...

_pkg2_dont_use/heroservices/billing/models/account.go

@@ -0,0 +1,115 @@
+package models
+
+import (
+	"encoding/binary"
+	"errors"
+	"math"
+	"strings"
+)
+
+// Account represents a financial account in the billing system
+type Account struct {
+	ID       uint32  // Unique identifier, auto-incremented
+	UserID   uint32  // Link to the unique user ID
+	Name     string  // Name of the account
+	Currency string  // Currency code (e.g., USD, EUR), always uppercase, 3 letters
+	Amount   float64 // Current balance, always positive
+}
+
+// Serialize converts an Account to a binary representation
+func (a *Account) Serialize() []byte {
+	// Calculate the size of the serialized data
+	// 4 bytes for ID + 4 bytes for UserID + 2 bytes for name length + len(name) bytes +
+	// 3 bytes for currency + 8 bytes for amount
+	size := 4 + 4 + 2 + len(a.Name) + 3 + 8
+	data := make([]byte, size)
+
+	// Write ID (4 bytes)
+	binary.LittleEndian.PutUint32(data[0:4], a.ID)
+
+	// Write UserID (4 bytes)
+	binary.LittleEndian.PutUint32(data[4:8], a.UserID)
+
+	// Write name length (2 bytes) and name
+	nameLen := uint16(len(a.Name))
+	binary.LittleEndian.PutUint16(data[8:10], nameLen)
+	copy(data[10:10+nameLen], a.Name)
+
+	// Write currency (3 bytes)
+	currencyOffset := 10 + nameLen
+	copy(data[currencyOffset:currencyOffset+3], a.Currency)
+
+	// Write amount (8 bytes)
+	amountOffset := currencyOffset + 3
+	binary.LittleEndian.PutUint64(data[amountOffset:amountOffset+8], math.Float64bits(a.Amount))
+
+	return data
+}
+
+// DeserializeAccount converts a binary representation back to an Account
+func DeserializeAccount(data []byte) (*Account, error) {
+	if len(data) < 17 { // Minimum size: 4 (ID) + 4 (UserID) + 2 (name length) + 3 (currency) + 8 (amount)
+		return nil, errors.New("data too short to deserialize Account")
+	}
+
+	account := &Account{}
+
+	// Read ID
+	account.ID = binary.LittleEndian.Uint32(data[0:4])
+
+	// Read UserID
+	account.UserID = binary.LittleEndian.Uint32(data[4:8])
+
+	// Read name length and name
+	nameLen := binary.LittleEndian.Uint16(data[8:10])
+	if 10+nameLen > uint16(len(data)) {
+		return nil, errors.New("data too short to read name")
+	}
+	account.Name = string(data[10 : 10+nameLen])
+
+	// Read currency
+	currencyOffset := 10 + nameLen
+	if int(currencyOffset)+3 > len(data) {
+		return nil, errors.New("data too short to read currency")
+	}
+	account.Currency = string(data[currencyOffset : currencyOffset+3])
+
+	// Read amount
+	amountOffset := currencyOffset + 3
+	if int(amountOffset)+8 > len(data) {
+		return nil, errors.New("data too short to read amount")
+	}
+	account.Amount = math.Float64frombits(binary.LittleEndian.Uint64(data[amountOffset : amountOffset+8]))
+
+	return account, nil
+}
+
+// Validate checks if the account data is valid
+func (a *Account) Validate() error {
+	if a.UserID == 0 {
+		return errors.New("user ID cannot be zero")
+	}
+
+	if a.Name == "" {
+		return errors.New("account name cannot be empty")
+	}
+
+	// Check currency format (3 uppercase letters)
+	if len(a.Currency) != 3 {
+		return errors.New("currency must be 3 characters")
+	}
+
+	a.Currency = strings.ToUpper(a.Currency)
+	for _, r := range a.Currency {
+		if r < 'A' || r > 'Z' {
+			return errors.New("currency must contain only uppercase letters")
+		}
+	}
+
+	// Ensure amount is non-negative
+	if a.Amount < 0 {
+		return errors.New("amount cannot be negative")
+	}
+
+	return nil
+}

_pkg2_dont_use/heroservices/billing/models/cmd/main.go

@@ -0,0 +1,348 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"runtime"
+	"runtime/pprof"
+	"strings"
+	"time"
+
+	"git.ourworld.tf/herocode/heroagent/pkg/heroservices/billing/models"
+)
+
+const (
+	numUsers        = 1000
+	numAccounts     = 3000  // Average 3 accounts per user
+	numTransactions = 10000 // Reduced for quicker testing
+	currencies      = "USD,EUR,GBP,JPY,CNY,AUD,CAD,CHF,HKD,SGD"
+	accountTypes    = "Checking,Savings,Investment,Retirement,Business,Credit,Loan,Mortgage,Travel,Emergency"
+	companies       = "Apple,Google,Microsoft,Amazon,Facebook,Tesla,Walmart,Target,Costco,HomeDepot,Lowes,BestBuy,Starbucks,McDonalds,Chipotle,Nike,Adidas,Uber,Lyft,Airbnb"
+	firstNames      = "John,Jane,Michael,Emily,David,Sarah,Robert,Jennifer,William,Elizabeth,James,Linda,Richard,Barbara,Joseph,Susan,Thomas,Jessica,Charles,Mary"
+	lastNames       = "Smith,Johnson,Williams,Jones,Brown,Davis,Miller,Wilson,Moore,Taylor,Anderson,Thomas,Jackson,White,Harris,Martin,Thompson,Garcia,Martinez,Robinson"
+)
+
+var (
+	currencyList  []string
+	accountList   []string
+	companyList   []string
+	firstNameList []string
+	lastNameList  []string
+)
+
+func init() {
+	// Initialize random seed
+	rand.Seed(time.Now().UnixNano())
+
+	// Split the constant strings into slices
+	currencyList = strings.Split(currencies, ",")
+	accountList = strings.Split(accountTypes, ",")
+	companyList = strings.Split(companies, ",")
+	firstNameList = strings.Split(firstNames, ",")
+	lastNameList = strings.Split(lastNames, ",")
+}
+
+// generateRandomName generates a random user name
+func generateRandomName() string {
+	firstName := firstNameList[rand.Intn(len(firstNameList))]
+	lastName := lastNameList[rand.Intn(len(lastNameList))]
+	// Add timestamp and random number to ensure uniqueness
+	return fmt.Sprintf("%s_%s_%d_%d", firstName, lastName, time.Now().UnixNano()%1000000, rand.Intn(1000))
+}
+
+// generateRandomAccountName generates a random account name
+func generateRandomAccountName() string {
+	accountType := accountList[rand.Intn(len(accountList))]
+
+	// 30% chance to add a company name
+	if rand.Intn(100) < 30 {
+		company := companyList[rand.Intn(len(companyList))]
+		return fmt.Sprintf("%s %s", company, accountType)
+	}
+
+	return accountType
+}
+
+// generateRandomCurrency returns a random currency code
+func generateRandomCurrency() string {
+	return currencyList[rand.Intn(len(currencyList))]
+}
+
+// generateRandomAmount generates a random amount between min and max
+func generateRandomAmount(min, max float64) float64 {
+	return min + rand.Float64()*(max-min)
+}
+
+// generateRandomComment generates a realistic transaction comment
+func generateRandomComment(fromAccount, toAccount *models.Account, amount float64) string {
+	commentTypes := []string{
+		"Payment",
+		"Transfer",
+		"Deposit",
+		"Withdrawal",
+		"Refund",
+		"Purchase",
+		"Subscription",
+		"Salary",
+		"Dividend",
+		"Interest",
+	}
+
