import Foundation
import UIKit
import AsyncDisplayKit
import Postbox
import TelegramCore
import Display
import SwiftSignalKit
import TelegramPresentationData
import TelegramUIPreferences
import MergeLists
import AccountContext
import StickerPackPreviewUI
import ContextUI

private struct ChatContextResultStableId: Hashable {
    let result: ChatContextResult
    
    var hashValue: Int {
        return result.id.hashValue
    }
    
    static func ==(lhs: ChatContextResultStableId, rhs: ChatContextResultStableId) -> Bool {
        return lhs.result == rhs.result
    }
}

private struct HorizontalListContextResultsChatInputContextPanelEntry: Comparable, Identifiable {
    let index: Int
    let theme: PresentationTheme
    let result: ChatContextResult
    
    var stableId: ChatContextResultStableId {
        return ChatContextResultStableId(result: self.result)
    }
    
    static func ==(lhs: HorizontalListContextResultsChatInputContextPanelEntry, rhs: HorizontalListContextResultsChatInputContextPanelEntry) -> Bool {
        return lhs.index == rhs.index && lhs.theme === rhs.theme && lhs.result == rhs.result
    }
    
    static func <(lhs: HorizontalListContextResultsChatInputContextPanelEntry, rhs: HorizontalListContextResultsChatInputContextPanelEntry) -> Bool {
        return lhs.index < rhs.index
    }
    
    func item(account: Account, resultSelected: @escaping (ChatContextResult, ASDisplayNode, CGRect) -> Bool) -> ListViewItem {
        return HorizontalListContextResultsChatInputPanelItem(account: account, theme: self.theme, result: self.result, resultSelected: resultSelected)
    }
}

private struct HorizontalListContextResultsChatInputContextPanelTransition {
    let deletions: [ListViewDeleteItem]
    let insertions: [ListViewInsertItem]
    let updates: [ListViewUpdateItem]
    let entryCount: Int
    let hasMore: Bool
}

private final class HorizontalListContextResultsOpaqueState {
    let entryCount: Int
    let hasMore: Bool
    
    init(entryCount: Int, hasMore: Bool) {
        self.entryCount = entryCount
        self.hasMore = hasMore
    }
}

private func preparedTransition(from fromEntries: [HorizontalListContextResultsChatInputContextPanelEntry], to toEntries: [HorizontalListContextResultsChatInputContextPanelEntry], hasMore: Bool, account: Account, resultSelected: @escaping (ChatContextResult, ASDisplayNode, CGRect) -> Bool) -> HorizontalListContextResultsChatInputContextPanelTransition {
    let (deleteIndices, indicesAndItems, updateIndices) = mergeListsStableWithUpdates(leftList: fromEntries, rightList: toEntries)
    
    let deletions = deleteIndices.map { ListViewDeleteItem(index: $0, directionHint: nil) }
    let insertions = indicesAndItems.map { ListViewInsertItem(index: $0.0, previousIndex: $0.2, item: $0.1.item(account: account, resultSelected: resultSelected), directionHint: nil) }
    let updates = updateIndices.map { ListViewUpdateItem(index: $0.0, previousIndex: $0.2, item: $0.1.item(account: account, resultSelected: resultSelected), directionHint: nil) }
    
    return HorizontalListContextResultsChatInputContextPanelTransition(deletions: deletions, insertions: insertions, updates: updates, entryCount: toEntries.count, hasMore: hasMore)
}

final class HorizontalListContextResultsChatInputContextPanelNode: ChatInputContextPanelNode {
    private var strings: PresentationStrings
    
    private let listView: ListView
    private let separatorNode: ASDisplayNode
    private var currentExternalResults: ChatContextResultCollection?
    private var currentProcessedResults: ChatContextResultCollection?
    private var currentEntries: [HorizontalListContextResultsChatInputContextPanelEntry]?
    private var isLoadingMore = false
    private let loadMoreDisposable = MetaDisposable()
    
    private var enqueuedTransitions: [(HorizontalListContextResultsChatInputContextPanelTransition, Bool)] = []
    private var hasValidLayout = false
    
    override init(context: AccountContext, theme: PresentationTheme, strings: PresentationStrings, fontSize: PresentationFontSize) {
        self.strings = strings
        
        self.separatorNode = ASDisplayNode()
        self.separatorNode.isLayerBacked = true
        self.separatorNode.backgroundColor = theme.list.itemPlainSeparatorColor
        self.separatorNode.isHidden = true
        
