Simplifies URL Preview call

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

@@ -1,26 +1,21 @@
 package com.vitorpamplona.amethyst.model
 
+import android.util.LruCache
 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
 
 object UrlCachedPreviewer {
-    var cache = mapOf<String, UrlInfoItem>()
-        private set
-    var failures = mapOf<String, Throwable>()
+    var cache = LruCache<String, UrlPreviewState>(100)
         private set
 
-    fun previewInfo(url: String, callback: IUrlPreviewCallback? = null) {
+    fun previewInfo(url: String, onReady: (UrlPreviewState) -> Unit) {
         checkNotInMainThread()
 
         cache[url]?.let {
-            callback?.onComplete(it)
-            return
-        }
-
-        failures[url]?.let {
-            callback?.onFailed(it)
+            onReady(it)
             return
         }
 
@@ -28,13 +23,32 @@ object UrlCachedPreviewer {
             url,
             object : IUrlPreviewCallback {
                 override fun onComplete(urlInfo: UrlInfoItem) {
-                    cache = cache + Pair(url, urlInfo)
-                    callback?.onComplete(urlInfo)
+                    cache[url]?.let {
+                        if (it is UrlPreviewState.Loaded || it is UrlPreviewState.Empty) {
+                            onReady(it)
+                            return
+                        }
+                    }
+
+                    val state = if (urlInfo.allFetchComplete() && urlInfo.url == url) {
+                        UrlPreviewState.Loaded(urlInfo)
+                    } else {
+                        UrlPreviewState.Empty
+                    }
+
+                    cache.put(url, state)
+                    onReady(state)
                 }
 
                 override fun onFailed(throwable: Throwable) {
-                    failures = failures + Pair(url, throwable)
-                    callback?.onFailed(throwable)
+                    cache[url]?.let {
+                        onReady(it)
+                        return
+                    }
+
+                    val state = UrlPreviewState.Error(throwable.message ?: "Error Loading url preview")
+                    cache.put(url, state)
+                    onReady(state)
                 }
             }
         ).fetchUrlPreview()

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

@@ -8,56 +8,25 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
-import androidx.compose.ui.platform.LocalContext
-import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.model.UrlCachedPreviewer
-import com.vitorpamplona.amethyst.service.previews.IUrlPreviewCallback
-import com.vitorpamplona.amethyst.service.previews.UrlInfoItem
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 
 @Composable
 fun UrlPreview(url: String, urlText: String) {
-    val context = LocalContext.current
-
     var urlPreviewState by remember(url) {
-        val default = UrlCachedPreviewer.cache[url]?.let {
-            if (it.allFetchComplete() && it.url == url) {
-                UrlPreviewState.Loaded(it)
-            } else {
-                UrlPreviewState.Empty
-            }
-        } ?: UrlPreviewState.Loading
-
-        mutableStateOf(default)
+        mutableStateOf(
+            UrlCachedPreviewer.cache.get(url)?.let { it } ?: UrlPreviewState.Loading
+        )
     }
 
     // Doesn't use a viewModel because of viewModel reusing issues (too many UrlPreview are created).
     LaunchedEffect(url) {
         if (urlPreviewState == UrlPreviewState.Loading) {
             launch(Dispatchers.IO) {
-                UrlCachedPreviewer.previewInfo(
-                    url,
-                    object : IUrlPreviewCallback {
-                        override fun onComplete(urlInfo: UrlInfoItem) {
-                            if (urlInfo.allFetchComplete() && urlInfo.url == url) {
-                                urlPreviewState = UrlPreviewState.Loaded(urlInfo)
-                            } else {
-                                urlPreviewState = UrlPreviewState.Empty
-                            }
-                        }
-
-                        override fun onFailed(throwable: Throwable) {
-                            urlPreviewState = UrlPreviewState.Error(
-                                context.getString(
-                                    R.string.error_parsing_preview_for,
-                                    url,
-                                    throwable.message
-                                )
-                            )
-                        }
-                    }
-                )
+                UrlCachedPreviewer.previewInfo(url) {
+                    urlPreviewState = it
+                }
             }
         }
     }

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

@@ -5,8 +5,16 @@ import com.vitorpamplona.amethyst.service.previews.UrlInfoItem
 
 @Immutable
 sealed class UrlPreviewState {
+
+    @Immutable
     object Loading : UrlPreviewState()
+
+    @Immutable
     class Loaded(val previewInfo: UrlInfoItem) : UrlPreviewState()
+
+    @Immutable
     object Empty : UrlPreviewState()
+
+    @Immutable
     class Error(val errorMessage: String) : UrlPreviewState()
 }