Moves URL Previews into suspend functions

app/src/main/java/com/vitorpamplona/amethyst/model/UrlCachedPreviewer.kt

@@ -2,33 +2,35 @@ package com.vitorpamplona.amethyst.model
 
 import android.util.LruCache
 import androidx.compose.runtime.Stable
-import com.vitorpamplona.amethyst.service.checkNotInMainThread
 import com.vitorpamplona.amethyst.service.previews.BahaUrlPreview
 import com.vitorpamplona.amethyst.service.previews.IUrlPreviewCallback
 import com.vitorpamplona.amethyst.service.previews.UrlInfoItem
 import com.vitorpamplona.amethyst.ui.components.UrlPreviewState
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
 
 @Stable
 object UrlCachedPreviewer {
     var cache = LruCache<String, UrlPreviewState>(100)
         private set
 
-    fun previewInfo(url: String, onReady: (UrlPreviewState) -> Unit) {
-        checkNotInMainThread()
-
+    suspend fun previewInfo(
+        url: String,
+        onReady: suspend (UrlPreviewState) -> Unit
+    ) = withContext(Dispatchers.IO) {
         cache[url]?.let {
             onReady(it)
-            return
+            return@withContext
         }
 
         BahaUrlPreview(
             url,
             object : IUrlPreviewCallback {
-                override fun onComplete(urlInfo: UrlInfoItem) {
+                override suspend fun onComplete(urlInfo: UrlInfoItem) = withContext(Dispatchers.IO) {
                     cache[url]?.let {
                         if (it is UrlPreviewState.Loaded || it is UrlPreviewState.Empty) {
                             onReady(it)
-                            return
+                            return@withContext
                         }
                     }
 
@@ -42,10 +44,10 @@ object UrlCachedPreviewer {
                     onReady(state)
                 }
 
-                override fun onFailed(throwable: Throwable) {
+                override suspend fun onFailed(throwable: Throwable) = withContext(Dispatchers.IO) {
                     cache[url]?.let {
                         onReady(it)
-                        return
+                        return@withContext
                     }
 
                     val state = UrlPreviewState.Error(throwable.message ?: "Error Loading url preview")

app/src/main/java/com/vitorpamplona/amethyst/service/previews/BahaUrlPreview.kt

@@ -1,25 +1,21 @@
 package com.vitorpamplona.amethyst.service.previews
 
 import android.net.Uri
-import com.vitorpamplona.amethyst.service.checkNotInMainThread
 import kotlinx.coroutines.*
 import java.util.*
 
 class BahaUrlPreview(val url: String, var callback: IUrlPreviewCallback?) {
-    val scope = CoroutineScope(Job() + Dispatchers.IO)
     private val imageExtensionArray = arrayOf(".gif", ".png", ".jpg", ".jpeg", ".bmp", ".webp")
 
-    fun fetchUrlPreview(timeOut: Int = 30000) {
-        val exceptionHandler = CoroutineExceptionHandler { coroutineContext, throwable ->
-            callback?.onFailed(throwable)
-        }
-        scope.launch(exceptionHandler) {
+    suspend fun fetchUrlPreview(timeOut: Int = 30000) = withContext(Dispatchers.IO) {
+        try {
             fetch(timeOut)
+        } catch (t: Throwable) {
+            callback?.onFailed(t)
         }
     }
 
     private suspend fun fetch(timeOut: Int = 30000) {
-        checkNotInMainThread()
         lateinit var urlInfoItem: UrlInfoItem
         if (checkIsImageUrl()) {
             urlInfoItem = UrlInfoItem(url = url, image = url)
@@ -43,7 +39,6 @@ class BahaUrlPreview(val url: String, var callback: IUrlPreviewCallback?) {
     }
 
     fun cleanUp() {
-        scope.cancel()
         callback = null
     }
 }

app/src/main/java/com/vitorpamplona/amethyst/service/previews/IUrlPreviewCallback.kt

@@ -1,6 +1,6 @@
 package com.vitorpamplona.amethyst.service.previews
 
 interface IUrlPreviewCallback {
-    fun onComplete(urlInfo: UrlInfoItem)
-    fun onFailed(throwable: Throwable)
+    suspend fun onComplete(urlInfo: UrlInfoItem)
+    suspend fun onFailed(throwable: Throwable)
 }

app/src/main/java/com/vitorpamplona/amethyst/ui/components/UrlPreview.kt

@@ -30,7 +30,7 @@ fun UrlPreview(url: String, urlText: String, accountViewModel: AccountViewModel)
     } else {
         var urlPreviewState by remember(url) {
             mutableStateOf(
-                UrlCachedPreviewer.cache.get(url)?.let { it } ?: UrlPreviewState.Loading
+                UrlCachedPreviewer.cache.get(url) ?: UrlPreviewState.Loading
             )
         }
 
@@ -39,9 +39,7 @@ fun UrlPreview(url: String, urlText: String, accountViewModel: AccountViewModel)
             LaunchedEffect(url) {
                 launch(Dispatchers.IO) {
                     UrlCachedPreviewer.previewInfo(url) {
-                        launch(Dispatchers.Main) {
-                            urlPreviewState = it
-                        }
+                        urlPreviewState = it
                     }
                 }
             }