        self.listView = ListView()
        self.listView.isOpaque = true
        self.listView.backgroundColor = theme.list.plainBackgroundColor
        self.listView.transform = CATransform3DMakeRotation(-CGFloat(CGFloat.pi / 2.0), 0.0, 0.0, 1.0)
        self.listView.isHidden = true
        self.listView.accessibilityPageScrolledString = { row, count in
            return strings.VoiceOver_ScrollStatus(row, count).string
        }
        
        super.init(context: context, theme: theme, strings: strings, fontSize: fontSize)
        
        self.isOpaque = false
        self.clipsToBounds = true
        
        self.addSubnode(self.listView)
        self.addSubnode(self.separatorNode)
        
        self.listView.displayedItemRangeChanged = { [weak self] displayedRange, opaqueTransactionState in
            if let strongSelf = self, let state = opaqueTransactionState as? HorizontalListContextResultsOpaqueState {
                if let visible = displayedRange.visibleRange {
                    if state.hasMore && visible.lastIndex >= state.entryCount - 10 {
                        strongSelf.loadMore()
                    }
                }
            }
        }
    }
    
    deinit {
        self.loadMoreDisposable.dispose()
    }
    
    override func didLoad() {
        super.didLoad()
        
        self.listView.view.disablesInteractiveTransitionGestureRecognizer = true
        self.listView.view.disablesInteractiveKeyboardGestureRecognizer = true
        self.view.addGestureRecognizer(PeekControllerGestureRecognizer(contentAtPoint: { [weak self] point in
            if let strongSelf = self {
                let convertedPoint = strongSelf.listView.view.convert(point, from: strongSelf.view)
                
                if !strongSelf.listView.bounds.contains(convertedPoint) {
                    return nil
                }
                
                var selectedItemNodeAndContent: (ASDisplayNode, PeekControllerContent)?
                strongSelf.listView.forEachItemNode { itemNode in
                    if itemNode.frame.contains(convertedPoint), let itemNode = itemNode as? HorizontalListContextResultsChatInputPanelItemNode, let item = itemNode.item {
                        if case let .internalReference(internalReference) = item.result, let file = internalReference.file, file.isSticker {
                            var menuItems: [ContextMenuItem] = []
                            menuItems.append(.action(ContextMenuActionItem(text: strongSelf.strings.StickerPack_Send, icon: { theme in generateTintedImage(image: UIImage(bundleImageName: "Chat/Context Menu/Resend"), color: theme.contextMenu.primaryColor) }, action: { _, f in
                                f(.default)
                                
                                let _ = item.resultSelected(item.result, itemNode, itemNode.bounds)
                            })))
                            for case let .Sticker(_, packReference, _) in file.attributes {
                                guard let packReference = packReference else {
                                    continue
                                }
                                menuItems.append(.action(ContextMenuActionItem(text: strongSelf.strings.StickerPack_ViewPack, icon: { theme in generateTintedImage(image: UIImage(bundleImageName: "Chat/Context Menu/Sticker"), color: theme.contextMenu.primaryColor) }, action: { [weak self] _, f in
                                    f(.default)
                                    
                                    if let strongSelf = self {
                                        let controller = StickerPackScreen(context: strongSelf.context, mainStickerPack: packReference, stickerPacks: [packReference], parentNavigationController: strongSelf.interfaceInteraction?.getNavigationController(), sendSticker: { file, sourceNode, sourceRect in
                                            if let strongSelf = self {
                                                return strongSelf.interfaceInteraction?.sendSticker(file, false, sourceNode, sourceRect) ?? false
                                            } else {
                                                return false
                                            }
                                        })
                                                    
                                        strongSelf.interfaceInteraction?.getNavigationController()?.view.window?.endEditing(true)
                                        strongSelf.interfaceInteraction?.presentController(controller, nil)
                                    }
                                })))
                            }
                            selectedItemNodeAndContent = (itemNode, StickerPreviewPeekContent(account: item.account, item: .found(FoundStickerItem(file: file, stringRepresentations: [])), menu: menuItems))
                        } else {
                            var menuItems: [ContextMenuItem] = []
                            if case let .internalReference(internalReference) = item.result, let file = internalReference.file, file.isAnimated {
                                menuItems.append(.action(ContextMenuActionItem(text: strongSelf.strings.Preview_SaveGif, icon: { theme in
                                    return generateTintedImage(image: UIImage(bundleImageName: "Chat/Context Menu/Save"), color: theme.actionSheet.primaryTextColor)
                                }, action: { _, f in
                                    f(.dismissWithoutContent)
                                    
