Rework code to enable UI rendered error messages (#172)

app/src/main/java/exh/recs/RecommendsPager.kt

@@ -4,15 +4,18 @@ import eu.kanade.tachiyomi.data.database.models.Manga
 import eu.kanade.tachiyomi.network.await
 import eu.kanade.tachiyomi.source.model.MangasPage
 import eu.kanade.tachiyomi.source.model.SMangaImpl
+import eu.kanade.tachiyomi.ui.browse.source.browse.NoResultsException
 import eu.kanade.tachiyomi.ui.browse.source.browse.Pager
+import eu.kanade.tachiyomi.util.lang.asObservable
 import exh.log.maybeInjectEHLogger
 import exh.util.MangaType
 import exh.util.mangaType
-import kotlinx.coroutines.CoroutineExceptionHandler
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
-import kotlinx.coroutines.launch
+import kotlinx.coroutines.async
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.supervisorScope
 import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.JsonArray
@@ -28,6 +31,7 @@ import okhttp3.OkHttpClient
 import okhttp3.Request
 import okhttp3.RequestBody.Companion.toRequestBody
 import rx.Observable
+import rx.android.schedulers.AndroidSchedulers
 import timber.log.Timber
 
 abstract class API(_endpoint: String) {
@@ -37,21 +41,14 @@ abstract class API(_endpoint: String) {
         .build()
     val scope = CoroutineScope(Job() + Dispatchers.Default)
 
-    abstract fun getRecsBySearch(
+    abstract suspend fun getRecsBySearch(search: String): List<SMangaImpl>
-        search: String,
-        callback: (onResolve: List<SMangaImpl>?, onReject: Throwable?) -> Unit
-    )
 }
 
 class MyAnimeList : API("https://api.jikan.moe/v3/") {
-    private fun getRecsById(
+    private suspend fun getRecsById(id: String): List<SMangaImpl> {
-        id: String,
-        callback: (resolve: List<SMangaImpl>?, reject: Throwable?) -> Unit
-    ) {
         val httpUrl = endpoint.toHttpUrlOrNull()
         if (httpUrl == null) {
-            callback.invoke(null, Exception("Could not convert endpoint url"))
+            throw Exception("Could not convert endpoint url")
-            return
         }
         val urlBuilder = httpUrl.newBuilder()
         urlBuilder.addPathSegment("manga")
@@ -64,11 +61,6 @@ class MyAnimeList : API("https://api.jikan.moe/v3/") {
             .get()
             .build()
 
-        val handler = CoroutineExceptionHandler { _, exception ->
-            callback.invoke(null, exception)
-        }
-
-        scope.launch(handler) {
         val response = client.newCall(request).await()
         val body = response.body?.string().orEmpty()
         if (body.isEmpty()) {
@@ -79,8 +71,7 @@ class MyAnimeList : API("https://api.jikan.moe/v3/") {
             ?: throw Exception("Unexpected response")
         val recs = recommendations.map { rec ->
             rec as? JsonObject ?: throw Exception("Invalid json")
-                Timber.tag("RECOMMENDATIONS")
+            Timber.tag("RECOMMENDATIONS").d("MYANIMELIST > RECOMMENDATION: %s", rec["title"]!!.jsonPrimitive.content)
-                    .d("MYANIMELIST > FOUND RECOMMENDATION > %s", rec["title"]!!.jsonPrimitive.content)
             SMangaImpl().apply {
                 this.title = rec["title"]!!.jsonPrimitive.content
                 this.thumbnail_url = rec["image_url"]!!.jsonPrimitive.content
@@ -88,19 +79,14 @@ class MyAnimeList : API("https://api.jikan.moe/v3/") {
                 this.url = rec["url"]!!.jsonPrimitive.content
             }
         }
-            callback.invoke(recs, null)
+        return recs
-        }
     }
 
-    override fun getRecsBySearch(
+    override suspend fun getRecsBySearch(search: String): List<SMangaImpl> {
-        search: String,
-        callback: (recs: List<SMangaImpl>?, error: Throwable?) -> Unit
-    ) {
         val httpUrl =
             endpoint.toHttpUrlOrNull()
         if (httpUrl == null) {
-            callback.invoke(null, Exception("Could not convert endpoint url"))
+            throw Exception("Could not convert endpoint url")
-            return
         }
         val urlBuilder = httpUrl.newBuilder()
         urlBuilder.addPathSegment("search")
@@ -113,11 +99,6 @@ class MyAnimeList : API("https://api.jikan.moe/v3/") {
             .get()
             .build()
 
-        val handler = CoroutineExceptionHandler { _, exception ->
-            callback.invoke(null, exception)
-        }
-
-        scope.launch(handler) {
         val response = client.newCall(request).await()
         val body = response.body?.string().orEmpty()
         if (body.isEmpty()) {
@@ -129,11 +110,8 @@ class MyAnimeList : API("https://api.jikan.moe/v3/") {
             throw Exception("'$search' not found")
         }
         val result = results.first().jsonObject
-            Timber.tag("RECOMMENDATIONS")
-                .d("MYANIMELIST > FOUND TITLE > %s", result["title"]!!.jsonPrimitive.content)
         val id = result["mal_id"]!!.jsonPrimitive.content
-            getRecsById(id, callback)
+        return getRecsById(id)
-        }
     }
 }
 
@@ -157,10 +135,7 @@ class Anilist : API("https://graphql.anilist.co/") {
         }
     }
 
