Add support for OPDS v1.2 to browse stored CBZ files (#1257)

* Añadiendo algunos cambios iniciales para probar OPDS

* Add suport to OPDS v1.2

* Added support for OPDS-PSE and reorganized controllers

* Rename chapterIndex to chapterId in the API and controller, and update descriptions in OPDS

* Refactor OPDS to use formatted timestamps and proxy thumbnail URLs

* Refactor OPDS to use formatted timestamps and proxy thumbnail URLs

* Update Manga API to download chapters cbz using only chapterId and improve chapter download query

* Optimize OPDS queries

* Update Manga API to download chapters cbz using only chapterId and improve chapter download query

* Optimize OPDS queries

* Use SourceDataClass to map sources and optimize thumbnail URL retrieval

* Kotlin lint errors in ChapterDownloadHelper and Opds

* Kotlin lint errors in ChapterDownloadHelper and Opds

server/src/main/kotlin/suwayomi/tachidesk/manga/MangaAPI.kt

@@ -82,6 +82,7 @@ object MangaAPI {
 
         path("chapter") {
             post("batch", MangaController.anyChapterBatch)
+            get("{chapterId}/download", MangaController.downloadChapter)
         }
 
         path("category") {

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

@@ -11,6 +11,7 @@ import io.javalin.http.HttpStatus
 import kotlinx.serialization.json.Json
 import suwayomi.tachidesk.manga.impl.CategoryManga
 import suwayomi.tachidesk.manga.impl.Chapter
+import suwayomi.tachidesk.manga.impl.ChapterDownloadHelper
 import suwayomi.tachidesk.manga.impl.Library
 import suwayomi.tachidesk.manga.impl.Manga
 import suwayomi.tachidesk.manga.impl.Page
@@ -424,4 +425,29 @@ object MangaController {
                 httpCode(HttpStatus.NOT_FOUND)
             },
         )
+
+    val downloadChapter =
+        handler(
+            pathParam<Int>("chapterId"),
+            documentWith = {
+                withOperation {
+                    summary("Download chapter as CBZ")
+                    description("Get the CBZ file of the specified chapter")
+                }
+            },
+            behaviorOf = { ctx, chapterId ->
+                ctx.future {
+                    future { ChapterDownloadHelper.getCbzDownload(chapterId) }
+                        .thenApply { (inputStream, contentType, fileName) ->
+                            ctx.header("Content-Type", contentType)
+                            ctx.header("Content-Disposition", "attachment; filename=\"$fileName\"")
+                            ctx.result(inputStream)
+                        }
+                }
+            },
+            withResults = {
+                httpCode(HttpStatus.OK)
+                httpCode(HttpStatus.NOT_FOUND)
+            },
+        )
 }

server/src/main/kotlin/suwayomi/tachidesk/manga/impl/ChapterDownloadHelper.kt

@@ -1,14 +1,19 @@
 package suwayomi.tachidesk.manga.impl
 
 import kotlinx.coroutines.CoroutineScope
+import org.jetbrains.exposed.sql.transactions.transaction
 import suwayomi.tachidesk.manga.impl.download.fileProvider.ChaptersFilesProvider
 import suwayomi.tachidesk.manga.impl.download.fileProvider.impl.ArchiveProvider
 import suwayomi.tachidesk.manga.impl.download.fileProvider.impl.FolderProvider
 import suwayomi.tachidesk.manga.impl.download.model.DownloadChapter
 import suwayomi.tachidesk.manga.impl.util.getChapterCbzPath
 import suwayomi.tachidesk.manga.impl.util.getChapterDownloadPath
+import suwayomi.tachidesk.manga.model.table.ChapterTable
+import suwayomi.tachidesk.manga.model.table.MangaTable
+import suwayomi.tachidesk.manga.model.table.toDataClass
 import suwayomi.tachidesk.server.serverConfig
 import java.io.File
+import java.io.IOException
 import java.io.InputStream
 
