feat: 🏗️ simplify viewmodel state (#26)

- apply state on UI layer for search
- apply state on UI layer for suggestions
- little changes and package movements

Author: ffgiraldez

app/src/main/java/es/ffgiraldez/comicsearch/platform/LiveDataExt.kt

@@ -9,7 +9,7 @@ import io.reactivex.android.MainThreadDisposable
 fun <T> LiveData<T>.toFlowable(): Flowable<T> =
         Flowable.create({ emitter ->
             val observer = Observer<T> {
-                it?.let { emitter.onNext(it) }
+                it?.let(emitter::onNext)
             }
             observeForever(observer)
 

app/src/main/java/es/ffgiraldez/comicsearch/platform/Utilities.kt

@@ -3,14 +3,12 @@ package es.ffgiraldez.comicsearch.platform
 import arrow.core.Either
 import arrow.core.left
 import arrow.core.right
-
-fun <A, B, C> safe(first: A?, second: B?, block: (A, B) -> C): C? {
-    return if (first != null && second != null) {
-        block(first, second)
-    } else {
-        null
-    }
-}
+import io.reactivex.disposables.CompositeDisposable
+import io.reactivex.disposables.Disposable
 
 fun <A, B> left(a: A): Either<A, B> = a.left()
-fun <A, B> right(b: B): Either<A, B> = b.right()
+fun <A, B> right(b: B): Either<A, B> = b.right()
+
+operator fun CompositeDisposable.plus(disposable: Disposable): CompositeDisposable = apply {
+    add(disposable)
+}

app/src/main/java/es/ffgiraldez/comicsearch/platform/ViewBinding.kt

@@ -1,10 +1,8 @@
 package es.ffgiraldez.comicsearch.platform
 
-import androidx.databinding.BindingAdapter
 import android.view.View
 
-@BindingAdapter("gone")
-fun bindImage(view: View, gone: Boolean) = with(view) {
+fun View.gone(gone: Boolean) = with(this) {
     visibility = when (gone) {
         true -> View.GONE
         false -> View.VISIBLE

app/src/main/java/es/ffgiraldez/comicsearch/query/base/presentation/QueryStateViewModel.kt

@@ -0,0 +1,32 @@
+package es.ffgiraldez.comicsearch.query.base.presentation
+
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import es.ffgiraldez.comicsearch.platform.plus
+import es.ffgiraldez.comicsearch.platform.toFlowable
+import io.reactivex.Flowable
+import io.reactivex.disposables.CompositeDisposable
+import org.reactivestreams.Publisher
+
+open class QueryStateViewModel<T>(
+        transformer: (Flowable<String>) -> Publisher<QueryViewState<T>>
+) : ViewModel() {
+
+    private val _state: MutableLiveData<QueryViewState<T>> = MutableLiveData()
+    val state: LiveData<QueryViewState<T>>
+        get() = _state
+    val query: MutableLiveData<String> = MutableLiveData()
+
+    private val disposable: CompositeDisposable = CompositeDisposable()
+
+    init {
+        disposable + query.toFlowable()
+                .compose { transformer(it) }
+                .subscribe { _state.postValue(it) }
+    }
+
+    override fun onCleared(): Unit = disposable.clear()
+}
+

app/src/main/java/es/ffgiraldez/comicsearch/query/base/presentation/QueryViewModel.kt

@@ -13,7 +13,8 @@ sealed class QueryViewState<out T> {
 
     object Idle : QueryViewState<Nothing>()
     object Loading : QueryViewState<Nothing>()
-    data class Result<out T>(val results: List<T>) : QueryViewState<T>()
-    data class Error(val error: ComicError) : QueryViewState<Nothing>()
+    data class Result<out T>(val _results: List<T>) : QueryViewState<T>()
+    data class Error(val _error: ComicError) : QueryViewState<Nothing>()
+
+}
 
-}

app/src/main/java/es/ffgiraldez/comicsearch/query/base/presentation/QueryViewState.kt

@@ -12,12 +12,12 @@ class QueryScreenDelegate(
         val adapter: QueryVolumeAdapter,
         private val navigator: Navigator
 ) {
-    fun onVolumeSelected(volume: Volume) =
+    fun onVolumeSelected(volume: Volume): Unit =
             navigator.to(Screen.Detail(volume))
 
