import Foundation
import UIKit
import AsyncDisplayKit
import Postbox
import TelegramCore
import SwiftSignalKit
import Display
import TelegramPresentationData
import MergeLists
import AvatarNode
import AccountContext
import PeerPresenceStatusManager
import AppBundle

private let subtitleFont = Font.regular(12.0)

private struct SharePeerEntry: Comparable, Identifiable {
    let index: Int32
    let peer: RenderedPeer
    let presence: PeerPresence?
    let theme: PresentationTheme
    let strings: PresentationStrings
    
    var stableId: Int64 {
        return self.peer.peerId.toInt64()
    }
    
    static func ==(lhs: SharePeerEntry, rhs: SharePeerEntry) -> Bool {
        if lhs.index != rhs.index {
            return false
        }
        if lhs.peer != rhs.peer {
            return false
        }
        if let lhsPresence = lhs.presence, let rhsPresence = rhs.presence {
            if !lhsPresence.isEqual(to: rhsPresence) {
                return false
            }
        } else if (lhs.presence != nil) != (rhs.presence != nil) {
            return false
        }
        return true
    }
    
    static func <(lhs: SharePeerEntry, rhs: SharePeerEntry) -> Bool {
        return lhs.index < rhs.index
    }
    
    func item(account: Account, interfaceInteraction: ShareControllerInteraction) -> GridItem {
        return ShareControllerPeerGridItem(account: account, theme: self.theme, strings: self.strings, peer: self.peer, presence: self.presence, controllerInteraction: interfaceInteraction, search: false)
    }
}

private struct ShareGridTransaction {
    let deletions: [Int]
    let insertions: [GridNodeInsertItem]
    let updates: [GridNodeUpdateItem]
    let animated: Bool
}

private let avatarFont = UIFont(name: ".SFCompactRounded-Semibold", size: 17.0)!

private func preparedGridEntryTransition(account: Account, from fromEntries: [SharePeerEntry], to toEntries: [SharePeerEntry], interfaceInteraction: ShareControllerInteraction) -> ShareGridTransaction {
    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, interfaceInteraction: interfaceInteraction), previousIndex: $0.2) }
    let updates = updateIndices.map { GridNodeUpdateItem(index: $0.0, previousIndex: $0.2, item: $0.1.item(account: account, interfaceInteraction: interfaceInteraction)) }
    
    return ShareGridTransaction(deletions: deletions, insertions: insertions, updates: updates, animated: false)
}

final class SharePeersContainerNode: ASDisplayNode, ShareContentContainerNode {
    private let sharedContext: SharedAccountContext
    private let account: Account
    private let theme: PresentationTheme
    private let strings: PresentationStrings
    private let controllerInteraction: ShareControllerInteraction
    private let switchToAnotherAccount: () -> Void
    
    let accountPeer: Peer
    private let foundPeers = Promise<[RenderedPeer]>([])
    
    private let disposable = MetaDisposable()
    private var entries: [SharePeerEntry] = []
    private var enqueuedTransitions: [(ShareGridTransaction, Bool)] = []
    
    private let contentGridNode: GridNode
    private let contentTitleNode: ASTextNode
    private let contentSubtitleNode: ASTextNode
    private let contentTitleAccountNode: AvatarNode
    private let contentSeparatorNode: ASDisplayNode
    private let searchButtonNode: HighlightableButtonNode
    private let shareButtonNode: HighlightableButtonNode
    
    private var contentOffsetUpdated: ((CGFloat, ContainedViewLayoutTransition) -> Void)?
    
    var openSearch: (() -> Void)?
    var openShare: (() -> Void)?
    
    private var ensurePeerVisibleOnLayout: PeerId?
    private var validLayout: (CGSize, CGFloat)?
    private var overrideGridOffsetTransition: ContainedViewLayoutTransition?
    
    let peersValue = Promise<[(RenderedPeer, PeerPresence?)]>()
    
    init(sharedContext: SharedAccountContext, account: Account, switchableAccounts: [AccountWithInfo], theme: PresentationTheme, strings: PresentationStrings, peers: [(RenderedPeer, PeerPresence?)], accountPeer: Peer, controllerInteraction: ShareControllerInteraction, externalShare: Bool, switchToAnotherAccount: @escaping () -> Void) {
        self.sharedContext = sharedContext
        self.account = account
        self.theme = theme
        self.strings = strings
        self.controllerInteraction = controllerInteraction
        self.accountPeer = accountPeer
        self.switchToAnotherAccount = switchToAnotherAccount
        
        self.peersValue.set(.single(peers))
        
        let items: Signal<[SharePeerEntry], NoError> = combineLatest(self.peersValue.get(), self.foundPeers.get())
        |> map { initialPeers, foundPeers -> [SharePeerEntry] in
            var entries: [SharePeerEntry] = []
            var index: Int32 = 0
            
