::transaction"`).
+		WithArgs(chat.ID, false).
+		WillReturnRows(sqlmock.NewRows([]string{"value"}).
+			// 5 * 1000
+			AddRow(strings.Repeat("**********", 100)).
+			AddRow(strings.Repeat("**********", 100)).
+			AddRow(strings.Repeat("**********", 100)).
+			AddRow(strings.Repeat("**********", 100)).
+			AddRow(strings.Repeat("**********", 100)),
+		)
+
+	bc := NewBotController(db)
+	bot := &MockBot{}
+	bc.AddBotAndStart(bot)
+
+	// < 4096 chars tx
+	bc.commandList(&tb.Message{Chat: chat})
+	if len(bot.AllLastSentWhat) != 1 {
+		t.Errorf("Expected exactly one message to be sent out: %v", bot.AllLastSentWhat)
+	}
+
+	bot.reset()
+
+	// > 4096 chars tx
+	bc.commandList(&tb.Message{Chat: chat})
+	if len(bot.AllLastSentWhat) != 2 {
+		t.Errorf("Expected exactly two messages to be sent out: %v", strings.Join(stringArr(bot.AllLastSentWhat), ", "))
+	}
+	if bot.LastSentWhat != strings.Repeat("**********", 100)+"\n" {
+		t.Errorf("Expected last message to contain last transaction as it flowed over the first message: %v", bot.LastSentWhat)
+	}
+}
+
+func stringArr(i []interface{}) []string {
+	arr := []string{}
+	for _, e := range i {
+		arr = append(arr, fmt.Sprintf("%v", e))
+	}
+	return arr
+}

db/crud/bot_transaction.go

@@ -12,27 +12,26 @@ func (r *Repo) RecordTransaction(chatId int64, tx string) error {
 	return err
 }
 
-func (r *Repo) GetTransactions(m *tb.Message, isArchived bool) (string, error) {
+func (r *Repo) GetTransactions(m *tb.Message, isArchived bool) ([]string, error) {
 	LogDbf(r, helpers.TRACE, m, "Getting transactions")
 	rows, err := r.db.Query(`
 		SELECT "value" FROM "bot::transaction"
 		WHERE "tgChatId" = $1 AND "archived" = $2
 		ORDER BY "created" ASC
 	`, m.Chat.ID, isArchived)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer rows.Close()
 
-	SEP := "\n"
-	allTransactionsMessage := ""
+	allTransactionsMessage := []string{}
 	var transactionString string
 	for rows.Next() {
 		err = rows.Scan(&transactionString)
 		if err != nil {
-			return "", err
+			return nil, err
 		}
-		allTransactionsMessage += transactionString + SEP
+		allTransactionsMessage = append(allTransactionsMessage, transactionString)
 	}
 	return allTransactionsMessage, nil
 }