import Foundation
import UIKit
import AsyncDisplayKit
import Postbox
import TelegramCore
import Display
import TelegramPresentationData
import TelegramUIPreferences
import MergeLists
import TextFormat
import AccountContext
import LocalizedPeerData
import ItemListUI

private struct MentionChatInputContextPanelEntry: Comparable, Identifiable {
    let index: Int
    let peer: Peer
    let revealed: Bool
    
    var stableId: Int64 {
        return self.peer.id.toInt64()
    }
    
    static func ==(lhs: MentionChatInputContextPanelEntry, rhs: MentionChatInputContextPanelEntry) -> Bool {
        return lhs.index == rhs.index && lhs.peer.isEqual(rhs.peer) && lhs.revealed == rhs.revealed
    }
    
    static func <(lhs: MentionChatInputContextPanelEntry, rhs: MentionChatInputContextPanelEntry) -> Bool {
        return lhs.index < rhs.index
    }
    
    func item(context: AccountContext, presentationData: PresentationData, inverted: Bool, setPeerIdRevealed: @escaping (PeerId?) -> Void, peerSelected: @escaping (Peer) -> Void, removeRequested: @escaping (PeerId) -> Void) -> ListViewItem {
        return MentionChatInputPanelItem(context: context, presentationData: ItemListPresentationData(presentationData), inverted: inverted, peer: self.peer, revealed: self.revealed, setPeerIdRevealed: setPeerIdRevealed, peerSelected: peerSelected, removeRequested: removeRequested)
    }
}

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

private func preparedTransition(from fromEntries: [MentionChatInputContextPanelEntry], to toEntries: [MentionChatInputContextPanelEntry], context: AccountContext, presentationData: PresentationData, inverted: Bool, forceUpdate: Bool, setPeerIdRevealed: @escaping (PeerId?) -> Void, peerSelected: @escaping (Peer) -> Void, removeRequested: @escaping (PeerId) -> Void) -> CommandChatInputContextPanelTransition {
    let (deleteIndices, indicesAndItems, updateIndices) = mergeListsStableWithUpdates(leftList: fromEntries, rightList: toEntries, allUpdated: forceUpdate)
    
    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, inverted: inverted, setPeerIdRevealed: setPeerIdRevealed, peerSelected: peerSelected, removeRequested: removeRequested), directionHint: nil) }
    let updates = updateIndices.map { ListViewUpdateItem(index: $0.0, previousIndex: $0.2, item: $0.1.item(context: context, presentationData: presentationData, inverted: inverted, setPeerIdRevealed: setPeerIdRevealed, peerSelected: peerSelected, removeRequested: removeRequested), directionHint: nil) }
    
    return CommandChatInputContextPanelTransition(deletions: deletions, insertions: insertions, updates: updates)
}

enum MentionChatInputContextPanelMode {
    case input
    case search
}

final class MentionChatInputContextPanelNode: ChatInputContextPanelNode {
    let mode: MentionChatInputContextPanelMode
    
    private let listView: ListView
    private var currentEntries: [MentionChatInputContextPanelEntry]?
    
    private var currentResults: [Peer] = []
    private var revealedPeerId: PeerId?
    
    private var enqueuedTransitions: [(CommandChatInputContextPanelTransition, Bool)] = []
    private var validLayout: (CGSize, CGFloat, CGFloat, CGFloat)?
    
    init(context: AccountContext, theme: PresentationTheme, strings: PresentationStrings, fontSize: PresentationFontSize, mode: MentionChatInputContextPanelMode) {
        self.mode = mode
        
