[WIP] Base for push notification system using websockets

server/src/main/kotlin/suwayomi/tachidesk/event/Event.kt

@@ -0,0 +1,10 @@
+package suwayomi.tachidesk.event
+
+import suwayomi.tachidesk.event.enums.EventType
+import java.util.UUID
+
+data class Event<T>(
+    val id: UUID? = UUID.randomUUID(),
+    val type: EventType,
+    val entity: T
+)

server/src/main/kotlin/suwayomi/tachidesk/event/EventDispatcher.kt

@@ -0,0 +1,41 @@
+package suwayomi.tachidesk.event
+
+import io.javalin.websocket.WsContext
+import io.javalin.websocket.WsMessageContext
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.CopyOnWriteArrayList
+
+abstract class EventDispatcher<T : EventEntity> {
+    private val clients = ConcurrentHashMap<String, WsContext>()
+    private val eventQueue = CopyOnWriteArrayList<Event<T>>()
+
+    fun addClient(ctx: WsContext) {
+        clients[ctx.sessionId] = ctx
+    }
+
+    fun removeClient(ctx: WsContext) {
+        clients.remove(key = ctx.sessionId)
+    }
+
+    abstract fun notifyClient(ctx: WsContext, event: Event<T>)
+
+    abstract fun handleRequest(ctx: WsMessageContext)
+
+    fun notifyAllClients(event: Event<T>) {
+        clients.forEach {
+            notifyClient(ctx = it.value, event = event)
+        }
+    }
+
+    fun enqueue(event: Event<T>) {
+        eventQueue += event
+    }
+
+    // to be consumed in the client based on
+    // the event type in a notifications screen
+    fun queue() = eventQueue
+
+    fun dequeue(event: Event<T>) {
+        eventQueue.removeIf { it.id == event.id }
+    }
+}

server/src/main/kotlin/suwayomi/tachidesk/event/EventEntity.kt

@@ -0,0 +1,3 @@
+package suwayomi.tachidesk.event
+
+abstract class EventEntity

server/src/main/kotlin/suwayomi/tachidesk/event/enums/EventType.kt

@@ -0,0 +1,8 @@
+package suwayomi.tachidesk.event.enums
+
+enum class EventType {
+    SYSTEM,
+    INFORMATIVE,
+    STATIC,
+    DYNAMIC
+}

server/src/main/kotlin/suwayomi/tachidesk/manga/controller/DownloadController.kt

@@ -19,14 +19,14 @@ object DownloadController {
     /** Download queue stats */
     fun downloadsWS(ws: WsConfig) {
         ws.onConnect { ctx ->
-            DownloadManager.addClient(ctx)
+            DownloadManager.eventDispatcher.addClient(ctx)
             DownloadManager.notifyClient(ctx)
         }
         ws.onMessage { ctx ->
-            DownloadManager.handleRequest(ctx)
+            DownloadManager.eventDispatcher.handleRequest(ctx)
         }
         ws.onClose { ctx ->
-            DownloadManager.removeClient(ctx)
+            DownloadManager.eventDispatcher.removeClient(ctx)
         }
     }
 

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/DownloadEventDispatcher.kt

@@ -0,0 +1,30 @@
+package suwayomi.tachidesk.manga.impl.download
+
+import io.javalin.websocket.WsContext
+import io.javalin.websocket.WsMessageContext
+import suwayomi.tachidesk.event.Event
+import suwayomi.tachidesk.event.EventDispatcher
+import suwayomi.tachidesk.manga.impl.download.model.DownloadStatus
+
+class DownloadEventDispatcher : EventDispatcher<DownloadStatus>() {
+    override fun notifyClient(ctx: WsContext, event: Event<DownloadStatus>) {
+        ctx.send(
+            event.entity
+        )
+    }
+
+    override fun handleRequest(ctx: WsMessageContext) {
+        when (ctx.message()) {
+            "STATUS" -> DownloadManager.notifyClient(ctx)
+            else -> ctx.send(
+                """
+                        |Invalid command.
+                        |Supported commands are:
+                        |    - STATUS
+                        |       sends the current download status
+                        |
+                """.trimMargin()
+            )
+        }
+    }
+}

