import Foundation
import UIKit
import Display
import Vision
import CoreImage
import CoreImage.CIFilterBuiltins
import VideoToolbox
import SwiftSignalKit
import TelegramCore
import AccountContext
import FileMediaResourceStatus
import ZipArchive
import ImageTransparency

private let queue = Queue()

public enum CutoutAvailability {
    case available
    case progress(Float)
    case unavailable
}

private var forceCoreMLVariant: Bool {
#if targetEnvironment(simulator)
    return true
#else
    return false
#endif
}

private func modelPath() -> String {
    return NSTemporaryDirectory() + "u2netp.mlmodelc"
}

public func cutoutAvailability(context: AccountContext) -> Signal<CutoutAvailability, NoError> {
    if #available(iOS 17.0, *), !forceCoreMLVariant {
        return .single(.available)
    } else if #available(iOS 14.0, *) {
        let compiledModelPath = modelPath()
                
        if FileManager.default.fileExists(atPath: compiledModelPath) {
            return .single(.available)
        }
        return context.engine.peers.resolvePeerByName(name: "stickersbackgroundseparation", referrer: nil)
        |> mapToSignal { result -> Signal<CutoutAvailability, NoError> in
            guard case let .result(maybePeer) = result else {
                return .complete()
            }
            guard let peer = maybePeer else {
                return .single(.unavailable)
            }
            
            return context.account.viewTracker.aroundMessageHistoryViewForLocation(.peer(peerId: peer.id, threadId: nil), index: .lowerBound, anchorIndex: .lowerBound, count: 5, fixedCombinedReadStates: nil)
            |> mapToSignal { view -> Signal<(TelegramMediaFile, EngineMessage)?, NoError> in
                if !view.0.isLoading {
                    if let message = view.0.entries.last?.message, let file = message.media.first(where: { $0 is TelegramMediaFile }) as? TelegramMediaFile {
                        return .single((file, EngineMessage(message)))
                    } else {
                        return .single(nil)
                    }
                } else {
                    return .complete()
                }
            }
            |> take(1)
            |> mapToSignal { maybeFileAndMessage -> Signal<CutoutAvailability, NoError> in
                if let (file, message) = maybeFileAndMessage {
                    let fetchedData = context.engine.resources.fetch(reference: FileMediaReference.message(message: MessageReference(message._asMessage()), media: file).resourceReference(file.resource), userLocation: .other, userContentType: .file)
                    
                    enum FetchStatus {
                        case completed(String)
                        case progress(Float)
                        case failed
                    }
                                        
                    let fetchStatus = Signal<FetchStatus, NoError> { subscriber in
                        let fetchedDisposable = fetchedData.start()
                        let resourceDataDisposable = context.engine.resources.data(resource: EngineMediaResource(file.resource)).start(next: { next in
                            if next.isComplete {
                                SSZipArchive.unzipFile(atPath: next.path, toDestination: NSTemporaryDirectory())
                                subscriber.putNext(.completed(compiledModelPath))
                                subscriber.putCompletion()
                            }
                        }, error: subscriber.putError, completed: subscriber.putCompletion)
                        let progressDisposable = messageFileMediaResourceStatus(context: context, file: file, message: message, isRecentActions: false).start(next: { status in
                            switch status.fetchStatus {
                            case let .Remote(progress), let .Fetching(_, progress), let .Paused(progress):
                                subscriber.putNext(.progress(progress))
                            default:
                                break
                            }
                        })
                        return ActionDisposable {
                            fetchedDisposable.dispose()
                            resourceDataDisposable.dispose()
                            progressDisposable.dispose()
                        }
                    }
                    return fetchStatus
                    |> mapToSignal { status -> Signal<CutoutAvailability, NoError> in
                        switch status {
                        case .completed:
                            return .single(.available)
                        case let .progress(progress):
                            return .single(.progress(progress))
                        case .failed:
                            return .single(.unavailable)
                        }
                    }
                } else {
                    return .single(.unavailable)
                }
            }
        }
    } else {
        return .single(.unavailable)
    }
}

