import Foundation
import UIKit
import Display
import SwiftSignalKit
import AsyncDisplayKit
import Postbox
import TelegramCore
import SyncCore
import AVFoundation
import ContextUI

private final class MultiplexedVideoTrackingNode: ASDisplayNode {
    var inHierarchyUpdated: ((Bool) -> Void)?
    
    override func willEnterHierarchy() {
        super.willEnterHierarchy()
        
        self.inHierarchyUpdated?(true)
    }
    
    override func didExitHierarchy() {
        super.didExitHierarchy()
        
        self.inHierarchyUpdated?(false)
    }
}

private final class VisibleVideoItem {
    let fileReference: FileMediaReference
    let frame: CGRect
    
    init(fileReference: FileMediaReference, frame: CGRect) {
        self.fileReference = fileReference
        self.frame = frame
    }
}

final class MultiplexedVideoNode: ASDisplayNode, UIScrollViewDelegate {
    private let account: Account
    private let trackingNode: MultiplexedVideoTrackingNode
    var didScroll: ((CGFloat, CGFloat) -> Void)?
    var didEndScrolling: (() -> Void)?
    
    var topInset: CGFloat = 0.0 {
        didSet {
            self.setNeedsLayout()
        }
    }
    
    var bottomInset: CGFloat = 0.0 {
        didSet {
            self.setNeedsLayout()
        }
    }
    
    var idealHeight: CGFloat = 93.0 {
        didSet {
            self.setNeedsLayout()
        }
    }
    
    var files: [FileMediaReference] = [] {
        didSet {
            let startTime = CFAbsoluteTimeGetCurrent()
            self.updateVisibleItems()
            print("MultiplexedVideoNode files updateVisibleItems: \((CFAbsoluteTimeGetCurrent() - startTime) * 1000.0) ms")
        }
    }
    private var displayItems: [VisibleVideoItem] = []
    private var visibleThumbnailLayers: [MediaId: SoftwareVideoThumbnailLayer] = [:]
    private var statusDisposable: [MediaId : MetaDisposable] = [:]

    private let contextContainerNode: ContextControllerSourceNode
    let scrollNode: ASScrollNode
    
    private var visibleLayers: [MediaId: (SoftwareVideoLayerFrameManager, SampleBufferLayer)] = [:]
    
    private var displayLink: CADisplayLink!
    private var timeOffset = 0.0
    private var pauseTime = 0.0
    
    private let timebase: CMTimebase
    
    var fileSelected: ((FileMediaReference, ASDisplayNode, CGRect) -> Void)?
    var fileContextMenu: ((FileMediaReference, ASDisplayNode, CGRect, ContextGesture) -> Void)?
    var enableVideoNodes = false
    
    init(account: Account) {
        self.account = account
        self.trackingNode = MultiplexedVideoTrackingNode()
        self.trackingNode.isLayerBacked = true
        
        var timebase: CMTimebase?
        CMTimebaseCreateWithMasterClock(allocator: nil, masterClock: CMClockGetHostTimeClock(), timebaseOut: &timebase)
        CMTimebaseSetRate(timebase!, rate: 0.0)
        self.timebase = timebase!
        
        self.contextContainerNode = ContextControllerSourceNode()
        self.scrollNode = ASScrollNode()
        
        super.init()
        
        self.isOpaque = true
        self.scrollNode.view.showsVerticalScrollIndicator = false
        self.scrollNode.view.showsHorizontalScrollIndicator = false
        self.scrollNode.view.alwaysBounceVertical = true
        
        self.addSubnode(self.trackingNode)
        self.addSubnode(self.contextContainerNode)
        self.contextContainerNode.addSubnode(self.scrollNode)
        
        class DisplayLinkProxy: NSObject {
            weak var target: MultiplexedVideoNode?
            init(target: MultiplexedVideoNode) {
                self.target = target
            }
            