+	commentType := commentTypes[rand.Intn(len(commentTypes))]
+
+	switch commentType {
+	case "Payment":
+		return fmt.Sprintf("Payment to %s", toAccount.Name)
+	case "Transfer":
+		return fmt.Sprintf("Transfer to %s", toAccount.Name)
+	case "Deposit":
+		return fmt.Sprintf("Deposit to %s", toAccount.Name)
+	case "Withdrawal":
+		return fmt.Sprintf("Withdrawal from %s", fromAccount.Name)
+	case "Refund":
+		return fmt.Sprintf("Refund from %s", fromAccount.Name)
+	case "Purchase":
+		company := companyList[rand.Intn(len(companyList))]
+		return fmt.Sprintf("Purchase at %s", company)
+	case "Subscription":
+		company := companyList[rand.Intn(len(companyList))]
+		return fmt.Sprintf("%s subscription", company)
+	case "Salary":
+		company := companyList[rand.Intn(len(companyList))]
+		return fmt.Sprintf("Salary from %s", company)
+	case "Dividend":
+		company := companyList[rand.Intn(len(companyList))]
+		return fmt.Sprintf("Dividend from %s", company)
+	case "Interest":
+		return fmt.Sprintf("Interest payment %.2f%%", rand.Float64()*5)
+	default:
+		return fmt.Sprintf("Transfer of %.2f %s", amount, fromAccount.Currency)
+	}
+}
+
+func main() {
+	// Create a temporary directory for the test
+	tempDir, err := os.MkdirTemp("", "billing-perf-test-*")
+	if err != nil {
+		log.Fatalf("Failed to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	// Create subdirectories
+	dbPath := filepath.Join(tempDir, "db")
+	metaPath := filepath.Join(tempDir, "meta")
+
+	if err := os.MkdirAll(dbPath, 0755); err != nil {
+		log.Fatalf("Failed to create db directory: %v", err)
+	}
+
+	if err := os.MkdirAll(metaPath, 0755); err != nil {
+		log.Fatalf("Failed to create meta directory: %v", err)
+	}
+
+	// Set environment variables to use the temp directory
+	originalHome := os.Getenv("HOME")
+	os.Setenv("HOME", tempDir)
+	defer os.Setenv("HOME", originalHome)
+
+	// Start CPU profiling
+	cpuProfile, err := os.Create("cpu_profile.prof")
+	if err != nil {
+		log.Fatalf("Failed to create CPU profile: %v", err)
+	}
+	pprof.StartCPUProfile(cpuProfile)
+	defer pprof.StopCPUProfile()
+
+	// Create a new database store
+	fmt.Println("Creating database store...")
+	startTime := time.Now()
+	dbStore, err := models.NewDBStore()
+	if err != nil {
+		log.Fatalf("Failed to create database store: %v", err)
+	}
+	defer dbStore.Close()
+	fmt.Printf("Database store created in %v\n", time.Since(startTime))
+
+	// Create user, account, and transaction stores
+	userStore := &models.UserStore{Store: dbStore}
+	accountStore := models.NewAccountStore(dbStore)
+	transactionStore := models.NewTransactionStore(dbStore)
+
+	// Create users
+	fmt.Printf("Creating %d users...\n", numUsers)
+	startTime = time.Now()
+	users := make([]*models.User, numUsers)
+	for i := 0; i < numUsers; i++ {
+		user := &models.User{
+			Key:      generateRandomName(),
+			Accounts: []uint32{},
+		}
+
+		if err := userStore.Save(user); err != nil {
+			log.Fatalf("Failed to save user %d: %v", i, err)
+		}
+
+		users[i] = user
+
+		if (i+1)%100 == 0 {
+			fmt.Printf("Created %d users...\n", i+1)
+		}
+	}
+	fmt.Printf("Created %d users in %v\n", numUsers, time.Since(startTime))
+
+	// Create accounts
+	fmt.Printf("Creating %d accounts...\n", numAccounts)
+	startTime = time.Now()
+	accounts := make([]*models.Account, numAccounts)
+	for i := 0; i < numAccounts; i++ {
+		// Assign to a random user
+		userIndex := rand.Intn(numUsers)
+		user := users[userIndex]
+
+		account := &models.Account{
+			UserID:   user.ID,
+			Name:     generateRandomAccountName(),
+			Currency: generateRandomCurrency(),
+			Amount:   generateRandomAmount(1000, 10000),
+		}
+
+		if err := accountStore.Save(account); err != nil {
+			log.Fatalf("Failed to save account %d: %v", i, err)
+		}
+
+		accounts[i] = account
+
+		if (i+1)%300 == 0 {
+			fmt.Printf("Created %d accounts...\n", i+1)
+		}
+	}
+	fmt.Printf("Created %d accounts in %v\n", numAccounts, time.Since(startTime))
+
+	// Create transactions
+	fmt.Printf("Creating %d transactions...\n", numTransactions)
+	startTime = time.Now()
+	var memStats runtime.MemStats
+
+	for i := 0; i < numTransactions; i++ {
+		// Select random source and destination accounts
+		fromIndex := rand.Intn(numAccounts)
+		var toIndex int
+		for {
+			toIndex = rand.Intn(numAccounts)
+			if toIndex != fromIndex {
+				break
+			}
+		}
+
+		fromAccount := accounts[fromIndex]
+		toAccount := accounts[toIndex]
+
+		// Generate a realistic amount (usually smaller than the available balance)
+		maxAmount := fromAccount.Amount * 0.2
+		if maxAmount < 10 {
+			maxAmount = 10
+		}
+		amount := generateRandomAmount(1, maxAmount)
+
+		transaction := &models.Transaction{
+			From:    fromAccount.ID,
+			To:      toAccount.ID,
+			Comment: generateRandomComment(fromAccount, toAccount, amount),
+			Amount:  amount,
+		}
+
+		if err := transactionStore.Save(transaction); err != nil {
+			log.Fatalf("Failed to save transaction %d: %v", i, err)
+		}
+
+		// Update our local copy of the accounts
+		fromAccount.Amount -= amount
+		toAccount.Amount += amount
+
+		if (i+1)%1000 == 0 {
+			elapsed := time.Since(startTime)
+			transPerSec := float64(i+1) / elapsed.Seconds()
+
+			// Collect memory stats
+			runtime.ReadMemStats(&memStats)
+
+			fmt.Printf("Created %d transactions (%.2f/sec), Memory: %.2f MB\n",
+				i+1,
+				transPerSec,
+				float64(memStats.Alloc)/1024/1024)
+		}
+	}
+
+	totalTime := time.Since(startTime)
+	transPerSec := float64(numTransactions) / totalTime.Seconds()
+	fmt.Printf("Created %d transactions in %v (%.2f transactions/sec)\n",
+		numTransactions,
+		totalTime,
+		transPerSec)
+
+	// Memory profile
+	memProfile, err := os.Create("mem_profile.prof")
+	if err != nil {
+		log.Fatalf("Failed to create memory profile: %v", err)
+	}
+	runtime.GC() // Run garbage collection before taking memory profile
+	if err := pprof.WriteHeapProfile(memProfile); err != nil {
+		log.Fatalf("Failed to write memory profile: %v", err)
+	}
+	memProfile.Close()
+
+	// Final memory stats
+	runtime.ReadMemStats(&memStats)
+	fmt.Printf("\nFinal Memory Stats:\n")
+	fmt.Printf("Alloc: %.2f MB\n", float64(memStats.Alloc)/1024/1024)
+	fmt.Printf("TotalAlloc: %.2f MB\n", float64(memStats.TotalAlloc)/1024/1024)
+	fmt.Printf("Sys: %.2f MB\n", float64(memStats.Sys)/1024/1024)
+	fmt.Printf("NumGC: %d\n", memStats.NumGC)
+
+	// Test retrieving random transactions
+	fmt.Println("\nTesting random transaction retrieval...")