            var existingPeerIds: Set<PeerId> = Set()
            
            entries.append(SharePeerEntry(index: index, peer: RenderedPeer(peer: accountPeer), presence: nil, theme: theme, strings: strings))
            index += 1
            
            for peer in foundPeers.reversed() {
                entries.append(SharePeerEntry(index: index, peer: peer, presence: nil, theme: theme, strings: strings))
                existingPeerIds.insert(peer.peerId)
                index += 1
            }
            
            for (peer, presence) in initialPeers {
                if !existingPeerIds.contains(peer.peerId) {
                    entries.append(SharePeerEntry(index: index, peer: peer, presence: presence, theme: theme, strings: strings))
                    existingPeerIds.insert(peer.peerId)
                    index += 1
                }
            }
            return entries
        }
        
        self.contentGridNode = GridNode()
        
        self.contentTitleNode = ASTextNode()
        self.contentTitleNode.attributedText = NSAttributedString(string: strings.ShareMenu_ShareTo, font: Font.medium(20.0), textColor: self.theme.actionSheet.primaryTextColor)
        
        self.contentSubtitleNode = ASTextNode()
        self.contentSubtitleNode.maximumNumberOfLines = 1
        self.contentSubtitleNode.isUserInteractionEnabled = false
        self.contentSubtitleNode.displaysAsynchronously = false
        self.contentSubtitleNode.truncationMode = .byTruncatingTail
        self.contentSubtitleNode.attributedText = NSAttributedString(string: strings.ShareMenu_SelectChats, font: subtitleFont, textColor: self.theme.actionSheet.secondaryTextColor)
        
        self.contentTitleAccountNode = AvatarNode(font: avatarFont)
        var hasOtherAccounts = false
        if switchableAccounts.count > 1, let info = switchableAccounts.first(where: { $0.account.id == account.id }) {
            hasOtherAccounts = true
            self.contentTitleAccountNode.setPeer(account: account, theme: theme, peer: info.peer, emptyColor: nil, synchronousLoad: false)
        } else {
            self.contentTitleAccountNode.isHidden = true
        }
        
        self.searchButtonNode = HighlightableButtonNode()
        self.searchButtonNode.setImage(generateTintedImage(image: UIImage(bundleImageName: "Share/SearchIcon"), color: self.theme.actionSheet.controlAccentColor), for: [])
        
        self.shareButtonNode = HighlightableButtonNode()
        self.shareButtonNode.setImage(generateTintedImage(image: UIImage(bundleImageName: "Share/ShareIcon"), color: self.theme.actionSheet.controlAccentColor), for: [])
        
        self.contentSeparatorNode = ASDisplayNode()
        self.contentSeparatorNode.isLayerBacked = true
        self.contentSeparatorNode.displaysAsynchronously = false
        self.contentSeparatorNode.backgroundColor = self.theme.actionSheet.opaqueItemSeparatorColor
        
        if !externalShare || hasOtherAccounts {
            self.shareButtonNode.isHidden = true
        }
        
        super.init()
        
        self.addSubnode(self.contentGridNode)
        
        self.addSubnode(self.contentTitleNode)
        self.addSubnode(self.contentSubtitleNode)
        self.addSubnode(self.contentTitleAccountNode)
        self.addSubnode(self.searchButtonNode)
        self.addSubnode(self.shareButtonNode)
        self.addSubnode(self.contentSeparatorNode)
        
        let previousItems = Atomic<[SharePeerEntry]?>(value: [])
        self.disposable.set((items
        |> deliverOnMainQueue).start(next: { [weak self] entries in
            if let strongSelf = self {
                let previousEntries = previousItems.swap(entries)
                strongSelf.entries = entries
                
                let firstTime = previousEntries == nil
                let transition = preparedGridEntryTransition(account: account, from: previousEntries ?? [], to: entries, interfaceInteraction: controllerInteraction)
                strongSelf.enqueueTransition(transition, firstTime: firstTime)
            }
        }))

        self.contentGridNode.presentationLayoutUpdated = { [weak self] presentationLayout, transition in
            self?.gridPresentationLayoutUpdated(presentationLayout, transition: transition)
        }
        
        self.searchButtonNode.addTarget(self, action: #selector(self.searchPressed), forControlEvents: .touchUpInside)
        self.shareButtonNode.addTarget(self, action: #selector(self.sharePressed), forControlEvents: .touchUpInside)
        self.contentTitleAccountNode.view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.accountTapGesture(_:))))
    }
    
    deinit {
        self.disposable.dispose()
    }
    
    private func enqueueTransition(_ transition: ShareGridTransaction, firstTime: Bool) {
        self.enqueuedTransitions.append((transition, firstTime))
        
        if self.validLayout != nil {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
    }
    