-    fun onQueryChange(new: String) =
+    fun onQueryChange(new: String): Unit =
             with(suggestions) { query.value = new }
 
-    fun onSuggestionSelected(suggestion: String) =
+    fun onSuggestionSelected(suggestion: String): Unit =
             with(search) { query.value = suggestion }
 }

app/src/main/java/es/ffgiraldez/comicsearch/query/base/ui/QueryScreenDelegate.kt

@@ -0,0 +1,24 @@
+package es.ffgiraldez.comicsearch.query.base.ui
+
+import arrow.core.Option
+import arrow.core.toOption
+import es.ffgiraldez.comicsearch.comics.domain.ComicError
+import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewState
+
+val <T>QueryViewState<T>.error: Option<ComicError>
+    get() = when (this) {
+        is QueryViewState.Error -> _error.toOption()
+        else -> Option.empty()
+    }
+
+val <T>QueryViewState<T>.results: List<T>
+    get() = when (this) {
+        is QueryViewState.Result -> _results
+        else -> emptyList()
+    }
+
+val <T>QueryViewState<T>.loading: Boolean
+    get() = when (this) {
+        is QueryViewState.Loading -> true
+        else -> false
+    }

app/src/main/java/es/ffgiraldez/comicsearch/query/base/ui/QueryViewStateExt.kt

@@ -10,7 +10,7 @@ import es.ffgiraldez.comicsearch.databinding.QueryItemBinding
 
 class QueryVolumeAdapter : ListAdapter<Volume, QueryVolumeViewHolder>(asyncDiff) {
 
-    var onVolumeSelectedListener: OnVolumeSelectedListener? = null
+    var onVolumeSelectedListener: OnVolumeSelectedListener = OnVolumeSelectedListener.empty
 
     companion object {
         val asyncDiff: DiffUtil.ItemCallback<Volume> = object : DiffUtil.ItemCallback<Volume>() {
@@ -28,11 +28,17 @@ class QueryVolumeAdapter : ListAdapter<Volume, QueryVolumeViewHolder>(asyncDiff)
 
     override fun onBindViewHolder(holder: QueryVolumeViewHolder, position: Int) {
         holder.bind(getItem(position))
-        holder.itemView.setOnClickListener { onVolumeSelectedListener?.onVolumeSelected(getItem(position)) }
+        holder.itemView.setOnClickListener { onVolumeSelectedListener.onVolumeSelected(getItem(position)) }
     }
 }
 
 interface OnVolumeSelectedListener {
+    companion object {
+        val empty: OnVolumeSelectedListener = object : OnVolumeSelectedListener {
+            override fun onVolumeSelected(volume: Volume) {}
+        }
+    }
+
     fun onVolumeSelected(volume: Volume)
 }
 

app/src/main/java/es/ffgiraldez/comicsearch/query/base/ui/QueryVolumeAdapter.kt

@@ -1,17 +1,17 @@
 package es.ffgiraldez.comicsearch.query.search.presentation
 
 import es.ffgiraldez.comicsearch.comics.domain.Volume
-import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewModel
+import es.ffgiraldez.comicsearch.query.base.presentation.QueryStateViewModel
 import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewState
 import es.ffgiraldez.comicsearch.query.search.data.SearchRepository
 import io.reactivex.Flowable
 import org.reactivestreams.Publisher
 
 class SearchViewModel private constructor(
         queryToResult: (Flowable<String>) -> Publisher<QueryViewState<Volume>>
-) : QueryViewModel<Volume>(queryToResult) {
+) : QueryStateViewModel<Volume>(queryToResult) {
     companion object {
-        operator fun invoke(repo: SearchRepository): SearchViewModel = SearchViewModel {
+        operator fun invoke(repo: SearchRepository): SearchViewModel = SearchViewModel { it ->
             it.switchMap { handleQuery(repo, it) }
                     .startWith(QueryViewState.idle())
         }

app/src/main/java/es/ffgiraldez/comicsearch/query/search/presentation/SearchViewModel.kt