public func cutoutStickerImage(from image: UIImage, context: AccountContext? = nil, onlyCheck: Bool = false) -> Signal<UIImage?, NoError> {
    guard let cgImage = image.cgImage else {
        return .single(nil)
    }
    if #available(iOS 17.0, *), !forceCoreMLVariant {
        return Signal { subscriber in
            let ciContext = CIContext(options: nil)
            let inputImage = CIImage(cgImage: cgImage)
            let handler = VNImageRequestHandler(cgImage: cgImage, options: [:])
            let request = VNGenerateForegroundInstanceMaskRequest { [weak handler] request, error in
                guard let handler, let result = request.results?.first as? VNInstanceMaskObservation else {
                    subscriber.putNext(nil)
                    subscriber.putCompletion()
                    return
                }
                if onlyCheck {
                    subscriber.putNext(UIImage())
                    subscriber.putCompletion()
                } else {
                    let instances = instances(atPoint: nil, inObservation: result)
                    if let mask = try? result.generateScaledMaskForImage(forInstances: instances, from: handler) {
                        let filter = CIFilter.blendWithMask()
                        filter.inputImage = inputImage
                        filter.backgroundImage = CIImage(color: .clear)
                        filter.maskImage = CIImage(cvPixelBuffer: mask)
                        if let output  = filter.outputImage, let cgImage = ciContext.createCGImage(output, from: inputImage.extent) {
                            let image = UIImage(cgImage: cgImage)
                            subscriber.putNext(image)
                            subscriber.putCompletion()
                            return
                        }
                    }
                    subscriber.putNext(nil)
                    subscriber.putCompletion()
                }
            }
            try? handler.perform([request])
            return ActionDisposable {
                request.cancel()
            }
        }
        |> runOn(queue)
    } else if #available(iOS 14.0, *), onlyCheck {
        return Signal { subscriber in
            U2netp.load(contentsOf: URL(fileURLWithPath: modelPath()), completionHandler: { result in
                switch result {
                case let .success(model):
                    let modelImageSize = CGSize(width: 320, height: 320)
                    if let squareImage = scaleImageToPixelSize(image: image, size: modelImageSize),
                          let pixelBuffer = buffer(from: squareImage),
                          let result = try? model.prediction(in_0: pixelBuffer),
                          let resultImage = UIImage(pixelBuffer: result.out_p1),
                          imageHasSubject(resultImage) {
                        subscriber.putNext(UIImage())
                    } else {
                        subscriber.putNext(nil)
                    }
                    subscriber.putCompletion()
                case .failure:
                    subscriber.putNext(nil)
                    subscriber.putCompletion()
                }
            })
            return EmptyDisposable
        }
        |> runOn(queue)
    } else {
        return .single(nil)
    }
}

public struct CutoutResult {
    public enum Image {
        case image(UIImage, CIImage)
        case pixelBuffer(CVPixelBuffer)
    }
    
    public let index: Int
    public let extractedImage: Image?
    public let edgesMaskImage: Image?
    public let maskImage: Image?
    public let backgroundImage: Image?
}

public enum CutoutTarget {
    case point(CGPoint?)
    case index(Int)
    case all
}


func refineEdges(_ maskImage: CIImage) -> CIImage? {
    let maskImage = maskImage.clampedToExtent()
    
    let blurFilter = CIFilter(name: "CIGaussianBlur")!
    blurFilter.setValue(maskImage, forKey: kCIInputImageKey)
    blurFilter.setValue(11.4, forKey: kCIInputRadiusKey)
    
    let controlsFilter = CIFilter(name: "CIColorControls")!
    controlsFilter.setValue(blurFilter.outputImage, forKey: kCIInputImageKey)
    controlsFilter.setValue(6.61, forKey: kCIInputContrastKey)
    
    let sharpenFilter = CIFilter(name: "CISharpenLuminance")!
    sharpenFilter.setValue(controlsFilter.outputImage, forKey: kCIInputImageKey)
    sharpenFilter.setValue(250.0, forKey: kCIInputSharpnessKey)
    
    return sharpenFilter.outputImage?.cropped(to: maskImage.extent)
}

public func cutoutImage(
    from image: UIImage,
    editedImage: UIImage? = nil,
    crop: (offset: CGPoint, rotation: CGFloat, scale: CGFloat)?,
    target: CutoutTarget,
    includeExtracted: Bool = true,
    completion: @escaping ([CutoutResult]) -> Void
) {
    guard #available(iOS 14.0, *), let cgImage = image.cgImage else {
        completion([])
        return
    }
    