            @objc func displayLinkEvent() {
                self.target?.displayLinkEvent()
            }
        }
        
        self.displayLink = CADisplayLink(target: DisplayLinkProxy(target: self), selector: #selector(DisplayLinkProxy.displayLinkEvent))
        self.displayLink.add(to: RunLoop.main, forMode: .common)
        if #available(iOS 10.0, *) {
            self.displayLink.preferredFramesPerSecond = 25
        } else {
            self.displayLink.frameInterval = 2
        }
        self.displayLink.isPaused = true
        
        self.trackingNode.inHierarchyUpdated = { [weak self] value in
            if let strongSelf = self {
                if !value {
                    CMTimebaseSetRate(strongSelf.timebase, rate: 0.0)
                } else {
                    CMTimebaseSetRate(strongSelf.timebase, rate: 1.0)
                }
                strongSelf.displayLink.isPaused = !value
                if value && !strongSelf.enableVideoNodes {
                    strongSelf.enableVideoNodes = true
                    strongSelf.validVisibleItemsOffset = nil
                    strongSelf.updateImmediatelyVisibleItems()
                } else if !value {
                    strongSelf.enableVideoNodes = false
                }
            }
        }
        
        self.scrollNode.view.delegate = self
        
        let recognizer = UITapGestureRecognizer(target: self, action: #selector(self.tapGesture(_:)))
        self.view.addGestureRecognizer(recognizer)
        
        var gestureLocation: CGPoint?
        
        self.contextContainerNode.shouldBegin = { [weak self] point in
            guard let strongSelf = self else {
                return false
            }
            gestureLocation = point
            return strongSelf.fileAt(point: point) != nil
        }
        
        self.contextContainerNode.activated = { [weak self] gesture, _ in
            guard let strongSelf = self, let gestureLocation = gestureLocation else {
                return
            }
            if let (file, rect) = strongSelf.fileAt(point: gestureLocation) {
                strongSelf.fileContextMenu?(file, strongSelf, rect.offsetBy(dx: 0.0, dy: -strongSelf.scrollNode.bounds.minY), gesture)
            } else {
                gesture.cancel()
            }
        }
        
        self.contextContainerNode.customActivationProgress = { [weak self] progress, update in
            guard let strongSelf = self, let gestureLocation = gestureLocation else {
                return
            }
            /*let minScale: CGFloat = (strongSelf.bounds.width - 10.0) / strongSelf.bounds.width
            let currentScale = 1.0 * (1.0 - progress) + minScale * progress
            switch update {
            case .update:
                strongSelf.layer.sublayerTransform = CATransform3DMakeScale(currentScale, currentScale, 1.0)
            case .begin:
                strongSelf.layer.sublayerTransform = CATransform3DMakeScale(currentScale, currentScale, 1.0)
            case let .ended(previousProgress):
                let previousScale = 1.0 * (1.0 - previousProgress) + minScale * previousProgress
                strongSelf.layer.sublayerTransform = CATransform3DMakeScale(currentScale, currentScale, 1.0)
                strongSelf.layer.animateSpring(from: previousScale as NSNumber, to: currentScale as NSNumber, keyPath: "sublayerTransform.scale", duration: 0.5, delay: 0.0, initialVelocity: 0.0, damping: 90.0)
            }*/
        }
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    deinit {
        self.displayLink.invalidate()
        self.displayLink.isPaused = true
        for(_, disposable) in self.statusDisposable {
            disposable.dispose()
        }
        for (_, value) in self.visibleLayers {
            value.1.isFreed = true
        }
        clearSampleBufferLayerPoll()
    }
    
    private func displayLinkEvent() {
        let timestamp = CMTimebaseGetTime(self.timebase).seconds
        for (_, (manager, _)) in self.visibleLayers {
            manager.tick(timestamp: timestamp)
        }
    }
    
    private var validSize: CGSize?
    func updateLayout(size: CGSize, transition: ContainedViewLayoutTransition) {
        if self.validSize == nil || !self.validSize!.equalTo(size) {
            self.validSize = size
            self.contextContainerNode.frame = CGRect(origin: CGPoint(), size: size)
            self.scrollNode.frame = CGRect(origin: CGPoint(), size: size)
            let startTime = CFAbsoluteTimeGetCurrent()
            self.updateVisibleItems(transition: transition)
            print("MultiplexedVideoNode layout updateVisibleItems: \((CFAbsoluteTimeGetCurrent() - startTime) * 1000.0) ms")
        }
    }
    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        self.updateImmediatelyVisibleItems()
        self.didScroll?(scrollView.contentOffset.y, scrollView.contentSize.height)
    }
    
    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        self.didEndScrolling?()
    }
    
