/* Copyright 2022 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.instanceinfo

import android.util.Log
import at.connyduck.calladapter.networkresult.fold
import at.connyduck.calladapter.networkresult.getOrElse
import at.connyduck.calladapter.networkresult.onSuccess
import com.keylesspalace.tusky.db.AccountManager
import com.keylesspalace.tusky.db.AppDatabase
import com.keylesspalace.tusky.db.EmojisEntity
import com.keylesspalace.tusky.db.InstanceInfoEntity
import com.keylesspalace.tusky.entity.Emoji
import com.keylesspalace.tusky.network.MastodonApi
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.withContext
import javax.inject.Inject

class InstanceInfoRepository @Inject constructor(
    private val api: MastodonApi,
    db: AppDatabase,
    accountManager: AccountManager
) {

    private val dao = db.instanceDao()
    private val instanceName = accountManager.activeAccount!!.domain

    /**
     * Returns the custom emojis of the instance.
     * Will always try to fetch them from the api, falls back to cached Emojis in case it is not available.
     * Never throws, returns empty list in case of error.
     */
    suspend fun getEmojis(): List<Emoji> = withContext(Dispatchers.IO) {
        api.getCustomEmojis()
            .onSuccess { emojiList -> dao.insertOrReplace(EmojisEntity(instanceName, emojiList)) }
            .getOrElse { throwable ->
                Log.w(TAG, "failed to load custom emojis, falling back to cache", throwable)
                getCachedEmojis()
            }
    }

    suspend fun getCachedEmojis(): List<Emoji> =
        dao.getEmojiInfo(instanceName)?.emojiList.orEmpty()

    /**
     * Returns information about the instance.
     * Will always try to fetch the most up-to-date data from the api, falls back to cache in case it is not available.
     * Never throws, returns defaults of vanilla Mastodon in case of error.
     */
    suspend fun getInstanceInfo(): InstanceInfo = withContext(Dispatchers.IO) {
        api.getInstance()
            .fold(
                { instance ->
                    val instanceEntity = InstanceInfoEntity(
                        instance = instanceName,
                        maximumTootCharacters = instance.configuration?.statuses?.maxCharacters ?: instance.maxTootChars,
                        maxPollOptions = instance.configuration?.polls?.maxOptions ?: instance.pollConfiguration?.maxOptions,
                        maxPollOptionLength = instance.configuration?.polls?.maxCharactersPerOption ?: instance.pollConfiguration?.maxOptionChars,
                        minPollDuration = instance.configuration?.polls?.minExpiration ?: instance.pollConfiguration?.minExpiration,
                        maxPollDuration = instance.configuration?.polls?.maxExpiration ?: instance.pollConfiguration?.maxExpiration,
                        charactersReservedPerUrl = instance.configuration?.statuses?.charactersReservedPerUrl,
                        version = instance.version
                    )
                    dao.insertOrReplace(instanceEntity)
                    instanceEntity
                },
                { throwable ->
                    Log.w(TAG, "failed to instance, falling back to cache and default values", throwable)
                    getCachedInstanceInfoEntity()
                }
            ).toInstanceInfo()
    }

    private suspend fun getCachedInstanceInfoEntity(): InstanceInfoEntity? =
        dao.getInstanceInfo(instanceName)

    suspend fun getCachedInstanceInfo(): InstanceInfo =
        getCachedInstanceInfoEntity().toInstanceInfo()

    companion object {
        private const val TAG = "InstanceInfoRepo"

        const val DEFAULT_CHARACTER_LIMIT = 500
        private const val DEFAULT_MAX_OPTION_COUNT = 4
        private const val DEFAULT_MAX_OPTION_LENGTH = 50
        private const val DEFAULT_MIN_POLL_DURATION = 300
        private const val DEFAULT_MAX_POLL_DURATION = 604800

        @JvmField
        val CAN_USE_QUOTE_ID = arrayOf(
            "odakyu.app",
            "itabashi.0j0.jp",
            "biwakodon.com",
            "dtp-mstdn.jp",
            "nitiasa.com",
            "comm.cx",
            "fedibird.com",
            "qoto.org",
            "kurage.cc",
            "m.eula.dev",
            "otogamer.me",
            "sgp.hostdon.ne.jp",
            "pomdon.work",
            "obapom.work",
        )

        // Mastodon only counts URLs as this long in terms of status character limits
        const val DEFAULT_CHARACTERS_RESERVED_PER_URL = 23

        fun InstanceInfoEntity?.toInstanceInfo(): InstanceInfo =
            InstanceInfo(
                maxChars = this?.maximumTootCharacters ?: DEFAULT_CHARACTER_LIMIT,
                pollMaxOptions = this?.maxPollOptions ?: DEFAULT_MAX_OPTION_COUNT,
                pollMaxLength = this?.maxPollOptionLength ?: DEFAULT_MAX_OPTION_LENGTH,
                pollMinDuration = this?.minPollDuration ?: DEFAULT_MIN_POLL_DURATION,
                pollMaxDuration = this?.maxPollDuration ?: DEFAULT_MAX_POLL_DURATION,
                charactersReservedPerUrl = this?.charactersReservedPerUrl ?: DEFAULT_CHARACTERS_RESERVED_PER_URL
            )
    }
}