SubwayTooter-Android-App/app/src/main/java/jp/juggler/subwaytooter/api/entity/TootInstance.kt

package jp.juggler.subwaytooter.api.entity

import android.os.SystemClock
import jp.juggler.subwaytooter.App1
import jp.juggler.subwaytooter.Pref
import jp.juggler.subwaytooter.api.TootApiClient
import jp.juggler.subwaytooter.api.TootApiResult
import jp.juggler.subwaytooter.api.TootParser
import jp.juggler.subwaytooter.table.SavedAccount
import jp.juggler.subwaytooter.util.LinkHelper
import jp.juggler.subwaytooter.util.VersionString
import jp.juggler.util.*
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.channels.Channel
import kotlinx.coroutines.launch
import okhttp3.Request
import java.util.*
import java.util.regex.Pattern
import kotlin.collections.ArrayList
import kotlin.math.max

// インスタンスの種別
enum class InstanceType {
    Mastodon,
    Misskey,
    Pixelfed,
    Pleroma
}

enum class CapabilitySource {
    Fedibird,
}

enum class InstanceCapability(
    private val capabilitySource: CapabilitySource,
    private val id: String
) {
    FavouriteHashtag(CapabilitySource.Fedibird, "favourite_hashtag"),
    FavouriteDomain(CapabilitySource.Fedibird, "favourite_domain"),
    StatusExpire(CapabilitySource.Fedibird, "status_expire"),
    FollowNoDelivery(CapabilitySource.Fedibird, "follow_no_delivery"),
    FollowHashtag(CapabilitySource.Fedibird, "follow_hashtag"),
    SubscribeAccount(CapabilitySource.Fedibird, "subscribe_account"),
    SubscribeDomain(CapabilitySource.Fedibird, "subscribe_domain"),
    SubscribeKeyword(CapabilitySource.Fedibird, "subscribe_keyword"),
    TimelineNoLocal(CapabilitySource.Fedibird, "timeline_no_local"),
    TimelineDomain(CapabilitySource.Fedibird, "timeline_domain"),
    TimelineGroup(CapabilitySource.Fedibird, "timeline_group"),
    TimelineGroupDirectory(CapabilitySource.Fedibird, "timeline_group_directory"),
    VisibilityMutual(CapabilitySource.Fedibird, "visibility_mutual"),
    VisibilityLimited(CapabilitySource.Fedibird, "visibility_limited"),
    ;

    fun hasCapability(instance: TootInstance): Boolean {
        when (capabilitySource) {
            CapabilitySource.Fedibird -> {
                if (instance.fedibird_capabilities?.any { it == id } == true) return true
            }
        }
        // XXX: もし機能がMastodon公式に取り込まれたならバージョン番号で判断できるはず
        return false
    }
}

class TootInstance(parser: TootParser, src: JsonObject) {

    // いつ取得したか(内部利用)
    private var time_parse: Long = SystemClock.elapsedRealtime()

    val isExpire: Boolean
        get() = SystemClock.elapsedRealtime() - time_parse >= EXPIRE

    //	URI of the current instance
    // apiHost ではなく apDomain を示す
    val uri: String?

    //	The instance's title
    val title: String?

    //	A description for the instance
    // (HTML)
    // (Mastodon: 3.0.0より後のWebUIでは全く使われなくなる見込み。 https://github.com/tootsuite/mastodon/pull/12119)
    val description: String?

    // (Mastodon 3.0.0以降)
    // (HTML)
    val short_description: String?

    // An email address which can be used to contact the instance administrator
    // misskeyの場合はURLらしい
    val email: String?

    val version: String?

    // バージョンの内部表現
    private val decoded_version: VersionString

    // インスタンスのサムネイル。推奨サイズ1200x630px。マストドン1.6.1以降。
    val thumbnail: String?

    // ユーザ数等の数字。マストドン1.6以降。
    val stats: Stats?

    // 言語のリスト。マストドン2.3.0以降
    val languages: ArrayList<String>?

    val contact_account: TootAccount?

    // (Pleroma only) トゥートの最大文字数
    val max_toot_chars: Int?