+	startTime = time.Now()
+	for i := 0; i < 1000; i++ {
+		txID := rand.Uint32()%uint32(numTransactions) + 1
+		_, err := transactionStore.GetByID(txID)
+		if err != nil {
+			// Skip errors for non-existent transactions
+			continue
+		}
+	}
+	fmt.Printf("Retrieved 1000 random transactions in %v\n", time.Since(startTime))
+
+	// Test retrieving random accounts
+	fmt.Println("\nTesting random account retrieval...")
+	startTime = time.Now()
+	for i := 0; i < 1000; i++ {
+		accountID := rand.Uint32()%uint32(numAccounts) + 1
+		_, err := accountStore.GetByID(accountID)
+		if err != nil {
+			// Skip errors for non-existent accounts
+			continue
+		}
+	}
+	fmt.Printf("Retrieved 1000 random accounts in %v\n", time.Since(startTime))
+
+	// Test retrieving random users
+	fmt.Println("\nTesting random user retrieval...")
+	startTime = time.Now()
+	for i := 0; i < 1000; i++ {
+		userID := rand.Uint32()%uint32(numUsers) + 1
+		_, err := userStore.GetByID(userID)
+		if err != nil {
+			// Skip errors for non-existent users
+			continue
+		}
+	}
+	fmt.Printf("Retrieved 1000 random users in %v\n", time.Since(startTime))
+
+	fmt.Println("\nPerformance test completed successfully!")
+	fmt.Printf("CPU profile saved to cpu_profile.prof\n")
+	fmt.Printf("Memory profile saved to mem_profile.prof\n")
+	fmt.Printf("To analyze profiles, run: go tool pprof cpu_profile.prof\n")
+}

_pkg2_dont_use/heroservices/billing/models/db.go

@@ -0,0 +1,546 @@
+package models
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"git.ourworld.tf/herocode/heroagent/pkg/data/ourdb"
+	"git.ourworld.tf/herocode/heroagent/pkg/data/radixtree"
+	"git.ourworld.tf/herocode/heroagent/pkg/tools"
+)
+
+// DBStore represents the central database store for all models
+type DBStore struct {
+	DB   *ourdb.OurDB
+	Meta *radixtree.RadixTree
+}
+
+// NewDBStore creates a new database store
+func NewDBStore() (*DBStore, error) {
+	// Get home directory
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get home directory: %w", err)
+	}
+
+	// Create paths
+	dbPath := filepath.Join(homeDir, "hero", "var", "server", "users", "db")
+	metaPath := filepath.Join(homeDir, "hero", "var", "server", "users", "meta")
+
+	// Create directories if they don't exist
+	if err := os.MkdirAll(dbPath, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create db directory: %w", err)
+	}
+	if err := os.MkdirAll(metaPath, 0755); err != nil {
+		return nil, fmt.Errorf("failed to create meta directory: %w", err)
+	}
+
+	// Create ourdb
+	dbConfig := ourdb.DefaultConfig()
+	dbConfig.Path = dbPath
+	dbConfig.IncrementalMode = true
+	db, err := ourdb.New(dbConfig)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create ourdb: %w", err)
+	}
+
+	// Create radixtree
+	meta, err := radixtree.New(radixtree.NewArgs{
+		Path: metaPath,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to create radixtree: %w", err)
+	}
+
+	return &DBStore{
+		DB:   db,
+		Meta: meta,
+	}, nil
+}
+
+// Close closes the database connections
+func (s *DBStore) Close() error {
+	err1 := s.DB.Close()
+	err2 := s.Meta.Close()
+
+	if err1 != nil {
+		return err1
+	}
+	return err2
+}
+
+// UserStore handles the storage and retrieval of User objects
+type UserStore struct {
+	Store *DBStore
+}
+
+// NewUserStore creates a new UserStore
+func NewUserStore() (*UserStore, *DBStore, error) {
+	store, err := NewDBStore()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return &UserStore{
+		Store: store,
+	}, store, nil
+}
+
+// Save saves a User to the database
+func (s *UserStore) Save(user *User) error {
+	// If ID is 0, this is a new user
+	if user.ID == 0 {
+		// Fix the key
+		fixedKey := tools.NameFix(user.Key)
+		if fixedKey == "" {
+			return errors.New("key cannot be empty")
+		}
+		user.Key = fixedKey
+
+		// Check if key already exists
+		existingID, err := s.GetIDByKey(user.Key)
+		if err == nil && existingID != 0 {
+			return fmt.Errorf("user with key %s already exists", user.Key)
+		}
+
+		// Get next ID
+		nextID, err := s.Store.DB.GetNextID()
+		if err != nil {
+			return fmt.Errorf("failed to get next ID: %w", err)
+		}
+		user.ID = nextID
+
+		// Save to ourdb
+		data := user.Serialize()
+		_, err = s.Store.DB.Set(ourdb.OurDBSetArgs{
+			Data: data,
+		})
+		if err != nil {
+			return fmt.Errorf("failed to save user to ourdb: %w", err)
+		}
+
+		// Save key to radixtree
+		idBytes := make([]byte, 4)
+		binary.LittleEndian.PutUint32(idBytes, user.ID)
+		err = s.Store.Meta.Set(user.Key, idBytes)
+		if err != nil {
+			return fmt.Errorf("failed to save user key to radixtree: %w", err)
+		}
+	} else {
+		// Update existing user
+		// Get existing user to verify key
+		existingUser, err := s.GetByID(user.ID)
+		if err != nil {
+			return fmt.Errorf("failed to get existing user: %w", err)
+		}
+
+		// If key changed, update radixtree
+		if existingUser.Key != user.Key {
+			// Fix the new key
+			fixedKey := tools.NameFix(user.Key)
+			if fixedKey == "" {
+				return errors.New("key cannot be empty")
+			}
+			user.Key = fixedKey
+
+			// Check if new key already exists
+			existingID, err := s.GetIDByKey(user.Key)
+			if err == nil && existingID != 0 && existingID != user.ID {
+				return fmt.Errorf("user with key %s already exists", user.Key)
+			}
+
+			// Delete old key from radixtree
+			err = s.Store.Meta.Delete(existingUser.Key)
+			if err != nil {
+				return fmt.Errorf("failed to delete old user key from radixtree: %w", err)
+			}
+
+			// Save new key to radixtree
+			idBytes := make([]byte, 4)
+			binary.LittleEndian.PutUint32(idBytes, user.ID)
+			err = s.Store.Meta.Set(user.Key, idBytes)
+			if err != nil {
