import Foundation
import UIKit
import AsyncDisplayKit
import Postbox
import TelegramCore
import Display
import TelegramPresentationData
import TelegramUIPreferences
import MergeLists
import AccountContext
import ChatPresentationInterfaceState
import ChatControllerInteraction
import ItemListUI
import ChatContextQuery

private struct CommandChatInputContextPanelEntryStableId: Hashable {
    let command: PeerCommand
}

private struct CommandChatInputContextPanelEntry: Comparable, Identifiable {
    let index: Int
    let command: PeerCommand
    let theme: PresentationTheme
    
    var stableId: CommandChatInputContextPanelEntryStableId {
        return CommandChatInputContextPanelEntryStableId(command: self.command)
    }
    
    func withUpdatedTheme(_ theme: PresentationTheme) -> CommandChatInputContextPanelEntry {
        return CommandChatInputContextPanelEntry(index: self.index, command: self.command, theme: theme)
    }
    
    static func ==(lhs: CommandChatInputContextPanelEntry, rhs: CommandChatInputContextPanelEntry) -> Bool {
        return lhs.index == rhs.index && lhs.command == rhs.command && lhs.theme === rhs.theme
    }
    
    static func <(lhs: CommandChatInputContextPanelEntry, rhs: CommandChatInputContextPanelEntry) -> Bool {
        return lhs.index < rhs.index
    }
    
    func item(context: AccountContext, presentationData: PresentationData, commandSelected: @escaping (PeerCommand, Bool) -> Void) -> ListViewItem {
        return CommandChatInputPanelItem(context: context, presentationData: ItemListPresentationData(presentationData), command: self.command, commandSelected: commandSelected)
    }
}

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

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

final class CommandChatInputContextPanelNode: ChatInputContextPanelNode {
    private let listView: ListView
    private var currentEntries: [CommandChatInputContextPanelEntry]?
    
    private var enqueuedTransitions: [(CommandChatInputContextPanelTransition, Bool)] = []
    private var validLayout: (CGSize, CGFloat, CGFloat, CGFloat)?
    
    override init(context: AccountContext, theme: PresentationTheme, strings: PresentationStrings, fontSize: PresentationFontSize, chatPresentationContext: ChatPresentationContext) {
        self.listView = ListView()
        self.listView.isOpaque = false
        self.listView.stackFromBottom = true
        self.listView.keepBottomItemOverscrollBackground = theme.list.plainBackgroundColor
        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, chatPresentationContext: chatPresentationContext)
        
        self.isOpaque = false
        self.clipsToBounds = true
        
        self.addSubnode(self.listView)
    }
    
    func updateResults(_ results: [PeerCommand]) {
        var entries: [CommandChatInputContextPanelEntry] = []
        var index = 0
        var stableIds = Set<CommandChatInputContextPanelEntryStableId>()
        for command in results {
            let entry = CommandChatInputContextPanelEntry(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: [CommandChatInputContextPanelEntry]? , to: [CommandChatInputContextPanelEntry]) {
        let firstTime = self.currentEntries == nil
        let presentationData = self.context.sharedContext.currentPresentationData.with { $0 }
        let transition = preparedTransition(from: from ?? [], to: to, context: self.context, presentationData: presentationData, 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.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)
                        }
                        return (textInputState, inputMode)
                    }
                }
            }
        })
        self.currentEntries = to
        self.enqueueTransition(transition, firstTime: firstTime)
    }
    
    private func enqueueTransition(_ transition: CommandChatInputContextPanelTransition, 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 * 3.5)
        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
    }
}