usecase

Claude Rules - Use Case Pattern

Overview

Rules for implementing Use Cases in go-crypto-wallet. Use Cases represent single business operations and are the core of the Application layer.

Applicable Files

• internal/application/usecase/**/*.go

Use Case Structure

Interface Definition

Each use case is defined as an interface in the appropriate interfaces.go file:

// ✅ GOOD: Interface with clear single responsibility
type CreateTransactionUseCase interface {
    Execute(ctx context.Context, input CreateTransactionInput) (CreateTransactionOutput, error)
}

// ✅ GOOD: Multiple related operations in one interface
type GenerateSeedUseCase interface {
    Generate(ctx context.Context) (GenerateSeedOutput, error)
    Store(ctx context.Context, input StoreSeedInput) (StoreSeedOutput, error)
}

Implementation Structure

// Private struct (unexported)
type createTransactionUseCase struct {
    btcClient  apibtc.Bitcoiner           // Ports only
    addrRepo   repowatch.AddressRepositorier
    txRepo     repowatch.BTCTxRepositorier
    // ... other dependencies
}

// Public constructor
func NewCreateTransactionUseCase(
    btcClient apibtc.Bitcoiner,
    addrRepo repowatch.AddressRepositorier,
    txRepo repowatch.BTCTxRepositorier,
    // ... pass all dependencies
) watchusecase.CreateTransactionUseCase {
    return &createTransactionUseCase{
        btcClient: btcClient,
        addrRepo:  addrRepo,
        txRepo:    txRepo,
    }
}

// Implementation
func (u *createTransactionUseCase) Execute(
    ctx context.Context,
    input watchusecase.CreateTransactionInput,
) (watchusecase.CreateTransactionOutput, error) {
    // Business logic here
}

Method Naming Conventions

Operation Type	Method Name	Example
Create/Generate	Execute, Generate, Create	CreateTransactionUseCase.Execute
Read/Get	Get, Find, List	GetAccountUseCase.Get
Update	Update, Modify	UpdateStatusUseCase.Update
Delete	Delete, Remove	DeleteAccountUseCase.Delete
Import/Export	Import, Export	ImportAddressUseCase.Execute
Sign	Sign	SignTransactionUseCase.Sign
Monitor	UpdateTxStatus, MonitorBalance	MonitorTransactionUseCase.UpdateTxStatus