                                    guard let strongSelf = self else {
                                        return
                                    }
                                    let _ = addSavedGif(postbox: strongSelf.context.account.postbox, fileReference: .standalone(media: file)).start()
                                })))
                            }
                            menuItems.append(.action(ContextMenuActionItem(text: strongSelf.strings.ShareMenu_Send, icon: { theme in
                                return generateTintedImage(image: UIImage(bundleImageName: "Chat/Context Menu/Resend"), color: theme.actionSheet.primaryTextColor)
                            }, action: { _, f in
                                f(.default)
                                let _ = item.resultSelected(item.result, itemNode, itemNode.bounds)
                            })))
                            selectedItemNodeAndContent = (itemNode, ChatContextResultPeekContent(account: item.account, contextResult: item.result, menu: menuItems))
                        }
                    }
                }
                return .single(selectedItemNodeAndContent)
            }
            return nil
        }, present: { [weak self] content, sourceNode in
            if let strongSelf = self {
                let presentationData = strongSelf.context.sharedContext.currentPresentationData.with { $0 }
                let controller = PeekController(presentationData: presentationData, content: content, sourceNode: {
                    return sourceNode
                })
                strongSelf.interfaceInteraction?.presentGlobalOverlayController(controller, nil)
                return controller
            }
            return nil
        }))
    }
    
    func updateResults(_ results: ChatContextResultCollection) {
        if self.currentExternalResults == results {
            return
        }
        self.currentExternalResults = results
        self.currentProcessedResults = results
        
        self.isLoadingMore = false
        self.loadMoreDisposable.set(nil)
        self.updateInternalResults(results)
    }
    
    private func loadMore() {
        guard !self.isLoadingMore, let currentProcessedResults = self.currentProcessedResults, let nextOffset = currentProcessedResults.nextOffset else {
            return
        }
        self.isLoadingMore = true
        let geoPoint = currentProcessedResults.geoPoint.flatMap { geoPoint -> (Double, Double) in
            return (geoPoint.latitude, geoPoint.longitude)
        }
        self.loadMoreDisposable.set((self.context.engine.messages.requestChatContextResults(botId: currentProcessedResults.botId, peerId: currentProcessedResults.peerId, query: currentProcessedResults.query, location: .single(geoPoint), offset: nextOffset)
        |> map { results -> ChatContextResultCollection? in
            return results?.results
        }
        |> deliverOnMainQueue).start(next: { [weak self] nextResults in
            guard let strongSelf = self, let nextResults = nextResults else {
                return
            }
            strongSelf.isLoadingMore = false
            var results: [ChatContextResult] = []
            var existingIds = Set<String>()
            for result in currentProcessedResults.results {
                results.append(result)
                existingIds.insert(result.id)
            }
            for result in nextResults.results {
                if !existingIds.contains(result.id) {
                    results.append(result)
                    existingIds.insert(result.id)
                }
            }
            let mergedResults = ChatContextResultCollection(botId: currentProcessedResults.botId, peerId: currentProcessedResults.peerId, query: currentProcessedResults.query, geoPoint: currentProcessedResults.geoPoint, queryId: nextResults.queryId, nextOffset: nextResults.nextOffset, presentation: currentProcessedResults.presentation, switchPeer: currentProcessedResults.switchPeer, results: results, cacheTimeout: currentProcessedResults.cacheTimeout)
            strongSelf.currentProcessedResults = mergedResults
            strongSelf.updateInternalResults(mergedResults)
        }))
    }
    
    private func updateInternalResults(_ results: ChatContextResultCollection) {
        var entries: [HorizontalListContextResultsChatInputContextPanelEntry] = []
        var index = 0
        var resultIds = Set<ChatContextResultStableId>()
        for result in results.results {
            let entry = HorizontalListContextResultsChatInputContextPanelEntry(index: index, theme: self.theme, result: result)
            if resultIds.contains(entry.stableId) {
                continue
            } else {
                resultIds.insert(entry.stableId)
            }
            entries.append(entry)
            index += 1
        }
        
        let firstTime = self.currentEntries == nil
        let transition = preparedTransition(from: self.currentEntries ?? [], to: entries, hasMore: results.nextOffset != nil, account: self.context.account, resultSelected: { [weak self] result, node, rect in
            if let strongSelf = self, let interfaceInteraction = strongSelf.interfaceInteraction {
                return interfaceInteraction.sendContextResult(results, result, node, rect)
            } else {
                return false
            }
        })
        self.currentEntries = entries
        self.enqueueTransition(transition, firstTime: firstTime)
    }
    
    private func enqueueTransition(_ transition: HorizontalListContextResultsChatInputContextPanelTransition, firstTime: Bool) {
        enqueuedTransitions.append((transition, firstTime))
        
        if self.hasValidLayout {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
    }
    
