downloader backend done

server/src/main/kotlin/suwayomi/tachidesk/TachideskAPI.kt

@@ -33,6 +33,7 @@ import suwayomi.tachidesk.impl.Source.getSourceList
 import suwayomi.tachidesk.impl.backup.BackupFlags
 import suwayomi.tachidesk.impl.backup.legacy.LegacyBackupExport.createLegacyBackup
 import suwayomi.tachidesk.impl.backup.legacy.LegacyBackupImport.restoreLegacyBackup
+import suwayomi.tachidesk.impl.download.DownloadManager
 import suwayomi.tachidesk.impl.extension.Extension.getExtensionIcon
 import suwayomi.tachidesk.impl.extension.Extension.installExtension
 import suwayomi.tachidesk.impl.extension.Extension.uninstallExtension
@@ -383,15 +384,56 @@ object TachideskAPI {
         // Download queue stats
         app.ws("/api/v1/downloads") { ws ->
             ws.onConnect { ctx ->
-                // TODO: send current stat
+                DownloadManager.addClient(ctx)
-                // TODO: add to downlad subscribers
+                DownloadManager.notifyClient(ctx)
             }
-            ws.onMessage {
+            ws.onMessage { ctx ->
-                // TODO: send current stat
+                DownloadManager.handleRequest(ctx)
             }
             ws.onClose { ctx ->
-                // TODO: remove from subscribers
+                DownloadManager.removeClient(ctx)
             }
         }
+
+        // Start the downloader
+        app.get("/api/v1/downloads/start") { ctx ->
+            DownloadManager.start()
+
+            ctx.status(200)
+        }
+
+        // Stop the downloader
+        app.get("/api/v1/downloads/stop") { ctx ->
+            DownloadManager.stop()
+
+            ctx.status(200)
+        }
+
+        // clear download queue
+        app.get("/api/v1/downloads/clear") { ctx ->
+            DownloadManager.clear()
+
+            ctx.status(200)
+        }
+
+        // Queue chapter for download
+        app.get("/api/v1/download/:mangaId/chapter/:chapterIndex") { ctx ->
+            val chapterIndex = ctx.pathParam("chapterIndex").toInt()
+            val mangaId = ctx.pathParam("mangaId").toInt()
+
+            DownloadManager.enqueue(chapterIndex, mangaId)
+
+            ctx.status(200)
+        }
+
+        // delete chapter from download queue
+        app.delete("/api/v1/download/:mangaId/chapter/:chapterIndex") { ctx ->
+            val chapterIndex = ctx.pathParam("chapterIndex").toInt()
+            val mangaId = ctx.pathParam("mangaId").toInt()
+
+            DownloadManager.unqueue(chapterIndex, mangaId)
+
+            ctx.status(200)
+        }
     }
 }

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

@@ -0,0 +1,124 @@
+package suwayomi.tachidesk.impl.download
+
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * 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 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.impl.download.model.DownloadChapter
+import suwayomi.tachidesk.impl.download.model.DownloadState.Downloading
+import suwayomi.tachidesk.impl.download.model.DownloadStatus
+import suwayomi.tachidesk.model.table.ChapterTable
+import suwayomi.tachidesk.model.table.toDataClass
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.CopyOnWriteArrayList
+
+object DownloadManager {
+    private val clients = ConcurrentHashMap<String, WsContext>()
+    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)
+        }
+    }
+
+    private fun getStatus(): DownloadStatus {
+        return DownloadStatus(
+            if (downloader == null ||
+                downloadQueue.none { it.state == Downloading }
+            ) "Stopped" else "Started",
+            downloadQueue
+        )
+    }
+
+    fun enqueue(chapterIndex: Int, mangaId: Int) {
+        if (downloadQueue.none { it.mangaId == mangaId && it.chapterIndex == chapterIndex }) {
+            downloadQueue.add(
+                DownloadChapter(
+                    chapterIndex,
+                    mangaId,
+                    chapter = ChapterTable.toDataClass(
+                        transaction {
+                            ChapterTable.select { (ChapterTable.manga eq mangaId) and (ChapterTable.chapterIndex eq chapterIndex) }
+                                .first()
+                        }
+                    )
+                )
+            )
+        }
+        notifyAllClients()
+    }
+
+    fun unqueue(chapterIndex: Int, mangaId: Int) {
+        downloadQueue.removeIf { it.mangaId == mangaId && it.chapterIndex == chapterIndex }
+        notifyAllClients()
+    }
+
+    fun start() {
+        if (downloader == null) {
+            downloader = Downloader(downloadQueue) { notifyAllClients() }
+            downloader!!.start()
+        }
+        notifyAllClients()
+    }
+
+    fun stop() {
+        downloader?.let {
+            synchronized(it.shouldStop) {
+                it.shouldStop = true
+            }
+        }
+        downloader = null
+        notifyAllClients()
+    }
+
+    fun clear() {
+        stop()
+        downloadQueue.clear()
+        notifyAllClients()
+    }
+}
+
+enum class DownloaderState(val state: Int) {
+    Stopped(0),
+    Running(1),
+    Paused(2),
+}

