package com.vitorpamplona.amethyst.model

import androidx.lifecycle.LiveData
import com.vitorpamplona.amethyst.service.NostrSingleEventDataSource
import com.vitorpamplona.amethyst.service.model.*
import com.vitorpamplona.amethyst.service.relays.Relay
import com.vitorpamplona.amethyst.ui.note.toShortenHex
import fr.acinq.secp256k1.Hex
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlinx.coroutines.NonCancellable
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import java.math.BigDecimal
import java.time.Instant
import java.time.ZoneId
import java.time.format.DateTimeFormatter
import java.util.Date
import java.util.concurrent.atomic.AtomicBoolean
import java.util.regex.Pattern

val tagSearch = Pattern.compile("(?:\\s|\\A)\\#\\[([0-9]+)\\]")

class AddressableNote(val address: ATag) : Note(address.toTag()) {
    override fun idNote() = address.toNAddr()
    override fun idDisplayNote() = idNote().toShortenHex()
    override fun address() = address
    override fun createdAt() = (event as? LongTextNoteEvent)?.publishedAt() ?: event?.createdAt()
}

open class Note(val idHex: String) {
    // These fields are only available after the Text Note event is received.
    // They are immutable after that.
    var event: EventInterface? = null
    var author: User? = null
    var replyTo: List<Note>? = null

    // These fields are updated every time an event related to this note is received.
    var replies = setOf<Note>()
        private set
    var reactions = setOf<Note>()
        private set
    var boosts = setOf<Note>()
        private set
    var reports = mapOf<User, Set<Note>>()
        private set
    var zaps = mapOf<Note, Note?>()
        private set

    var relays = setOf<String>()
        private set

    var lastReactionsDownloadTime: Long? = null

    fun id() = Hex.decode(idHex)
    open fun idNote() = id().toNote()
    open fun idDisplayNote() = idNote().toShortenHex()

    fun channel(): Channel? {
        val channelHex =
            (event as? ChannelMessageEvent)?.channel()
                ?: (event as? ChannelMetadataEvent)?.channel()
                ?: (event as? ChannelCreateEvent)?.let { it.id }

        return channelHex?.let { LocalCache.checkGetOrCreateChannel(it) }
    }

    open fun address() = (event as? LongTextNoteEvent)?.address()

    open fun createdAt() = event?.createdAt()

    fun loadEvent(event: Event, author: User, replyTo: List<Note>) {
        this.event = event
        this.author = author
        this.replyTo = replyTo

        liveSet?.metadata?.invalidateData()
    }

    fun formattedDateTime(timestamp: Long): String {
        return Instant.ofEpochSecond(timestamp).atZone(ZoneId.systemDefault())
            .format(DateTimeFormatter.ofPattern("uuuu-MM-dd-HH:mm:ss"))
    }

    /**
     * This method caches signatures during each execution to avoid recalculation in longer threads
     */
    fun replyLevelSignature(cachedSignatures: MutableMap<Note, String> = mutableMapOf()): String {
        val replyTo = replyTo
        if (replyTo == null || replyTo.isEmpty()) {
            return "/" + formattedDateTime(createdAt() ?: 0) + ";"
        }

        return replyTo
            .map {
                cachedSignatures[it] ?: it.replyLevelSignature(cachedSignatures).apply { cachedSignatures.put(it, this) }
            }
            .maxBy { it.length }.removeSuffix(";") + "/" + formattedDateTime(createdAt() ?: 0) + ";"
    }

    fun replyLevel(cachedLevels: MutableMap<Note, Int> = mutableMapOf()): Int {
        val replyTo = replyTo
        if (replyTo == null || replyTo.isEmpty()) {
            return 0
        }

        return replyTo.maxOf {
            cachedLevels[it] ?: it.replyLevel(cachedLevels).apply { cachedLevels.put(it, this) }
        } + 1
    }

    fun addReply(note: Note) {
        if (note !in replies) {
            replies = replies + note
            liveSet?.replies?.invalidateData()
        }
    }