+				return fmt.Errorf("failed to save new user key to radixtree: %w", err)
+			}
+		}
+
+		// Save to ourdb
+		data := user.Serialize()
+		id := user.ID
+		_, err = s.Store.DB.Set(ourdb.OurDBSetArgs{
+			ID:   &id,
+			Data: data,
+		})
+		if err != nil {
+			return fmt.Errorf("failed to update user in ourdb: %w", err)
+		}
+	}
+
+	return nil
+}
+
+// GetByID retrieves a User by ID
+func (s *UserStore) GetByID(id uint32) (*User, error) {
+	data, err := s.Store.DB.Get(id)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get user from ourdb: %w", err)
+	}
+
+	user, err := DeserializeUser(data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to deserialize user: %w", err)
+	}
+
+	return user, nil
+}
+
+// GetByKey retrieves a User by key
+func (s *UserStore) GetByKey(key string) (*User, error) {
+	// Fix the key
+	fixedKey := tools.NameFix(key)
+	if fixedKey == "" {
+		return nil, errors.New("key cannot be empty")
+	}
+
+	// Get ID from radixtree
+	id, err := s.GetIDByKey(fixedKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get user ID from radixtree: %w", err)
+	}
+
+	// Get user from ourdb
+	return s.GetByID(id)
+}
+
+// GetIDByKey retrieves a user ID by key
+func (s *UserStore) GetIDByKey(key string) (uint32, error) {
+	// Get ID from radixtree
+	idBytes, err := s.Store.Meta.Get(key)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get user ID from radixtree: %w", err)
+	}
+
+	if len(idBytes) != 4 {
+		return 0, fmt.Errorf("invalid ID bytes length: %d", len(idBytes))
+	}
+
+	return binary.LittleEndian.Uint32(idBytes), nil
+}
+
+// Delete deletes a User by ID
+func (s *UserStore) Delete(id uint32) error {
+	// Get user to get key
+	user, err := s.GetByID(id)
+	if err != nil {
+		return fmt.Errorf("failed to get user: %w", err)
+	}
+
+	// Delete from radixtree
+	err = s.Store.Meta.Delete(user.Key)
+	if err != nil {
+		return fmt.Errorf("failed to delete user key from radixtree: %w", err)
+	}
+
+	// Delete from ourdb
+	err = s.Store.DB.Delete(id)
+	if err != nil {
+		return fmt.Errorf("failed to delete user from ourdb: %w", err)
+	}
+
+	return nil
+}
+
+// AccountStore handles the storage and retrieval of Account objects
+type AccountStore struct {
+	Store *DBStore
+}
+
+// NewAccountStore creates a new AccountStore using the provided DBStore
+func NewAccountStore(store *DBStore) *AccountStore {
+	return &AccountStore{
+		Store: store,
+	}
+}
+
+// Save saves an Account to the database
+func (s *AccountStore) Save(account *Account) error {
+	// Validate account data
+	if err := account.Validate(); err != nil {
+		return err
+	}
+
+	// If ID is 0, this is a new account
+	if account.ID == 0 {
+		// Get next ID
+		nextID, err := s.Store.DB.GetNextID()
+		if err != nil {
+			return fmt.Errorf("failed to get next ID: %w", err)
+		}
+		account.ID = nextID
+
+		// Save to ourdb
+		data := account.Serialize()
+		_, err = s.Store.DB.Set(ourdb.OurDBSetArgs{
+			Data: data,
+		})
+		if err != nil {
+			return fmt.Errorf("failed to save account to ourdb: %w", err)
+		}
+
+		// Update user's accounts list
+		userStore := &UserStore{Store: s.Store}
+		user, err := userStore.GetByID(account.UserID)
+		if err != nil {
+			return fmt.Errorf("failed to get user: %w", err)
+		}
+
+		// Add account ID to user's accounts
+		user.Accounts = append(user.Accounts, account.ID)
+
+		// Save updated user
+		err = userStore.Save(user)
+		if err != nil {
+			return fmt.Errorf("failed to update user's accounts: %w", err)
+		}
+	} else {
+		// Update existing account
+		// Get existing account to verify it exists
+		_, err := s.GetByID(account.ID)
+		if err != nil {
+			return fmt.Errorf("failed to get existing account: %w", err)
+		}
+
+		// Save to ourdb
+		data := account.Serialize()
+		id := account.ID
+		_, err = s.Store.DB.Set(ourdb.OurDBSetArgs{
+			ID:   &id,
+			Data: data,
+		})
+		if err != nil {
+			return fmt.Errorf("failed to update account in ourdb: %w", err)
+		}
+	}
+
+	return nil
+}
+
+// GetByID retrieves an Account by ID
+func (s *AccountStore) GetByID(id uint32) (*Account, error) {
+	data, err := s.Store.DB.Get(id)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get account from ourdb: %w", err)
+	}
+
+	account, err := DeserializeAccount(data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to deserialize account: %w", err)
+	}
+
+	return account, nil
+}
+
+// GetByUserID retrieves all Accounts for a user
+func (s *AccountStore) GetByUserID(userID uint32) ([]*Account, error) {
+	// Get user to get account IDs
+	userStore := &UserStore{Store: s.Store}
+	user, err := userStore.GetByID(userID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get user: %w", err)
+	}
+
+	// Get accounts
+	accounts := make([]*Account, 0, len(user.Accounts))
+	for _, accountID := range user.Accounts {
+		account, err := s.GetByID(accountID)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get account %d: %w", accountID, err)
+		}
+		accounts = append(accounts, account)
+	}
+
+	return accounts, nil
+}
+
+// Delete deletes an Account by ID
+func (s *AccountStore) Delete(id uint32) error {
+	// Get account to get user ID
+	account, err := s.GetByID(id)
+	if err != nil {
+		return fmt.Errorf("failed to get account: %w", err)
+	}
+
+	// Get user to remove account from accounts list
+	userStore := &UserStore{Store: s.Store}
+	user, err := userStore.GetByID(account.UserID)
+	if err != nil {
+		return fmt.Errorf("failed to get user: %w", err)
+	}
+
+	// Remove account ID from user's accounts
+	for i, accountID := range user.Accounts {
+		if accountID == id {
+			user.Accounts = append(user.Accounts[:i], user.Accounts[i+1:]...)
