import Foundation
import UIKit
import AsyncDisplayKit
import Display
import Postbox
import TelegramCore
import SwiftSignalKit
import TelegramPresentationData
import MergeLists
import OverlayStatusController
import AccountContext
import StickerPackPreviewUI
import PresentationDataUtils
import UndoUI

final class TrendingPaneInteraction {
    let installPack: (ItemCollectionInfo) -> Void
    let openPack: (ItemCollectionInfo) -> Void
    let getItemIsPreviewed: (StickerPackItem) -> Bool
    let openSearch: () -> Void
    let itemContext = StickerPaneSearchGlobalItemContext()
    
    init(installPack: @escaping (ItemCollectionInfo) -> Void, openPack: @escaping (ItemCollectionInfo) -> Void, getItemIsPreviewed: @escaping (StickerPackItem) -> Bool, openSearch: @escaping () -> Void) {
        self.installPack = installPack
        self.openPack = openPack
        self.getItemIsPreviewed = getItemIsPreviewed
        self.openSearch = openSearch
    }
}

final class TrendingPanePackEntry: Identifiable, Comparable {
    let index: Int
    let info: StickerPackCollectionInfo
    let theme: PresentationTheme
    let strings: PresentationStrings
    let topItems: [StickerPackItem]
    let installed: Bool
    let unread: Bool
    let topSeparator: Bool
    
    init(index: Int, info: StickerPackCollectionInfo, theme: PresentationTheme, strings: PresentationStrings, topItems: [StickerPackItem], installed: Bool, unread: Bool, topSeparator: Bool) {
        self.index = index
        self.info = info
        self.theme = theme
        self.strings = strings
        self.topItems = topItems
        self.installed = installed
        self.unread = unread
        self.topSeparator = topSeparator
    }
    
    var stableId: ItemCollectionId {
        return self.info.id
    }
    
    static func ==(lhs: TrendingPanePackEntry, rhs: TrendingPanePackEntry) -> Bool {
        if lhs.index != rhs.index {
            return false
        }
        if lhs.info != rhs.info {
            return false
        }
        if lhs.theme !== rhs.theme {
            return false
        }
        if lhs.strings !== rhs.strings {
            return false
        }
        if lhs.topItems != rhs.topItems {
            return false
        }
        if lhs.installed != rhs.installed {
            return false
        }
        if lhs.unread != rhs.unread {
            return false
        }
        if lhs.topSeparator != rhs.topSeparator {
            return false
        }
        return true
    }
    
    static func <(lhs: TrendingPanePackEntry, rhs: TrendingPanePackEntry) -> Bool {
        return lhs.index < rhs.index
    }
    
    func item(account: Account, interaction: TrendingPaneInteraction, grid: Bool) -> GridItem {
        let info = self.info
        return StickerPaneSearchGlobalItem(account: account, theme: self.theme, strings: self.strings, listAppearance: false, info: self.info, topItems: self.topItems, topSeparator: self.topSeparator, regularInsets: false, installed: self.installed, unread: self.unread, open: {
            interaction.openPack(info)
        }, install: {
            interaction.installPack(info)
        }, getItemIsPreviewed: { item in
            return interaction.getItemIsPreviewed(item)
        }, itemContext: interaction.itemContext)
    }
}

private enum TrendingPaneEntryId: Hashable {
    case search
    case pack(ItemCollectionId)
}

private enum TrendingPaneEntry: Identifiable, Comparable {
    case search(theme: PresentationTheme, strings: PresentationStrings)
    case pack(TrendingPanePackEntry)
    
    var stableId: TrendingPaneEntryId {
        switch self {
        case .search:
            return .search
        case let .pack(pack):
            return .pack(pack.stableId)
        }
    }
    
    static func ==(lhs: TrendingPaneEntry, rhs: TrendingPaneEntry) -> Bool {
        switch lhs {
        case let .search(lhsTheme, lhsStrings):
            if case let .search(rhsTheme, rhsStrings) = rhs, lhsTheme === rhsTheme, lhsStrings === rhsStrings {
                return true
            } else {
                return false
            }
        case let .pack(pack):
            if case .pack(pack) = rhs {
                return true
            } else {
                return false
            }
        }
    }
    