    fun removeReply(note: Note) {
        replies = replies - note
        liveSet?.replies?.invalidateData()
    }
    fun removeBoost(note: Note) {
        boosts = boosts - note
        liveSet?.boosts?.invalidateData()
    }
    fun removeReaction(note: Note) {
        reactions = reactions - note
        liveSet?.reactions?.invalidateData()
    }

    fun removeReport(deleteNote: Note) {
        val author = deleteNote.author ?: return

        if (author in reports.keys && reports[author]?.contains(deleteNote) == true) {
            reports[author]?.let {
                reports = reports + Pair(author, it.minus(deleteNote))
                liveSet?.reports?.invalidateData()
            }
        }
    }

    fun removeZap(note: Note) {
        if (zaps[note] != null) {
            zaps = zaps.minus(note)
            liveSet?.zaps?.invalidateData()
        } else if (zaps.containsValue(note)) {
            val toRemove = zaps.filterValues { it == note }
            zaps = zaps.minus(toRemove.keys)
            liveSet?.zaps?.invalidateData()
        }
    }

    fun addBoost(note: Note) {
        if (note !in boosts) {
            boosts = boosts + note
            liveSet?.boosts?.invalidateData()
        }
    }

    fun addZap(zapRequest: Note, zap: Note?) {
        if (zapRequest !in zaps.keys) {
            zaps = zaps + Pair(zapRequest, zap)
            liveSet?.zaps?.invalidateData()
        } else if (zapRequest in zaps.keys && zaps[zapRequest] == null) {
            zaps = zaps + Pair(zapRequest, zap)
            liveSet?.zaps?.invalidateData()
        }
    }

    fun addReaction(note: Note) {
        if (note !in reactions) {
            reactions = reactions + note
            liveSet?.reactions?.invalidateData()
        }
    }

    fun addReport(note: Note) {
        val author = note.author ?: return

        if (author !in reports.keys) {
            reports = reports + Pair(author, setOf(note))
            liveSet?.reports?.invalidateData()
        } else if (reports[author]?.contains(note) == false) {
            reports = reports + Pair(author, (reports[author] ?: emptySet()) + note)
            liveSet?.reports?.invalidateData()
        }
    }

    fun addRelay(relay: Relay) {
        if (relay.url !in relays) {
            relays = relays + relay.url
            liveSet?.relays?.invalidateData()
        }
    }

    fun isZappedBy(user: User): Boolean {
        // Zaps who the requester was the user
        return zaps.any { it.key.author == user }
    }

    fun isReactedBy(user: User): Boolean {
        return reactions.any { it.author == user }
    }

    fun isBoostedBy(user: User): Boolean {
        return boosts.any { it.author == user }
    }

    fun reportsBy(user: User): Set<Note> {
        return reports[user] ?: emptySet()
    }

    fun reportAuthorsBy(users: Set<HexKey>): List<User> {
        return reports.keys.filter { it.pubkeyHex in users }
    }

    fun countReportAuthorsBy(users: Set<HexKey>): Int {
        return reports.keys.count { it.pubkeyHex in users }
    }

    fun reportsBy(users: Set<HexKey>): List<Note> {
        return reportAuthorsBy(users).mapNotNull {
            reports[it]
        }.flatten()
    }

    fun zappedAmount(): BigDecimal {
        return zaps.mapNotNull { it.value?.event }
            .filterIsInstance<LnZapEvent>()
            .mapNotNull {
                it.amount
            }.sumOf { it }
    }

    fun hasAnyReports(): Boolean {
        val dayAgo = Date().time / 1000 - 24 * 60 * 60
        return reports.isNotEmpty() ||
            (
                author?.reports?.values?.filter {
                    it.firstOrNull { (it.createdAt() ?: 0) > dayAgo } != null
                }?.isNotEmpty() ?: false
                )
    }

    fun directlyCiteUsersHex(): Set<HexKey> {
        val matcher = tagSearch.matcher(event?.content() ?: "")
        val returningList = mutableSetOf<String>()
        while (matcher.find()) {
            try {
                val tag = matcher.group(1)?.let { event?.tags()?.get(it.toInt()) }
                if (tag != null && tag[0] == "p") {
                    returningList.add(tag[1])
                }
            } catch (e: Exception) {
            }
        }
        return returningList
    }

