refactor: Simplify use of BackgroundMessageView (#539)

Previous code expected callers to typically provide the drawable and the
error message string resource, resulting in duplicate code at many
callsites.

Replace with three canned messages for empty containers, generic errors,
and network errors respectively. The images for these are fixed, the
caller may choose a different string resource for the error if there is
a more specific option.

Update and simplify the call sites.

app/src/main/java/app/pachli/components/account/media/AccountMediaFragment.kt

@@ -42,6 +42,7 @@ import app.pachli.core.designsystem.R as DR
 import app.pachli.core.navigation.AttachmentViewData
 import app.pachli.core.navigation.ViewMediaActivityIntent
 import app.pachli.core.network.model.Attachment
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentTimelineBinding
 import com.google.android.material.color.MaterialColors
 import com.mikepenz.iconics.IconicsDrawable
@@ -113,7 +114,7 @@ class AccountMediaFragment :
                     is LoadState.NotLoading -> {
                         if (loadState.append is LoadState.NotLoading && loadState.source.refresh is LoadState.NotLoading) {
                             binding.statusView.show()
-                            binding.statusView.setup(app.pachli.core.ui.R.drawable.elephant_friend_empty, app.pachli.core.ui.R.string.message_empty, null)
+                            binding.statusView.setup(BackgroundMessage.Empty())
                         }
                     }
                     is LoadState.Error -> {

app/src/main/java/app/pachli/components/accountlist/AccountListFragment.kt

@@ -54,6 +54,7 @@ import app.pachli.core.network.model.TimelineAccount
 import app.pachli.core.network.retrofit.MastodonApi
 import app.pachli.core.preferences.PrefKeys
 import app.pachli.core.preferences.SharedPreferencesRepository
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentAccountListBinding
 import app.pachli.interfaces.AccountActionListener
 import app.pachli.interfaces.AppBarLayoutHost
@@ -376,11 +377,7 @@ class AccountListFragment :
 
         if (adapter.itemCount == 0) {
             binding.messageView.show()
-            binding.messageView.setup(
+            binding.messageView.setup(BackgroundMessage.Empty())
-                app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                app.pachli.core.ui.R.string.message_empty,
-                null,
-            )
         } else {
             binding.messageView.hide()
         }

app/src/main/java/app/pachli/components/announcements/AnnouncementsActivity.kt

@@ -35,6 +35,7 @@ import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.common.util.unsafeLazy
 import app.pachli.core.navigation.StatusListActivityIntent
 import app.pachli.core.preferences.PrefKeys
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.ActivityAnnouncementsBinding
 import app.pachli.util.Error
 import app.pachli.util.Loading
@@ -109,7 +110,7 @@ class AnnouncementsActivity :
                     binding.progressBar.hide()
                     binding.swipeRefreshLayout.isRefreshing = false
                     if (it.data.isNullOrEmpty()) {
-                        binding.errorMessageView.setup(app.pachli.core.ui.R.drawable.elephant_friend_empty, R.string.no_announcements)
+                        binding.errorMessageView.setup(BackgroundMessage.Empty(R.string.no_announcements))
                         binding.errorMessageView.show()
                     } else {
                         binding.errorMessageView.hide()
@@ -122,7 +123,7 @@ class AnnouncementsActivity :
                 is Error -> {
                     binding.progressBar.hide()
                     binding.swipeRefreshLayout.isRefreshing = false
-                    binding.errorMessageView.setup(app.pachli.core.ui.R.drawable.errorphant_error, app.pachli.core.ui.R.string.error_generic) {
+                    binding.errorMessageView.setup(BackgroundMessage.GenericError()) {
                         refreshAnnouncements()
                     }
                     binding.errorMessageView.show()

app/src/main/java/app/pachli/components/conversation/ConversationsFragment.kt

@@ -49,6 +49,7 @@ import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.Status
 import app.pachli.core.preferences.PrefKeys
 import app.pachli.core.preferences.SharedPreferencesRepository
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentTimelineBinding
 import app.pachli.fragment.SFragment
 import app.pachli.interfaces.ActionButtonActivity
@@ -126,11 +127,7 @@ class ConversationsFragment :
                             binding.swipeRefreshLayout.isRefreshing = false
                             if (loadState.append is LoadState.NotLoading && loadState.source.refresh is LoadState.NotLoading) {
                                 binding.statusView.show()
-                                binding.statusView.setup(
+                                binding.statusView.setup(BackgroundMessage.Empty())
-                                    app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                                    app.pachli.core.ui.R.string.message_empty,
-                                    null,
-                                )
                             }
                         }
 

app/src/main/java/app/pachli/components/drafts/DraftsActivity.kt

@@ -30,6 +30,7 @@ import app.pachli.core.database.model.DraftEntity
 import app.pachli.core.navigation.ComposeActivityIntent
 import app.pachli.core.navigation.ComposeActivityIntent.ComposeOptions
 import app.pachli.core.network.parseAsMastodonHtml
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.ActivityDraftsBinding
 import app.pachli.db.DraftsAlert
 import at.connyduck.calladapter.networkresult.fold
@@ -67,7 +68,7 @@ class DraftsActivity : BaseActivity(), DraftActionListener {
             setDisplayShowHomeEnabled(true)
         }
 