    private func dequeueTransition() {
        if let (transition, _) = self.enqueuedTransitions.first {
            self.enqueuedTransitions.remove(at: 0)
            
            var itemTransition: ContainedViewLayoutTransition = .immediate
            if transition.animated {
                itemTransition = .animated(duration: 0.3, curve: .spring)
            }
            self.contentGridNode.transaction(GridNodeTransaction(deleteItems: transition.deletions, insertItems: transition.insertions, updateItems: transition.updates, scrollToItem: nil, updateLayout: nil, itemTransition: itemTransition, stationaryItems: .none, updateFirstIndexInSectionOffset: nil), completion: { _ in })
        }
    }
    
    func setEnsurePeerVisibleOnLayout(_ peerId: PeerId?) {
        self.ensurePeerVisibleOnLayout = peerId
    }
    
    func setContentOffsetUpdated(_ f: ((CGFloat, ContainedViewLayoutTransition) -> Void)?) {
        self.contentOffsetUpdated = f
    }
    
    private func calculateMetrics(size: CGSize) -> (topInset: CGFloat, itemWidth: CGFloat) {
        let itemCount = self.entries.count
        
        let itemInsets = UIEdgeInsets(top: 0.0, left: 12.0, bottom: 0.0, right: 12.0)
        let minimalItemWidth: CGFloat = size.width > 301.0 ? 70.0 : 60.0
        let effectiveWidth = size.width - itemInsets.left - itemInsets.right
        
        let itemsPerRow = Int(effectiveWidth / minimalItemWidth)
        
        let itemWidth = floor(effectiveWidth / CGFloat(itemsPerRow))
        var rowCount = itemCount / itemsPerRow + (itemCount % itemsPerRow != 0 ? 1 : 0)
        rowCount = max(rowCount, 4)
        
        let minimallyRevealedRowCount: CGFloat = 3.7
        let initiallyRevealedRowCount = min(minimallyRevealedRowCount, CGFloat(rowCount))
        
        let gridTopInset = max(0.0, size.height - floor(initiallyRevealedRowCount * itemWidth) - 14.0)
        return (gridTopInset, itemWidth)
    }
    
    func activate() {
    }
    
    func deactivate() {
    }
    
    func updateLayout(size: CGSize, bottomInset: CGFloat, transition: ContainedViewLayoutTransition) {
        let firstLayout = self.validLayout == nil
        self.validLayout = (size, bottomInset)
        
        let gridLayoutTransition: ContainedViewLayoutTransition
        if firstLayout {
            gridLayoutTransition = .immediate
            self.overrideGridOffsetTransition = transition
        } else {
            gridLayoutTransition = transition
            self.overrideGridOffsetTransition = nil
        }
        
        let (gridTopInset, itemWidth) = self.calculateMetrics(size: size)
        
        var scrollToItem: GridNodeScrollToItem?
        if let ensurePeerVisibleOnLayout = self.ensurePeerVisibleOnLayout {
            self.ensurePeerVisibleOnLayout = nil
            if let index = self.entries.firstIndex(where: { $0.peer.peerId == ensurePeerVisibleOnLayout }) {
                scrollToItem = GridNodeScrollToItem(index: index, position: .visible, transition: transition, directionHint: .up, adjustForSection: false)
            }
        }
        
        let gridSize = CGSize(width: size.width - 12.0, height: size.height)
        
        self.contentGridNode.transaction(GridNodeTransaction(deleteItems: [], insertItems: [], updateItems: [], scrollToItem: scrollToItem, updateLayout: GridNodeUpdateLayout(layout: GridNodeLayout(size: gridSize, insets: UIEdgeInsets(top: gridTopInset, left: 0.0, bottom: bottomInset, right: 0.0), preloadSize: 80.0, type: .fixed(itemSize: CGSize(width: itemWidth, height: itemWidth + 25.0), fillWidth: nil, lineSpacing: 0.0, itemSpacing: nil)), transition: gridLayoutTransition), itemTransition: .immediate, stationaryItems: .none, updateFirstIndexInSectionOffset: nil), completion: { _ in })
        gridLayoutTransition.updateFrame(node: self.contentGridNode, frame: CGRect(origin: CGPoint(x: floor((size.width - gridSize.width) / 2.0), y: 0.0), size: gridSize))
        
        if firstLayout {
            while !self.enqueuedTransitions.isEmpty {
                self.dequeueTransition()
            }
        }
    }
    
    private func gridPresentationLayoutUpdated(_ presentationLayout: GridNodeCurrentPresentationLayout, transition: ContainedViewLayoutTransition) {
        guard let (size, _) = self.validLayout else {
            return
        }
        
        let actualTransition = self.overrideGridOffsetTransition ?? transition
        self.overrideGridOffsetTransition = nil
        
