refactor: Extract currency interfaces and GORM models into separate files

- Move Repository, ExchangeRateProvider, BillingService, and AnalyticsService interfaces from types.go to new interface.go
- Move BillingSummary and CurrencyUsageStats structs to interface.go
- Move CurrencyModel, ExchangeRateModel, and TransactionModel to new models.go
- Move GORM hooks (BeforeCreate, BeforeUpdate) and TableName methods to models.go
- Remove redundant comments from exchange_rate_service.go

apps/carrier-connector/internal/currency/exchange_rate_service.go

@@ -8,7 +8,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-// ExchangeRateService manages currency exchange rates
 type ExchangeRateService struct {
 	repository   Repository
 	logger       *logrus.Logger
@@ -16,7 +15,6 @@ type ExchangeRateService struct {
 	baseCurrency string
 }
 
-// NewExchangeRateService creates a new exchange rate service
 func NewExchangeRateService(repository Repository, logger *logrus.Logger, baseCurrency string) *ExchangeRateService {
 	return &ExchangeRateService{
 		repository:   repository,
@@ -26,12 +24,10 @@ func NewExchangeRateService(repository Repository, logger *logrus.Logger, baseCu
 	}
 }
 
-// AddProvider adds an exchange rate provider
 func (s *ExchangeRateService) AddProvider(provider ExchangeRateProvider) {
 	s.providers = append(s.providers, provider)
 }
 
-// GetExchangeRate gets the current exchange rate between two currencies
 func (s *ExchangeRateService) GetExchangeRate(ctx context.Context, fromCurrency, toCurrency string) (*ExchangeRate, error) {
 	if fromCurrency == toCurrency {
 		return &ExchangeRate{
@@ -44,17 +40,14 @@ func (s *ExchangeRateService) GetExchangeRate(ctx context.Context, fromCurrency,
 		}, nil
 	}
 
-	// Try to get from repository first
 	rate, err := s.repository.GetLatestExchangeRate(ctx, fromCurrency, toCurrency)
 	if err == nil {
 		return rate, nil
 	}
 
-	// If not found, try to get from providers
 	for _, provider := range s.providers {
 		providerRate, err := provider.GetRate(ctx, fromCurrency, toCurrency)
 		if err == nil {
-			// Save to repository
 			newRate := &ExchangeRate{
 				ID:           fmt.Sprintf("%s_%s_%d", fromCurrency, toCurrency, time.Now().Unix()),
 				FromCurrency: fromCurrency,
@@ -76,7 +69,6 @@ func (s *ExchangeRateService) GetExchangeRate(ctx context.Context, fromCurrency,
 	return nil, fmt.Errorf("exchange rate not found: %s to %s", fromCurrency, toCurrency)
 }
 
-// ConvertAmount converts an amount from one currency to another
 func (s *ExchangeRateService) ConvertAmount(ctx context.Context, amount float64, fromCurrency, toCurrency string) (*CurrencyConversionResponse, error) {
 	rate, err := s.GetExchangeRate(ctx, fromCurrency, toCurrency)
 	if err != nil {
@@ -95,7 +87,6 @@ func (s *ExchangeRateService) ConvertAmount(ctx context.Context, amount float64,
 	}, nil
 }
 
-// RefreshRates refreshes exchange rates from all providers
 func (s *ExchangeRateService) RefreshRates(ctx context.Context) error {
 	s.logger.Info("Refreshing exchange rates")
 
@@ -110,7 +101,6 @@ func (s *ExchangeRateService) RefreshRates(ctx context.Context) error {
 	return nil
 }
 
-// GetRateHistory gets historical exchange rates
 func (s *ExchangeRateService) GetRateHistory(ctx context.Context, fromCurrency, toCurrency string, days int) ([]*ExchangeRate, error) {
 	filter := &ExchangeRateFilter{
 		FromCurrency: fromCurrency,
@@ -129,9 +119,7 @@ func (s *ExchangeRateService) GetRateHistory(ctx context.Context, fromCurrency,
 	return rates, nil
 }
 