        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)
        
        self.isOpaque = false
        self.clipsToBounds = true
        
        self.addSubnode(self.listView)
        
        if mode == .search {
            self.transform = CATransform3DMakeRotation(CGFloat(Double.pi), 0.0, 0.0, 1.0)
        }
    }
    
    func updateResults(_ results: [Peer]) {
        self.currentResults = results
        
        var entries: [MentionChatInputContextPanelEntry] = []
        var index = 0
        var peerIdSet = Set<Int64>()
        for peer in results {
            let peerId = peer.id.toInt64()
            if peerIdSet.contains(peerId) {
                continue
            }
            peerIdSet.insert(peerId)
            entries.append(MentionChatInputContextPanelEntry(index: index, peer: peer, revealed: self.revealedPeerId == peer.id))
            index += 1
        }
        self.updateToEntries(entries: entries, forceUpdate: false)
    }
    
    private func updateToEntries(entries: [MentionChatInputContextPanelEntry], forceUpdate: Bool) {
        let firstTime = self.currentEntries == nil
        let presentationData = self.context.sharedContext.currentPresentationData.with { $0 }
        let transition = preparedTransition(from: self.currentEntries ?? [], to: entries, context: self.context, presentationData: presentationData, inverted: self.mode == .search, forceUpdate: forceUpdate, setPeerIdRevealed: { [weak self] peerId in
            if let strongSelf = self {
                strongSelf.revealedPeerId = peerId
                strongSelf.updateResults(strongSelf.currentResults)
            }
        }, peerSelected: { [weak self] peer in
            if let strongSelf = self, let interfaceInteraction = strongSelf.interfaceInteraction {
                switch strongSelf.mode {
                    case .input:
                        interfaceInteraction.updateTextInputStateAndMode { textInputState, inputMode in
                            var mentionQueryRange: NSRange?
                            inner: for (range, type, _) in textInputStateContextQueryRangeAndType(textInputState) {
                                if type == [.mention] {
                                    mentionQueryRange = range
                                    break inner
                                }
                            }
                            
                            if let range = mentionQueryRange {
                                let inputText = NSMutableAttributedString(attributedString: textInputState.inputText)
                                
                                if let addressName = peer.addressName, !addressName.isEmpty {
                                    let replacementText = addressName + " "
                                    
                                    inputText.replaceCharacters(in: range, with: replacementText)
                                    
                                    let selectionPosition = range.lowerBound + (replacementText as NSString).length
                                    
                                    return (ChatTextInputState(inputText: inputText, selectionRange: selectionPosition ..< selectionPosition), inputMode)
                                } else if !peer.compactDisplayTitle.isEmpty {
                                    let replacementText = NSMutableAttributedString()
                                    replacementText.append(NSAttributedString(string: peer.compactDisplayTitle, attributes: [ChatTextInputAttributes.textMention: ChatTextInputTextMentionAttribute(peerId: peer.id)]))
                                    replacementText.append(NSAttributedString(string: " "))
                                    
                                    let updatedRange = NSRange(location: range.location - 1, length: range.length + 1)
                                    
                                    inputText.replaceCharacters(in: updatedRange, with: replacementText)
                                    
                                    let selectionPosition = updatedRange.lowerBound + replacementText.length
                                    
                                    return (ChatTextInputState(inputText: inputText, selectionRange: selectionPosition ..< selectionPosition), inputMode)
                                }
                            }
                            return (textInputState, inputMode)
                        }
                    case .search:
                        interfaceInteraction.beginMessageSearch(.member(peer), "")
                }
            }
        }, removeRequested: { [weak self] peerId in
            if let strongSelf = self {
                let _ = strongSelf.context.engine.peers.removeRecentlyUsedInlineBot(peerId: peerId).start()
                
                strongSelf.revealedPeerId = nil
                strongSelf.currentResults = strongSelf.currentResults.filter { $0.id != peerId }
                strongSelf.updateResults(strongSelf.currentResults)
            }
        })
        self.currentEntries = entries
        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: validLayout.0, 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 {
        var 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)
        
        if self.theme !== interfaceState.theme {
            self.theme = interfaceState.theme
            self.listView.keepBottomItemOverscrollBackground = self.theme.list.plainBackgroundColor
            
            if let currentEntries = self.currentEntries {
                self.updateToEntries(entries: currentEntries, forceUpdate: true)
            }
        }
        
        var insets = UIEdgeInsets()
        insets.top = 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()
            }
        }
    }
    
    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
    }
}