server/src/main/kotlin/suwayomi/tachidesk/impl/download/Downloader.kt

@@ -1,8 +1,5 @@
 package suwayomi.tachidesk.impl.download
 
-import org.jetbrains.exposed.sql.ResultRow
-import java.util.concurrent.LinkedBlockingQueue
-
 /*
  * Copyright (C) Contributors to the Suwayomi project
  *
@@ -10,19 +7,59 @@ import java.util.concurrent.LinkedBlockingQueue
  * 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/. */
 
-data class Download(
+import kotlinx.coroutines.runBlocking
-    val chapter: ResultRow,
+import suwayomi.tachidesk.impl.Chapter.getChapter
-)
+import suwayomi.tachidesk.impl.Page.getPageImage
+import suwayomi.tachidesk.impl.download.model.DownloadChapter
+import suwayomi.tachidesk.impl.download.model.DownloadState.Downloading
+import suwayomi.tachidesk.impl.download.model.DownloadState.Error
+import suwayomi.tachidesk.impl.download.model.DownloadState.Finished
+import suwayomi.tachidesk.impl.download.model.DownloadState.Queued
+import java.util.concurrent.CopyOnWriteArrayList
 
-private val downloadQueue = LinkedBlockingQueue<Download>()
+class Downloader(private val downloadQueue: CopyOnWriteArrayList<DownloadChapter>, val notifier: () -> Unit) : Thread() {
+    var shouldStop: Boolean = false
 
-class Downloader {
+    class DownloadShouldStopException : Exception()
 
-    fun start() {
+    fun step() {
-        TODO()
+        notifier()
+        synchronized(shouldStop) {
+            if (shouldStop) throw DownloadShouldStopException()
+        }
     }
 
-    fun stop() {
+    override fun run() {
-        TODO()
+        do {
+            val download = downloadQueue.firstOrNull { it.state == Queued } ?: break
+
+            try {
+                download.state = Downloading
+                step()
+
+                download.chapter = runBlocking { getChapter(download.chapterIndex, download.mangaId) }
+                step()
+
+                val pageCount = download.chapter!!.pageCount!!
+                for (pageNum in 0 until pageCount) {
+                    runBlocking { getPageImage(download.mangaId, download.chapterIndex, pageNum) }
+                    // TODO: retry on error with 2,4,8 seconds of wait
+                    // TODO: download multiple pages at once, possible solution: rx observer's strategy is used in Tachiyomi
+                    download.progress = (pageNum + 1).toFloat() / pageCount
+                    step()
+                }
+                download.state = Finished
+                step()
+            } catch (e: DownloadShouldStopException) {
+                println("Downloader was stopped")
+                downloadQueue.filter { it.state == Downloading }.forEach { it.state = Queued }
+            } catch (e: Exception) {
+                println("Downloader faced an exception")
+                downloadQueue.filter { it.state == Downloading }.forEach { it.state = Error }
+                e.printStackTrace()
+            } finally {
+                notifier()
+            }
+        } while (!shouldStop)
     }
 }

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

@@ -0,0 +1,18 @@
+package suwayomi.tachidesk.impl.download.model
+
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * 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.model.dataclass.ChapterDataClass
+
+class DownloadChapter(
+    val chapterIndex: Int,
+    val mangaId: Int,
+    var state: DownloadState = DownloadState.Queued,
+    var progress: Float = 0f,
+    var chapter: ChapterDataClass? = null,
+)

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

@@ -0,0 +1,15 @@
+package suwayomi.tachidesk.impl.download.model
+
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+enum class DownloadState(val state: Int) {
+    Queued(0),
+    Downloading(1),
+    Finished(2),
+    Error(3),
+}

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

@@ -0,0 +1,13 @@
+package suwayomi.tachidesk.impl.download.model
+
+/*
+ * Copyright (C) Contributors to the Suwayomi project
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+data class DownloadStatus(
+    val status: String,
+    val queue: List<DownloadChapter>,
+)