import AVFoundation
import Photos
import SwiftUI

struct SelectedMedia {
    let path: String
}

struct AttachmentMediaPickerView: View {
    @State private var isCameraAccessGranted = AVCaptureDevice.authorizationStatus(for: .video) == .authorized
    @State private var isGalleryAccessGranted = PHPhotoLibrary.authorizationStatus() == .authorized

    @State private var thumbnails = [ThumbnailView]()
    @State private var selectedMedia = [SelectedMedia]()

    let gridSize = UIScreen.main.bounds.width / 3

    var body: some View {
        let columns = Array(repeating: GridItem(.flexible(), spacing: 0), count: 3)

        ScrollView(showsIndicators: false) {
            LazyVGrid(columns: columns, spacing: 0) {
                // For camera
                if isCameraAccessGranted {
                    ZStack {
                        CameraView()
                            .aspectRatio(1, contentMode: .fit)
                            .frame(maxWidth: .infinity)
                        Image(systemName: "camera")
                            .resizable()
                            .aspectRatio(contentMode: .fit)
                            .frame(width: 40, height: 40)
                            .foregroundColor(.white)
                            .padding(8)
                            .background(Color.black.opacity(0.5))
                            .clipShape(Circle())
                            .padding(8)
                    }
                } else {
                    Button {
                        openAppSettings()
                    } label: {
                        ZStack {
                            Rectangle()
                                .fill(Color.Material.Background.light)
                                .overlay {
                                    VStack {
                                        Image(systemName: "camera")
                                            .foregroundColor(.Material.Elements.active)
                                            .font(.system(size: 30))
                                        Text("Allow camera access")
                                            .foregroundColor(.Material.Text.main)
                                            .font(.body3)
                                    }
                                }
                                .frame(height: 100)
                        }
                    }
                }

                // For pictures
                if isGalleryAccessGranted {
                    ForEach(thumbnails) { photo in
                        photo
                    }
                } else {
                    Button {
                        openAppSettings()
                    } label: {
                        ZStack {
                            Rectangle()
                                .fill(Color.Material.Background.light)
                                .overlay {
                                    VStack {
                                        Image(systemName: "photo")
                                            .foregroundColor(.Material.Elements.active)
                                            .font(.system(size: 30))
                                        Text("Allow gallery access")
                                            .foregroundColor(.Material.Text.main)
                                            .font(.body3)
                                    }
                                }
                                .frame(height: 100)
                        }
                    }
                }
            }
        }
        .onAppear {
            DispatchQueue.global(qos: .background).asyncAfter(deadline: .now() + 0.2) {
                checkCameraAccess()
                checkGalleryAccess()
            }
        }
    }

    private func checkCameraAccess() {
        let status = AVCaptureDevice.authorizationStatus(for: .video)
        switch status {
        case .authorized:
            isCameraAccessGranted = true

        case .notDetermined:
            AVCaptureDevice.requestAccess(for: .video) { granted in
                DispatchQueue.main.async {
                    self.isCameraAccessGranted = granted
                }
            }

        case .denied, .restricted:
            isCameraAccessGranted = false

        @unknown default:
            isCameraAccessGranted = false
        }
    }

    private func checkGalleryAccess() {
        let status = PHPhotoLibrary.authorizationStatus()
        switch status {
        case .authorized, .limited:
            isGalleryAccessGranted = true
            fetchImages()

        case .notDetermined:
            PHPhotoLibrary.requestAuthorization { status in
                DispatchQueue.main.async {
                    self.isGalleryAccessGranted = status == .authorized
                    if self.isGalleryAccessGranted {
                        self.fetchImages()
                    }
                }
            }

        case .denied, .restricted:
            isGalleryAccessGranted = false

        @unknown default:
            isGalleryAccessGranted = false
        }
    }

    private func fetchImages() {
        let fetchOptions = PHFetchOptions()
        fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
        let assets = PHAsset.fetchAssets(with: fetchOptions)

        let manager = PHImageManager.default()
        let option = PHImageRequestOptions()
        option.isSynchronous = true