@@ -1,21 +1,30 @@
 package es.ffgiraldez.comicsearch.query.search.ui
 
-import androidx.databinding.BindingAdapter
 import android.view.View
 import android.widget.FrameLayout
+import android.widget.ProgressBar
 import android.widget.TextView
+import androidx.databinding.BindingAdapter
 import androidx.recyclerview.widget.RecyclerView
 import arrow.core.Option
 import com.arlib.floatingsearchview.FloatingSearchView
 import com.arlib.floatingsearchview.suggestions.model.SearchSuggestion
 import es.ffgiraldez.comicsearch.comics.domain.ComicError
 import es.ffgiraldez.comicsearch.comics.domain.Volume
+import es.ffgiraldez.comicsearch.platform.gone
+import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewState
 import es.ffgiraldez.comicsearch.query.base.ui.OnVolumeSelectedListener
 import es.ffgiraldez.comicsearch.query.base.ui.QuerySearchSuggestion.ResultSuggestion
 import es.ffgiraldez.comicsearch.query.base.ui.QueryVolumeAdapter
+import es.ffgiraldez.comicsearch.query.base.ui.error
+import es.ffgiraldez.comicsearch.query.base.ui.loading
+import es.ffgiraldez.comicsearch.query.base.ui.results
 import es.ffgiraldez.comicsearch.query.base.ui.toHumanResponse
 import io.reactivex.functions.Consumer
 
+interface ClickConsumer : Consumer<SearchSuggestion>
+interface SearchConsumer : Consumer<String>
+
 @BindingAdapter("on_suggestion_click", "on_search", requireAll = false)
 fun bindSuggestionClick(search: FloatingSearchView, clickConsumer: ClickConsumer?, searchConsumer: SearchConsumer?) {
     search.setOnSearchListener(object : FloatingSearchView.OnSearchListener {
@@ -39,30 +48,38 @@ fun bindSuggestionClick(search: FloatingSearchView, clickConsumer: ClickConsumer
 /**
  * Limit scope to apply using RecyclerView as BindingAdapter
  */
-@BindingAdapter("adapter", "on_data_change", "on_selected", requireAll = false)
-fun bindData(recycler: RecyclerView, queryAdapter: QueryVolumeAdapter, data: List<Volume>?, consumer: OnVolumeSelectedListener) =
+@BindingAdapter("adapter", "state_change", "on_selected", requireAll = false)
+fun bindStateData(recycler: RecyclerView, inputAdapter: QueryVolumeAdapter, data: QueryViewState<Volume>?, consumer: OnVolumeSelectedListener) =
         with(recycler) {
             if (adapter == null) {
-                adapter = queryAdapter
-                queryAdapter.onVolumeSelectedListener = consumer
+                inputAdapter.onVolumeSelectedListener = consumer
+                adapter = inputAdapter
+            }
+
+            data?.let {
+                bindError(data.error)
+                bindResults(data.results)
             }
-            data?.let { queryAdapter.submitList(data) }
         }
 
-@BindingAdapter("error")
-fun bindDataError(recycler: RecyclerView, errorData: Option<ComicError>?) = errorData?.let { error ->
-    error.fold({ View.VISIBLE }, { View.GONE }).let { recycler.visibility = it }
+@BindingAdapter("state_change")
+fun bindStateVisibility(errorContainer: FrameLayout, data: QueryViewState<Volume>?) = data?.let { state ->
+    state.error.fold({ View.GONE }, { View.VISIBLE }).let { errorContainer.visibility = it }
 }
 
-@BindingAdapter("error")
-fun bindErrorVisibility(errorContainer: FrameLayout, errorData: Option<ComicError>?) = errorData?.let { error ->
-    error.fold({ View.GONE }, { View.VISIBLE }).let { errorContainer.visibility = it }
+@BindingAdapter("state_change")
+fun bindErrorText(errorText: TextView, data: QueryViewState<Volume>?) = data?.let { state ->
+    state.error.fold({ Unit }, { errorText.text = it.toHumanResponse() })
 }
 