    // (Mastodon 3.0.0)
    val approval_required: Boolean

    // (Mastodon 3.1.4)
    val invites_enabled: Boolean?


    val instanceType: InstanceType

    var feature_quote = false

    var fedibird_capabilities: JsonArray? = null

    // XXX: urls をパースしてない。使ってないから…

    init {
        if (parser.serviceType == ServiceType.MISSKEY) {

            this.uri = parser.apiHost.ascii
            this.title = parser.apiHost.pretty
            val sv = src.jsonObject("maintainer")?.string("url")
            this.email = when {
                sv?.startsWith("mailto:") == true -> sv.substring(7)
                else -> sv
            }

            this.version = src.string("version")
            this.decoded_version = VersionString(version)
            this.stats = null
            this.thumbnail = null
            this.max_toot_chars = src.int("maxNoteTextLength")
            this.instanceType = InstanceType.Misskey
            this.languages = src.jsonArray("langs")?.stringArrayList() ?: ArrayList()
            this.contact_account = null

            this.description = src.string("description")
            this.short_description = null
            this.approval_required = false

            this.feature_quote = true

            this.invites_enabled = null
        } else {
            this.uri = src.string("uri")
            this.title = src.string("title")

            val sv = src.string("email")
            this.email = when {
                sv?.startsWith("mailto:") == true -> sv.substring(7)
                else -> sv
            }

            this.version = src.string("version")
            this.decoded_version = VersionString(version)
            this.stats = parseItem(::Stats, src.jsonObject("stats"))
            this.thumbnail = src.string("thumbnail")

            this.max_toot_chars = src.int("max_toot_chars")

            this.instanceType = when {
                rePleroma.matcher(version ?: "").find() -> InstanceType.Pleroma
                rePixelfed.matcher(version ?: "").find() -> InstanceType.Pixelfed
                else -> InstanceType.Mastodon
            }

            languages = src.jsonArray("languages")?.stringArrayList()

            val parser2 = TootParser(
                parser.context,
                LinkHelper.create(Host.parse(uri ?: "?"))
            )
            contact_account =
                parseItem(::TootAccount, parser2, src.jsonObject("contact_account"))

            this.description = src.string("description")
            this.short_description = src.string("short_description")
            this.approval_required = src.boolean("approval_required") ?: false

            this.feature_quote = src.boolean("feature_quote") ?: false

            this.invites_enabled = src.boolean("invites_enabled")

            this.fedibird_capabilities = src.jsonArray("fedibird_capabilities")
        }
    }

    class Stats(src: JsonObject) {

        val user_count: Long
        val status_count: Long
        val domain_count: Long

        init {
            this.user_count = src.long("user_count") ?: -1L
            this.status_count = src.long("status_count") ?: -1L
            this.domain_count = src.long("domain_count") ?: -1L
        }
    }

    val misskeyVersion: Int
        get() = when {
            instanceType != InstanceType.Misskey -> 0
            versionGE(MISSKEY_VERSION_11) -> 11
            else -> 10
        }

    fun versionGE(check: VersionString): Boolean {
        if (decoded_version.isEmpty || check.isEmpty) return false
        val i = VersionString.compare(decoded_version, check)
        return i >= 0
    }

    fun hasCapability(cap: InstanceCapability) = cap.hasCapability(this)

    companion object {

        private val rePleroma = """\bpleroma\b""".asciiPattern(Pattern.CASE_INSENSITIVE)
        private val rePixelfed = """\bpixelfed\b""".asciiPattern(Pattern.CASE_INSENSITIVE)

        val VERSION_1_6 = VersionString("1.6")
        val VERSION_2_4_0_rc1 = VersionString("2.4.0rc1")
        val VERSION_2_4_0_rc2 = VersionString("2.4.0rc2")

