BankingClient/README.md

# Banking Client

Library to abstract over different banking client implementations like [fints4k](https://git.dankito.net/codinux/fints4k).

It's primary purpose is to abstract away the different implementation details and to create a common model that can be
used in all projects directly or indirectly referencing it - Web Service, Middleware, Native Apps, HTML Apps - so that
not each project has the implement to model again.

## Setup

### Gradle:

```
plugins {
    kotlin("jvm") version "2.0.10" // or kotlin("multiplatform"), depending on your requirements
}


repositories {
    mavenCentral()
    maven {
        setUrl("https://maven.dankito.net/api/packages/codinux/maven")
    }
}


dependencies {
    implementation("net.codinux.banking.client:fints4k-banking-client:0.5.0")
}
```


## Usage

For the full example source code see [ShowUsage](SampleApp/src/main/kotlin/net/codinux/banking/client/fints4k/example/ShowUsage.kt).

### Get AccountData 

Retrieves data like accounts, balance and booked transactions (Konten, Saldo und Kontoumsätze).

Simple example:

```kotlin
class ShowUsage {

    private val bankCode = "" // Bankleitzahl deiner Bank

    private val loginName = "" // Online-Banking Login Name mit dem du dich beim Online-Banking deiner Bank anmeldest

    private val password = "" // Online-Banking Password mit dem du dich beim Online-Banking deiner Bank anmeldest


    fun getAccountData() {
        val client = FinTs4kBankingClientForUser(bankCode, loginName, password, SimpleBankingClientCallback())

        val response = client.getAccountData()

        printReceivedData(response)
    }


    private fun printReceivedData(response: Response<GetAccountDataResponse>) {
        response.data?.let { data ->
            val user = data.user
            println("Kunde: ${user.customerName} ${user.accounts.size} Konten @ ${user.bic} ${user.bankName}")

            println()
            println("Konten:")
            user.accounts.sortedBy { it.type }.forEach { account ->
                println("${account.identifier} ${account.productName} ${account.balance} ${account.currency}")
            }

            println()
            println("Umsätze:")
            data.bookedTransactions.forEach { transaction ->
                println("${transaction.valueDate} ${transaction.amount} ${transaction.currency} ${transaction.otherPartyName ?: ""} - ${transaction.reference}")
            }
        }
    }
}
```

This fetches the booked account transactions of the last 90 days. In most cases no TAN is required for this.

In case there is, add TAN handling in Client Callback:

```kotlin
val client = FinTs4kBankingClientForUser(bankCode, loginName, password, SimpleBankingClientCallback { tanChallenge, callback ->
    val tan: String? = null // if a TAN is required, add a UI or ...
    callback.invoke(EnterTanResult(tan)) // ...  set a break point here, get TAN e.g. from your TAN app, set tan variable in debugger view and resume debugger
})
```

You can also specify options e.g. which transactions should be retrieved:

```kotlin
val options = GetAccountDataOptions(
    retrieveBalance = true, // retrieve balance (Saldo / Kontostand) yes or no
    retrieveTransactions = RetrieveTransactions.AccordingToRetrieveFromAndTo, // so that fromDate and toDate below determine of which time period transactions (Umsätze) should be retrieved; defaults to OfLast90Days which in most cases doesn't require a TAN
    retrieveTransactionsFrom = LocalDate(2023, 1, 1),
    retrieveTransactionsTo = LocalDate(2023, 12, 31),
    abortIfTanIsRequired = false // e.g. for command line application when entering TAN is either not possible or a TAN procedure is used that cannot be handled via a break point (e.g. showing a TAN image or flicker code)
)
val response = client.getAccountData(options)
```

Add some error handling by checking `response.error`:

```kotlin
response.error?.let{ error ->
    println("Could not fetch account data: ${error.internalError ?: error.errorMessagesFromBank.joinToString()}")
}
```