 object ChapterDownloadHelper {
@@ -42,4 +47,27 @@ object ChapterDownloadHelper {
         if (!chapterFolder.exists() && serverConfig.downloadAsCbz.value) return ArchiveProvider(mangaId, chapterId)
         return FolderProvider(mangaId, chapterId)
     }
+
+    suspend fun getCbzDownload(chapterId: Int): Triple<InputStream, String, String> {
+        val (chapterData, mangaTitle) =
+            transaction {
+                val row =
+                    (ChapterTable innerJoin MangaTable)
+                        .select(ChapterTable.columns + MangaTable.columns)
+                        .where { ChapterTable.id eq chapterId }
+                        .firstOrNull() ?: throw Exception("Chapter not found")
+                val chapter = ChapterTable.toDataClass(row)
+                val title = row[MangaTable.title]
+                Pair(chapter, title)
+            }
+
+        val provider = provider(chapterData.mangaId, chapterData.id)
+        return if (provider is ArchiveProvider) {
+            val cbzFile = File(getChapterCbzPath(chapterData.mangaId, chapterData.id))
+            val fileName = "$mangaTitle - [${chapterData.scanlator}] ${chapterData.name}.cbz"
+            Triple(cbzFile.inputStream(), "application/vnd.comicbook+zip", fileName)
+        } else {
+            throw IOException("Chapter not available as CBZ")
+        }
+    }
 }

server/src/main/kotlin/suwayomi/tachidesk/manga/model/dataclass/OpdsDataClass.kt

@@ -0,0 +1,117 @@
+package suwayomi.tachidesk.manga.model.dataclass
+
+import kotlinx.serialization.Serializable
+import nl.adaptivity.xmlutil.serialization.XmlElement
+import nl.adaptivity.xmlutil.serialization.XmlSerialName
+import nl.adaptivity.xmlutil.serialization.XmlValue
+
+@Serializable
+@XmlSerialName("feed", "", "")
+data class OpdsDataClass(
+    @XmlElement(true)
+    val id: String,
+    @XmlElement(true)
+    val title: String,
+    @XmlElement(true)
+    val icon: String? = null,
+    @XmlElement(true)
+    val updated: String, // ISO-8601
+    @XmlElement(true)
+    val author: Author? = null,
+    @XmlElement(true)
+    val links: List<Link>,
+    @XmlElement(true)
+    val entries: List<Entry>,
+    @XmlSerialName("xmlns", "", "")
+    val xmlns: String = "http://www.w3.org/2005/Atom",
+    @XmlSerialName("xmlns:xsd", "", "")
+    val xmlnsXsd: String = "http://www.w3.org/2001/XMLSchema",
+    @XmlSerialName("xmlns:xsi", "", "")
+    val xmlnsXsi: String = "http://www.w3.org/2001/XMLSchema-instance",
+    @XmlSerialName("xmlns:opds", "", "")
+    val xmlnsOpds: String = "http://opds-spec.org/2010/catalog",
+    @XmlSerialName("xmlns:dcterms", "", "")
+    val xmlnsDublinCore: String = "http://purl.org/dc/terms/",
+    @XmlSerialName("xmlns:pse", "", "")
+    val xmlnsPse: String = "http://vaemendis.net/opds-pse/ns",
+    @XmlElement(true)
+    @XmlSerialName("totalResults", "http://a9.com/-/spec/opensearch/1.1/", "")
+    val totalResults: Long? = null,
+    @XmlElement(true)
+    @XmlSerialName("itemsPerPage", "http://a9.com/-/spec/opensearch/1.1/", "")
+    val itemsPerPage: Int? = null,
+    @XmlElement(true)
+    @XmlSerialName("startIndex", "http://a9.com/-/spec/opensearch/1.1/", "")
+    val startIndex: Int? = null,
+) {
+    @Serializable
+    @XmlSerialName("author", "", "")
+    data class Author(
+        @XmlElement(true)
+        val name: String,
+        @XmlElement(true)
+        val uri: String? = null,
+        @XmlElement(true)
+        val email: String? = null,
+    )
+
+    @Serializable
+    @XmlSerialName("link", "", "")
+    data class Link(
+        val rel: String,
+        val href: String,
+        val type: String? = null,
+        val title: String? = null,
+        @XmlSerialName("pse:count", "", "")
+        val pseCount: Int? = null,
+    )
+
+    @Serializable
+    @XmlSerialName("entry", "", "")
+    data class Entry(
+        @XmlElement(true)
+        val id: String,
+        @XmlElement(true)
+        val title: String,
+        @XmlElement(true)
+        val updated: String,
+        @XmlElement(true)
+        val summary: Summary? = null,
+        @XmlElement(true)
+        val content: Content? = null,
+        @XmlElement(true)
+        val link: List<Link>,
+        @XmlElement(true)
+        val authors: List<Author>? = null,
+        @XmlElement(true)
+        val categories: List<Category>? = null,
+        @XmlElement(true)
+        @XmlSerialName("language", "http://purl.org/dc/terms/", "dc")
+        val extent: String? = null,
+        @XmlElement(true)
+        @XmlSerialName("format", "http://purl.org/dc/terms/format", "dc")
+        val format: String? = null,
+    )
+
+    @Serializable
+    @XmlSerialName("summary", "", "")
+    data class Summary(
+        val type: String = "text",
+        @XmlValue(true) val value: String = "",
+    )
+
+    @Serializable
+    @XmlSerialName("content", "", "")
+    data class Content(
+        val type: String = "text",
+        @XmlValue(true) val value: String = "",
+    )
+
+    @Serializable
+    @XmlSerialName("category", "", "")
+    data class Category(
+        val scheme: String? = null,
+        val term: String,
+        val label: String,
+    )
+}