    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if !decelerate {
            self.didEndScrolling?()
        }
    }
    
    private var validVisibleItemsOffset: CGFloat?
    private func updateImmediatelyVisibleItems(ensureFrames: Bool = false) {
        let visibleBounds = self.scrollNode.bounds
        let visibleThumbnailBounds = visibleBounds.insetBy(dx: 0.0, dy: -350.0)
        
        if let validVisibleItemsOffset = self.validVisibleItemsOffset, validVisibleItemsOffset.isEqual(to: visibleBounds.origin.y) {
            return
        }
        self.validVisibleItemsOffset = visibleBounds.origin.y
        let minVisibleY = visibleBounds.minY
        let maxVisibleY = visibleBounds.maxY
        
        let minVisibleThumbnailY = visibleThumbnailBounds.minY
        let maxVisibleThumbnailY = visibleThumbnailBounds.maxY
        
        var visibleThumbnailIds = Set<MediaId>()
        var visibleIds = Set<MediaId>()
        
        for item in self.displayItems {
            if item.frame.maxY < minVisibleThumbnailY {
                continue;
            }
            if item.frame.minY > maxVisibleThumbnailY {
                break;
            }
            
            visibleThumbnailIds.insert(item.fileReference.media.fileId)
            
            if let thumbnailLayer = self.visibleThumbnailLayers[item.fileReference.media.fileId] {
                if ensureFrames {
                    thumbnailLayer.frame = item.frame
                }
            } else {
                let thumbnailLayer = SoftwareVideoThumbnailLayer(account: self.account, fileReference: item.fileReference)
                thumbnailLayer.frame = item.frame
                self.scrollNode.layer.addSublayer(thumbnailLayer)
                self.visibleThumbnailLayers[item.fileReference.media.fileId] = thumbnailLayer
            }
            
            let progressSize = CGSize(width: 24.0, height: 24.0)
            let progressFrame =  CGRect(origin: CGPoint(x: item.frame.midX - progressSize.width / 2.0, y: item.frame.midY - progressSize.height / 2.0), size: progressSize)
            
            if item.frame.maxY < minVisibleY {
                continue
            }
            if item.frame.minY > maxVisibleY {
                continue
            }
            
            visibleIds.insert(item.fileReference.media.fileId)
            
            if let (_, layerHolder) = self.visibleLayers[item.fileReference.media.fileId] {
                if ensureFrames {
                    layerHolder.layer.frame = item.frame
                }
            } else {
                let layerHolder = takeSampleBufferLayer()
                layerHolder.layer.videoGravity = AVLayerVideoGravity.resizeAspectFill
                layerHolder.layer.frame = item.frame
                self.scrollNode.layer.addSublayer(layerHolder.layer)
                let manager = SoftwareVideoLayerFrameManager(account: self.account, fileReference: item.fileReference, layerHolder: layerHolder)
                self.visibleLayers[item.fileReference.media.fileId] = (manager, layerHolder)
                self.visibleThumbnailLayers[item.fileReference.media.fileId]?.ready = { [weak self] in
                    if let strongSelf = self {
                        strongSelf.visibleLayers[item.fileReference.media.fileId]?.0.start()
                    }
                }
            }
        }
        
        var removeIds: [MediaId] = []
        for id in self.visibleLayers.keys {
            if !visibleIds.contains(id) {
                removeIds.append(id)
            }
        }
        
        var removeThumbnailIds: [MediaId] = []
        for id in self.visibleThumbnailLayers.keys {
            if !visibleThumbnailIds.contains(id) {
                removeThumbnailIds.append(id)
            }
        }
        
        /*var removeProgressIds: [MediaId] = []
        for id in self.visibleProgressNodes.keys {
            if !visibleIds.contains(id) {
                removeProgressIds.append(id)
            }
        }*/
        
        for id in removeIds {
            let (_, layerHolder) = self.visibleLayers[id]!
            layerHolder.layer.removeFromSuperlayer()
            self.visibleLayers.removeValue(forKey: id)
        }
        
        for id in removeThumbnailIds {
            let thumbnailLayer = self.visibleThumbnailLayers[id]!
            thumbnailLayer.removeFromSuperlayer()
            self.visibleThumbnailLayers.removeValue(forKey: id)
        }
        