-// UpdateExchangeRate updates an exchange rate
 func (s *ExchangeRateService) UpdateExchangeRate(ctx context.Context, rate *ExchangeRate) error {
-	// Validate rate
 	if rate.Rate <= 0 {
 		return fmt.Errorf("invalid exchange rate: must be positive")
 	}
@@ -140,12 +128,10 @@ func (s *ExchangeRateService) UpdateExchangeRate(ctx context.Context, rate *Exch
 		return fmt.Errorf("invalid currency pair: from and to currencies cannot be the same")
 	}
 
-	// Set validity
 	now := time.Now()
 	rate.ValidFrom = now
 	rate.IsActive = true
 
-	// Deactivate old rates
 	filter := &ExchangeRateFilter{
 		FromCurrency: rate.FromCurrency,
 		ToCurrency:   rate.ToCurrency,
@@ -162,7 +148,6 @@ func (s *ExchangeRateService) UpdateExchangeRate(ctx context.Context, rate *Exch
 		}
 	}
 
-	// Create new rate
 	rate.ID = fmt.Sprintf("%s_%s_%d", rate.FromCurrency, rate.ToCurrency, time.Now().Unix())
 	if err := s.repository.CreateExchangeRate(ctx, rate); err != nil {
 		return fmt.Errorf("failed to create exchange rate: %w", err)
@@ -178,7 +163,6 @@ func (s *ExchangeRateService) UpdateExchangeRate(ctx context.Context, rate *Exch
 	return nil
 }
 
-// GetSupportedCurrencies gets all supported currencies
 func (s *ExchangeRateService) GetSupportedCurrencies(ctx context.Context) ([]*Currency, error) {
 	filter := &CurrencyFilter{
 		IsActive: &[]bool{true}[0],
@@ -192,9 +176,7 @@ func (s *ExchangeRateService) GetSupportedCurrencies(ctx context.Context) ([]*Cu
 	return currencies, nil
 }
 
-// ValidateCurrencyPair validates if a currency pair is supported
 func (s *ExchangeRateService) ValidateCurrencyPair(ctx context.Context, fromCurrency, toCurrency string) error {
-	// Check if currencies exist
 	_, err := s.repository.GetCurrency(ctx, fromCurrency)
 	if err != nil {
 		return fmt.Errorf("unsupported from currency: %s", fromCurrency)
@@ -205,7 +187,6 @@ func (s *ExchangeRateService) ValidateCurrencyPair(ctx context.Context, fromCurr
 		return fmt.Errorf("unsupported to currency: %s", toCurrency)
 	}
 
-	// Check if exchange rate exists or can be obtained
 	_, err = s.GetExchangeRate(ctx, fromCurrency, toCurrency)
 	if err != nil {
 		return fmt.Errorf("no exchange rate available: %s to %s", fromCurrency, toCurrency)

