package suwayomi.tachidesk.manga.impl

/*
 * 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.SChapter
import eu.kanade.tachiyomi.source.model.SManga
import eu.kanade.tachiyomi.source.online.HttpSource
import eu.kanade.tachiyomi.util.chapter.ChapterRecognition
import kotlinx.serialization.Serializable
import mu.KotlinLogging
import org.jetbrains.exposed.dao.id.EntityID
import org.jetbrains.exposed.sql.Op
import org.jetbrains.exposed.sql.ResultRow
import org.jetbrains.exposed.sql.SortOrder
import org.jetbrains.exposed.sql.SortOrder.ASC
import org.jetbrains.exposed.sql.SqlExpressionBuilder.eq
import org.jetbrains.exposed.sql.and
import org.jetbrains.exposed.sql.deleteWhere
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.Manga.getManga
import suwayomi.tachidesk.manga.impl.download.DownloadManager
import suwayomi.tachidesk.manga.impl.download.DownloadManager.EnqueueInput
import suwayomi.tachidesk.manga.impl.util.source.GetCatalogueSource.getCatalogueSourceOrStub
import suwayomi.tachidesk.manga.model.dataclass.ChapterDataClass
import suwayomi.tachidesk.manga.model.dataclass.MangaChapterDataClass
import suwayomi.tachidesk.manga.model.dataclass.PaginatedList
import suwayomi.tachidesk.manga.model.dataclass.paginatedFrom
import suwayomi.tachidesk.manga.model.table.ChapterMetaTable
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
import suwayomi.tachidesk.server.serverConfig
import java.time.Instant

object Chapter {
    private val logger = KotlinLogging.logger { }

    /** get chapter list when showing a manga */
    suspend fun getChapterList(
        mangaId: Int,
        onlineFetch: Boolean = false,
    ): List<ChapterDataClass> {
        return if (onlineFetch) {
            getSourceChapters(mangaId)
        } else {
            transaction {
                ChapterTable.select { ChapterTable.manga eq mangaId }
                    .orderBy(ChapterTable.sourceOrder to SortOrder.DESC)
                    .map {
                        ChapterTable.toDataClass(it)
                    }
            }.ifEmpty {
                getSourceChapters(mangaId)
            }
        }
    }

    fun getCountOfMangaChapters(mangaId: Int): Int {
        return transaction { ChapterTable.select { ChapterTable.manga eq mangaId }.count().toInt() }
    }

    private suspend fun getSourceChapters(mangaId: Int): List<ChapterDataClass> {
        val chapterList = fetchChapterList(mangaId)

        val dbChapterMap =
            transaction {
                ChapterTable.select { ChapterTable.manga eq mangaId }
                    .associateBy({ it[ChapterTable.url] }, { it })
            }

        val chapterIds = chapterList.map { dbChapterMap.getValue(it.url)[ChapterTable.id] }
        val chapterMetas = getChaptersMetaMaps(chapterIds)

        return chapterList.mapIndexed { index, it ->

            val dbChapter = dbChapterMap.getValue(it.url)

            ChapterDataClass(
                id = dbChapter[ChapterTable.id].value,
                url = it.url,
                name = it.name,
                uploadDate = it.date_upload,
                chapterNumber = it.chapter_number,
                scanlator = it.scanlator,
                mangaId = mangaId,
                read = dbChapter[ChapterTable.isRead],
                bookmarked = dbChapter[ChapterTable.isBookmarked],
                lastPageRead = dbChapter[ChapterTable.lastPageRead],
                lastReadAt = dbChapter[ChapterTable.lastReadAt],
                index = chapterList.size - index,
                fetchedAt = dbChapter[ChapterTable.fetchedAt],
                realUrl = dbChapter[ChapterTable.realUrl],
                downloaded = dbChapter[ChapterTable.isDownloaded],
                pageCount = dbChapter[ChapterTable.pageCount],
                chapterCount = chapterList.size,
                meta = chapterMetas.getValue(dbChapter[ChapterTable.id]),
            )
        }
    }

    suspend fun fetchChapterList(mangaId: Int): List<SChapter> {
        val manga = getManga(mangaId)
        val source = getCatalogueSourceOrStub(manga.sourceId.toLong())

        val sManga =
            SManga.create().apply {
                title = manga.title
                url = manga.url
            }

        val numberOfCurrentChapters = getCountOfMangaChapters(mangaId)
        val chapterList = source.getChapterList(sManga)