        /*for id in removeProgressIds {
            let progressNode = self.visibleProgressNodes[id]!
            progressNode.removeFromSupernode()
            self.visibleProgressNodes.removeValue(forKey: id)
            self.statusDisposable.removeValue(forKey: id)?.dispose()
        }*/
    }
    
    private func updateVisibleItems(transition: ContainedViewLayoutTransition = .immediate) {
        let drawableSize = self.scrollNode.bounds.size
        if !drawableSize.width.isZero {
            var displayItems: [VisibleVideoItem] = []
            
            let idealHeight = self.idealHeight
            
            var weights: [Int] = []
            var totalItemSize: CGFloat = 0.0
            for item in self.files {
                let aspectRatio: CGFloat
                if let dimensions = item.media.dimensions {
                    aspectRatio = dimensions.cgSize.width / dimensions.cgSize.height
                } else {
                    aspectRatio = 1.0
                }
                weights.append(Int(aspectRatio * 100))
                totalItemSize += aspectRatio * idealHeight
            }
            
            let numberOfRows = max(Int(round(totalItemSize / drawableSize.width)), 1)
            
            let partition = linearPartitionForWeights(weights, numberOfPartitions:numberOfRows)
            
            var i = 0
            var offset = CGPoint(x: 0.0, y: self.topInset)
            var previousItemSize: CGFloat = 0.0
            var contentMaxValueInScrollDirection: CGFloat = self.topInset
            let maxWidth = drawableSize.width
            
            let minimumInteritemSpacing: CGFloat = 1.0
            let minimumLineSpacing: CGFloat = 1.0
            
            let viewportWidth: CGFloat = drawableSize.width
            
            let preferredRowSize = idealHeight
            
            var rowIndex = -1
            for row in partition {
                rowIndex += 1
                
                var summedRatios: CGFloat = 0.0
                
                var j = i
                var n = i + row.count
                
                while j < n {
                    let aspectRatio: CGFloat
                    if let dimensions = self.files[j].media.dimensions {
                        aspectRatio = dimensions.cgSize.width / dimensions.cgSize.height
                    } else {
                        aspectRatio = 1.0
                    }
                    
                    summedRatios += aspectRatio
                    
                    j += 1
                }
                
                var rowSize = drawableSize.width - (CGFloat(row.count - 1) * minimumInteritemSpacing)
                
                if rowIndex == partition.count - 1 {
                    if row.count < 2 {
                        rowSize = floor(viewportWidth / 3.0) - (CGFloat(row.count - 1) * minimumInteritemSpacing)
                    } else if row.count < 3 {
                        rowSize = floor(viewportWidth * 2.0 / 3.0) - (CGFloat(row.count - 1) * minimumInteritemSpacing)
                    }
                }
                
                j = i
                n = i + row.count
                
                while j < n {
                    let aspectRatio: CGFloat
                    if let dimensions = self.files[j].media.dimensions {
                        aspectRatio = dimensions.cgSize.width / dimensions.cgSize.height
                    } else {
                        aspectRatio = 1.0
                    }
                    let preferredAspectRatio = aspectRatio
                    
                    let actualSize = CGSize(width: round(rowSize / summedRatios * (preferredAspectRatio)), height: preferredRowSize)
                    
                    var frame = CGRect(x: offset.x, y: offset.y, width: actualSize.width, height: actualSize.height)
                    if frame.origin.x + frame.size.width >= maxWidth - 2.0 {
                        frame.size.width = max(1.0, maxWidth - frame.origin.x)
                    }
                    
                    displayItems.append(VisibleVideoItem(fileReference: self.files[j], frame: frame))
                    
                    offset.x += actualSize.width + minimumInteritemSpacing
                    previousItemSize = actualSize.height
                    contentMaxValueInScrollDirection = frame.maxY
                    
                    j += 1
                }
                
                if row.count > 0 {
                    offset = CGPoint(x: 0.0, y: offset.y + previousItemSize + minimumLineSpacing)
                }
                
                i += row.count
            }
            let contentSize = CGSize(width: drawableSize.width, height: contentMaxValueInScrollDirection + self.bottomInset)
            self.scrollNode.view.contentSize = contentSize
            
            self.displayItems = displayItems
            
            self.validVisibleItemsOffset = nil
            self.updateImmediatelyVisibleItems(ensureFrames: true)
        }
    }
    