apps/carrier-connector/internal/currency/interface.go

@@ -0,0 +1,81 @@
+package currency
+
+import (
+	"context"
+	"time"
+)
+
+// Repository defines the interface for currency data operations
+type Repository interface {
+	// Currency operations
+	CreateCurrency(ctx context.Context, currency *Currency) error
+	GetCurrency(ctx context.Context, code string) (*Currency, error)
+	UpdateCurrency(ctx context.Context, currency *Currency) error
+	DeleteCurrency(ctx context.Context, code string) error
+	ListCurrencies(ctx context.Context, filter *CurrencyFilter) ([]*Currency, error)
+	CountCurrencies(ctx context.Context, filter *CurrencyFilter) (int, error)
+
+	// Exchange rate operations
+	CreateExchangeRate(ctx context.Context, rate *ExchangeRate) error
+	GetExchangeRate(ctx context.Context, fromCurrency, toCurrency string) (*ExchangeRate, error)
+	UpdateExchangeRate(ctx context.Context, rate *ExchangeRate) error
+	DeleteExchangeRate(ctx context.Context, id string) error
+	ListExchangeRates(ctx context.Context, filter *ExchangeRateFilter) ([]*ExchangeRate, error)
+	GetLatestExchangeRate(ctx context.Context, fromCurrency, toCurrency string) (*ExchangeRate, error)
+
+	// Transaction operations
+	CreateTransaction(ctx context.Context, transaction *Transaction) error
+	GetTransaction(ctx context.Context, id string) (*Transaction, error)
+	UpdateTransaction(ctx context.Context, transaction *Transaction) error
+	DeleteTransaction(ctx context.Context, id string) error
+	ListTransactions(ctx context.Context, filter *TransactionFilter) ([]*Transaction, error)
+	CountTransactions(ctx context.Context, filter *TransactionFilter) (int, error)
+}
+
+// ExchangeRateProvider defines the interface for external exchange rate providers
+type ExchangeRateProvider interface {
+	GetRates(ctx context.Context) (map[string]float64, error)
+	GetRate(ctx context.Context, fromCurrency, toCurrency string) (float64, error)
+	RefreshRates(ctx context.Context) error
+}
+
+// BillingService defines the interface for multi-currency billing operations
+type BillingService interface {
+	ProcessBilling(ctx context.Context, req *BillingRequest) (*BillingResponse, error)
+	ConvertAmount(ctx context.Context, req *CurrencyConversionRequest) (*CurrencyConversionResponse, error)
+	GetBillingHistory(ctx context.Context, profileID string, filter *TransactionFilter) ([]*Transaction, error)
+	CalculateTotalBilling(ctx context.Context, profileID string, fromDate, toDate time.Time) (*BillingSummary, error)
+}
+
+// AnalyticsService defines the interface for currency analytics
+type AnalyticsService interface {
+	GetRevenueByCurrency(ctx context.Context, filter *TransactionFilter) (map[string]float64, error)
+	GetTransactionVolumeByCurrency(ctx context.Context, filter *TransactionFilter) (map[string]int64, error)
+	GetExchangeRateTrends(ctx context.Context, fromCurrency, toCurrency string, days int) ([]*ExchangeRate, error)
+	GetCurrencyUsageStats(ctx context.Context) (*CurrencyUsageStats, error)
+}
+
+// BillingSummary represents a billing summary for a profile
+type BillingSummary struct {
+	ProfileID        string                 `json:"profile_id"`
+	TotalAmount      float64                `json:"total_amount"`
+	Currency         string                 `json:"currency"`
+	BaseTotalAmount  float64                `json:"base_total_amount"`
+	BaseCurrency     string                 `json:"base_currency"`
+	TransactionCount int                    `json:"transaction_count"`
+	FromDate         time.Time              `json:"from_date"`
+	ToDate           time.Time              `json:"to_date"`
+	Breakdown        map[string]interface{} `json:"breakdown"`
+}
+
+// CurrencyUsageStats represents statistics about currency usage
+type CurrencyUsageStats struct {
+	TotalCurrencies      int              `json:"total_currencies"`
+	ActiveCurrencies     int              `json:"active_currencies"`
+	TotalTransactions    int64            `json:"total_transactions"`
+	TotalVolume          float64          `json:"total_volume"`
+	MostUsedCurrency     string           `json:"most_used_currency"`
+	CurrencyDistribution map[string]int64 `json:"currency_distribution"`
+	ExchangeRateCount    int              `json:"exchange_rate_count"`
+	LastUpdated          time.Time        `json:"last_updated"`
+}