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/DownloadManager.kt

@@ -8,62 +8,30 @@ package suwayomi.tachidesk.manga.impl.download
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 import io.javalin.websocket.WsContext
-import io.javalin.websocket.WsMessageContext
 import org.jetbrains.exposed.sql.and
 import org.jetbrains.exposed.sql.select
 import org.jetbrains.exposed.sql.transactions.transaction
+import suwayomi.tachidesk.event.Event
+import suwayomi.tachidesk.event.enums.EventType
 import suwayomi.tachidesk.manga.impl.Manga.getManga
 import suwayomi.tachidesk.manga.impl.download.model.DownloadChapter
 import suwayomi.tachidesk.manga.impl.download.model.DownloadState.Downloading
 import suwayomi.tachidesk.manga.impl.download.model.DownloadStatus
 import suwayomi.tachidesk.manga.model.table.ChapterTable
 import suwayomi.tachidesk.manga.model.table.toDataClass
-import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.CopyOnWriteArrayList
 
 object DownloadManager {
-    private val clients = ConcurrentHashMap<String, WsContext>()
+    val eventDispatcher = DownloadEventDispatcher()
     private val downloadQueue = CopyOnWriteArrayList<DownloadChapter>()
     private var downloader: Downloader? = null
 
-    fun addClient(ctx: WsContext) {
-        clients[ctx.sessionId] = ctx
-    }
-
-    fun removeClient(ctx: WsContext) {
-        clients.remove(ctx.sessionId)
-    }
-
     fun notifyClient(ctx: WsContext) {
-        ctx.send(
-            getStatus()
-        )
-    }
-
-    fun handleRequest(ctx: WsMessageContext) {
-        when (ctx.message()) {
-            "STATUS" -> notifyClient(ctx)
-            else -> ctx.send(
-                """
-                        |Invalid command.
-                        |Supported commands are:
-                        |    - STATUS
-                        |       sends the current download status
-                        |
-                """.trimMargin()
-            )
-        }
-    }
-
-    private fun notifyAllClients() {
-        val status = getStatus()
-        clients.forEach {
-            it.value.send(status)
-        }
+        eventDispatcher.notifyClient(ctx, getStatus())
     }
 
-    private fun getStatus(): DownloadStatus {
-        return DownloadStatus(
+    private fun getStatus(): Event<DownloadStatus> {
+        val status = DownloadStatus(
             if (downloader == null ||
                 downloadQueue.none { it.state == Downloading }
             ) {
@@ -73,6 +41,10 @@ object DownloadManager {
             },
             downloadQueue
         )
+        return Event(
+            type = EventType.STATIC,
+            entity = status
+        )
     }
 
     suspend fun enqueue(chapterIndex: Int, mangaId: Int) {
@@ -92,12 +64,16 @@ object DownloadManager {
             )
             start()
         }
-        notifyAllClients()
+        val status = getStatus()
+        eventDispatcher.enqueue(status)
+        eventDispatcher.notifyAllClients(status)
     }
 
     fun unqueue(chapterIndex: Int, mangaId: Int) {
         downloadQueue.removeIf { it.mangaId == mangaId && it.chapterIndex == chapterIndex }
-        notifyAllClients()
+        val status = getStatus()
+        eventDispatcher.dequeue(status)
+        eventDispatcher.notifyAllClients(status)
     }
 
     fun start() {
@@ -107,11 +83,11 @@ object DownloadManager {
         }
 
         if (downloader == null) {
-            downloader = Downloader(downloadQueue) { notifyAllClients() }
+            downloader = Downloader(downloadQueue) { eventDispatcher.notifyAllClients(getStatus()) }
             downloader!!.start()
         }
 
-        notifyAllClients()
+        eventDispatcher.notifyAllClients(getStatus())
     }
 
     fun stop() {
@@ -121,13 +97,13 @@ object DownloadManager {
             }
         }
         downloader = null
-        notifyAllClients()
+        eventDispatcher.notifyAllClients(getStatus())
     }
 
     fun clear() {
         stop()
         downloadQueue.clear()
-        notifyAllClients()
+        eventDispatcher.notifyAllClients(getStatus())
     }
 }
 

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/model/DownloadChapter.kt

@@ -7,6 +7,7 @@ package suwayomi.tachidesk.manga.impl.download.model
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+import suwayomi.tachidesk.event.EventEntity
 import suwayomi.tachidesk.manga.impl.download.model.DownloadState.Queued
 import suwayomi.tachidesk.manga.model.dataclass.ChapterDataClass
 import suwayomi.tachidesk.manga.model.dataclass.MangaDataClass
@@ -19,4 +20,4 @@ class DownloadChapter(
     var state: DownloadState = Queued,
     var progress: Float = 0f,
     var tries: Int = 0
-)
+) : EventEntity()

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/download/model/DownloadStatus.kt

@@ -1,5 +1,7 @@
 package suwayomi.tachidesk.manga.impl.download.model
 
+import suwayomi.tachidesk.event.EventEntity
+
 /*
  * Copyright (C) Contributors to the Suwayomi project
  *
@@ -10,4 +12,4 @@ package suwayomi.tachidesk.manga.impl.download.model
 data class DownloadStatus(
     val status: String,
     val queue: List<DownloadChapter>
-)
+) : EventEntity()