        let titleAreaHeight: CGFloat = 64.0
        
        let rawTitleOffset = -titleAreaHeight - presentationLayout.contentOffset.y
        let titleOffset = max(-titleAreaHeight, rawTitleOffset)
        
        let titleSize = self.contentTitleNode.measure(size)
        let titleFrame = CGRect(origin: CGPoint(x: floor((size.width - titleSize.width) / 2.0), y: titleOffset + 15.0), size: titleSize)
        transition.updateFrame(node: self.contentTitleNode, frame: titleFrame)
        
        let subtitleSize = self.contentSubtitleNode.measure(CGSize(width: size.width - 44.0 * 2.0 - 8.0 * 2.0, height: titleAreaHeight))
        let subtitleFrame = CGRect(origin: CGPoint(x: floor((size.width - subtitleSize.width) / 2.0), y: titleOffset + 40.0), size: subtitleSize)
        var originalSubtitleFrame = self.contentSubtitleNode.frame
        originalSubtitleFrame.origin.x = subtitleFrame.origin.x
        originalSubtitleFrame.size = subtitleFrame.size
        self.contentSubtitleNode.frame = originalSubtitleFrame
        transition.updateFrame(node: self.contentSubtitleNode, frame: subtitleFrame)
        
        let titleButtonSize = CGSize(width: 44.0, height: 44.0)
        let searchButtonFrame = CGRect(origin: CGPoint(x: 12.0, y: titleOffset + 12.0), size: titleButtonSize)
        transition.updateFrame(node: self.searchButtonNode, frame: searchButtonFrame)
        
        let shareButtonFrame = CGRect(origin: CGPoint(x: size.width - titleButtonSize.width - 12.0, y: titleOffset + 12.0), size: titleButtonSize)
        transition.updateFrame(node: self.shareButtonNode, frame: shareButtonFrame)
        
        let avatarButtonSize = CGSize(width: 36.0, height: 36.0)
        let avatarButtonFrame = CGRect(origin: CGPoint(x: size.width - avatarButtonSize.width - 20.0, y: titleOffset + 15.0), size: avatarButtonSize)
        transition.updateFrame(node: self.contentTitleAccountNode, frame: avatarButtonFrame)
        
        transition.updateFrame(node: self.contentSeparatorNode, frame: CGRect(origin: CGPoint(x: 0.0, y: titleOffset + titleAreaHeight), size: CGSize(width: size.width, height: UIScreenPixel)))
        
        if rawTitleOffset.isLess(than: -titleAreaHeight) {
            self.contentSeparatorNode.alpha = 1.0
        } else {
            self.contentSeparatorNode.alpha = 0.0
        }
        
        self.contentOffsetUpdated?(presentationLayout.contentOffset.y, actualTransition)
    }
    
    func updateVisibleItemsSelection(animated: Bool) {
        self.contentGridNode.forEachItemNode { itemNode in
            if let itemNode = itemNode as? ShareControllerPeerGridItemNode {
                itemNode.updateSelection(animated: animated)
            }
        }
    }
    
    func updateFoundPeers() {
        self.foundPeers.set(.single(self.controllerInteraction.foundPeers))
    }
    
    func updateSelectedPeers() {
        var subtitleText = self.strings.ShareMenu_SelectChats
        if !self.controllerInteraction.selectedPeers.isEmpty {
            subtitleText = self.controllerInteraction.selectedPeers.reduce("", { string, peer in
                let text: String
                if peer.peerId == self.accountPeer.id {
                    text = self.strings.DialogList_SavedMessages
                } else {
                    text = peer.chatMainPeer?.displayTitle ?? ""
                }
                
                if !string.isEmpty {
                    return string + ", " + text
                } else {
                    return string + text
                }
            })
        }
        self.contentSubtitleNode.attributedText = NSAttributedString(string: subtitleText, font: subtitleFont, textColor: self.theme.actionSheet.secondaryTextColor)
        
        self.contentGridNode.forEachItemNode { itemNode in
            if let itemNode = itemNode as? ShareControllerPeerGridItemNode {
                itemNode.updateSelection(animated: true)
            }
        }
    }
    
    @objc func searchPressed() {
        self.openSearch?()
    }
    
    @objc func sharePressed() {
        self.openShare?()
    }
    
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        let nodes: [ASDisplayNode] = [self.searchButtonNode, self.shareButtonNode, self.contentTitleAccountNode]
        for node in nodes {
            let nodeFrame = node.frame
            if node.isHidden {
                continue
            }
            if let result = node.hitTest(point.offsetBy(dx: -nodeFrame.minX, dy: -nodeFrame.minY), with: event) {
                return result
            }
        }
        
        return super.hitTest(point, with: event)
    }
    
    @objc private func accountTapGesture(_ recognizer: UITapGestureRecognizer) {
        self.switchToAnotherAccount()
    }
}