+			break
+		}
+	}
+
+	// Save updated user
+	err = userStore.Save(user)
+	if err != nil {
+		return fmt.Errorf("failed to update user's accounts: %w", err)
+	}
+
+	// Delete from ourdb
+	err = s.Store.DB.Delete(id)
+	if err != nil {
+		return fmt.Errorf("failed to delete account from ourdb: %w", err)
+	}
+
+	return nil
+}
+
+// TransactionStore handles the storage and retrieval of Transaction objects
+type TransactionStore struct {
+	Store *DBStore
+}
+
+// NewTransactionStore creates a new TransactionStore using the provided DBStore
+func NewTransactionStore(store *DBStore) *TransactionStore {
+	return &TransactionStore{
+		Store: store,
+	}
+}
+
+// Save saves a Transaction to the database and updates account balances
+func (s *TransactionStore) Save(transaction *Transaction) error {
+	// Validate transaction data
+	if err := transaction.Validate(); err != nil {
+		return err
+	}
+
+	// Get account store
+	accountStore := &AccountStore{Store: s.Store}
+
+	// Get source account
+	fromAccount, err := accountStore.GetByID(transaction.From)
+	if err != nil {
+		return fmt.Errorf("failed to get source account: %w", err)
+	}
+
+	// Get destination account
+	toAccount, err := accountStore.GetByID(transaction.To)
+	if err != nil {
+		return fmt.Errorf("failed to get destination account: %w", err)
+	}
+
+	// Check if source account has enough balance
+	if fromAccount.Amount < transaction.Amount {
+		return errors.New("insufficient balance in source account")
+	}
+
+	// If TxID is 0, this is a new transaction
+	if transaction.TxID == 0 {
+		// Get next ID
+		nextID, err := s.Store.DB.GetNextID()
+		if err != nil {
+			return fmt.Errorf("failed to get next ID: %w", err)
+		}
+		transaction.TxID = nextID
+
+		// Update account balances
+		fromAccount.Amount -= transaction.Amount
+		toAccount.Amount += transaction.Amount
+
+		// Save updated accounts
+		if err := accountStore.Save(fromAccount); err != nil {
+			return fmt.Errorf("failed to update source account: %w", err)
+		}
+
+		if err := accountStore.Save(toAccount); err != nil {
+			// Rollback source account change if destination update fails
+			fromAccount.Amount += transaction.Amount
+			if rollbackErr := accountStore.Save(fromAccount); rollbackErr != nil {
+				return fmt.Errorf("failed to update destination account and rollback failed: %w, rollback error: %v", err, rollbackErr)
+			}
+			return fmt.Errorf("failed to update destination account: %w", err)
+		}
+
+		// Save transaction to ourdb
+		data := transaction.Serialize()
+		_, err = s.Store.DB.Set(ourdb.OurDBSetArgs{
+			Data: data,
+		})
+		if err != nil {
+			// Rollback account changes if transaction save fails
+			fromAccount.Amount += transaction.Amount
+			toAccount.Amount -= transaction.Amount
+			if rollbackErr1 := accountStore.Save(fromAccount); rollbackErr1 != nil {
+				return fmt.Errorf("failed to save transaction and rollback failed: %w, rollback error 1: %v", err, rollbackErr1)
+			}
+			if rollbackErr2 := accountStore.Save(toAccount); rollbackErr2 != nil {
+				return fmt.Errorf("failed to save transaction and rollback failed: %w, rollback error 2: %v", err, rollbackErr2)
+			}
+			return fmt.Errorf("failed to save transaction to ourdb: %w", err)
+		}
+	} else {
+		// Updating existing transactions is not allowed as it would affect account balances
+		return errors.New("updating existing transactions is not allowed")
+	}
+
+	return nil
+}
+
+// GetByID retrieves a Transaction by ID
+func (s *TransactionStore) GetByID(id uint32) (*Transaction, error) {
+	data, err := s.Store.DB.Get(id)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get transaction from ourdb: %w", err)
+	}
+
+	transaction, err := DeserializeTransaction(data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to deserialize transaction: %w", err)
+	}
+
+	return transaction, nil
+}
+
+// GetByAccount retrieves all Transactions for an account (either as source or destination)
+func (s *TransactionStore) GetByAccount(accountID uint32) ([]*Transaction, error) {
+	// This is a simplified implementation that would be inefficient in a real system
+	// In a real system, we would maintain indexes for account transactions
+
+	// Get the next ID to determine the range of transaction IDs
+	nextID, err := s.Store.DB.GetNextID()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get next ID: %w", err)
+	}
+
+	transactions := make([]*Transaction, 0)
+
+	// Iterate through all transactions (this is inefficient but works for a simple implementation)
+	for i := uint32(1); i < nextID; i++ {
+		transaction, err := s.GetByID(i)
+		if err != nil {
+			// Skip if transaction doesn't exist or can't be deserialized
+			continue
+		}
+
+		// Include transaction if it involves the specified account
+		if transaction.From == accountID || transaction.To == accountID {
+			transactions = append(transactions, transaction)
+		}
+	}
+
+	return transactions, nil
+}
+
+// Delete is not implemented for transactions as it would affect account balances
+// In a real system, you might want to implement a "void" or "reverse" transaction instead
+func (s *TransactionStore) Delete(id uint32) error {
+	return errors.New("deleting transactions is not allowed")
+}

_pkg2_dont_use/heroservices/billing/models/models_test.go

@@ -0,0 +1,489 @@
+package models
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// setupTestEnvironment creates a temporary test environment
+func setupTestEnvironment(t *testing.T) (string, func()) {
+	// Create a temporary directory for the test
+	tempDir, err := os.MkdirTemp("", "billing-test-*")
+	if err != nil {
+		t.Fatalf("Failed to create temp directory: %v", err)
+	}
+
+	// Create subdirectories
+	dbPath := filepath.Join(tempDir, "db")
+	metaPath := filepath.Join(tempDir, "meta")
+
+	if err := os.MkdirAll(dbPath, 0755); err != nil {
+		t.Fatalf("Failed to create db directory: %v", err)
+	}
+
+	if err := os.MkdirAll(metaPath, 0755); err != nil {
+		t.Fatalf("Failed to create meta directory: %v", err)
+	}
+
+	// Set environment variables to use the temp directory
+	originalHome := os.Getenv("HOME")
+	os.Setenv("HOME", tempDir)
+
+	// Return cleanup function
+	cleanup := func() {
+		os.Setenv("HOME", originalHome)
+		os.RemoveAll(tempDir)
+	}
+
+	return tempDir, cleanup
+}
+