-        binding.draftsErrorMessageView.setup(app.pachli.core.ui.R.drawable.elephant_friend_empty, R.string.no_drafts)
+        binding.draftsErrorMessageView.setup(BackgroundMessage.Empty(R.string.no_drafts))
 
         val adapter = DraftsAdapter(this)
 

app/src/main/java/app/pachli/components/filters/FiltersActivity.kt

@@ -13,6 +13,7 @@ import app.pachli.core.common.extensions.visible
 import app.pachli.core.designsystem.R as DR
 import app.pachli.core.navigation.EditFilterActivityIntent
 import app.pachli.core.network.model.Filter
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.ActivityFiltersBinding
 import com.google.android.material.color.MaterialColors
 import dagger.hilt.android.AndroidEntryPoint
@@ -62,13 +63,13 @@ class FiltersActivity : BaseActivity(), FiltersListener {
                 when (state.loadingState) {
                     FiltersViewModel.LoadingState.INITIAL, FiltersViewModel.LoadingState.LOADING -> binding.messageView.hide()
                     FiltersViewModel.LoadingState.ERROR_NETWORK -> {
-                        binding.messageView.setup(app.pachli.core.ui.R.drawable.errorphant_offline, app.pachli.core.ui.R.string.error_network) {
+                        binding.messageView.setup(BackgroundMessage.Network()) {
                             loadFilters()
                         }
                         binding.messageView.show()
                     }
                     FiltersViewModel.LoadingState.ERROR_OTHER -> {
-                        binding.messageView.setup(app.pachli.core.ui.R.drawable.errorphant_error, app.pachli.core.ui.R.string.error_generic) {
+                        binding.messageView.setup(BackgroundMessage.GenericError()) {
                             loadFilters()
                         }
                         binding.messageView.show()
@@ -76,11 +77,7 @@ class FiltersActivity : BaseActivity(), FiltersListener {
                     FiltersViewModel.LoadingState.LOADED -> {
                         binding.filtersList.adapter = FiltersAdapter(this@FiltersActivity, state.filters)
                         if (state.filters.isEmpty()) {
-                            binding.messageView.setup(
+                            binding.messageView.setup(BackgroundMessage.Empty())
-                                app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                                app.pachli.core.ui.R.string.message_empty,
-                                null,
-                            )
                             binding.messageView.show()
                         } else {
                             binding.messageView.hide()

app/src/main/java/app/pachli/components/instancemute/fragment/InstanceListFragment.kt

@@ -14,6 +14,7 @@ import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.network.model.HttpHeaderLink
 import app.pachli.core.network.retrofit.MastodonApi
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentInstanceListBinding
 import app.pachli.view.EndlessOnScrollListener
 import at.connyduck.calladapter.networkresult.fold
@@ -123,11 +124,7 @@ class InstanceListFragment :
 
         if (adapter.itemCount == 0) {
             binding.messageView.show()
-            binding.messageView.setup(
+            binding.messageView.setup(BackgroundMessage.Empty())
-                app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                app.pachli.core.ui.R.string.message_empty,
-                null,
-            )
         } else {
             binding.messageView.hide()
         }

app/src/main/java/app/pachli/components/notifications/NotificationsFragment.kt

@@ -56,6 +56,7 @@ import app.pachli.core.network.model.Filter
 import app.pachli.core.network.model.Notification
 import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.Status
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentTimelineNotificationsBinding
 import app.pachli.fragment.SFragment
 import app.pachli.interfaces.AccountActionListener
@@ -420,10 +421,7 @@ class NotificationsFragment :
                         binding.statusView.hide()
                         if (loadState.refresh is LoadState.NotLoading) {
                             if (adapter.itemCount == 0) {
-                                binding.statusView.setup(
+                                binding.statusView.setup(BackgroundMessage.Empty())
-                                    app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                                    app.pachli.core.ui.R.string.message_empty,
-                                )
                                 binding.recyclerView.hide()
                                 binding.statusView.show()
                             } else {

