Compose Worker

package com.squareup.sample.compose.hellocomposebinding

import com.squareup.sample.compose.hellocomposebinding.HelloWorkflow.Rendering
import com.squareup.sample.compose.hellocomposebinding.HelloWorkflow.HG
import com.squareup.sample.compose.hellocomposebinding.HelloWorkflow.HG.Goodbye
import com.squareup.sample.compose.hellocomposebinding.HelloWorkflow.HG.Hello
import com.squareup.sample.compose.hellocomposebinding.HelloWorkflow.State
import com.squareup.sample.compose.hellocomposeworkflow.HelloWorkflow
import com.squareup.workflow1.Snapshot
import com.squareup.workflow1.StatefulWorkflow
import com.squareup.workflow1.action
import com.squareup.workflow1.asWorker
import com.squareup.workflow1.parse
import com.squareup.workflow1.runningWorker
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.flow

object HelloWorkflow : StatefulWorkflow<Unit, State, Nothing, Rendering>() {
  data class State(
    val hg: HG = Hello,
    val plus: String = ""
  )

  enum class HG {
    Hello,
    Goodbye;

    fun toggle(): HG = when (this) {
      Hello -> Goodbye
      Goodbye -> Hello
    }
  }

  data class Rendering(
    val message: String,
    val onClick: () -> Unit
  )

  private val helloAction = action {
    state = state.copy(hg = state.hg.toggle())
  }

  private val pulseAction = action {
    state = state.copy(plus = if (state.plus.isBlank()) "*" else "")
  }

  private val pulseWorker = flow {
    while (true) {
      delay(1000L)
      emit(Unit)
    }
  }.asWorker()

  override fun initialState(
    props: Unit,
    snapshot: Snapshot?
  ): State =
    snapshot?.bytes?.parse { source -> if (source.readInt() == 1) State() else State(Goodbye) }
      ?: State()

  override fun render(
    renderProps: Unit,
    renderState: State,
    context: RenderContext
  ): Rendering {
    context.runningWorker(pulseWorker) { pulseAction }
    return Rendering(
      message = renderState.hg.name + renderState.plus,
      onClick = { context.actionSink.send(helloAction) }
    )
  }

  override fun snapshotState(state: State): Snapshot = Snapshot.of(if (state.hg == Hello) 1 else 0)
}

A tweak to the Hello Compose Binding sample that shows off running a simple worker. See line 66.