+// TestUserCRUD tests the CRUD operations for User
+func TestUserCRUD(t *testing.T) {
+	_, cleanup := setupTestEnvironment(t)
+	defer cleanup()
+
+	// Create a new database store
+	dbStore, err := NewDBStore()
+	if err != nil {
+		t.Fatalf("Failed to create database store: %v", err)
+	}
+	defer dbStore.Close()
+
+	// Create a new user store
+	userStore := &UserStore{Store: dbStore}
+
+	// Create a new user
+	user := &User{
+		Key:      "john_doe",
+		Accounts: []uint32{},
+	}
+
+	// Save the user
+	err = userStore.Save(user)
+	if err != nil {
+		t.Fatalf("Failed to save user: %v", err)
+	}
+
+	// Verify the user ID was set
+	if user.ID == 0 {
+		t.Fatalf("User ID was not set")
+	}
+
+	// Get the user by ID
+	retrievedUser, err := userStore.GetByID(user.ID)
+	if err != nil {
+		t.Fatalf("Failed to get user by ID: %v", err)
+	}
+
+	// Verify the user data
+	if retrievedUser.ID != user.ID {
+		t.Errorf("Expected user ID %d, got %d", user.ID, retrievedUser.ID)
+	}
+	if retrievedUser.Key != user.Key {
+		t.Errorf("Expected user key %s, got %s", user.Key, retrievedUser.Key)
+	}
+
+	// Get the user by key
+	retrievedUser, err = userStore.GetByKey("john_doe")
+	if err != nil {
+		t.Fatalf("Failed to get user by key: %v", err)
+	}
+
+	// Verify the user data
+	if retrievedUser.ID != user.ID {
+		t.Errorf("Expected user ID %d, got %d", user.ID, retrievedUser.ID)
+	}
+
+	// Update the user
+	user.Key = "jane_doe"
+	err = userStore.Save(user)
+	if err != nil {
+		t.Fatalf("Failed to update user: %v", err)
+	}
+
+	// Verify the update
+	retrievedUser, err = userStore.GetByKey("jane_doe")
+	if err != nil {
+		t.Fatalf("Failed to get updated user by key: %v", err)
+	}
+	if retrievedUser.Key != "jane_doe" {
+		t.Errorf("Expected updated user key 'jane_doe', got %s", retrievedUser.Key)
+	}
+
+	// Delete the user
+	err = userStore.Delete(user.ID)
+	if err != nil {
+		t.Fatalf("Failed to delete user: %v", err)
+	}
+
+	// Verify the user was deleted
+	_, err = userStore.GetByID(user.ID)
+	if err == nil {
+		t.Errorf("Expected error when getting deleted user, got nil")
+	}
+}
+
+// TestAccountCRUD tests the CRUD operations for Account
+func TestAccountCRUD(t *testing.T) {
+	_, cleanup := setupTestEnvironment(t)
+	defer cleanup()
+
+	// Create a new database store
+	dbStore, err := NewDBStore()
+	if err != nil {
+		t.Fatalf("Failed to create database store: %v", err)
+	}
+	defer dbStore.Close()
+
+	// Create a new user store
+	userStore := &UserStore{Store: dbStore}
+
+	// Create a new user
+	user := &User{
+		Key:      "john_doe",
+		Accounts: []uint32{},
+	}
+
+	// Save the user
+	err = userStore.Save(user)
+	if err != nil {
+		t.Fatalf("Failed to save user: %v", err)
+	}
+
+	// Create a new account store
+	accountStore := NewAccountStore(dbStore)
+
+	// Create a new account
+	account := &Account{
+		UserID:   user.ID,
+		Name:     "Savings",
+		Currency: "USD",
+		Amount:   1000.0,
+	}
+
+	// Save the account
+	err = accountStore.Save(account)
+	if err != nil {
+		t.Fatalf("Failed to save account: %v", err)
+	}
+
+	// Verify the account ID was set
+	if account.ID == 0 {
+		t.Fatalf("Account ID was not set")
+	}
+
+	// Get the account by ID
+	retrievedAccount, err := accountStore.GetByID(account.ID)
+	if err != nil {
+		t.Fatalf("Failed to get account by ID: %v", err)
+	}
+
+	// Verify the account data
+	if retrievedAccount.ID != account.ID {
+		t.Errorf("Expected account ID %d, got %d", account.ID, retrievedAccount.ID)
+	}
+	if retrievedAccount.UserID != user.ID {
+		t.Errorf("Expected account user ID %d, got %d", user.ID, retrievedAccount.UserID)
+	}
+	if retrievedAccount.Name != "Savings" {
+		t.Errorf("Expected account name 'Savings', got %s", retrievedAccount.Name)
+	}
+	if retrievedAccount.Currency != "USD" {
+		t.Errorf("Expected account currency 'USD', got %s", retrievedAccount.Currency)
+	}
+	if retrievedAccount.Amount != 1000.0 {
+		t.Errorf("Expected account amount 1000.0, got %f", retrievedAccount.Amount)
+	}
+
+	// Verify the user's accounts list was updated
+	retrievedUser, err := userStore.GetByID(user.ID)
+	if err != nil {
+		t.Fatalf("Failed to get user: %v", err)
+	}
+	if len(retrievedUser.Accounts) != 1 {
+		t.Errorf("Expected user to have 1 account, got %d", len(retrievedUser.Accounts))
+	}
+	if retrievedUser.Accounts[0] != account.ID {
+		t.Errorf("Expected user account ID %d, got %d", account.ID, retrievedUser.Accounts[0])
+	}
+
+	// Update the account
+	account.Name = "Checking"
+	account.Amount = 2000.0
+	err = accountStore.Save(account)
+	if err != nil {
+		t.Fatalf("Failed to update account: %v", err)
+	}
+
+	// Verify the update
+	retrievedAccount, err = accountStore.GetByID(account.ID)
+	if err != nil {
+		t.Fatalf("Failed to get updated account: %v", err)
+	}
+	if retrievedAccount.Name != "Checking" {
+		t.Errorf("Expected updated account name 'Checking', got %s", retrievedAccount.Name)
+	}
+	if retrievedAccount.Amount != 2000.0 {
+		t.Errorf("Expected updated account amount 2000.0, got %f", retrievedAccount.Amount)
+	}
+
+	// Delete the account
+	err = accountStore.Delete(account.ID)
+	if err != nil {
+		t.Fatalf("Failed to delete account: %v", err)
+	}
+
+	// Verify the account was deleted
+	_, err = accountStore.GetByID(account.ID)
+	if err == nil {
+		t.Errorf("Expected error when getting deleted account, got nil")
+	}
+
+	// Verify the user's accounts list was updated
+	retrievedUser, err = userStore.GetByID(user.ID)
+	if err != nil {
+		t.Fatalf("Failed to get user after account deletion: %v", err)
+	}
+	if len(retrievedUser.Accounts) != 0 {
+		t.Errorf("Expected user to have 0 accounts after deletion, got %d", len(retrievedUser.Accounts))
+	}
+}
+
+// TestTransactionCRUD tests the CRUD operations for Transaction
+func TestTransactionCRUD(t *testing.T) {
+	_, cleanup := setupTestEnvironment(t)
+	defer cleanup()
+
+	// Create a new database store
+	dbStore, err := NewDBStore()
+	if err != nil {
+		t.Fatalf("Failed to create database store: %v", err)
+	}
+	defer dbStore.Close()
+
+	// Create a new user store
+	userStore := &UserStore{Store: dbStore}
+
+	// Create a new user
+	user := &User{
+		Key:      "john_doe",
+		Accounts: []uint32{},
+	}
+
+	// Save the user
+	err = userStore.Save(user)
+	if err != nil {
+		t.Fatalf("Failed to save user: %v", err)
+	}