app/src/main/java/app/pachli/components/scheduled/ScheduledStatusActivity.kt

@@ -36,6 +36,7 @@ import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.navigation.ComposeActivityIntent
 import app.pachli.core.navigation.ComposeActivityIntent.ComposeOptions
 import app.pachli.core.network.model.ScheduledStatus
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.ActivityScheduledStatusBinding
 import com.google.android.material.color.MaterialColors
 import com.google.android.material.divider.MaterialDividerItemDecoration
@@ -107,7 +108,7 @@ class ScheduledStatusActivity :
             if (loadState.refresh is LoadState.NotLoading) {
                 binding.progressBar.hide()
                 if (adapter.itemCount == 0) {
-                    binding.errorMessageView.setup(app.pachli.core.ui.R.drawable.elephant_friend_empty, R.string.no_scheduled_posts)
+                    binding.errorMessageView.setup(BackgroundMessage.Empty(R.string.no_scheduled_posts))
                     binding.errorMessageView.show()
                 } else {
                     binding.errorMessageView.hide()

app/src/main/java/app/pachli/components/timeline/TimelineFragment.kt

@@ -60,7 +60,7 @@ import app.pachli.core.navigation.AttachmentViewData
 import app.pachli.core.network.model.Poll
 import app.pachli.core.network.model.Status
 import app.pachli.core.network.model.TimelineKind
-import app.pachli.core.ui.extensions.getDrawableRes
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.core.ui.extensions.getErrorString
 import app.pachli.databinding.FragmentTimelineBinding
 import app.pachli.fragment.SFragment
@@ -441,8 +441,7 @@ class TimelineFragment :
                                             .setAction(app.pachli.core.ui.R.string.action_retry) { adapter.retry() }
                                         snackbar!!.show()
                                     } else {
-                                        val drawableRes = error.getDrawableRes()
+                                        binding.statusView.setup(error) {
-                                        binding.statusView.setup(drawableRes, message) {
                                             snackbar?.dismiss()
                                             adapter.retry()
                                         }
@@ -453,10 +452,7 @@ class TimelineFragment :
 
                                 PresentationState.PRESENTED -> {
                                     if (adapter.itemCount == 0) {
-                                        binding.statusView.setup(
+                                        binding.statusView.setup(BackgroundMessage.Empty())
-                                            app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                                            app.pachli.core.ui.R.string.message_empty,
-                                        )
                                         if (timelineKind == TimelineKind.Home) {
                                             binding.statusView.showHelp(R.string.help_empty_home)
                                         }

app/src/main/java/app/pachli/components/trending/TrendingLinksFragment.kt

@@ -43,6 +43,7 @@ import app.pachli.core.common.extensions.hide
 import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.designsystem.R as DR
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentTrendingLinksBinding
 import app.pachli.interfaces.ActionButtonActivity
 import app.pachli.interfaces.AppBarLayoutHost
@@ -110,11 +111,7 @@ class TrendingLinksFragment :
                         binding.progressBar.hide()
                         binding.swipeRefreshLayout.isRefreshing = false
                         if (it.data.isEmpty()) {
-                            binding.messageView.setup(
+                            binding.messageView.setup(BackgroundMessage.Empty())
-                                app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                                app.pachli.core.ui.R.string.message_empty,
-                                null,
-                            )
                             binding.messageView.show()
                         } else {
                             binding.messageView.hide()

app/src/main/java/app/pachli/components/trending/TrendingTagsFragment.kt

@@ -44,6 +44,7 @@ import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.designsystem.R as DR
 import app.pachli.core.navigation.StatusListActivityIntent
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentTrendingTagsBinding
 import app.pachli.interfaces.ActionButtonActivity
 import app.pachli.interfaces.AppBarLayoutHost
@@ -199,11 +200,7 @@ class TrendingTagsFragment :
         if (viewData.isEmpty()) {
             binding.recyclerView.hide()
             binding.messageView.show()
-            binding.messageView.setup(
+            binding.messageView.setup(BackgroundMessage.Empty())
-                app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                app.pachli.core.ui.R.string.message_empty,
-                null,
-            )
         } else {
             binding.recyclerView.show()
             binding.messageView.hide()
@@ -233,10 +230,7 @@ class TrendingTagsFragment :
         binding.progressBar.hide()
 
         binding.swipeRefreshLayout.isRefreshing = false
-        binding.messageView.setup(
+        binding.messageView.setup(BackgroundMessage.Network()) { refreshContent() }
-            app.pachli.core.ui.R.drawable.errorphant_offline,
-            app.pachli.core.ui.R.string.error_network,
-        ) { refreshContent() }
     }
 