    let ciContext = CIContext(options: nil)
    let inputImage = CIImage(cgImage: cgImage)
    var results: [CutoutResult] = []
    
    func process(instance: Int, mask originalMaskImage: CIImage) {
        let extractedImage: CutoutResult.Image?
        if includeExtracted {
            let filter = CIFilter.blendWithMask()
            filter.backgroundImage = CIImage(color: .clear)
            
            let dimensions: CGSize
            var maskImage = originalMaskImage
            if let editedImage = editedImage?.cgImage.flatMap({ CIImage(cgImage: $0) }) {
                filter.inputImage = editedImage
                dimensions = editedImage.extent.size
                
                if let (cropOffset, cropRotation, cropScale) = crop {
                    let initialScale: CGFloat
                    if maskImage.extent.height > maskImage.extent.width {
                        initialScale = dimensions.width / maskImage.extent.width
                    } else {
                        initialScale = dimensions.width / maskImage.extent.height
                    }
                    
                    let dimensions = editedImage.extent.size
                    maskImage = maskImage.transformed(by: CGAffineTransform(translationX: -maskImage.extent.width / 2.0, y: -maskImage.extent.height / 2.0))
                    
                    var transform = CGAffineTransform.identity
                    transform = transform.translatedBy(x: dimensions.width / 2.0 + cropOffset.x, y: dimensions.height / 2.0 + cropOffset.y * -1.0)
                    transform = transform.rotated(by: -cropRotation)
                    transform = transform.scaledBy(x: cropScale * initialScale, y: cropScale * initialScale)
                    maskImage = maskImage.transformed(by: transform)
                }
            } else {
                filter.inputImage = inputImage
                dimensions = inputImage.extent.size
            }
            filter.maskImage = maskImage
            
            if let output = filter.outputImage, let cgImage = ciContext.createCGImage(output, from: CGRect(origin: .zero, size: dimensions)) {
                extractedImage = .image(UIImage(cgImage: cgImage), output)
            } else {
                extractedImage = nil
            }
        } else {
            extractedImage = nil
        }
        
        let whiteImage = CIImage(color: .white)
        let blackImage = CIImage(color: .black)
        
        let maskFilter = CIFilter.blendWithMask()
        maskFilter.inputImage = whiteImage
        maskFilter.backgroundImage = blackImage
        maskFilter.maskImage = originalMaskImage
        
        let refinedMaskFilter = CIFilter.blendWithMask()
        refinedMaskFilter.inputImage = whiteImage
        refinedMaskFilter.backgroundImage = blackImage
        refinedMaskFilter.maskImage = refineEdges(originalMaskImage)
        
        let edgesMaskImage: CutoutResult.Image?
        let maskImage: CutoutResult.Image?
        if let maskOutput = maskFilter.outputImage?.cropped(to: inputImage.extent), let maskCgImage = ciContext.createCGImage(maskOutput, from: inputImage.extent), let refinedMaskOutput = refinedMaskFilter.outputImage?.cropped(to: inputImage.extent), let refinedMaskCgImage = ciContext.createCGImage(refinedMaskOutput, from: inputImage.extent) {
            edgesMaskImage = .image(UIImage(cgImage: maskCgImage), maskOutput)
            maskImage = .image(UIImage(cgImage: refinedMaskCgImage), refinedMaskOutput)
        } else {
            edgesMaskImage = nil
            maskImage = nil
        }
        
        if extractedImage != nil || maskImage != nil {
            results.append(CutoutResult(index: instance, extractedImage: extractedImage, edgesMaskImage: edgesMaskImage, maskImage: maskImage, backgroundImage: nil))
        }
    }

    if #available(iOS 17.0, *), !forceCoreMLVariant {
        queue.async {
            let handler = VNImageRequestHandler(cgImage: cgImage, options: [:])
            let request = VNGenerateForegroundInstanceMaskRequest { [weak handler] request, error in
                guard let handler, let result = request.results?.first as? VNInstanceMaskObservation else {
                    completion([])
                    return
                }
                
                let targetInstances: IndexSet
                switch target {
                case let .point(point):
                    targetInstances = instances(atPoint: point, inObservation: result)
                case let .index(index):
                    targetInstances = IndexSet([index])
                case .all:
                    targetInstances = result.allInstances
                }
                