server/src/main/kotlin/suwayomi/tachidesk/opds/OpdsAPI.kt

@@ -0,0 +1,22 @@
+package suwayomi.tachidesk.opds
+
+/*
+ * 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.apibuilder.ApiBuilder.get
+import io.javalin.apibuilder.ApiBuilder.path
+import suwayomi.tachidesk.opds.controller.OpdsController
+
+object OpdsAPI {
+    fun defineEndpoints() {
+        path("opds/v1.2") {
+            get(OpdsController.rootFeed)
+            get("source/{sourceId}", OpdsController.sourceFeed)
+            get("manga/{mangaId}", OpdsController.mangaFeed)
+        }
+    }
+}

server/src/main/kotlin/suwayomi/tachidesk/opds/controller/OpdsController.kt

@@ -0,0 +1,86 @@
+package suwayomi.tachidesk.opds.controller
+
+import io.javalin.http.HttpStatus
+import suwayomi.tachidesk.opds.impl.Opds
+import suwayomi.tachidesk.server.JavalinSetup.future
+import suwayomi.tachidesk.server.util.handler
+import suwayomi.tachidesk.server.util.pathParam
+import suwayomi.tachidesk.server.util.queryParam
+import suwayomi.tachidesk.server.util.withOperation
+
+object OpdsController {
+    private const val OPDS_MIME = "application/xml;profile=opds-catalog;charset=UTF-8"
+    private const val BASE_URL = "/api/opds/v1.2"
+
+    val rootFeed =
+        handler(
+            documentWith = {
+                withOperation {
+                    summary("OPDS Root Feed")
+                    description("OPDS feed for the list of available manga sources")
+                }
+            },
+            behaviorOf = { ctx ->
+                ctx.future {
+                    future {
+                        Opds.getRootFeed(BASE_URL)
+                    }.thenApply { xml ->
+                        ctx.contentType(OPDS_MIME).result(xml)
+                    }
+                }
+            },
+            withResults = {
+                httpCode(HttpStatus.OK)
+            },
+        )
+
+    val sourceFeed =
+        handler(
+            pathParam<Long>("sourceId"),
+            queryParam<Int?>("pageNumber"),
+            documentWith = {
+                withOperation {
+                    summary("OPDS Source Feed")
+                    description("OPDS feed for a specific manga source")
+                }
+            },
+            behaviorOf = { ctx, sourceId, pageNumber ->
+                ctx.future {
+                    future {
+                        Opds.getSourceFeed(sourceId, BASE_URL, pageNumber ?: 1)
+                    }.thenApply { xml ->
+                        ctx.contentType(OPDS_MIME).result(xml)
+                    }
+                }
+            },
+            withResults = {
+                httpCode(HttpStatus.OK)
+                httpCode(HttpStatus.NOT_FOUND)
+            },
+        )
+
+    val mangaFeed =
+        handler(
+            pathParam<Int>("mangaId"),
+            queryParam<Int?>("pageNumber"),
+            documentWith = {
+                withOperation {
+                    summary("OPDS Manga Feed")
+                    description("OPDS feed for chapters of a specific manga")
+                }
+            },
+            behaviorOf = { ctx, mangaId, pageNumber ->
+                ctx.future {
+                    future {
+                        Opds.getMangaFeed(mangaId, BASE_URL, pageNumber ?: 1)
+                    }.thenApply { xml ->
+                        ctx.contentType(OPDS_MIME).result(xml)
+                    }
+                }
+            },
+            withResults = {
+                httpCode(HttpStatus.OK)
+                httpCode(HttpStatus.NOT_FOUND)
+            },
+        )
+}