     private fun otherError() {
@@ -245,10 +239,7 @@ class TrendingTagsFragment :
         binding.progressBar.hide()
 
         binding.swipeRefreshLayout.isRefreshing = false
-        binding.messageView.setup(
+        binding.messageView.setup(BackgroundMessage.GenericError()) { refreshContent() }
-            app.pachli.core.ui.R.drawable.errorphant_error,
-            app.pachli.core.ui.R.string.error_generic,
-        ) { refreshContent() }
     }
 
     private fun actionButtonPresent(): Boolean {

app/src/main/java/app/pachli/components/viewthread/edits/ViewEditsFragment.kt

@@ -42,6 +42,7 @@ import app.pachli.core.navigation.AccountActivityIntent
 import app.pachli.core.navigation.StatusListActivityIntent
 import app.pachli.core.preferences.PrefKeys
 import app.pachli.core.preferences.SharedPreferencesRepository
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.databinding.FragmentViewEditsBinding
 import app.pachli.interfaces.LinkListener
 import com.google.android.material.color.MaterialColors
@@ -112,10 +113,7 @@ class ViewEditsFragment :
 
                         when (uiState.throwable) {
                             is ViewEditsViewModel.MissingEditsException -> {
-                                binding.statusView.setup(
+                                binding.statusView.setup(BackgroundMessage.Empty(R.string.error_missing_edits))
-                                    app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                                    R.string.error_missing_edits,
-                                )
                             }
                             else -> {
                                 binding.statusView.setup(uiState.throwable) {

core/ui/src/main/kotlin/app/pachli/core/ui/BackgroundMessageView.kt

@@ -40,6 +40,41 @@ import com.mikepenz.iconics.IconicsDrawable
 import com.mikepenz.iconics.typeface.library.googlematerial.GoogleMaterial
 import java.util.regex.Pattern
 
+/** Kinds of message that can be shown */
+sealed interface BackgroundMessage {
+    @get:DrawableRes val drawableRes: Int
+
+    @get:StringRes val stringRes: Int
+
+    /**
+     * Generic "Nothing here" message and image, for use when a collection has
+     * no items.
+     *
+     * @param stringRes Alternative string resource to use as the message
+     */
+    data class Empty(override val stringRes: Int = R.string.message_empty) : BackgroundMessage {
+        override val drawableRes: Int = R.drawable.elephant_friend_empty
+    }
+
+    /**
+     * Generic "An error occurred" message and image
+     *
+     * @param stringRes Alternative string resource to use as the message
+     */
+    data class GenericError(override val stringRes: Int = R.string.error_generic) : BackgroundMessage {
+        override val drawableRes: Int = R.drawable.errorphant_error
+    }
+
+    /**
+     * Generic "A network error occurred" message and image
+     *
+     * @param stringRes Alternative string resource to use as the message
+     */
+    data class Network(override val stringRes: Int = R.string.error_network) : BackgroundMessage {
+        override val drawableRes: Int = R.drawable.errorphant_offline
+    }
+}
+
 /**
  * This view is used for screens with content which may be empty or might have failed to download.
  */
@@ -56,7 +91,7 @@ class BackgroundMessageView @JvmOverloads constructor(
         orientation = VERTICAL
 
         if (isInEditMode) {
-            setup(app.pachli.core.ui.R.drawable.errorphant_offline, app.pachli.core.ui.R.string.error_network) {}
+            setup(BackgroundMessage.Network())
         }
     }
 
@@ -64,7 +99,11 @@ class BackgroundMessageView @JvmOverloads constructor(
         setup(throwable.getDrawableRes(), throwable.getErrorString(context), listener)
     }
 
-    fun setup(
+    fun setup(message: BackgroundMessage, listener: ((v: View) -> Unit)? = null) {
+        setup(message.drawableRes, message.stringRes, listener)
+    }
+
+    private fun setup(
         @DrawableRes imageRes: Int,
         @StringRes messageRes: Int,
         clickListener: ((v: View) -> Unit)? = null,
@@ -74,7 +113,7 @@ class BackgroundMessageView @JvmOverloads constructor(
      * Setup image, message and button.
      * If [clickListener] is `null` then the button will be hidden.
      */
-    fun setup(
+    private fun setup(
         @DrawableRes imageRes: Int,
         message: String,
         clickListener: ((v: View) -> Unit)? = null,

core/ui/src/main/kotlin/app/pachli/core/ui/extensions/ThrowableExtensions.kt

@@ -25,20 +25,20 @@ import retrofit2.HttpException
 
 /** @return A drawable resource to accompany the error message for this throwable */
 fun Throwable.getDrawableRes(): Int = when (this) {
-    is IOException -> app.pachli.core.ui.R.drawable.errorphant_offline
+    is IOException -> R.drawable.errorphant_offline
     is HttpException -> {
         if (this.code() == 404) {
-            app.pachli.core.ui.R.drawable.elephant_friend_empty
+            R.drawable.elephant_friend_empty
         } else {
-            app.pachli.core.ui.R.drawable.errorphant_offline
+            R.drawable.errorphant_offline
         }
     }
-    else -> app.pachli.core.ui.R.drawable.errorphant_error
+    else -> R.drawable.errorphant_error
 }
 
