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

private struct CommandMenuChatInputContextPanelEntryStableId: Hashable {
    let command: PeerCommand
}

private struct CommandMenuChatInputContextPanelEntry: Comparable, Identifiable {
    let index: Int
    let command: PeerCommand
    let theme: PresentationTheme
    
    var stableId: CommandMenuChatInputContextPanelEntryStableId {
        return CommandMenuChatInputContextPanelEntryStableId(command: self.command)
    }
    
    func withUpdatedTheme(_ theme: PresentationTheme) -> CommandMenuChatInputContextPanelEntry {
        return CommandMenuChatInputContextPanelEntry(index: self.index, command: self.command, theme: theme)
    }
    
    static func ==(lhs: CommandMenuChatInputContextPanelEntry, rhs: CommandMenuChatInputContextPanelEntry) -> Bool {
        return lhs.index == rhs.index && lhs.command == rhs.command && lhs.theme === rhs.theme
    }
    
    static func <(lhs: CommandMenuChatInputContextPanelEntry, rhs: CommandMenuChatInputContextPanelEntry) -> Bool {
        return lhs.index < rhs.index
    }
    
    func item(context: AccountContext, fontSize: PresentationFontSize, commandSelected: @escaping (PeerCommand, Bool) -> Void) -> ListViewItem {
        return CommandMenuChatInputPanelItem(context: context, theme: self.theme, fontSize: fontSize, command: self.command, commandSelected: commandSelected)
    }
}

private struct CommandMenuChatInputContextPanelTransition {
    let deletions: [ListViewDeleteItem]
    let insertions: [ListViewInsertItem]
    let updates: [ListViewUpdateItem]
}

private func preparedTransition(from fromEntries: [CommandMenuChatInputContextPanelEntry], to toEntries: [CommandMenuChatInputContextPanelEntry], context: AccountContext, fontSize: PresentationFontSize, commandSelected: @escaping (PeerCommand, Bool) -> Void) -> CommandMenuChatInputContextPanelTransition {
    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(context: context, fontSize: fontSize, commandSelected: commandSelected), directionHint: nil) }
    let updates = updateIndices.map { ListViewUpdateItem(index: $0.0, previousIndex: $0.2, item: $0.1.item(context: context, fontSize: fontSize, commandSelected: commandSelected), directionHint: nil) }
    
    return CommandMenuChatInputContextPanelTransition(deletions: deletions, insertions: insertions, updates: updates)
}

final class CommandMenuChatInputContextPanelNode: ChatInputContextPanelNode {
    private let listView: ListView
    private var currentEntries: [CommandMenuChatInputContextPanelEntry]?
    
    private var enqueuedTransitions: [(CommandMenuChatInputContextPanelTransition, Bool)] = []
    private var validLayout: (CGSize, CGFloat, CGFloat, CGFloat)?
    
    private let disposable = MetaDisposable()
    
    init(context: AccountContext, theme: PresentationTheme, strings: PresentationStrings, fontSize: PresentationFontSize, peerId: PeerId) {
        self.listView = ListView()
        self.listView.clipsToBounds = false
        self.listView.isOpaque = false
        self.listView.stackFromBottom = true
        self.listView.limitHitTestToNodes = true
        self.listView.view.disablesInteractiveTransitionGestureRecognizer = 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.disposable.set((context.engine.peers.peerCommands(id: peerId)
        |> deliverOnMainQueue).start(next: { [weak self] results in
            if let strongSelf = self {
                strongSelf.updateResults(results.commands)
            }
        }))
    }
    
    deinit {
        self.disposable.dispose()
    }
    
    func updateResults(_ results: [PeerCommand]) {
        var entries: [CommandMenuChatInputContextPanelEntry] = []
        var index = 0
        var stableIds = Set<CommandMenuChatInputContextPanelEntryStableId>()
        for command in results {
            let entry = CommandMenuChatInputContextPanelEntry(index: index, command: command, theme: self.theme)
            if stableIds.contains(entry.stableId) {
                continue
            }
            stableIds.insert(entry.stableId)
            entries.append(entry)
            index += 1
        }
        self.prepareTransition(from: self.currentEntries ?? [], to: entries)
    }
    
    private func prepareTransition(from: [CommandMenuChatInputContextPanelEntry]? , to: [CommandMenuChatInputContextPanelEntry]) {
        let firstTime = self.currentEntries == nil
        let transition = preparedTransition(from: from ?? [], to: to, context: self.context, fontSize: self.fontSize, commandSelected: { [weak self] command, sendImmediately in
            if let strongSelf = self, let interfaceInteraction = strongSelf.interfaceInteraction {
                if sendImmediately {
                    interfaceInteraction.sendBotCommand(command.peer, "/" + command.command.text)
                } else {
                    interfaceInteraction.updateShowCommands { _ in return false }
                    interfaceInteraction.updateTextInputStateAndMode { textInputState, inputMode in
                        var commandQueryRange: NSRange?
                        inner: for (range, type, _) in textInputStateContextQueryRangeAndType(textInputState) {
                            if type == [.command] {
                                commandQueryRange = range
                                break inner
                            }
                        }
                        if let range = commandQueryRange {
                            let inputText = NSMutableAttributedString(attributedString: textInputState.inputText)
                            