    private func dequeueTransition() {
        if let (transition, firstTime) = self.enqueuedTransitions.first {
            self.enqueuedTransitions.remove(at: 0)
            
            var options = ListViewDeleteAndInsertOptions()
            options.insert(.Synchronous)
            options.insert(.LowLatency)
            options.insert(.PreferSynchronousResourceLoading)
            if firstTime {
                //options.insert(.Synchronous)
                //options.insert(.LowLatency)
            } else {
                //options.insert(.AnimateTopItemPosition)
                //options.insert(.AnimateCrossfade)
            }
            
            self.listView.transaction(deleteIndices: transition.deletions, insertIndicesAndItems: transition.insertions, updateIndicesAndItems: transition.updates, options: options, updateSizeAndInsets: nil, updateOpaqueState: HorizontalListContextResultsOpaqueState(entryCount: transition.entryCount, hasMore: transition.hasMore), completion: { [weak self] _ in
                if let strongSelf = self, firstTime {
                    let position = strongSelf.listView.position
                    let separatorPosition = strongSelf.separatorNode.layer.position
                    
                    strongSelf.listView.isHidden = false
                    strongSelf.separatorNode.isHidden = false
                    
                    strongSelf.listView.position = CGPoint(x: position.x, y: position.y + strongSelf.listView.bounds.size.width)
                    strongSelf.separatorNode.position = CGPoint(x: separatorPosition.x, y: separatorPosition.y + strongSelf.listView.bounds.size.width)
                    ContainedViewLayoutTransition.animated(duration: 0.3, curve: .spring).animateView {
                        strongSelf.listView.position = position
                        strongSelf.separatorNode.position = separatorPosition
                    }
                }
            })
        }
    }
    
    override func updateLayout(size: CGSize, leftInset: CGFloat, rightInset: CGFloat, bottomInset: CGFloat, transition: ContainedViewLayoutTransition, interfaceState: ChatPresentationInterfaceState) {
        let listHeight: CGFloat = 105.0
        
        transition.updateFrame(node: self.separatorNode, frame: CGRect(origin: CGPoint(x: 0.0, y: size.height - listHeight), size: CGSize(width: size.width, height: UIScreenPixel)))
        self.listView.bounds = CGRect(x: 0.0, y: 0.0, width: listHeight, height: size.width)
        
        //transition.updateFrame(node: self.listView, frame: CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height))
        
        transition.updatePosition(node: self.listView, position: CGPoint(x: size.width / 2.0, y: size.height - listHeight / 2.0))
        
        var insets = UIEdgeInsets()
        insets.top = leftInset
        insets.bottom = rightInset

        let (duration, curve) = listViewAnimationDurationAndCurve(transition: transition)
        let updateSizeAndInsets = ListViewUpdateSizeAndInsets(size: CGSize(width: listHeight, height: size.width), insets: insets, duration: duration, curve: curve)
        
        self.listView.transaction(deleteIndices: [], insertIndicesAndItems: [], updateIndicesAndItems: [], options: [.Synchronous, .LowLatency], scrollToItem: nil, updateSizeAndInsets: updateSizeAndInsets, stationaryItemRange: nil, updateOpaqueState: nil, completion: { _ in })
        
        if !hasValidLayout {
            hasValidLayout = true
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
        
        if self.theme !== interfaceState.theme {
            self.theme = interfaceState.theme
            self.separatorNode.backgroundColor = theme.list.itemPlainSeparatorColor
            self.listView.backgroundColor = theme.list.plainBackgroundColor
        }
    }
    
    override func animateOut(completion: @escaping () -> Void) {
        let position = self.listView.layer.position
        self.listView.layer.animatePosition(from: position, to: CGPoint(x: position.x, y: position.y + self.listView.bounds.size.width), duration: 0.3, timingFunction: kCAMediaTimingFunctionSpring, removeOnCompletion: false, completion: { _ in
            completion()
        })
        let separatorPosition = self.separatorNode.layer.position
        self.separatorNode.layer.animatePosition(from: separatorPosition, to: CGPoint(x: separatorPosition.x, y: separatorPosition.y + listView.bounds.size.width), duration: 0.3, timingFunction: kCAMediaTimingFunctionSpring, removeOnCompletion: false)
    }
    
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        let listViewBounds = self.listView.bounds
        let listViewPosition = self.listView.position
        let listViewFrame = CGRect(origin: CGPoint(x: listViewPosition.x - listViewBounds.height / 2.0, y: listViewPosition.y - listViewBounds.width / 2.0), size: CGSize(width: listViewBounds.height, height: listViewBounds.width))
        if !listViewFrame.contains(point) {
            return nil
        }
        return super.hitTest(point, with: event)
    }
}