        //		val VERSION_2_4_0 = VersionString("2.4.0")
        //		val VERSION_2_4_1_rc1 = VersionString("2.4.1rc1")
        val VERSION_2_4_1 = VersionString("2.4.1")
        val VERSION_2_6_0 = VersionString("2.6.0")
        val VERSION_2_7_0_rc1 = VersionString("2.7.0rc1")
        val VERSION_2_8_0_rc1 = VersionString("2.8.0rc1")
        val VERSION_3_0_0_rc1 = VersionString("3.0.0rc1")
        val VERSION_3_1_0_rc1 = VersionString("3.1.0rc1")
        val VERSION_3_1_3 = VersionString("3.1.3")
        val VERSION_3_3_0_rc1 = VersionString("3.3.0rc1")
        val VERSION_3_4_0_rc1 = VersionString("3.4.0rc1")

        val MISSKEY_VERSION_11 = VersionString("11.0")
        val MISSKEY_VERSION_12 = VersionString("12.0")
        val MISSKEY_VERSION_12_75_0 = VersionString("12.75.0")

        private val reDigits = """(\d+)""".asciiPattern()

        private const val EXPIRE = (1000 * 3600).toLong()

        const val DESCRIPTION_DEFAULT = "(no description)"

        // 引数はtoken_infoかTootInstanceのパース前のいずれか
        fun parseMisskeyVersion(token_info: JsonObject): Int {
            return when (val o = token_info[TootApiClient.KEY_MISSKEY_VERSION]) {
                is Int -> o
                is Boolean -> if (o) 10 else 0
                else -> 0
            }
        }

        // 疑似アカウントの追加時に、インスタンスの検証を行う
        private suspend fun TootApiClient.getInstanceInformationMastodon(
            forceAccessToken: String? = null
        ): TootApiResult? {
            val result = TootApiResult.makeWithCaption(apiHost?.pretty)
            if (result.error != null) return result

            if (sendRequest(result) {
                    val builder = Request.Builder().url("https://${apiHost?.ascii}/api/v1/instance")

                    (forceAccessToken ?: account?.getAccessToken() )
                        ?.notEmpty()?.let { builder.header("Authorization", "Bearer $it") }
                    builder.build()
                }
            ) {
                parseJson(result) ?: return null
            }

            return result
        }

        // 疑似アカウントの追加時に、インスタンスの検証を行う
        private suspend fun TootApiClient.getInstanceInformationMisskey(
            forceAccessToken: String? = null
        ): TootApiResult? {
            val result = TootApiResult.makeWithCaption(apiHost?.pretty)
            if (result.error != null) return result

            if (sendRequest(result) {
                    jsonObject {
                        put("dummy", 1)
                        (forceAccessToken ?: account?.misskeyApiToken )
                            ?.notEmpty()?.let { put("i", it) }
                    }.toPostRequestBuilder()
                        .url("https://${apiHost?.ascii}/api/meta")
                        .build()
                }
            ) {
                parseJson(result) ?: return null

                result.jsonObject?.apply {
                    val m = reDigits.matcher(string("version") ?: "")
                    if (m.find()) {
                        put(TootApiClient.KEY_MISSKEY_VERSION, max(1, m.groupEx(1)!!.toInt()))
                    }
                }
            }
            return result
        }

        // 疑似アカウントの追加時に、インスタンスの検証を行う
        private suspend fun TootApiClient.getInstanceInformation(
            forceAccessToken: String? = null
        ): TootApiResult? {

            // misskeyのインスタンス情報を読めたら、それはmisskeyのインスタンス
            val r2 = getInstanceInformationMisskey(forceAccessToken) ?: return null
            if (r2.jsonObject != null) return r2

            // マストドンのインスタンス情報を読めたら、それはマストドンのインスタンス
            val r1 = getInstanceInformationMastodon(forceAccessToken) ?: return null
            if (r1.jsonObject != null) return r1

            return r1 // ホワイトリストモードの問題があるのでマストドン側のエラーを返す
        }

        class QueuedRequest(
            val allowPixelfed: Boolean,
            val get: suspend (cached: TootInstance?) -> Pair<TootInstance?, TootApiResult?>,
        ) {
            val result = Channel<Pair<TootInstance?, TootApiResult?>>()
        }

        fun queuedRequest(
            allowPixelfed: Boolean,
            get: suspend (cached: TootInstance?) -> Pair<TootInstance?, TootApiResult?>
        ) = QueuedRequest(allowPixelfed, get)

        // インスタンス情報のキャッシュ。同期オブジェクトを兼ねる
        class CacheEntry {
            // インスタンス情報のキャッシュ
            var cacheData: TootInstance? = null