+
+	// Create a new account store
+	accountStore := NewAccountStore(dbStore)
+
+	// Create source account
+	sourceAccount := &Account{
+		UserID:   user.ID,
+		Name:     "Checking",
+		Currency: "USD",
+		Amount:   1000.0,
+	}
+
+	// Save the source account
+	err = accountStore.Save(sourceAccount)
+	if err != nil {
+		t.Fatalf("Failed to save source account: %v", err)
+	}
+
+	// Create destination account
+	destAccount := &Account{
+		UserID:   user.ID,
+		Name:     "Savings",
+		Currency: "USD",
+		Amount:   500.0,
+	}
+
+	// Save the destination account
+	err = accountStore.Save(destAccount)
+	if err != nil {
+		t.Fatalf("Failed to save destination account: %v", err)
+	}
+
+	// Create a new transaction store
+	transactionStore := NewTransactionStore(dbStore)
+
+	// Create a new transaction
+	transaction := &Transaction{
+		From:    sourceAccount.ID,
+		To:      destAccount.ID,
+		Comment: "Transfer to savings",
+		Amount:  200.0,
+	}
+
+	// Save the transaction
+	err = transactionStore.Save(transaction)
+	if err != nil {
+		t.Fatalf("Failed to save transaction: %v", err)
+	}
+
+	// Verify the transaction ID was set
+	if transaction.TxID == 0 {
+		t.Fatalf("Transaction ID was not set")
+	}
+
+	// Get the transaction by ID
+	retrievedTransaction, err := transactionStore.GetByID(transaction.TxID)
+	if err != nil {
+		t.Fatalf("Failed to get transaction by ID: %v", err)
+	}
+
+	// Verify the transaction data
+	if retrievedTransaction.TxID != transaction.TxID {
+		t.Errorf("Expected transaction ID %d, got %d", transaction.TxID, retrievedTransaction.TxID)
+	}
+	if retrievedTransaction.From != sourceAccount.ID {
+		t.Errorf("Expected transaction from %d, got %d", sourceAccount.ID, retrievedTransaction.From)
+	}
+	if retrievedTransaction.To != destAccount.ID {
+		t.Errorf("Expected transaction to %d, got %d", destAccount.ID, retrievedTransaction.To)
+	}
+	if retrievedTransaction.Comment != "Transfer to savings" {
+		t.Errorf("Expected transaction comment 'Transfer to savings', got %s", retrievedTransaction.Comment)
+	}
+	if retrievedTransaction.Amount != 200.0 {
+		t.Errorf("Expected transaction amount 200.0, got %f", retrievedTransaction.Amount)
+	}
+
+	// Verify account balances were updated
+	updatedSourceAccount, err := accountStore.GetByID(sourceAccount.ID)
+	if err != nil {
+		t.Fatalf("Failed to get updated source account: %v", err)
+	}
+	if updatedSourceAccount.Amount != 800.0 {
+		t.Errorf("Expected source account amount 800.0, got %f", updatedSourceAccount.Amount)
+	}
+
+	updatedDestAccount, err := accountStore.GetByID(destAccount.ID)
+	if err != nil {
+		t.Fatalf("Failed to get updated destination account: %v", err)
+	}
+	if updatedDestAccount.Amount != 700.0 {
+		t.Errorf("Expected destination account amount 700.0, got %f", updatedDestAccount.Amount)
+	}
+
+	// Verify getting transactions by account
+	sourceTransactions, err := transactionStore.GetByAccount(sourceAccount.ID)
+	if err != nil {
+		t.Fatalf("Failed to get transactions by source account: %v", err)
+	}
+	if len(sourceTransactions) != 1 {
+		t.Errorf("Expected 1 transaction for source account, got %d", len(sourceTransactions))
+	}
+
+	destTransactions, err := transactionStore.GetByAccount(destAccount.ID)
+	if err != nil {
+		t.Fatalf("Failed to get transactions by destination account: %v", err)
+	}
+	if len(destTransactions) != 1 {
+		t.Errorf("Expected 1 transaction for destination account, got %d", len(destTransactions))
+	}
+
+	// Verify that deleting transactions is not allowed
+	err = transactionStore.Delete(transaction.TxID)
+	if err == nil {
+		t.Errorf("Expected error when deleting transaction, got nil")
+	}
+}
+
+// TestSerializationDeserialization tests the serialization and deserialization of models
+func TestSerializationDeserialization(t *testing.T) {
+	// Test User serialization/deserialization
+	user := &User{
+		ID:       42,
+		Key:      "test_user",
+		Accounts: []uint32{1, 2, 3},
+	}
+
+	userData := user.Serialize()
+	deserializedUser, err := DeserializeUser(userData)
+	if err != nil {
+		t.Fatalf("Failed to deserialize user: %v", err)
+	}
+
+	if deserializedUser.ID != user.ID {
+		t.Errorf("Expected user ID %d, got %d", user.ID, deserializedUser.ID)
+	}
+	if deserializedUser.Key != user.Key {
+		t.Errorf("Expected user key %s, got %s", user.Key, deserializedUser.Key)
+	}
+	if len(deserializedUser.Accounts) != len(user.Accounts) {
+		t.Errorf("Expected %d accounts, got %d", len(user.Accounts), len(deserializedUser.Accounts))
+	}
+	for i, accountID := range user.Accounts {
+		if deserializedUser.Accounts[i] != accountID {
+			t.Errorf("Expected account ID %d at index %d, got %d", accountID, i, deserializedUser.Accounts[i])
+		}
+	}
+
+	// Test Account serialization/deserialization
+	account := &Account{
+		ID:       24,
+		UserID:   42,
+		Name:     "Test Account",
+		Currency: "USD",
+		Amount:   123.45,
+	}
+
+	accountData := account.Serialize()
+	deserializedAccount, err := DeserializeAccount(accountData)
+	if err != nil {
+		t.Fatalf("Failed to deserialize account: %v", err)
+	}
+
+	if deserializedAccount.ID != account.ID {
+		t.Errorf("Expected account ID %d, got %d", account.ID, deserializedAccount.ID)
+	}
+	if deserializedAccount.UserID != account.UserID {
+		t.Errorf("Expected account user ID %d, got %d", account.UserID, deserializedAccount.UserID)
+	}
+	if deserializedAccount.Name != account.Name {
+		t.Errorf("Expected account name %s, got %s", account.Name, deserializedAccount.Name)
+	}
+	if deserializedAccount.Currency != account.Currency {
+		t.Errorf("Expected account currency %s, got %s", account.Currency, deserializedAccount.Currency)
+	}
+	if deserializedAccount.Amount != account.Amount {
+		t.Errorf("Expected account amount %f, got %f", account.Amount, deserializedAccount.Amount)
+	}
+
+	// Test Transaction serialization/deserialization
+	transaction := &Transaction{
+		TxID:    123,
+		From:    42,
+		To:      24,
+		Comment: "Test Transaction",
+		Amount:  67.89,
+	}
+
+	transactionData := transaction.Serialize()
+	deserializedTransaction, err := DeserializeTransaction(transactionData)
+	if err != nil {
+		t.Fatalf("Failed to deserialize transaction: %v", err)
+	}
+
+	if deserializedTransaction.TxID != transaction.TxID {
