refactor getChapter (#268)

* refactor

* better naming

* fix copytight notice

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/chapter/ChapterForDownload.kt

@@ -0,0 +1,148 @@
+package suwayomi.tachidesk.manga.impl.chapter
+
+/*
+ * 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 eu.kanade.tachiyomi.source.model.Page
+import eu.kanade.tachiyomi.source.model.SChapter
+import org.jetbrains.exposed.sql.ResultRow
+import org.jetbrains.exposed.sql.and
+import org.jetbrains.exposed.sql.insert
+import org.jetbrains.exposed.sql.select
+import org.jetbrains.exposed.sql.transactions.transaction
+import org.jetbrains.exposed.sql.update
+import suwayomi.tachidesk.manga.impl.Page.getPageName
+import suwayomi.tachidesk.manga.impl.util.getChapterDir
+import suwayomi.tachidesk.manga.impl.util.lang.awaitSingle
+import suwayomi.tachidesk.manga.impl.util.source.GetCatalogueSource.getCatalogueSourceOrStub
+import suwayomi.tachidesk.manga.impl.util.storage.ImageResponse
+import suwayomi.tachidesk.manga.model.dataclass.ChapterDataClass
+import suwayomi.tachidesk.manga.model.table.ChapterTable
+import suwayomi.tachidesk.manga.model.table.MangaTable
+import suwayomi.tachidesk.manga.model.table.PageTable
+import suwayomi.tachidesk.manga.model.table.toDataClass
+
+
+suspend fun getChapterDownloadReady(chapterIndex: Int, mangaId: Int): ChapterDataClass {
+    val chapter = ChapterForDownload(chapterIndex, mangaId)
+
+    return chapter.asDownloadReady()
+}
+
+private class ChapterForDownload(
+    private val chapterIndex: Int,
+    private val mangaId: Int
+) {
+    suspend fun asDownloadReady(): ChapterDataClass {
+
+        if (isNotCompletelyDownloaded()) {
+            markAsNotDownloaded()
+
+            val pageList = fetchPageList()
+
+            updateDatabasePages(pageList)
+        }
+
+        return asDataClass()
+    }
+
+    private fun asDataClass() = ChapterTable.toDataClass(chapterEntry)
+
+    var chapterEntry: ResultRow = freshChapterEntry()
+
+    private fun freshChapterEntry() = transaction {
+        ChapterTable.select {
+            (ChapterTable.sourceOrder eq chapterIndex) and (ChapterTable.manga eq mangaId)
+        }.first()
+    }
+
+    private suspend fun fetchPageList(): List<Page> {
+        val mangaEntry = transaction { MangaTable.select { MangaTable.id eq mangaId }.first() }
+        val source = getCatalogueSourceOrStub(mangaEntry[MangaTable.sourceReference])
+
+        return source.fetchPageList(
+            SChapter.create().apply {
+                url = chapterEntry[ChapterTable.url]
+                name = chapterEntry[ChapterTable.name]
+            }
+        ).awaitSingle()
+    }
+
+    private fun markAsNotDownloaded() {
+        // chapter may be downloaded but if we are here, then images might be deleted and database data be false
+        transaction {
+            ChapterTable.update({ (ChapterTable.sourceOrder eq chapterIndex) and (ChapterTable.manga eq mangaId) }) {
+                it[isDownloaded] = false
+            }
+        }
+    }
+
+    private fun updateDatabasePages(pageList: List<Page>) {
+        val chapterId = chapterEntry[ChapterTable.id].value
+        val chapterIndex = chapterEntry[ChapterTable.sourceOrder]
+        val mangaId = chapterEntry[ChapterTable.manga].value
+
+        transaction {
+            pageList.forEach { page ->
+                val pageEntry = transaction {
+                    PageTable.select { (PageTable.chapter eq chapterId) and (PageTable.index eq page.index) }
+                        .firstOrNull()
+                }
+                if (pageEntry == null) {
+                    PageTable.insert {
+                        it[index] = page.index
+                        it[url] = page.url
+                        it[imageUrl] = page.imageUrl
+                        it[chapter] = chapterId
+                    }
+                } else {
+                    PageTable.update({ (PageTable.chapter eq chapterId) and (PageTable.index eq page.index) }) {
+                        it[url] = page.url
+                        it[imageUrl] = page.imageUrl
+                    }
+                }
+            }
+        }
+
+        updatePageCount(pageList, mangaId, chapterIndex)
+
+        // chapter was updated
+        chapterEntry = freshChapterEntry()
+    }
+
+    private fun updatePageCount(
+        pageList: List<Page>,
+        mangaId: Int,
+        chapterIndex: Int
+    ) {
+        val pageCount = pageList.count()
+
+        transaction {
+            ChapterTable.update({ (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder eq chapterIndex) }) {
+                it[ChapterTable.pageCount] = pageCount
+            }
+        }
+    }
+
+    private fun isNotCompletelyDownloaded(): Boolean {
+        return !(chapterEntry[ChapterTable.isDownloaded] && firstPageExists())
+    }
+
+    private fun firstPageExists(): Boolean {
+        val chapterId = chapterEntry[ChapterTable.id].value
+
+        val chapterDir = getChapterDir(mangaId, chapterId)
+
+        println(chapterDir)
+        println(getPageName(0))
+
+        return ImageResponse.findFileNameStartingWith(
+            chapterDir,
+            getPageName(0)
+        ) != null
+    }
+}