    static func <(lhs: TrendingPaneEntry, rhs: TrendingPaneEntry) -> Bool {
        switch lhs {
        case .search:
            return false
        case let .pack(lhsPack):
            switch rhs {
            case .search:
                return false
            case let .pack(rhsPack):
                return lhsPack < rhsPack
            }
        }
    }
    
    func item(account: Account, interaction: TrendingPaneInteraction, grid: Bool) -> GridItem {
        switch self {
        case let .search(theme, strings):
            return PaneSearchBarPlaceholderItem(theme: theme, strings: strings, type: .stickers, activate: {
                interaction.openSearch()
            })
        case let .pack(pack):
            return pack.item(account: account, interaction: interaction, grid: grid)
        }
    }
}

private struct TrendingPaneTransition {
    let deletions: [Int]
    let insertions: [GridNodeInsertItem]
    let updates: [GridNodeUpdateItem]
    let initial: Bool
}

private func preparedTransition(from fromEntries: [TrendingPaneEntry], to toEntries: [TrendingPaneEntry], account: Account, interaction: TrendingPaneInteraction, initial: Bool) -> TrendingPaneTransition {
    let (deleteIndices, indicesAndItems, updateIndices) = mergeListsStableWithUpdates(leftList: fromEntries, rightList: toEntries)
    
    let deletions = deleteIndices
    let insertions = indicesAndItems.map { GridNodeInsertItem(index: $0.0, item: $0.1.item(account: account, interaction: interaction, grid: false), previousIndex: $0.2) }
    let updates = updateIndices.map { GridNodeUpdateItem(index: $0.0, previousIndex: $0.2, item: $0.1.item(account: account, interaction: interaction, grid: false)) }
    
    return TrendingPaneTransition(deletions: deletions, insertions: insertions, updates: updates, initial: initial)
}

private func trendingPaneEntries(trendingEntries: [FeaturedStickerPackItem], installedPacks: Set<ItemCollectionId>, theme: PresentationTheme, strings: PresentationStrings, isPane: Bool) -> [TrendingPaneEntry] {
    var result: [TrendingPaneEntry] = []
    var index = 0
    if isPane {
        result.append(.search(theme: theme, strings: strings))
    }
    for item in trendingEntries {
        if !installedPacks.contains(item.info.id) {
            result.append(.pack(TrendingPanePackEntry(index: index, info: item.info, theme: theme, strings: strings, topItems: item.topItems, installed: installedPacks.contains(item.info.id), unread: item.unread, topSeparator: index != 0)))
            index += 1
        }
    }
    return result
}

final class ChatMediaInputTrendingPane: ChatMediaInputPane {
    private let context: AccountContext
    private let controllerInteraction: ChatControllerInteraction
    private let getItemIsPreviewed: (StickerPackItem) -> Bool
    private let isPane: Bool
    
    let gridNode: GridNode
    
    private var enqueuedTransitions: [TrendingPaneTransition] = []
    private var validLayout: (CGSize, CGFloat)?
    
    private var disposable: Disposable?
    private var isActivated = false
    
    private let _ready = Promise<Void>()
    private var didSetReady = false
    var ready: Signal<Void, NoError> {
        return self._ready.get()
    }
    
    var scrollingInitiated: (() -> Void)?
    
    private let installDisposable = MetaDisposable()
    
    init(context: AccountContext, controllerInteraction: ChatControllerInteraction, getItemIsPreviewed: @escaping (StickerPackItem) -> Bool, isPane: Bool) {
        self.context = context
        self.controllerInteraction = controllerInteraction
        self.getItemIsPreviewed = getItemIsPreviewed
        self.isPane = isPane
        
        self.gridNode = GridNode()
        
        super.init()
        
        self.addSubnode(self.gridNode)
        
        self.gridNode.scrollingInitiated = { [weak self] in
            self?.scrollingInitiated?()
        }
    }
    
    deinit {
        self.disposable?.dispose()
        self.installDisposable.dispose()
    }
    
    func activate() {
        if self.isActivated {
            return
        }
        self.isActivated = true
        
