Login flow state proxy

LoginFlowProxy.kt

/**
 * Proxy definition (for readability)
 */
private typealias LoginProxy = ProxyMachineState<
        WelcomeGesture, // Host gesture system
        WelcomeUiState, // Host ui-state system
        LoginGesture,   // Feature gesture system
        LoginUiState    // Feature ui-state system
>

class LoginFlowState(
    private val context: WelcomeContext,
    private val data: WelcomeDataState,
    private val loginComponentBuilder: LoginComponentBuilder
) : LoginProxy(), WelcomeFeatureHost {

    /**
     * Should have valid email at this point
     */
    private val email = requireNotNull(data.email) {
      "Email is not provided"
    }
  
    /**
     * Creates initial child state
     */
    override fun init(): CommonMachineState<LoginGesture, LoginUiState> {
        val component = loginComponentBuilder.host(this).build()
        val starter = EntryPoints.get(component, LoginEntryPoint::class.java).flowStarter()

        return starter.start(email)
    }

    override fun mapGesture(parent: WelcomeGesture): LoginGesture? = when (parent) {
        is WelcomeGesture.Login -> parent.value   // Unwraps LoginGesture from host system
        WelcomeGesture.Back -> LoginGesture.Back  // Translates from one system to another
        else -> null                              // Ignores irrelevant gestures
    }

    override fun mapUiState(child: LoginUiState): WelcomeUiState = WelcomeUiState.Login(child)

    override fun backToEmailEntry() {
        Timber.d("Transferring to e-mail entry...")
        setMachineState(context.factory.emailEntry(data))
    }

    override fun complete() {
        Timber.d("Transferring to complete screen...")
        setMachineState(context.factory.complete(email))
    }
}