server/src/main/kotlin/suwayomi/tachidesk/opds/impl/Opds.kt

@@ -0,0 +1,350 @@
+package suwayomi.tachidesk.opds.impl
+
+import nl.adaptivity.xmlutil.XmlDeclMode
+import nl.adaptivity.xmlutil.core.XmlVersion
+import nl.adaptivity.xmlutil.serialization.XML
+import org.jetbrains.exposed.sql.JoinType
+import org.jetbrains.exposed.sql.SortOrder
+import org.jetbrains.exposed.sql.and
+import org.jetbrains.exposed.sql.selectAll
+import org.jetbrains.exposed.sql.transactions.transaction
+import suwayomi.tachidesk.manga.impl.MangaList.proxyThumbnailUrl
+import suwayomi.tachidesk.manga.impl.extension.Extension.getExtensionIconUrl
+import suwayomi.tachidesk.manga.impl.util.getChapterCbzPath
+import suwayomi.tachidesk.manga.model.dataclass.ChapterDataClass
+import suwayomi.tachidesk.manga.model.dataclass.MangaDataClass
+import suwayomi.tachidesk.manga.model.dataclass.OpdsDataClass
+import suwayomi.tachidesk.manga.model.dataclass.SourceDataClass
+import suwayomi.tachidesk.manga.model.table.ChapterTable
+import suwayomi.tachidesk.manga.model.table.ExtensionTable
+import suwayomi.tachidesk.manga.model.table.MangaTable
+import suwayomi.tachidesk.manga.model.table.SourceTable
+import suwayomi.tachidesk.manga.model.table.toDataClass
+import java.io.File
+import java.time.Instant
+import java.time.ZoneOffset
+import java.time.format.DateTimeFormatter
+
+object Opds {
+    private const val ITEMS_PER_PAGE = 20
+
+    fun getRootFeed(baseUrl: String): String {
+        val formattedNow = opdsDateFormatter.format(Instant.now())
+        val sources =
+            transaction {
+                SourceTable
+                    .join(MangaTable, JoinType.INNER) {
+                        MangaTable.sourceReference eq SourceTable.id
+                    }.join(ChapterTable, JoinType.INNER) {
+                        ChapterTable.manga eq MangaTable.id
+                    }.selectAll()
+                    .where { ChapterTable.isDownloaded eq true }
+                    .orderBy(SourceTable.name to SortOrder.ASC)
+                    .distinct()
+                    .map {
+                        SourceDataClass(
+                            id = it[SourceTable.id].value.toString(),
+                            name = it[SourceTable.name],
+                            lang = it[SourceTable.lang],
+                            iconUrl = "",
+                            supportsLatest = false,
+                            isConfigurable = false,
+                            isNsfw = it[SourceTable.isNsfw],
+                            displayName = "",
+                        )
+                    }
+            }
+
+        return serialize(
+            OpdsDataClass(
+                id = "opds",
+                title = "Suwayomi OPDS Catalog",
+                icon = "/favicon",
+                updated = formattedNow,
+                author = OpdsDataClass.Author("Suwayomi", "https://suwayomi.org/"),
+                links =
+                    listOf(
+                        OpdsDataClass.Link(
+                            rel = "self",
+                            href = baseUrl,
+                            type = "application/atom+xml;profile=opds-catalog;kind=navigation",
+                        ),
+                        OpdsDataClass.Link(
+                            rel = "start",
+                            href = baseUrl,
+                            type = "application/atom+xml;profile=opds-catalog;kind=navigation",
+                        ),
+                    ),
+                entries =
+                    sources.map {
+                        OpdsDataClass.Entry(
+                            updated = formattedNow,
+                            id = it.id,
+                            title = it.name,
+                            link =
+                                listOf(
+                                    OpdsDataClass.Link(
+                                        rel = "subsection",
+                                        href = "$baseUrl/source/${it.id}",