        let interaction = TrendingPaneInteraction(installPack: { [weak self] info in
            if let strongSelf = self, let info = info as? StickerPackCollectionInfo {
                let context = strongSelf.context
                var installSignal = context.engine.stickers.loadedStickerPack(reference: .id(id: info.id.id, accessHash: info.accessHash), forceActualized: false)
                |> mapToSignal { result -> Signal<(StickerPackCollectionInfo, [ItemCollectionItem]), NoError> in
                    switch result {
                    case let .result(info, items, installed):
                        if installed {
                            return .complete()
                        } else {
                            return preloadedStickerPackThumbnail(account: context.account, info: info, items: items)
                            |> filter { $0 }
                            |> ignoreValues
                            |> then(
                                context.engine.stickers.addStickerPackInteractively(info: info, items: items)
                                |> ignoreValues
                            )
                            |> mapToSignal { _ -> Signal<(StickerPackCollectionInfo, [ItemCollectionItem]), NoError> in
                            }
                            |> then(.single((info, items)))
                        }
                    case .fetching:
                        break
                    case .none:
                        break
                    }
                    return .complete()
                }
                |> deliverOnMainQueue

                var cancelImpl: (() -> Void)?
                let progressSignal = Signal<Never, NoError> { subscriber in
                    let presentationData = context.sharedContext.currentPresentationData.with { $0 }
                    let controller = OverlayStatusController(theme: presentationData.theme, type: .loading(cancelled: {
                        cancelImpl?()
                    }))
                    self?.controllerInteraction.presentController(controller, nil)
                    return ActionDisposable { [weak controller] in
                        Queue.mainQueue().async() {
                            controller?.dismiss()
                        }
                    }
                }
                |> runOn(Queue.mainQueue())
                |> delay(1.0, queue: Queue.mainQueue())
                let progressDisposable = progressSignal.start()
                
                installSignal = installSignal
                |> afterDisposed {
                    Queue.mainQueue().async {
                        progressDisposable.dispose()
                    }
                }
                cancelImpl = {
                    self?.installDisposable.set(nil)
                }
                    
                strongSelf.installDisposable.set(installSignal.start(next: { info, items in
                    guard let strongSelf = self else {
                        return
                    }
                    
                    var animateInAsReplacement = false
                    if let navigationController = strongSelf.controllerInteraction.navigationController() {
                        for controller in navigationController.overlayControllers {
                            if let controller = controller as? UndoOverlayController {
                                controller.dismissWithCommitActionAndReplacementAnimation()
                                animateInAsReplacement = true
                            }
                        }
                    }
                    
                    let presentationData = strongSelf.context.sharedContext.currentPresentationData.with { $0 }
                    strongSelf.controllerInteraction.navigationController()?.presentOverlay(controller: UndoOverlayController(presentationData: presentationData, content: .stickersModified(title: presentationData.strings.StickerPackActionInfo_AddedTitle, text: presentationData.strings.StickerPackActionInfo_AddedText(info.title).string, undo: false, info: info, topItem: items.first, context: strongSelf.context), elevatedLayout: false, animateInAsReplacement: animateInAsReplacement, action: { _ in
                        return true
                    }))
                }))
            }
        }, openPack: { [weak self] info in
            if let strongSelf = self, let info = info as? StickerPackCollectionInfo {
                strongSelf.view.window?.endEditing(true)
                let packReference: StickerPackReference = .id(id: info.id.id, accessHash: info.accessHash)
                let controller = StickerPackScreen(context: strongSelf.context, mainStickerPack: packReference, stickerPacks: [packReference], parentNavigationController: strongSelf.controllerInteraction.navigationController(), sendSticker: { fileReference, sourceNode, sourceRect in
                    if let strongSelf = self {
                        return strongSelf.controllerInteraction.sendSticker(fileReference, false, false, nil, false, sourceNode, sourceRect)
                    } else {
                        return false
                    }
                })
                strongSelf.controllerInteraction.presentController(controller, nil)
            }
        }, getItemIsPreviewed: self.getItemIsPreviewed,
        openSearch: { [weak self] in
            self?.inputNodeInteraction?.toggleSearch(true, .trending, "")
        })
        interaction.itemContext.canPlayMedia = true
        
