75 lines
3.2 KiB
Kotlin
75 lines
3.2 KiB
Kotlin
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package cash.z.ecc.ui.screen.home.viewmodel
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import android.app.Application
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import androidx.lifecycle.AndroidViewModel
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import androidx.lifecycle.viewModelScope
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import cash.z.ecc.sdk.SynchronizerCompanion
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import cash.z.ecc.sdk.model.PersistableWallet
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import cash.z.ecc.ui.common.ANDROID_STATE_FLOW_TIMEOUT_MILLIS
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import cash.z.ecc.ui.preference.EncryptedPreferenceKeys
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import cash.z.ecc.ui.preference.EncryptedPreferenceSingleton
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import kotlinx.coroutines.flow.SharingStarted
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import kotlinx.coroutines.flow.emitAll
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import kotlinx.coroutines.flow.flow
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import kotlinx.coroutines.flow.map
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import kotlinx.coroutines.flow.stateIn
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import kotlinx.coroutines.launch
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// To make this more multiplatform compatible, we need to remove the dependency on Context
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// for loading the preferences.
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class WalletViewModel(application: Application) : AndroidViewModel(application) {
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/**
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* A flow of the user's stored wallet. Null indicates that no wallet has been stored.
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*/
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/*
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* This is exposed, because loading the value here is faster than loading the entire Zcash SDK.
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*
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* This allows the UI to load the first launch onboarding experience a few hundred milliseconds
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* faster.
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*/
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val persistableWallet = flow {
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// EncryptedPreferenceSingleton.getInstance() is a suspending function, which is why we need
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// the flow builder to provide a coroutine context.
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val encryptedPreferenceProvider = EncryptedPreferenceSingleton.getInstance(application)
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emitAll(EncryptedPreferenceKeys.PERSISTABLE_WALLET.observe(encryptedPreferenceProvider))
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}.stateIn(
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viewModelScope,
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SharingStarted.WhileSubscribed(stopTimeoutMillis = ANDROID_STATE_FLOW_TIMEOUT_MILLIS),
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null
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)
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/**
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* A flow of the Zcash SDK initialized with the user's stored wallet. Null indicates that no
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* wallet has been stored.
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*/
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// Note: in the future we might want to convert this to emitting a sealed class with states like:
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// - No wallet
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// - Current wallet
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// - Error loading wallet
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val synchronizer = persistableWallet.map { persistableWallet ->
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persistableWallet?.let { SynchronizerCompanion.load(application, persistableWallet) }
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}.stateIn(
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viewModelScope,
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SharingStarted.WhileSubscribed(stopTimeoutMillis = ANDROID_STATE_FLOW_TIMEOUT_MILLIS),
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null
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)
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/**
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* Persists a wallet asynchronously. Clients observe either [persistableWallet] or [synchronizer]
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* to see the side effects.
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*
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* This method does not prevent multiple calls, so clients should be careful not to call this
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* method multiple times in rapid succession. While the persistableWallet write is atomic,
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* the ordering of the writes is not specified. If the same persistableWallet is passed in,
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* then there's no problem. But if different persistableWallets are passed in, then which one
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* actually gets written is non-deterministic.
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*/
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fun persistWallet(persistableWallet: PersistableWallet) {
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viewModelScope.launch {
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val preferenceProvider = EncryptedPreferenceSingleton.getInstance(getApplication())
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EncryptedPreferenceKeys.PERSISTABLE_WALLET.putValue(preferenceProvider, persistableWallet)
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}
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}
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}
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