+                                        type = "application/atom+xml;profile=opds-catalog;kind=navigation",
+                                    ),
+                                ),
+                        )
+                    },
+            ),
+        )
+    }
+
+    fun getSourceFeed(
+        sourceId: Long,
+        baseUrl: String,
+        pageNum: Int = 1,
+    ): String {
+        val formattedNow = opdsDateFormatter.format(Instant.now())
+        val (mangas, totalCount, sourceRow) =
+            transaction {
+                val sourceRow =
+                    SourceTable
+                        .join(ExtensionTable, JoinType.INNER, onColumn = SourceTable.extension, otherColumn = ExtensionTable.id)
+                        .select(SourceTable.name, ExtensionTable.apkName)
+                        .where { SourceTable.id eq sourceId }
+                        .firstOrNull()
+
+                val query =
+                    MangaTable
+                        .join(ChapterTable, JoinType.INNER, onColumn = MangaTable.id, otherColumn = ChapterTable.manga)
+                        .select(MangaTable.columns)
+                        .where {
+                            (MangaTable.sourceReference eq sourceId) and (ChapterTable.isDownloaded eq true)
+                        }.groupBy(MangaTable.id)
+                        .orderBy(MangaTable.title to SortOrder.ASC)
+
+                val totalCount = query.count()
+                val paginatedResults =
+                    query
+                        .limit(ITEMS_PER_PAGE)
+                        .offset(((pageNum - 1) * ITEMS_PER_PAGE).toLong())
+                        .map { MangaTable.toDataClass(it) }
+
+                Triple(paginatedResults, totalCount, sourceRow)
+            }
+
+        val sourceName = sourceRow?.get(SourceTable.name) ?: sourceId.toString()
+        val iconUrl = sourceRow?.get(ExtensionTable.apkName)?.let { getExtensionIconUrl(it) }
+
+        return serialize(
+            OpdsDataClass(
+                id = "source/$sourceId",
+                title = sourceName,
+                updated = formattedNow,
+                totalResults = totalCount,
+                itemsPerPage = ITEMS_PER_PAGE,
+                startIndex = (pageNum - 1) * ITEMS_PER_PAGE + 1,
+                icon = iconUrl,
+                author = OpdsDataClass.Author("Suwayomi", "https://suwayomi.org/"),
+                links =
+                    listOfNotNull(
+                        OpdsDataClass.Link(
+                            rel = "self",
+                            href = "$baseUrl/source/$sourceId?pageNumber=$pageNum",
+                            type = "application/atom+xml;profile=opds-catalog;kind=acquisition",
+                        ),
+                        OpdsDataClass.Link(
+                            rel = "start",
+                            href = baseUrl,
+                            type = "application/atom+xml;profile=opds-catalog;kind=navigation",
+                        ),
+                    ),
+                entries =
+                    mangas.map { manga ->
+                        OpdsDataClass.Entry(
+                            id = "manga/${manga.id}",
+                            title = manga.title,
+                            updated = formattedNow,
+                            authors = manga.author?.let { listOf(OpdsDataClass.Author(name = it)) } ?: emptyList(),
+                            categories =
+                                manga.genre.map { genre ->
+                                    OpdsDataClass.Category(term = "", label = genre)
+                                },
+                            summary = manga.description?.let { OpdsDataClass.Summary(value = it) },
+                            link =
+                                listOfNotNull(
+                                    OpdsDataClass.Link(
+                                        rel = "subsection",
+                                        href = "$baseUrl/manga/${manga.id}",
+                                        type = "application/atom+xml;profile=opds-catalog;kind=acquisition",