+		t.Errorf("Expected transaction ID %d, got %d", transaction.TxID, deserializedTransaction.TxID)
+	}
+	if deserializedTransaction.From != transaction.From {
+		t.Errorf("Expected transaction from %d, got %d", transaction.From, deserializedTransaction.From)
+	}
+	if deserializedTransaction.To != transaction.To {
+		t.Errorf("Expected transaction to %d, got %d", transaction.To, deserializedTransaction.To)
+	}
+	if deserializedTransaction.Comment != transaction.Comment {
+		t.Errorf("Expected transaction comment %s, got %s", transaction.Comment, deserializedTransaction.Comment)
+	}
+	if deserializedTransaction.Amount != transaction.Amount {
+		t.Errorf("Expected transaction amount %f, got %f", transaction.Amount, deserializedTransaction.Amount)
+	}
+}

_pkg2_dont_use/heroservices/billing/models/transaction.go

@@ -0,0 +1,100 @@
+package models
+
+import (
+	"encoding/binary"
+	"errors"
+	"math"
+)
+
+// Transaction represents a financial transaction in the billing system
+type Transaction struct {
+	TxID    uint32  // Transaction ID, auto-incremented
+	From    uint32  // Source account ID
+	To      uint32  // Destination account ID
+	Comment string  // Transaction comment
+	Amount  float64 // Transaction amount
+}
+
+// Serialize converts a Transaction to a binary representation
+func (t *Transaction) Serialize() []byte {
+	// Calculate the size of the serialized data
+	// 4 bytes for TxID + 4 bytes for From + 4 bytes for To +
+	// 2 bytes for comment length + len(comment) bytes + 8 bytes for amount
+	size := 4 + 4 + 4 + 2 + len(t.Comment) + 8
+	data := make([]byte, size)
+
+	// Write TxID (4 bytes)
+	binary.LittleEndian.PutUint32(data[0:4], t.TxID)
+
+	// Write From (4 bytes)
+	binary.LittleEndian.PutUint32(data[4:8], t.From)
+
+	// Write To (4 bytes)
+	binary.LittleEndian.PutUint32(data[8:12], t.To)
+
+	// Write comment length (2 bytes) and comment
+	commentLen := uint16(len(t.Comment))
+	binary.LittleEndian.PutUint16(data[12:14], commentLen)
+	copy(data[14:14+commentLen], t.Comment)
+
+	// Write amount (8 bytes)
+	amountOffset := 14 + int(commentLen)
+	binary.LittleEndian.PutUint64(data[amountOffset:amountOffset+8], math.Float64bits(t.Amount))
+
+	return data
+}
+
+// DeserializeTransaction converts a binary representation back to a Transaction
+func DeserializeTransaction(data []byte) (*Transaction, error) {
+	if len(data) < 22 { // Minimum size: 4 (TxID) + 4 (From) + 4 (To) + 2 (comment length) + 8 (amount)
+		return nil, errors.New("data too short to deserialize Transaction")
+	}
+
+	transaction := &Transaction{}
+
+	// Read TxID
+	transaction.TxID = binary.LittleEndian.Uint32(data[0:4])
+
+	// Read From
+	transaction.From = binary.LittleEndian.Uint32(data[4:8])
+
+	// Read To
+	transaction.To = binary.LittleEndian.Uint32(data[8:12])
+
+	// Read comment length and comment
+	commentLen := binary.LittleEndian.Uint16(data[12:14])
+	if 14+commentLen > uint16(len(data)) {
+		return nil, errors.New("data too short to read comment")
+	}
+	transaction.Comment = string(data[14 : 14+commentLen])
+
+	// Read amount
+	amountOffset := 14 + commentLen
+	if int(amountOffset)+8 > len(data) {
+		return nil, errors.New("data too short to read amount")
+	}
+	transaction.Amount = math.Float64frombits(binary.LittleEndian.Uint64(data[amountOffset : amountOffset+8]))
+
+	return transaction, nil
+}
+
+// Validate checks if the transaction data is valid
+func (t *Transaction) Validate() error {
+	if t.From == 0 {
+		return errors.New("source account ID cannot be zero")
+	}
+
+	if t.To == 0 {
+		return errors.New("destination account ID cannot be zero")
+	}
+
+	if t.From == t.To {
+		return errors.New("source and destination accounts cannot be the same")
+	}
+
+	if t.Amount <= 0 {
+		return errors.New("amount must be positive")
+	}
+
+	return nil
+}

_pkg2_dont_use/heroservices/billing/models/user.go

@@ -0,0 +1,78 @@
+package models
+
+import (
+	"encoding/binary"
+	"errors"
+)
+
+// User represents a user in the billing system
+type User struct {
+	ID       uint32   // Unique identifier, auto-incremented
+	Key      string   // Unique key for the user
+	Accounts []uint32 // Links to the accounts a user has
+}
+
+// Serialize converts a User to a binary representation
+func (u *User) Serialize() []byte {
+	// Calculate the size of the serialized data
+	// 4 bytes for ID + 2 bytes for key length + len(key) bytes + 2 bytes for accounts length + 4 bytes per account
+	size := 4 + 2 + len(u.Key) + 2 + (4 * len(u.Accounts))
+	data := make([]byte, size)
+
+	// Write ID (4 bytes)
+	binary.LittleEndian.PutUint32(data[0:4], u.ID)
+
+	// Write key length (2 bytes) and key
+	keyLen := uint16(len(u.Key))
+	binary.LittleEndian.PutUint16(data[4:6], keyLen)
+	copy(data[6:6+keyLen], u.Key)
+
+	// Write accounts length (2 bytes) and accounts
+	accountsOffset := 6 + keyLen
+	accountsLen := uint16(len(u.Accounts))
+	binary.LittleEndian.PutUint16(data[accountsOffset:accountsOffset+2], accountsLen)
+
+	for i, accountID := range u.Accounts {
+		offset := int(accountsOffset) + 2 + (4 * i)
+		binary.LittleEndian.PutUint32(data[offset:offset+4], accountID)
+	}
+
+	return data
+}
+
+// DeserializeUser converts a binary representation back to a User
+func DeserializeUser(data []byte) (*User, error) {
+	if len(data) < 8 { // Minimum size: 4 (ID) + 2 (key length) + 2 (accounts length)
+		return nil, errors.New("data too short to deserialize User")
+	}
+
+	user := &User{}
+
+	// Read ID
+	user.ID = binary.LittleEndian.Uint32(data[0:4])
+
+	// Read key length and key
+	keyLen := binary.LittleEndian.Uint16(data[4:6])
+	if 6+keyLen > uint16(len(data)) {
+		return nil, errors.New("data too short to read key")
+	}
+	user.Key = string(data[6 : 6+keyLen])
+
+	// Read accounts length and accounts
+	accountsOffset := 6 + keyLen
+	if accountsOffset+2 > uint16(len(data)) {
+		return nil, errors.New("data too short to read accounts length")
+	}
+	accountsLen := binary.LittleEndian.Uint16(data[accountsOffset : accountsOffset+2])
+
+	user.Accounts = make([]uint32, accountsLen)
+	for i := uint16(0); i < accountsLen; i++ {
+		offset := accountsOffset + 2 + (4 * i)
+		if offset+4 > uint16(len(data)) {
+			return nil, errors.New("data too short to read account ID")
+		}
+		user.Accounts[i] = binary.LittleEndian.Uint32(data[offset : offset+4])
+	}
+
+	return user, nil
+}