-@BindingAdapter("error")
-fun bindErrorText(errorText: TextView, errorData: Option<ComicError>?) = errorData?.let { error ->
-    error.fold({ Unit }, { errorText.text = it.toHumanResponse() })
+@BindingAdapter("state_change")
+fun bindProgress(progress: ProgressBar, data: QueryViewState<Volume>?) = data?.let { state ->
+    progress.gone(!state.loading)
 }
 
-interface ClickConsumer : Consumer<SearchSuggestion>
-interface SearchConsumer : Consumer<String>
+private fun RecyclerView.bindError(error: Option<ComicError>): Unit =
+        error.fold({ View.VISIBLE }, { View.GONE }).let { this.visibility = it }
+
+private fun RecyclerView.bindResults(error: List<Volume>): Unit = with(adapter as QueryVolumeAdapter) {
+    this.submitList(error)
+}

app/src/main/java/es/ffgiraldez/comicsearch/query/search/ui/SearchBindingAdapters.kt

@@ -1,6 +1,6 @@
 package es.ffgiraldez.comicsearch.query.sugestion.presentation
 
-import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewModel
+import es.ffgiraldez.comicsearch.query.base.presentation.QueryStateViewModel
 import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewState
 import es.ffgiraldez.comicsearch.query.sugestion.data.SuggestionRepository
 import io.reactivex.Flowable
@@ -9,7 +9,7 @@ import java.util.concurrent.TimeUnit
 
 class SuggestionViewModel private constructor(
         transformer: (Flowable<String>) -> Publisher<QueryViewState<String>>
-) : QueryViewModel<String>(transformer) {
+) : QueryStateViewModel<String>(transformer) {
     companion object {
         operator fun invoke(repo: SuggestionRepository): SuggestionViewModel = SuggestionViewModel {
             it.debounce(400, TimeUnit.MILLISECONDS)

app/src/main/java/es/ffgiraldez/comicsearch/query/sugestion/presentation/SuggestionViewModel.kt

@@ -1,36 +1,33 @@
 package es.ffgiraldez.comicsearch.query.sugestion.ui
 
 import androidx.databinding.BindingAdapter
-import arrow.core.Option
 import com.arlib.floatingsearchview.FloatingSearchView
-import es.ffgiraldez.comicsearch.comics.domain.ComicError
-import es.ffgiraldez.comicsearch.platform.safe
+import es.ffgiraldez.comicsearch.query.base.presentation.QueryViewState
 import es.ffgiraldez.comicsearch.query.base.ui.QuerySearchSuggestion.ErrorSuggestion
 import es.ffgiraldez.comicsearch.query.base.ui.QuerySearchSuggestion.ResultSuggestion
+import es.ffgiraldez.comicsearch.query.base.ui.error
+import es.ffgiraldez.comicsearch.query.base.ui.loading
+import es.ffgiraldez.comicsearch.query.base.ui.results
 import es.ffgiraldez.comicsearch.query.base.ui.toHumanResponse
 
 @BindingAdapter("on_change")
-fun bindQueryChangeListener(search: FloatingSearchView, listener: FloatingSearchView.OnQueryChangeListener) =
-        search.setOnQueryChangeListener(listener)
-
-@BindingAdapter("suggestions", "error")
-fun bindSuggestions(
+fun bindQueryChangeListener(
         search: FloatingSearchView,
-        resultData: List<String>?,
-        errorData: Option<ComicError>?
-) = safe(errorData, resultData) { error, results ->
+        listener: FloatingSearchView.OnQueryChangeListener
+): Unit = search.setOnQueryChangeListener(listener)
+
+@BindingAdapter("state_change")
+fun bindSuggestions(search: FloatingSearchView, data: QueryViewState<String>?): Unit? = data?.run {
+    search.toggleProgress(loading)
     error.fold({
         results.map { ResultSuggestion(it) }
     }, {
         listOf(ErrorSuggestion(it.toHumanResponse()))
     }).let { search.swapSuggestions(it) }
 }
 
-@BindingAdapter("show_progress")
-fun bindLoading(search: FloatingSearchView, liveData: Boolean?) = liveData?.let {
-    when (it) {
-        true -> search.showProgress()
-        false -> search.hideProgress()
-    }
+private fun FloatingSearchView.toggleProgress(show: Boolean): Unit = when (show) {
+    true -> showProgress()
+    false -> hideProgress()
 }