+                                    ),
+                                    OpdsDataClass.Link(
+                                        rel = "http://opds-spec.org/image",
+                                        href = proxyThumbnailUrl(manga.id),
+                                        type = "image/jpeg",
+                                    ),
+                                ),
+                            content =
+                                OpdsDataClass.Content(
+                                    type = "text",
+                                    value = manga.status,
+                                ),
+                        )
+                    },
+            ),
+        )
+    }
+
+    suspend fun getMangaFeed(
+        mangaId: Int,
+        baseUrl: String,
+        pageNum: Int = 1,
+    ): String {
+        val formattedNow = opdsDateFormatter.format(Instant.now())
+        val (manga, chapters, totalCount) =
+            transaction {
+                val mangaEntry =
+                    MangaTable
+                        .selectAll()
+                        .where { MangaTable.id eq mangaId }
+                        .first()
+                val mangaData = MangaTable.toDataClass(mangaEntry)
+                val chaptersQuery =
+                    ChapterTable
+                        .selectAll()
+                        .where {
+                            (ChapterTable.manga eq mangaId) and
+                                (ChapterTable.isDownloaded eq true) and
+                                (ChapterTable.pageCount greater 0)
+                        }.orderBy(ChapterTable.sourceOrder to SortOrder.DESC)
+                val total = chaptersQuery.count()
+                val chaptersData =
+                    chaptersQuery
+                        .limit(ITEMS_PER_PAGE)
+                        .offset(((pageNum - 1) * ITEMS_PER_PAGE).toLong())
+                        .map { ChapterTable.toDataClass(it) }
+                Triple(mangaData, chaptersData, total)
+            }
+
+        return serialize(
+            OpdsDataClass(
+                id = "manga/$mangaId",
+                title = manga.title,
+                updated = formattedNow,
+                icon = manga.thumbnailUrl,
+                author =
+                    OpdsDataClass.Author(
+                        name = "Suwayomi",
+                        uri = "https://suwayomi.org/",
+                    ),
+                totalResults = totalCount,
+                itemsPerPage = ITEMS_PER_PAGE,
+                startIndex = (pageNum - 1) * ITEMS_PER_PAGE + 1,
+                links =
+                    listOfNotNull(
+                        OpdsDataClass.Link(
+                            rel = "self",
+                            href = "$baseUrl/manga/$mangaId?pageNumber=$pageNum",
+                            type = "application/atom+xml;profile=opds-catalog;kind=acquisition",
+                        ),
+                        OpdsDataClass.Link(
+                            rel = "start",
+                            href = baseUrl,
+                            type = "application/atom+xml;profile=opds-catalog;kind=navigation",
+                        ),
+                        manga.thumbnailUrl?.let { url ->
+                            OpdsDataClass.Link(
+                                rel = "http://opds-spec.org/image",
+                                href = url,
+                                type = "image/jpeg",
+                            )
+                        },
+                        manga.thumbnailUrl?.let { url ->
+                            OpdsDataClass.Link(
+                                rel = "http://opds-spec.org/image/thumbnail",
+                                href = url,
+                                type = "image/jpeg",
+                            )
+                        },
+                        // OpdsDataClass.Link(
+                        //     rel = "search",
+                        //     type = "application/opensearchdescription+xml",