        // Recognize number for new chapters.
        chapterList.forEach { chapter ->
            (source as? HttpSource)?.prepareNewChapter(chapter, sManga)
            val chapterNumber = ChapterRecognition.parseChapterNumber(manga.title, chapter.name, chapter.chapter_number.toDouble())
            chapter.chapter_number = chapterNumber.toFloat()
        }

        var now = Instant.now().epochSecond

        transaction {
            chapterList.reversed().forEachIndexed { index, fetchedChapter ->
                val chapterEntry = ChapterTable.select { ChapterTable.url eq fetchedChapter.url }.firstOrNull()
                if (chapterEntry == null) {
                    ChapterTable.insert {
                        it[url] = fetchedChapter.url
                        it[name] = fetchedChapter.name
                        it[date_upload] = fetchedChapter.date_upload
                        it[chapter_number] = fetchedChapter.chapter_number
                        it[scanlator] = fetchedChapter.scanlator

                        it[sourceOrder] = index + 1
                        it[fetchedAt] = now++
                        it[ChapterTable.manga] = mangaId

                        it[realUrl] =
                            runCatching {
                                (source as? HttpSource)?.getChapterUrl(fetchedChapter)
                            }.getOrNull()
                    }
                } else {
                    ChapterTable.update({ ChapterTable.url eq fetchedChapter.url }) {
                        it[name] = fetchedChapter.name
                        it[date_upload] = fetchedChapter.date_upload
                        it[chapter_number] = fetchedChapter.chapter_number
                        it[scanlator] = fetchedChapter.scanlator

                        it[sourceOrder] = index + 1
                        it[ChapterTable.manga] = mangaId

                        it[realUrl] =
                            runCatching {
                                (source as? HttpSource)?.getChapterUrl(fetchedChapter)
                            }.getOrNull()
                    }
                }
            }

            MangaTable.update({ MangaTable.id eq mangaId }) {
                it[MangaTable.chaptersLastFetchedAt] = Instant.now().epochSecond
            }
        }

        val newChapters =
            transaction {
                ChapterTable.select { ChapterTable.manga eq mangaId }
                    .orderBy(ChapterTable.sourceOrder to SortOrder.DESC).toList()
            }

        // clear any orphaned/duplicate chapters that are in the db but not in `chapterList`
        val dbChapterCount = newChapters.count()
        if (dbChapterCount > chapterList.size) { // we got some clean up due
            val dbChapterList =
                transaction {
                    ChapterTable.select { ChapterTable.manga eq mangaId }
                        .orderBy(ChapterTable.url to ASC).toList()
                }
            val chapterUrls = chapterList.map { it.url }.toSet()

            dbChapterList.forEachIndexed { index, dbChapter ->
                if (
                    !chapterUrls.contains(dbChapter[ChapterTable.url]) || // is orphaned
                    (index < dbChapterList.lastIndex && dbChapter[ChapterTable.url] == dbChapterList[index + 1][ChapterTable.url]) // is duplicate
                ) {
                    transaction {
                        PageTable.deleteWhere { PageTable.chapter eq dbChapter[ChapterTable.id] }
                        ChapterTable.deleteWhere { ChapterTable.id eq dbChapter[ChapterTable.id] }
                    }
                }
            }
        }

        if (manga.inLibrary) {
            downloadNewChapters(mangaId, numberOfCurrentChapters, newChapters)
        }

        return chapterList
    }

    private fun downloadNewChapters(
        mangaId: Int,
        prevNumberOfChapters: Int,
        updatedChapterList: List<ResultRow>,
    ) {
        // convert numbers to be index based
        val currentNumberOfChapters = (prevNumberOfChapters - 1).coerceAtLeast(0)
        val updatedNumberOfChapters = (updatedChapterList.size - 1).coerceAtLeast(0)
        val numberOfNewChapters = updatedNumberOfChapters - currentNumberOfChapters

        val areNewChaptersAvailable = numberOfNewChapters > 0
        val wasInitialFetch = currentNumberOfChapters == -1 // has to be -1 - due to converting to index based 1 chapter will be 0

        // make sure to ignore initial fetch
        val isDownloadPossible =
            serverConfig.autoDownloadNewChapters.value && areNewChaptersAvailable && !wasInitialFetch
        if (!isDownloadPossible) {
            return
        }

        val newChapters = updatedChapterList.subList(0, numberOfNewChapters)