        let isPane = self.isPane
        let previousEntries = Atomic<[TrendingPaneEntry]?>(value: nil)
        let context = self.context
        self.disposable = (combineLatest(context.account.viewTracker.featuredStickerPacks(), context.account.postbox.combinedView(keys: [.itemCollectionInfos(namespaces: [Namespaces.ItemCollection.CloudStickerPacks])]), context.sharedContext.presentationData)
        |> map { trendingEntries, view, presentationData -> TrendingPaneTransition in
            var installedPacks = Set<ItemCollectionId>()
            if let stickerPacksView = view.views[.itemCollectionInfos(namespaces: [Namespaces.ItemCollection.CloudStickerPacks])] as? ItemCollectionInfosView {
                if let packsEntries = stickerPacksView.entriesByNamespace[Namespaces.ItemCollection.CloudStickerPacks] {
                    for entry in packsEntries {
                        installedPacks.insert(entry.id)
                    }
                }
            }
            let entries = trendingPaneEntries(trendingEntries: trendingEntries, installedPacks: installedPacks, theme: presentationData.theme, strings: presentationData.strings, isPane: isPane)
            let previous = previousEntries.swap(entries)
            
            return preparedTransition(from: previous ?? [], to: entries, account: context.account, interaction: interaction, initial: previous == nil)
        }
        |> deliverOnMainQueue).start(next: { [weak self] transition in
            guard let strongSelf = self else {
                return
            }
            strongSelf.enqueueTransition(transition)
            if !strongSelf.didSetReady {
                strongSelf.didSetReady = true
                strongSelf._ready.set(.single(Void()))
            }
        })
    }
    
    override func updateLayout(size: CGSize, topInset: CGFloat, bottomInset: CGFloat, isExpanded: Bool, isVisible: Bool, deviceMetrics: DeviceMetrics, transition: ContainedViewLayoutTransition) {
        let hadValidLayout = self.validLayout != nil
        self.validLayout = (size, bottomInset)
        
        let itemSize: CGSize
        if case .tablet = deviceMetrics.type, size.width > 480.0 {
            itemSize = CGSize(width: floor(size.width / 2.0), height: 128.0)
        } else {
            itemSize = CGSize(width: size.width, height: 128.0)
        }
        
        self.gridNode.transaction(GridNodeTransaction(deleteItems: [], insertItems: [], updateItems: [], scrollToItem: nil, updateLayout: GridNodeUpdateLayout(layout: GridNodeLayout(size: size, insets: UIEdgeInsets(top: topInset, left: 0.0, bottom: bottomInset, right: 0.0), preloadSize: isVisible ? 300.0 : 0.0, type: .fixed(itemSize: itemSize, fillWidth: nil, lineSpacing: 0.0, itemSpacing: nil)), transition: transition), itemTransition: .immediate, stationaryItems: .none, updateFirstIndexInSectionOffset: nil), completion: { _ in })
        
        transition.updateFrame(node: self.gridNode, frame: CGRect(origin: CGPoint(), size: CGSize(width: size.width, height: size.height)))
        
        if !hadValidLayout {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
    }
    
    private func enqueueTransition(_ transition: TrendingPaneTransition) {
        self.enqueuedTransitions.append(transition)
        
        if self.validLayout != nil {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
    }
    
    override func willEnterHierarchy() {
        super.willEnterHierarchy()
        
        self.activate()
    }
    
    private func dequeueTransition() {
        if let transition = self.enqueuedTransitions.first {
            self.enqueuedTransitions.remove(at: 0)
            
            let itemTransition: ContainedViewLayoutTransition = .immediate
            self.gridNode.transaction(GridNodeTransaction(deleteItems: transition.deletions, insertItems: transition.insertions, updateItems: transition.updates, scrollToItem: nil, updateLayout: nil, itemTransition: itemTransition, stationaryItems: .none, updateFirstIndexInSectionOffset: nil, synchronousLoads: transition.initial), completion: { _ in })
        }
    }
    
    func itemAt(point: CGPoint) -> (ASDisplayNode, StickerPackItem)? {
        let localPoint = self.view.convert(point, to: self.gridNode.view)
        var resultNode: StickerPaneSearchGlobalItemNode?
        self.gridNode.forEachItemNode { itemNode in
            if itemNode.frame.contains(localPoint), let itemNode = itemNode as? StickerPaneSearchGlobalItemNode {
                resultNode = itemNode
            }
        }
        if let resultNode = resultNode {
            return resultNode.itemAt(point: self.gridNode.view.convert(localPoint, to: resultNode.view))
        }
        return nil
    }
    
    func updatePreviewing(animated: Bool) {
        self.gridNode.forEachItemNode { itemNode in
            if let itemNode = itemNode as? StickerPaneSearchGlobalItemNode {
                itemNode.updatePreviewing(animated: animated)
            }
        }
    }
}