                for instance in targetInstances {
                    if let mask = try? result.generateScaledMaskForImage(forInstances: IndexSet(integer: instance), from: handler) {
                        process(instance: instance, mask: CIImage(cvPixelBuffer: mask))
                    }
                }
                completion(results)
            }
            
            try? handler.perform([request])
        }
    } else {
        U2netp.load(contentsOf: URL(fileURLWithPath: modelPath()), completionHandler: { result in
            switch result {
            case let .success(model):
                let modelImageSize = CGSize(width: 320, height: 320)
                if let squareImage = scaleImageToPixelSize(image: image, size: modelImageSize), let pixelBuffer = buffer(from: squareImage), let result = try? model.prediction(in_0: pixelBuffer), let maskImage = UIImage(pixelBuffer: result.out_p1), let scaledMaskImage = scaleImageToPixelSize(image: maskImage, size: image.size), let ciImage = CIImage(image: scaledMaskImage) {
                    process(instance: 0, mask: ciImage)
                }
            case .failure:
                break
            }
            completion(results)
        })
    }
}

@available(iOS 17.0, *)
private func instances(atPoint maybePoint: CGPoint?, inObservation observation: VNInstanceMaskObservation) -> IndexSet {
    guard let point = maybePoint else {
        return observation.allInstances
    }
    
    let instanceMap = observation.instanceMask
    let coords = VNImagePointForNormalizedPoint(point, CVPixelBufferGetWidth(instanceMap) - 1, CVPixelBufferGetHeight(instanceMap) - 1)
    
    CVPixelBufferLockBaseAddress(instanceMap, .readOnly)
    guard let pixels = CVPixelBufferGetBaseAddress(instanceMap) else {
        fatalError()
    }
    let bytesPerRow = CVPixelBufferGetBytesPerRow(instanceMap)
    let instanceLabel = pixels.load(fromByteOffset: Int(coords.y) * bytesPerRow + Int(coords.x), as: UInt8.self)
    CVPixelBufferUnlockBaseAddress(instanceMap, .readOnly)
    
    return instanceLabel == 0 ? observation.allInstances : [Int(instanceLabel)]
}

private extension UIImage {
    convenience init?(pixelBuffer: CVPixelBuffer) {
        var cgImage: CGImage?
        VTCreateCGImageFromCVPixelBuffer(pixelBuffer, options: nil, imageOut: &cgImage)
        
        guard let cgImage = cgImage else {
            return nil
        }
        
        self.init(cgImage: cgImage)
    }
}

private func scaleImageToPixelSize(image: UIImage, size: CGSize) -> UIImage? {
    UIGraphicsBeginImageContextWithOptions(size, true, 1.0)
    image.draw(in: CGRect(origin: CGPoint(), size: size), blendMode: .copy, alpha: 1.0)
    let result = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    
    return result
}

private func buffer(from image: UIImage) -> CVPixelBuffer? {
    let attrs = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue, kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue] as CFDictionary
    var pixelBuffer : CVPixelBuffer?
    let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(image.size.width), Int(image.size.height), kCVPixelFormatType_32ARGB, attrs, &pixelBuffer)
    guard (status == kCVReturnSuccess) else {
        return nil
    }
    
    guard let pixelBufferUnwrapped = pixelBuffer else {
        return nil
    }
    
    CVPixelBufferLockBaseAddress(pixelBufferUnwrapped, CVPixelBufferLockFlags(rawValue: 0))
    let pixelData = CVPixelBufferGetBaseAddress(pixelBufferUnwrapped)
    
    let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
    
    guard let context = CGContext(data: pixelData, width: Int(image.size.width), height: Int(image.size.height), bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(pixelBufferUnwrapped), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue) else {
        return nil
    }
    
    context.translateBy(x: 0, y: image.size.height)
    context.scaleBy(x: 1.0, y: -1.0)
    
    UIGraphicsPushContext(context)
    image.draw(in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
    UIGraphicsPopContext()
    CVPixelBufferUnlockBaseAddress(pixelBufferUnwrapped, CVPixelBufferLockFlags(rawValue: 0))
    
    return pixelBufferUnwrapped
}