 /** @return A string error message for this throwable */
 fun Throwable.getErrorString(context: Context): String = getServerErrorMessage() ?: when (this) {
-    is IOException -> context.getString(app.pachli.core.ui.R.string.error_network_fmt, this.message)
+    is IOException -> context.getString(R.string.error_network_fmt, this.message)
     is HttpException -> if (this.code() == 404) context.getString(R.string.error_404_not_found_fmt, this.message) else context.getString(R.string.error_generic_fmt, this.message)
     else -> context.getString(R.string.error_generic_fmt, this.message)
 }

feature/lists/src/main/kotlin/app/pachli/feature/lists/AccountsInListFragment.kt

@@ -202,7 +202,7 @@ class AccountsInListFragment : DialogFragment() {
 
     private fun handleError(error: Throwable) {
         binding.messageView.show()
-        binding.messageView.setup(error) { _: View ->
+        binding.messageView.setup(error) {
             binding.messageView.hide()
             viewModel.refresh()
         }

feature/lists/src/main/kotlin/app/pachli/feature/lists/ListsActivity.kt

@@ -49,6 +49,7 @@ import app.pachli.core.network.model.MastoList
 import app.pachli.core.network.model.UserListRepliesPolicy
 import app.pachli.core.network.retrofit.apiresult.ApiError
 import app.pachli.core.network.retrofit.apiresult.NetworkError
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.core.ui.extensions.await
 import app.pachli.feature.lists.databinding.ActivityListsBinding
 import app.pachli.feature.lists.databinding.DialogListBinding
@@ -205,13 +206,9 @@ class ListsActivity : BaseActivity(), MenuProvider {
             binding.swipeRefreshLayout.isRefreshing = false
 
             if (it is NetworkError) {
-                binding.messageView.setup(app.pachli.core.ui.R.drawable.errorphant_offline, app.pachli.core.ui.R.string.error_network) {
+                binding.messageView.setup(BackgroundMessage.Network()) { viewModel.refresh() }
-                    viewModel.refresh()
-                }
             } else {
-                binding.messageView.setup(app.pachli.core.ui.R.drawable.errorphant_error, app.pachli.core.ui.R.string.error_generic) {
+                binding.messageView.setup(BackgroundMessage.GenericError()) { viewModel.refresh() }
-                    viewModel.refresh()
-                }
             }
         }
 
@@ -222,11 +219,7 @@ class ListsActivity : BaseActivity(), MenuProvider {
                     binding.swipeRefreshLayout.isRefreshing = false
                     if (lists.lists.isEmpty()) {
                         binding.messageView.show()
-                        binding.messageView.setup(
+                        binding.messageView.setup(BackgroundMessage.Empty())
-                            app.pachli.core.ui.R.drawable.elephant_friend_empty,
-                            app.pachli.core.ui.R.string.message_empty,
-                            null,
-                        )
                     } else {
                         binding.messageView.hide()
                     }

feature/lists/src/main/kotlin/app/pachli/feature/lists/ListsForAccountFragment.kt

@@ -33,6 +33,7 @@ import app.pachli.core.common.extensions.show
 import app.pachli.core.common.extensions.viewBinding
 import app.pachli.core.common.extensions.visible
 import app.pachli.core.designsystem.R as DR
+import app.pachli.core.ui.BackgroundMessage
 import app.pachli.core.ui.BindingHolder
 import app.pachli.feature.lists.ListsForAccountViewModel.Error
 import app.pachli.feature.lists.ListsForAccountViewModel.FlowError
@@ -140,9 +141,7 @@ class ListsForAccountFragment : DialogFragment() {
                     binding.progressBar.hide()
                     if (it.listsWithMembership.isEmpty()) {
                         binding.messageView.show()
-                        binding.messageView.setup(app.pachli.core.ui.R.drawable.elephant_friend_empty, R.string.no_lists) {
+                        binding.messageView.setup(BackgroundMessage.Empty(R.string.no_lists)) { load() }
-                            load()
-                        }
                     } else {
                         binding.listsView.show()
                         adapter.submitList(it.listsWithMembership.values.toList())