apps/carrier-connector/internal/currency/models.go

@@ -0,0 +1,111 @@
+package currency
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// CurrencyModel represents the database model for currencies
+type CurrencyModel struct {
+	Code             string    `gorm:"primaryKey;column:code" json:"code"`
+	Name             string    `gorm:"column:name" json:"name"`
+	Symbol           string    `gorm:"column:symbol" json:"symbol"`
+	DecimalPlaces    int       `gorm:"column:decimal_places" json:"decimal_places"`
+	IsActive         bool      `gorm:"column:is_active" json:"is_active"`
+	SupportedRegions string    `gorm:"column:supported_regions;type:text" json:"supported_regions"`
+	CreatedAt        time.Time `gorm:"column:created_at" json:"created_at"`
+	UpdatedAt        time.Time `gorm:"column:updated_at" json:"updated_at"`
+}
+
+// TableName returns the table name for the currency model
+func (CurrencyModel) TableName() string {
+	return "currencies"
+}
+
+// ExchangeRateModel represents the database model for exchange rates
+type ExchangeRateModel struct {
+	ID           string     `gorm:"primaryKey;column:id" json:"id"`
+	FromCurrency string     `gorm:"column:from_currency;index" json:"from_currency"`
+	ToCurrency   string     `gorm:"column:to_currency;index" json:"to_currency"`
+	Rate         float64    `gorm:"column:rate" json:"rate"`
+	Source       string     `gorm:"column:source" json:"source"`
+	ValidFrom    time.Time  `gorm:"column:valid_from;index" json:"valid_from"`
+	ValidTo      *time.Time `gorm:"column:valid_to;index" json:"valid_to"`
+	IsActive     bool       `gorm:"column:is_active" json:"is_active"`
+	CreatedAt    time.Time  `gorm:"column:created_at" json:"created_at"`
+	UpdatedAt    time.Time  `gorm:"column:updated_at" json:"updated_at"`
+}
+
+// TableName returns the table name for the exchange rate model
+func (ExchangeRateModel) TableName() string {
+	return "exchange_rates"
+}
+
+// TransactionModel represents the database model for transactions
+type TransactionModel struct {
+	ID             string    `gorm:"primaryKey;column:id" json:"id"`
+	ProfileID      string    `gorm:"column:profile_id;index" json:"profile_id"`
+	SubscriptionID string    `gorm:"column:subscription_id;index" json:"subscription_id"`
+	Type           string    `gorm:"column:type;index" json:"type"`
+	Amount         float64   `gorm:"column:amount" json:"amount"`
+	Currency       string    `gorm:"column:currency;index" json:"currency"`
+	BaseAmount     float64   `gorm:"column:base_amount" json:"base_amount"`
+	BaseCurrency   string    `gorm:"column:base_currency" json:"base_currency"`
+	ExchangeRate   float64   `gorm:"column:exchange_rate" json:"exchange_rate"`
+	Description    string    `gorm:"column:description" json:"description"`
+	Status         string    `gorm:"column:status;index" json:"status"`
+	Metadata       string    `gorm:"column:metadata;type:text" json:"metadata"`
+	CreatedAt      time.Time `gorm:"column:created_at;index" json:"created_at"`
+	UpdatedAt      time.Time `gorm:"column:updated_at" json:"updated_at"`
+}
+
+// TableName returns the table name for the transaction model
+func (TransactionModel) TableName() string {
+	return "transactions"
+}
+
+// BeforeCreate hook for CurrencyModel
+func (c *CurrencyModel) BeforeCreate(tx *gorm.DB) error {
+	if c.CreatedAt.IsZero() {
+		c.CreatedAt = time.Now()
+	}
+	c.UpdatedAt = time.Now()
+	return nil
+}
+
+// BeforeUpdate hook for CurrencyModel
+func (c *CurrencyModel) BeforeUpdate(tx *gorm.DB) error {
+	c.UpdatedAt = time.Now()
+	return nil
+}
+
+// BeforeCreate hook for ExchangeRateModel
+func (e *ExchangeRateModel) BeforeCreate(tx *gorm.DB) error {
+	if e.CreatedAt.IsZero() {
+		e.CreatedAt = time.Now()
+	}
+	e.UpdatedAt = time.Now()
+	return nil
+}
+
+// BeforeUpdate hook for ExchangeRateModel
+func (e *ExchangeRateModel) BeforeUpdate(tx *gorm.DB) error {
+	e.UpdatedAt = time.Now()
+	return nil
+}
+
+// BeforeCreate hook for TransactionModel
+func (t *TransactionModel) BeforeCreate(tx *gorm.DB) error {
+	if t.CreatedAt.IsZero() {
+		t.CreatedAt = time.Now()
+	}
+	t.UpdatedAt = time.Now()
+	return nil
+}
+
+// BeforeUpdate hook for TransactionModel
+func (t *TransactionModel) BeforeUpdate(tx *gorm.DB) error {
+	t.UpdatedAt = time.Now()
+	return nil
+}