            // ホストごとに同時に1つしか実行しない、インスタンス情報更新キュー
            val requestQueue = Channel<QueuedRequest>(capacity = Channel.UNLIMITED)

            private suspend fun handleRequest(req: QueuedRequest) = try {
                val pair = req.get(cacheData)

                pair.first?.let { cacheData = it }

                when {

                    pair.first?.instanceType == InstanceType.Pixelfed &&
                        !Pref.bpEnablePixelfed(App1.pref) &&
                        !req.allowPixelfed ->
                        Pair(
                            null, TootApiResult("currently Pixelfed instance is not supported.")
                        )

                    else -> pair
                }

            } catch (ex: Throwable) {
                Pair(
                    null,
                    TootApiResult(ex.withCaption("can't get server information."))
                )
            }

            init {
                GlobalScope.launch(Dispatchers.IO) {
                    while (true) {
                        requestQueue.receive().let { it.result.send(handleRequest(it)) }
                    }
                }
            }
        }

        private val _hostCache = HashMap<String, CacheEntry>()

        private fun Host.getCacheEntry(): CacheEntry =
            synchronized(_hostCache) {
                val hostLower = ascii.lowercase()
                var item = _hostCache[hostLower]
                if (item == null) {
                    item = CacheEntry()
                    _hostCache[hostLower] = item
                }
                item
            }

        // get from cache
        // no request, no expiration check
        fun getCached(host: String) = Host.parse(host).getCacheEntry().cacheData

        suspend fun get(client: TootApiClient): Pair<TootInstance?, TootApiResult?> = getEx(client)

        suspend fun getEx(
            client: TootApiClient,
            hostArg: Host? = null,
            account: SavedAccount? = null,
            allowPixelfed: Boolean = false,
            forceUpdate: Boolean = false,
            forceAccessToken: String? = null, // マストドンのwhitelist modeでアカウント追加時に必要
        ): Pair<TootInstance?, TootApiResult?> {

            val cacheEntry = (hostArg ?: account?.apiHost ?: client.apiHost)?.getCacheEntry()
                ?: return Pair(null, TootApiResult("missing host."))

            // ホスト名ごとに用意したオブジェクトで同期する
            return queuedRequest(allowPixelfed) { cached ->

                // may use cached item.
                if (!forceUpdate && forceAccessToken == null && cached!=null) {
                    val now = SystemClock.elapsedRealtime()
                    if ( now - cached.time_parse <= EXPIRE)
                        return@queuedRequest Pair(cached, TootApiResult())
                }

                val tmpInstance = client.apiHost
                val tmpAccount = client.account

                val linkHelper: LinkHelper?

                // get new information
                val result = when {

                    // ストリームマネジャから呼ばれる
                    account != null -> try {
                        linkHelper = account
                        client.account = account // this may change client.apiHost
                        if (account.isMisskey) {
                            client.getInstanceInformationMisskey()
                        } else {
                            client.getInstanceInformationMastodon()
                        }
                    } finally {
                        client.account = tmpAccount
                        client.apiHost = tmpInstance // must be last.
                    }

                    // サーバ情報カラムやProfileDirectoryを開く場合
                    hostArg != null && hostArg != tmpInstance -> try {
                        linkHelper = null
                        client.account = null // don't use access token.
                        client.apiHost = hostArg
                        client.getInstanceInformation()
                    } finally {
                        client.account = tmpAccount
                        client.apiHost = tmpInstance // must be last.
                    }

                    // client にすでにあるアクセス情報でサーバ情報を取得する
                    // マストドンのホワイトリストモード用にアクセストークンを指定できる
                    else -> {
                        linkHelper = client.account // may null
                        client.getInstanceInformation(
                            forceAccessToken = forceAccessToken
                        )
                    }
                }

                val json = result?.jsonObject
                    ?: return@queuedRequest Pair(null, result)

                val item = parseItem(
                    ::TootInstance,
                    TootParser(
                        client.context,
                        linkHelper = linkHelper ?: LinkHelper.create(
                            (hostArg ?: client.apiHost)!!,
                            misskeyVersion = parseMisskeyVersion(json)
                        )
                    ),
                    json
                ) ?: return@queuedRequest Pair(
                    null,
                    result.setError("instance information parse error.")
                )

                Pair(item, result)
            }
                .also { cacheEntry.requestQueue.send(it) }
                .result.receive()
        }
    }
}