        assets.enumerateObjects { asset, _, _ in
            if asset.mediaType == .image {
                manager.requestImage(
                    for: asset,
                    targetSize: PHImageManagerMaximumSize,
                    contentMode: .aspectFill,
                    options: option
                ) { image, _ in
                    image?.scaleAndCropImage(toExampleSize: CGSize(width: gridSize, height: gridSize), completion: { image in
                        if let image {
                            DispatchQueue.main.async {
                                self.thumbnails.append(ThumbnailView(image: image, gridSize: gridSize, selected: $selectedMedia))
                            }
                        }
                    })
                }
            } else if asset.mediaType == .video {
                manager.requestAVAsset(forVideo: asset, options: nil) { avAsset, _, _ in
                    if let avAsset {
                        let imageGenerator = AVAssetImageGenerator(asset: avAsset)
                        imageGenerator.appliesPreferredTrackTransform = true
                        let time = CMTimeMake(value: 1, timescale: 2)
                        do {
                            let imageRef = try imageGenerator.copyCGImage(at: time, actualTime: nil)
                            let thumbnail = UIImage(cgImage: imageRef)
                            thumbnail.scaleAndCropImage(toExampleSize: CGSize(width: gridSize, height: gridSize), completion: { image in
                                if let image {
                                    DispatchQueue.main.async {
                                        self.thumbnails.append(ThumbnailView(image: image, gridSize: gridSize, selected: $selectedMedia, duration: asset.duration.minAndSec))
                                    }
                                }
                            })
                        } catch {
                            print("Failed to create thumbnail image")
                        }
                    }
                }
            }
        }
    }

    func openAppSettings() {
        if
            let appSettingsUrl = URL(string: UIApplication.openSettingsURLString),
            UIApplication.shared.canOpenURL(appSettingsUrl)
        {
            UIApplication.shared.open(appSettingsUrl, completionHandler: nil)
        }
    }
}

private struct ThumbnailView: Identifiable, View {
    let id = UUID()
    let gridSize: CGFloat
    let duration: String?

    @State private var image: UIImage
    @State private var ready = false
    @State private var selected = false
    @Binding var selectedMedia: [SelectedMedia]

    init(image: UIImage, gridSize: CGFloat, selected: Binding<[SelectedMedia]>, duration: String? = nil) {
        self.image = image
        self.gridSize = gridSize
        _selectedMedia = selected
        self.duration = duration
    }

    var body: some View {
        if ready {
            ZStack {
                Image(uiImage: image)
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .frame(width: gridSize, height: gridSize)
                    .clipped()
                if let duration {
                    VStack {
                        Spacer()
                        HStack {
                            Spacer()
                            Text(duration)
                                .foregroundColor(.Material.Text.white)
                                .font(.sub1)
                                .shadow(color: .black, radius: 2)
                                .padding(4)
                        }
                    }
                }
                if selected {
                    VStack {
                        HStack {
                            Spacer()
                            Circle()
                                .frame(width: 30, height: 30)
                                .shadow(color: .black, radius: 2)
                                .foregroundColor(.Material.Shape.white)
                                // Circle()
                                //     .fill(Color.Material.Shape.white)
                                //     .frame(width: 30, height: 30)
                                //     .shadow(color: .black, radius: 2)
                                .overlay {
                                    Image(systemName: "checkmark")
                                        .foregroundColor(.Material.Elements.active)
                                        .font(.body3)
                                }
                                .padding(4)
                        }
                        Spacer()
                    }
                }
            }
            .onTapGesture {
                withAnimation {
                    selected.toggle()
                    if selected {
                        selectedMedia.append(SelectedMedia(path: id.uuidString))
                    } else {
                        selectedMedia.removeAll { $0.path == id.uuidString }
                    }
                }
            }
        } else {
            ZStack {
                Rectangle()
                    .fill(Color.Material.Background.light)
                    .overlay {
                        ProgressView()
                    }
                    .frame(width: gridSize, height: gridSize)
            }
            .onAppear {
                image.scaleAndCropImage(toExampleSize: CGSize(width: gridSize, height: gridSize), completion: { image in
                    if let image {
                        self.image = image
                        ready = true
                    }
                })
            }
        }
    }
}

class CameraUIView: UIView {
    var previewLayer: AVCaptureVideoPreviewLayer?

    override func layoutSubviews() {
        super.layoutSubviews()
        previewLayer?.frame = bounds
    }
}

struct CameraView: UIViewRepresentable {
    func makeUIView(context _: Context) -> CameraUIView {
        let view = CameraUIView()

        let captureSession = AVCaptureSession()
        guard let captureDevice = AVCaptureDevice.default(for: .video) else { return view }
        guard let input = try? AVCaptureDeviceInput(device: captureDevice) else { return view }
        captureSession.addInput(input)

        let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        previewLayer.videoGravity = .resizeAspectFill
        view.layer.addSublayer(previewLayer)
        view.previewLayer = previewLayer

        captureSession.startRunning()

        return view
    }

    func updateUIView(_ uiView: CameraUIView, context _: Context) {
        uiView.previewLayer?.frame = uiView.bounds
    }
}