+                        //     href = "$baseUrl/search"
+                        // ),
+                    ),
+                entries =
+                    chapters.map { chapter ->
+                        createChapterEntry(chapter, manga)
+                    },
+            ),
+        )
+    }
+
+    private fun createChapterEntry(
+        chapter: ChapterDataClass,
+        manga: MangaDataClass,
+    ): OpdsDataClass.Entry {
+        val cbzFile = File(getChapterCbzPath(manga.id, chapter.id))
+        val isCbzAvailable = cbzFile.exists()
+
+        return OpdsDataClass.Entry(
+            id = "chapter/${chapter.id}",
+            title = chapter.name,
+            updated = opdsDateFormatter.format(Instant.ofEpochMilli(chapter.uploadDate)),
+            content = OpdsDataClass.Content(value = "${chapter.scanlator}"),
+            summary = manga.description?.let { OpdsDataClass.Summary(value = it) },
+            extent =
+                cbzFile.takeIf { it.exists() }?.let {
+                    formatFileSize(it.length())
+                },
+            format = cbzFile.takeIf { it.exists() }?.let { "CBZ" },
+            authors =
+                listOfNotNull(
+                    manga.author?.let { OpdsDataClass.Author(name = it) },
+                    manga.artist?.takeIf { it != manga.author }?.let { OpdsDataClass.Author(name = it) },
+                ),
+            link =
+                listOfNotNull(
+                    if (isCbzAvailable) {
+                        OpdsDataClass.Link(
+                            rel = "http://opds-spec.org/acquisition/open-access",
+                            href = "/api/v1/chapter/${chapter.id}/download",
+                            type = "application/vnd.comicbook+zip",
+                        )
+                    } else {
+                        OpdsDataClass.Link(
+                            rel = "http://vaemendis.net/opds-pse/stream",
+                            href = "/api/v1/manga/${manga.id}/chapter/${chapter.index}/page/{pageNumber}",
+                            type = "image/jpeg",
+                            pseCount = chapter.pageCount,
+                        )
+                    },
+                    OpdsDataClass.Link(
+                        rel = "http://opds-spec.org/image",
+                        href = "/api/v1/manga/${manga.id}/chapter/${chapter.index}/page/0",
+                        type = "image/jpeg",
+                    ),
+                ),
+        )
+    }
+
+    private val opdsDateFormatter =
+        DateTimeFormatter
+            .ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'")
+            .withZone(ZoneOffset.UTC)
+
+    private fun formatFileSize(size: Long): String =
+        when {
+            size >= 1_000_000 -> "%.2f MB".format(size / 1_000_000.0)
+            size >= 1_000 -> "%.2f KB".format(size / 1_000.0)
+            else -> "$size bytes"
+        }
+
+    private val xmlFormat =
+        XML {
+            indent = 2
+            xmlVersion = XmlVersion.XML10
+            xmlDeclMode = XmlDeclMode.Charset
+            defaultPolicy {
+                autoPolymorphic = true
+            }
+        }
+
+    private fun serialize(feed: OpdsDataClass): String = xmlFormat.encodeToString(OpdsDataClass.serializer(), feed)
+}

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

@@ -22,6 +22,7 @@ import org.eclipse.jetty.server.ServerConnector
 import suwayomi.tachidesk.global.GlobalAPI
 import suwayomi.tachidesk.graphql.GraphQL
 import suwayomi.tachidesk.manga.MangaAPI
+import suwayomi.tachidesk.opds.OpdsAPI
 import suwayomi.tachidesk.server.util.Browser
 import suwayomi.tachidesk.server.util.WebInterfaceManager
 import uy.kohesive.injekt.injectLazy
@@ -102,6 +103,8 @@ object JavalinSetup {
                             GlobalAPI.defineEndpoints()
                             MangaAPI.defineEndpoints()
                         }
+
+                        OpdsAPI.defineEndpoints()
                         GraphQL.defineEndpoints()
                     }
                 }