-    override fun getRecsBySearch(
+    override suspend fun getRecsBySearch(search: String): List<SMangaImpl> {
-        search: String,
-        callback: (onResolve: List<SMangaImpl>?, onReject: Throwable?) -> Unit
-    ) {
         val query =
             """
             |query Recommendations(${'$'}search: String!) {
@@ -207,11 +182,6 @@ class Anilist : API("https://graphql.anilist.co/") {
             .post(payloadBody)
             .build()
 
-        val handler = CoroutineExceptionHandler { _, exception ->
-            callback.invoke(null, exception)
-        }
-
-        scope.launch(handler) {
         val response = client.newCall(request).await()
         val body = response.body?.string().orEmpty()
         if (body.isEmpty()) {
@@ -232,13 +202,10 @@ class Anilist : API("https://graphql.anilist.co/") {
                 { countOccurrence(it.jsonObject["synonyms"]!!.jsonArray, search) > 0 }
             )
         ).last().jsonObject
-            Timber.tag("RECOMMENDATIONS")
-                .d("ANILIST > FOUND TITLE > %s", getTitle(result))
         val recommendations = result["recommendations"]!!.jsonObject["edges"]!!.jsonArray
         val recs = recommendations.map {
             val rec = it.jsonObject["node"]!!.jsonObject["mediaRecommendation"]!!.jsonObject
-                Timber.tag("RECOMMENDATIONS")
+            Timber.tag("RECOMMENDATIONS").d("ANILIST > RECOMMENDATION: %s", getTitle(rec))
-                    .d("ANILIST: FOUND RECOMMENDATION: %s", getTitle(rec))
             SMangaImpl().apply {
                 this.title = getTitle(rec)
                 this.thumbnail_url = rec["coverImage"]!!.jsonObject["large"]!!.jsonPrimitive.content
@@ -246,8 +213,7 @@ class Anilist : API("https://graphql.anilist.co/") {
                 this.url = rec["siteUrl"]!!.jsonPrimitive.content
             }
         }
-            callback.invoke(recs, null)
+        return recs
-        }
     }
 }
 
@@ -256,59 +222,43 @@ open class RecommendsPager(
     private val smart: Boolean = true,
     private var preferredApi: API = API.MYANIMELIST
 ) : Pager() {
-    private val apiList = API_MAP.toMutableMap()
-    private var currentApi: API? = null
-
-    private fun handleSuccess(recs: List<SMangaImpl>) {
-        if (recs.isEmpty()) {
-            Timber.tag("RECOMMENDATIONS").e("%s > Couldn't find any", currentApi.toString())
-            apiList.remove(currentApi)
-            val list = apiList.toList()
-            currentApi = if (list.isEmpty()) {
-                null
-            } else {
-                apiList.toList().first().first
-            }
-
-            if (currentApi != null) {
-                getRecs(currentApi!!)
-            } else {
-                Timber.tag("RECOMMENDATIONS").e("Couldn't find any")
-                onPageReceived(MangasPage(recs, false))
-            }
-        } else {
-            onPageReceived(MangasPage(recs, false))
-        }
-    }
-
-    private fun handleError(error: Throwable) {
-        Timber.tag("RECOMMENDATIONS").e(error)
-        handleSuccess(listOf()) // tmp workaround until errors can be displayed in app
-    }
-
-    private fun getRecs(api: API) {
-        Timber.tag("RECOMMENDATIONS").d("USING > %s", api.toString())
-        apiList[api]?.getRecsBySearch(manga.originalTitle) { recs, error ->
-            if (error != null) {
-                handleError(error)
-            }
-            if (recs != null) {
-                handleSuccess(recs)
-            }
-        }
-    }
-
     override fun requestNext(): Observable<MangasPage> {
-        if (smart) {
+        return flow {
-            preferredApi =
+            if (smart) preferredApi = if (manga.mangaType() != MangaType.TYPE_MANGA) API.ANILIST else preferredApi
-                if (manga.mangaType() != MangaType.TYPE_MANGA) API.ANILIST else preferredApi
+
-            Timber.tag("RECOMMENDATIONS").d("SMART > %s", preferredApi.toString())
+            val apiList = mapOf(preferredApi to API_MAP[preferredApi]!!) + API_MAP.filter { it.key != preferredApi }.toList()
+
+            val recs = supervisorScope {
+                apiList
+                    .asSequence()
+                    .map { (key, api) ->
+                        async(Dispatchers.Default) {
+                            try {
+                                val recs = api.getRecsBySearch(manga.originalTitle).orEmpty()
+                                Timber.tag("RECOMMENDATIONS").d("%s > Results: %s", key, recs.count())
+                                recs
+                            } catch (e: Exception) {
+                                Timber.tag("RECOMMENDATIONS").e("%s > Error: %s", key, e.message)
+                                listOf()
+                            }
+                        }
+                    }
+                    .firstOrNull { it.await().isNotEmpty() }
+                    ?.await().orEmpty()
             }
-        currentApi = preferredApi
 
-        getRecs(currentApi!!)
+            val page = MangasPage(recs, false)
-
+            emit(page)
-        return Observable.just(MangasPage(listOf(), false))
+        }
+            .asObservable()
+            .observeOn(AndroidSchedulers.mainThread())
+            .doOnNext {
+                if (it.mangas.isNotEmpty()) {
+                    onPageReceived(it)
+                } else {
+                    throw NoResultsException()
+                }
+            }
     }
 
     companion object {