                            let replacementText = command.command.text + " "
                            inputText.replaceCharacters(in: range, with: replacementText)
                            
                            let selectionPosition = range.lowerBound + (replacementText as NSString).length
                            
                            return (ChatTextInputState(inputText: inputText, selectionRange: selectionPosition ..< selectionPosition), inputMode)
                        } else {
                            let inputText = NSMutableAttributedString(string: "/" + command.command.text + " ")
                            let selectionPosition = (inputText.string as NSString).length + 1
                            return (ChatTextInputState(inputText: inputText, selectionRange: selectionPosition ..< selectionPosition), inputMode)
                        }
                    }
                }
            }
        })
        self.currentEntries = to
        self.enqueueTransition(transition, firstTime: firstTime)
    }
    
    private func enqueueTransition(_ transition: CommandMenuChatInputContextPanelTransition, firstTime: Bool) {
        enqueuedTransitions.append((transition, firstTime))
        
        if self.validLayout != nil {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
    }
    
    private func dequeueTransition() {
        if let validLayout = self.validLayout, let (transition, firstTime) = self.enqueuedTransitions.first {
            self.enqueuedTransitions.remove(at: 0)
            
            var options = ListViewDeleteAndInsertOptions()
            if firstTime {
                //options.insert(.Synchronous)
                //options.insert(.LowLatency)
            } else {
                options.insert(.AnimateTopItemPosition)
                options.insert(.AnimateCrossfade)
            }
            
            var insets = UIEdgeInsets()
            insets.top = topInsetForLayout(size: validLayout.0)
            insets.left = validLayout.1
            insets.right = validLayout.2
            
            let updateSizeAndInsets = ListViewUpdateSizeAndInsets(size: self.listView.bounds.size, insets: insets, duration: 0.0, curve: .Default(duration: nil))
            
            self.listView.transaction(deleteIndices: transition.deletions, insertIndicesAndItems: transition.insertions, updateIndicesAndItems: transition.updates, options: options, updateSizeAndInsets: updateSizeAndInsets, updateOpaqueState: nil, completion: { [weak self] _ in
                if let strongSelf = self, firstTime {
                    var topItemOffset: CGFloat?
                    strongSelf.listView.forEachItemNode { itemNode in
                        if topItemOffset == nil {
                            topItemOffset = itemNode.frame.minY
                        }
                    }
                    
                    if let topItemOffset = topItemOffset {
                        let position = strongSelf.listView.layer.position
                        strongSelf.listView.position = CGPoint(x: position.x, y: position.y + (strongSelf.listView.bounds.size.height - topItemOffset))
                        ContainedViewLayoutTransition.animated(duration: 0.3, curve: .spring).animateView {
                            strongSelf.listView.position = position
                        }
                    }
                }
            })
        }
    }
    
    private func topInsetForLayout(size: CGSize) -> CGFloat {
        let minimumItemHeights: CGFloat = floor(MentionChatInputPanelItemNode.itemHeight * 4.7)
        return max(size.height - minimumItemHeights, 0.0)
    }
    
    override func updateLayout(size: CGSize, leftInset: CGFloat, rightInset: CGFloat, bottomInset: CGFloat, transition: ContainedViewLayoutTransition, interfaceState: ChatPresentationInterfaceState) {
        let hadValidLayout = self.validLayout != nil
        self.validLayout = (size, leftInset, rightInset, bottomInset)
        
        var insets = UIEdgeInsets()
        insets.top = self.topInsetForLayout(size: size)
        insets.left = leftInset
        insets.right = rightInset
        
        transition.updateFrame(node: self.listView, frame: CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height))
        
        let (duration, curve) = listViewAnimationDurationAndCurve(transition: transition)
        let updateSizeAndInsets = ListViewUpdateSizeAndInsets(size: size, 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 !hadValidLayout {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
        
        if self.theme !== interfaceState.theme {
            self.theme = interfaceState.theme
            self.listView.keepBottomItemOverscrollBackground = self.theme.list.plainBackgroundColor
            
            let new = self.currentEntries?.map({$0.withUpdatedTheme(interfaceState.theme)}) ?? []
            prepareTransition(from: self.currentEntries, to: new)
        }
    }
    
    override func animateOut(completion: @escaping () -> Void) {
        var topItemOffset: CGFloat?
        self.listView.forEachItemNode { itemNode in
            if topItemOffset == nil {
                topItemOffset = itemNode.frame.minY
            }
        }
        
        if let topItemOffset = topItemOffset {
            let position = self.listView.layer.position
            self.listView.layer.animatePosition(from: position, to: CGPoint(x: position.x, y: position.y + (self.listView.bounds.size.height - topItemOffset)), duration: 0.3, timingFunction: kCAMediaTimingFunctionSpring, removeOnCompletion: false, completion: { _ in
                completion()
            })
        } else {
            completion()
        }
    }
    
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        let listViewFrame = self.listView.frame
        return self.listView.hitTest(CGPoint(x: point.x - listViewFrame.minX, y: point.y - listViewFrame.minY), with: event)
    }
    
    override var topItemFrame: CGRect? {
        var topItemFrame: CGRect?
        self.listView.forEachItemNode { itemNode in
            if topItemFrame == nil {
                topItemFrame = itemNode.frame
            }
        }
        return topItemFrame
    }
}