        // make sure to only consider the latest chapters. e.g. old unread chapters should be ignored
        val latestReadChapterIndex =
            updatedChapterList.indexOfFirst { it[ChapterTable.isRead] }.takeIf { it > -1 } ?: return
        val unreadChapters =
            updatedChapterList.subList(numberOfNewChapters, latestReadChapterIndex)
                .filter { !it[ChapterTable.isRead] }

        val skipDueToUnreadChapters = serverConfig.excludeEntryWithUnreadChapters.value && unreadChapters.isNotEmpty()
        if (skipDueToUnreadChapters) {
            return
        }

        val firstChapterToDownloadIndex =
            (numberOfNewChapters - serverConfig.autoDownloadAheadLimit.value).coerceAtLeast(0)

        val chapterIdsToDownload =
            newChapters.subList(firstChapterToDownloadIndex, numberOfNewChapters)
                .filter { !it[ChapterTable.isRead] && !it[ChapterTable.isDownloaded] }
                .map { it[ChapterTable.id].value }

        if (chapterIdsToDownload.isEmpty()) {
            return
        }

        logger.info { "downloadNewChapters($mangaId): Downloading \"${chapterIdsToDownload.size}\" new chapter(s)..." }

        DownloadManager.enqueue(EnqueueInput(chapterIdsToDownload))
    }

    fun modifyChapter(
        mangaId: Int,
        chapterIndex: Int,
        isRead: Boolean?,
        isBookmarked: Boolean?,
        markPrevRead: Boolean?,
        lastPageRead: Int?,
    ) {
        transaction {
            if (listOf(isRead, isBookmarked, lastPageRead).any { it != null }) {
                ChapterTable.update({ (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder eq chapterIndex) }) { update ->
                    isRead?.also {
                        update[ChapterTable.isRead] = it
                    }
                    isBookmarked?.also {
                        update[ChapterTable.isBookmarked] = it
                    }
                    lastPageRead?.also {
                        update[ChapterTable.lastPageRead] = it
                        update[ChapterTable.lastReadAt] = Instant.now().epochSecond
                    }
                }
            }

            markPrevRead?.let {
                ChapterTable.update({ (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder less chapterIndex) }) {
                    it[ChapterTable.isRead] = markPrevRead
                }
            }
        }
    }

    @Serializable
    data class ChapterChange(
        val isRead: Boolean? = null,
        val isBookmarked: Boolean? = null,
        val lastPageRead: Int? = null,
        val delete: Boolean? = null,
    )

    @Serializable
    data class MangaChapterBatchEditInput(
        val chapterIds: List<Int>? = null,
        val chapterIndexes: List<Int>? = null,
        val change: ChapterChange?,
    )

    @Serializable
    data class ChapterBatchEditInput(
        val chapterIds: List<Int>? = null,
        val change: ChapterChange?,
    )

    fun modifyChapters(
        input: MangaChapterBatchEditInput,
        mangaId: Int? = null,
    ) {
        // Make sure change is defined
        if (input.change == null) return
        val (isRead, isBookmarked, lastPageRead, delete) = input.change

        // Handle deleting separately
        if (delete == true) {
            deleteChapters(input, mangaId)
        }

        // return early if there are no other changes
        if (listOfNotNull(isRead, isBookmarked, lastPageRead).isEmpty()) return

        // Make sure some filter is defined
        val condition =
            when {
                mangaId != null ->
                    // mangaId is not null, scope query under manga
                    when {
                        input.chapterIds != null ->
                            Op.build { (ChapterTable.manga eq mangaId) and (ChapterTable.id inList input.chapterIds) }
                        input.chapterIndexes != null ->
                            Op.build { (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder inList input.chapterIndexes) }
                        else -> null
                    }
                else -> {
                    // mangaId is null, only chapterIndexes is valid for this case
                    when {
                        input.chapterIds != null ->
                            Op.build { (ChapterTable.id inList input.chapterIds) }
                        else -> null
                    }
                }
            } ?: return

        transaction {
            val now = Instant.now().epochSecond
            ChapterTable.update({ condition }) { update ->
                isRead?.also {
                    update[ChapterTable.isRead] = it
                }
                isBookmarked?.also {
                    update[ChapterTable.isBookmarked] = it
                }
                lastPageRead?.also {
                    update[ChapterTable.lastPageRead] = it
                    update[ChapterTable.lastReadAt] = now
                }
            }
        }
    }