    fun directlyCiteUsers(): Set<User> {
        val matcher = tagSearch.matcher(event?.content() ?: "")
        val returningList = mutableSetOf<User>()
        while (matcher.find()) {
            try {
                val tag = matcher.group(1)?.let { event?.tags()?.get(it.toInt()) }
                if (tag != null && tag[0] == "p") {
                    LocalCache.checkGetOrCreateUser(tag[1])?.let {
                        returningList.add(it)
                    }
                }
            } catch (e: Exception) {
            }
        }
        return returningList
    }

    fun directlyCites(userProfile: User): Boolean {
        return author == userProfile ||
            (userProfile in directlyCiteUsers()) ||
            (event is ReactionEvent && replyTo?.lastOrNull()?.directlyCites(userProfile) == true) ||
            (event is RepostEvent && replyTo?.lastOrNull()?.directlyCites(userProfile) == true)
    }

    fun isNewThread(): Boolean {
        return event is RepostEvent || replyTo == null || replyTo?.size == 0
    }

    fun hasZapped(loggedIn: User): Boolean {
        return zaps.any { it.key.author == loggedIn }
    }

    fun hasReacted(loggedIn: User, content: String): Boolean {
        return reactedBy(loggedIn, content).isNotEmpty()
    }

    fun reactedBy(loggedIn: User, content: String): List<Note> {
        return reactions.filter { it.author == loggedIn && it.event?.content() == content }
    }

    fun hasBoostedInTheLast5Minutes(loggedIn: User): Boolean {
        val currentTime = Date().time / 1000
        return boosts.firstOrNull { it.author == loggedIn && (it.createdAt() ?: 0) > currentTime - (60 * 5) } != null // 5 minute protection
    }

    fun boostedBy(loggedIn: User): List<Note> {
        return boosts.filter { it.author == loggedIn }
    }

    var liveSet: NoteLiveSet? = null

    fun live(): NoteLiveSet {
        if (liveSet == null) {
            liveSet = NoteLiveSet(this)
        }
        return liveSet!!
    }

    fun clearLive() {
        if (liveSet != null && liveSet?.isInUse() == false) {
            liveSet = null
        }
    }
}

class NoteLiveSet(u: Note) {
    // Observers line up here.
    val metadata: NoteLiveData = NoteLiveData(u)

    val reactions: NoteLiveData = NoteLiveData(u)
    val boosts: NoteLiveData = NoteLiveData(u)
    val replies: NoteLiveData = NoteLiveData(u)
    val reports: NoteLiveData = NoteLiveData(u)
    val relays: NoteLiveData = NoteLiveData(u)
    val zaps: NoteLiveData = NoteLiveData(u)

    fun isInUse(): Boolean {
        return metadata.hasObservers() ||
            reactions.hasObservers() ||
            boosts.hasObservers() ||
            replies.hasObservers() ||
            reports.hasObservers() ||
            relays.hasObservers() ||
            zaps.hasObservers()
    }
}

class NoteLiveData(val note: Note) : LiveData<NoteState>(NoteState(note)) {
    // Refreshes observers in batches.
    var handlerWaiting = AtomicBoolean()

    fun invalidateData() {
        if (!hasActiveObservers()) return
        if (handlerWaiting.getAndSet(true)) return

        val scope = CoroutineScope(Job() + Dispatchers.Main)
        scope.launch {
            try {
                delay(100)
                refresh()
            } finally {
                withContext(NonCancellable) {
                    handlerWaiting.set(false)
                }
            }
        }
    }

    fun refresh() {
        postValue(NoteState(note))
    }

    override fun onActive() {
        super.onActive()
        if (note is AddressableNote) {
            NostrSingleEventDataSource.addAddress(note)
        } else {
            NostrSingleEventDataSource.add(note)
        }
    }

    override fun onInactive() {
        super.onInactive()
        if (note is AddressableNote) {
            NostrSingleEventDataSource.removeAddress(note)
        } else {
            NostrSingleEventDataSource.remove(note)
        }
    }
}

class NoteState(val note: Note)