    @objc func tapGesture(_ recognizer: TapLongTapOrDoubleTapGestureRecognizer) {
        if case .ended = recognizer.state {
            let point = recognizer.location(in: self.view)
            if let (file, rect) = self.fileAt(point: point) {
                self.fileSelected?(file, self, rect)
            }
        }
    }
    
    func frameForItem(_ id: MediaId) -> CGRect? {
        for item in self.displayItems {
            if item.fileReference.media.fileId == id {
                return item.frame
            }
        }
        return nil
    }
    
    func fileAt(point: CGPoint) -> (FileMediaReference, CGRect)? {
        let offsetPoint = point.offsetBy(dx: 0.0, dy: self.scrollNode.bounds.minY)
        return self.offsetFileAt(point: offsetPoint)
    }
    
    private func offsetFileAt(point: CGPoint) -> (FileMediaReference, CGRect)? {
        for item in self.displayItems {
            if item.frame.contains(point) {
                return (item.fileReference, item.frame)
            }
        }
        return nil
    }
}

private func NH_LP_TABLE_LOOKUP(_ table: inout [Int], _ i: Int, _ j: Int, _ rowsize: Int) -> Int {
    return table[i * rowsize + j]
}

private func NH_LP_TABLE_LOOKUP_SET(_ table: inout [Int], _ i: Int, _ j: Int, _ rowsize: Int, _ value: Int) {
    table[i * rowsize + j] = value
}

private func linearPartitionTable(_ weights: [Int], numberOfPartitions: Int) -> [Int] {
    let n = weights.count
    let k = numberOfPartitions
    
    let tableSize = n * k;
    var tmpTable = Array<Int>(repeatElement(0, count: tableSize))
    
    let solutionSize = (n - 1) * (k - 1)
    var solution = Array<Int>(repeatElement(0, count: solutionSize))
    
    for i in 0 ..< n {
        let offset = i != 0 ? NH_LP_TABLE_LOOKUP(&tmpTable, i - 1, 0, k) : 0
        NH_LP_TABLE_LOOKUP_SET(&tmpTable, i, 0, k, Int(weights[i]) + offset)
    }
    
    for j in 0 ..< k {
        NH_LP_TABLE_LOOKUP_SET(&tmpTable, 0, j, k, Int(weights[0]))
    }
    
    for i in 1 ..< n {
        for j in 1 ..< k {
            var currentMin = 0
            var minX = Int.max
            
            for x in 0 ..< i {
                let c1 = NH_LP_TABLE_LOOKUP(&tmpTable, x, j - 1, k)
                let c2 = NH_LP_TABLE_LOOKUP(&tmpTable, i, 0, k) - NH_LP_TABLE_LOOKUP(&tmpTable, x, 0, k)
                let cost = max(c1, c2)
                
                if x == 0 || cost < currentMin {
                    currentMin = cost;
                    minX = x
                }
            }
            
            NH_LP_TABLE_LOOKUP_SET(&tmpTable, i, j, k, currentMin)
            NH_LP_TABLE_LOOKUP_SET(&solution, i - 1, j - 1, k - 1, minX)
        }
    }
    
    return solution
}

private func linearPartitionForWeights(_ weights: [Int], numberOfPartitions: Int) -> [[Int]] {
    var n = weights.count
    var k = numberOfPartitions
    
    if k <= 0 {
        return []
    }
    
    if k >= n {
        var partition: [[Int]] = []
        for weight in weights {
            partition.append([weight])
        }
        return partition
    }
    
    if n == 1 {
        return [weights]
    }
    
    var solution = linearPartitionTable(weights, numberOfPartitions: numberOfPartitions)
    let solutionRowSize = numberOfPartitions - 1
    
    k = k - 2;
    n = n - 1;
    
    var answer: [[Int]] = []
    
    while k >= 0 {
        if n < 1 {
            answer.insert([], at: 0)
        } else {
            var currentAnswer: [Int] = []
            
            var i = NH_LP_TABLE_LOOKUP(&solution, n - 1, k, solutionRowSize) + 1
            let range = n + 1
            while i < range {
                currentAnswer.append(weights[i])
                i += 1
            }
            
            answer.insert(currentAnswer, at: 0)
            
            n = NH_LP_TABLE_LOOKUP(&solution, n - 1, k, solutionRowSize)
        }
        
        k = k - 1
    }
    
    var currentAnswer: [Int] = []
    var i = 0
    let range = n + 1
    while i < range {
        currentAnswer.append(weights[i])
        i += 1
    }
    
    answer.insert(currentAnswer, at: 0)
    
    return answer
}