    fun getChaptersMetaMaps(chapterIds: List<EntityID<Int>>): Map<EntityID<Int>, Map<String, String>> {
        return transaction {
            ChapterMetaTable.select { ChapterMetaTable.ref inList chapterIds }
                .groupBy { it[ChapterMetaTable.ref] }
                .mapValues { it.value.associate { it[ChapterMetaTable.key] to it[ChapterMetaTable.value] } }
                .withDefault { emptyMap<String, String>() }
        }
    }

    fun getChapterMetaMap(chapter: EntityID<Int>): Map<String, String> {
        return transaction {
            ChapterMetaTable.select { ChapterMetaTable.ref eq chapter }
                .associate { it[ChapterMetaTable.key] to it[ChapterMetaTable.value] }
        }
    }

    fun modifyChapterMeta(
        mangaId: Int,
        chapterIndex: Int,
        key: String,
        value: String,
    ) {
        transaction {
            val chapterId =
                ChapterTable.select { (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder eq chapterIndex) }
                    .first()[ChapterTable.id].value
            modifyChapterMeta(chapterId, key, value)
        }
    }

    fun modifyChapterMeta(
        chapterId: Int,
        key: String,
        value: String,
    ) {
        transaction {
            val meta =
                ChapterMetaTable.select { (ChapterMetaTable.ref eq chapterId) and (ChapterMetaTable.key eq key) }
                    .firstOrNull()

            if (meta == null) {
                ChapterMetaTable.insert {
                    it[ChapterMetaTable.key] = key
                    it[ChapterMetaTable.value] = value
                    it[ChapterMetaTable.ref] = chapterId
                }
            } else {
                ChapterMetaTable.update({ (ChapterMetaTable.ref eq chapterId) and (ChapterMetaTable.key eq key) }) {
                    it[ChapterMetaTable.value] = value
                }
            }
        }
    }

    fun deleteChapter(
        mangaId: Int,
        chapterIndex: Int,
    ) {
        transaction {
            val chapterId =
                ChapterTable.select { (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder eq chapterIndex) }
                    .first()[ChapterTable.id].value

            ChapterDownloadHelper.delete(mangaId, chapterId)

            ChapterTable.update({ (ChapterTable.manga eq mangaId) and (ChapterTable.sourceOrder eq chapterIndex) }) {
                it[isDownloaded] = false
            }
        }
    }

    private fun deleteChapters(
        input: MangaChapterBatchEditInput,
        mangaId: Int? = null,
    ) {
        if (input.chapterIds != null) {
            deleteChapters(input.chapterIds)
        } else if (input.chapterIndexes != null && mangaId != null) {
            transaction {
                val chapterIds =
                    ChapterTable.slice(ChapterTable.manga, ChapterTable.id)
                        .select { (ChapterTable.sourceOrder inList input.chapterIndexes) and (ChapterTable.manga eq mangaId) }
                        .map { row ->
                            val chapterId = row[ChapterTable.id].value
                            ChapterDownloadHelper.delete(mangaId, chapterId)

                            chapterId
                        }

                ChapterTable.update({ ChapterTable.id inList chapterIds }) {
                    it[isDownloaded] = false
                }
            }
        }
    }

    fun deleteChapters(chapterIds: List<Int>) {
        transaction {
            ChapterTable.slice(ChapterTable.manga, ChapterTable.id)
                .select { ChapterTable.id inList chapterIds }
                .forEach { row ->
                    val chapterMangaId = row[ChapterTable.manga].value
                    val chapterId = row[ChapterTable.id].value
                    ChapterDownloadHelper.delete(chapterMangaId, chapterId)
                }

            ChapterTable.update({ ChapterTable.id inList chapterIds }) {
                it[isDownloaded] = false
            }
        }
    }

    fun getRecentChapters(pageNum: Int): PaginatedList<MangaChapterDataClass> {
        return paginatedFrom(pageNum) {
            transaction {
                (ChapterTable innerJoin MangaTable)
                    .select { (MangaTable.inLibrary eq true) and (ChapterTable.fetchedAt greater MangaTable.inLibraryAt) }
                    .orderBy(ChapterTable.fetchedAt to SortOrder.DESC)
                    .map {
                        MangaChapterDataClass(
                            MangaTable.toDataClass(it),
                            ChapterTable.toDataClass(it),
                        )
                    }
            }
        }
    }
}