/* Copyright 2020 Tusky Contributors
 *
 * This file is a part of Tusky.
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation; either version 3 of the
 * License, or (at your option) any later version.
 *
 * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
 * Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with Tusky; if not,
 * see <http://www.gnu.org/licenses>. */

package com.keylesspalace.tusky.components.announcements

import android.util.Log
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import com.keylesspalace.tusky.appstore.AnnouncementReadEvent
import com.keylesspalace.tusky.appstore.EventHub
import com.keylesspalace.tusky.db.AccountManager
import com.keylesspalace.tusky.db.AppDatabase
import com.keylesspalace.tusky.db.InstanceEntity
import com.keylesspalace.tusky.entity.Announcement
import com.keylesspalace.tusky.entity.Emoji
import com.keylesspalace.tusky.entity.Instance
import com.keylesspalace.tusky.network.MastodonApi
import com.keylesspalace.tusky.util.*
import io.reactivex.rxkotlin.Singles
import javax.inject.Inject

class AnnouncementsViewModel @Inject constructor(
        accountManager: AccountManager,
        private val appDatabase: AppDatabase,
        private val mastodonApi: MastodonApi,
        private val eventHub: EventHub
) : RxAwareViewModel() {

    private val announcementsMutable = MutableLiveData<Resource<List<Announcement>>>()
    val announcements: LiveData<Resource<List<Announcement>>> = announcementsMutable

    private val emojisMutable = MutableLiveData<List<Emoji>>()
    val emojis: LiveData<List<Emoji>> = emojisMutable

    init {
        Singles.zip(
                mastodonApi.getCustomEmojis(),
                appDatabase.instanceDao().loadMetadataForInstance(accountManager.activeAccount?.domain!!)
                        .map<Either<InstanceEntity, Instance>> { Either.Left(it) }
                        .onErrorResumeNext(
                                mastodonApi.getInstance()
                                        .map { Either.Right(it) }
                        )
        ) { emojis, either ->
            either.asLeftOrNull()?.copy(emojiList = emojis)
                    ?: InstanceEntity(
                            accountManager.activeAccount?.domain!!,
                            emojis,
                            either.asRight().maxTootChars,
                            either.asRight().pollLimits?.maxOptions,
                            either.asRight().pollLimits?.maxOptionChars,
                            either.asRight().version
                    )
        }
                .doOnSuccess {
                    appDatabase.instanceDao().insertOrReplace(it)
                }
                .subscribe({
                    emojisMutable.postValue(it.emojiList)
                }, {
                    Log.w(TAG, "Failed to get custom emojis.", it)
                })
                .autoDispose()
    }

    fun load() {
        announcementsMutable.postValue(Loading())
        mastodonApi.listAnnouncements()
                .subscribe({
                    announcementsMutable.postValue(Success(it))
                    it.filter { announcement -> !announcement.read }
                            .forEach { announcement ->
                                mastodonApi.dismissAnnouncement(announcement.id)
                                        .subscribe(
                                                {
                                                    eventHub.dispatch(AnnouncementReadEvent(announcement.id))
                                                },
                                                { throwable ->
                                                    Log.d(TAG, "Failed to mark announcement as read.", throwable)
                                                }
                                        )
                                        .autoDispose()
                            }
                }, {
                    announcementsMutable.postValue(Error(cause = it))
                })
                .autoDispose()
    }

    fun addReaction(announcementId: String, name: String) {
        mastodonApi.addAnnouncementReaction(announcementId, name)
                .subscribe({
                    announcementsMutable.postValue(
                            Success(
                                    announcements.value!!.data!!.map { announcement ->
                                        if (announcement.id == announcementId) {
                                            announcement.copy(
                                                    reactions = if (announcement.reactions.find { reaction -> reaction.name == name } != null) {
                                                        announcement.reactions.map { reaction ->
                                                            if (reaction.name == name) {
                                                                reaction.copy(
                                                                        count = reaction.count + 1,
                                                                        me = true
                                                                )
                                                            } else {
                                                                reaction
                                                            }
                                                        }
                                                    } else {
                                                        listOf(
                                                                *announcement.reactions.toTypedArray(),
                                                                emojis.value!!.find { emoji -> emoji.shortcode == name }
                                                                        !!.run {
                                                                            Announcement.Reaction(
                                                                                    name,
                                                                                    1,
                                                                                    true,
                                                                                    url,
                                                                                    staticUrl
                                                                            )
                                                                        }
                                                        )
                                                    }
                                            )
                                        } else {
                                            announcement
                                        }
                                    }
                            )
                    )
                }, {
                    Log.w(TAG, "Failed to add reaction to the announcement.", it)
                })
                .autoDispose()
    }

    fun removeReaction(announcementId: String, name: String) {
        mastodonApi.removeAnnouncementReaction(announcementId, name)
                .subscribe({
                    announcementsMutable.postValue(
                            Success(
                                    announcements.value!!.data!!.map { announcement ->
                                        if (announcement.id == announcementId) {
                                            announcement.copy(
                                                    reactions = announcement.reactions.mapNotNull { reaction ->
                                                        if (reaction.name == name) {
                                                            if (reaction.count > 1) {
                                                                reaction.copy(
                                                                        count = reaction.count - 1,
                                                                        me = false
                                                                )
                                                            } else {
                                                                null
                                                            }
                                                        } else {
                                                            reaction
                                                        }
                                                    }
                                            )
                                        } else {
                                            announcement
                                        }
                                    }
                            )
                    )
                }, {
                    Log.w(TAG, "Failed to remove reaction from the announcement.", it)
                })
                .autoDispose()
    }

    companion object {
        private const val TAG = "AnnouncementsViewModel"
    }
}