Signal-Android/app/src/main/java/org/thoughtcrime/securesms/components/settings/app/subscription/currency/SetCurrencyViewModel.kt

package org.thoughtcrime.securesms.components.settings.app.subscription.currency

import androidx.annotation.VisibleForTesting
import androidx.lifecycle.LiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import org.thoughtcrime.securesms.BuildConfig
import org.thoughtcrime.securesms.keyvalue.SignalStore
import org.thoughtcrime.securesms.subscription.Subscriber
import org.thoughtcrime.securesms.util.livedata.Store
import org.whispersystems.signalservice.api.subscriptions.SubscriberId
import java.util.Currency
import java.util.Locale

class SetCurrencyViewModel(
  private val isOneTime: Boolean,
  supportedCurrencyCodes: List<String>
) : ViewModel() {

  private val store = Store(
    SetCurrencyState(
      selectedCurrencyCode = if (isOneTime) {
        SignalStore.donationsValues().getOneTimeCurrency().currencyCode
      } else {
        SignalStore.donationsValues().getSubscriptionCurrency().currencyCode
      },
      currencies = supportedCurrencyCodes
        .map(Currency::getInstance)
        .sortedWith(CurrencyComparator(BuildConfig.DEFAULT_CURRENCIES.split(",")))
    )
  )

  val state: LiveData<SetCurrencyState> = store.stateLiveData

  fun setSelectedCurrency(selectedCurrencyCode: String) {
    store.update { it.copy(selectedCurrencyCode = selectedCurrencyCode) }

    if (isOneTime) {
      SignalStore.donationsValues().setOneTimeCurrency(Currency.getInstance(selectedCurrencyCode))
    } else {
      val currency = Currency.getInstance(selectedCurrencyCode)
      val subscriber = SignalStore.donationsValues().getSubscriber(currency)

      if (subscriber != null) {
        SignalStore.donationsValues().setSubscriber(subscriber)
      } else {
        SignalStore.donationsValues().setSubscriber(
          Subscriber(
            subscriberId = SubscriberId.generate(),
            currencyCode = currency.currencyCode
          )
        )
      }
    }
  }

  @VisibleForTesting
  class CurrencyComparator(private val defaults: List<String>) : Comparator<Currency> {

    companion object {
      private const val USD = "USD"
    }

    override fun compare(o1: Currency, o2: Currency): Int {
      val isO1Default = o1.currencyCode in defaults
      val isO2Default = o2.currencyCode in defaults

      return if (o1.currencyCode == o2.currencyCode) {
        0
      } else if (o1.currencyCode == USD) {
        -1
      } else if (o2.currencyCode == USD) {
        1
      } else if (isO1Default && isO2Default) {
        o1.getDisplayName(Locale.getDefault()).compareTo(o2.getDisplayName(Locale.getDefault()))
      } else if (isO1Default) {
        -1
      } else if (isO2Default) {
        1
      } else {
        o1.getDisplayName(Locale.getDefault()).compareTo(o2.getDisplayName(Locale.getDefault()))
      }
    }
  }

  class Factory(private val isOneTime: Boolean, private val supportedCurrencyCodes: List<String>) : ViewModelProvider.Factory {
    override fun <T : ViewModel> create(modelClass: Class<T>): T {
      return modelClass.cast(SetCurrencyViewModel(isOneTime, supportedCurrencyCodes))!!
    }
  }
}