import AVFoundation
import Combine
import Foundation
import Photos
import UIKit

final class SharingMiddleware {
    static let shared = SharingMiddleware()

    func middleware(state _: AppState, action: AppAction) -> AnyPublisher<AppAction, Never> {
        switch action {
        case .sharingAction(.checkCameraAccess):
            return Future<AppAction, Never> { promise in
                let status = AVCaptureDevice.authorizationStatus(for: .video)
                switch status {
                case .authorized:
                    promise(.success(.sharingAction(.setCameraAccess(true))))

                case .notDetermined:
                    AVCaptureDevice.requestAccess(for: .video) { granted in
                        promise(.success(.sharingAction(.setCameraAccess(granted))))
                    }

                case .denied, .restricted:
                    promise(.success(.sharingAction(.setCameraAccess(false))))

                @unknown default:
                    promise(.success(.sharingAction(.setCameraAccess(false))))
                }
            }
            .eraseToAnyPublisher()

        case .sharingAction(.checkGalleryAccess):
            return Future<AppAction, Never> { promise in
                let status = PHPhotoLibrary.authorizationStatus()
                switch status {
                case .authorized, .limited:
                    promise(.success(.sharingAction(.setGalleryAccess(true))))

                case .notDetermined:
                    PHPhotoLibrary.requestAuthorization { status in
                        promise(.success(.sharingAction(.setGalleryAccess(status == .authorized))))
                    }

                case .denied, .restricted:
                    promise(.success(.sharingAction(.setGalleryAccess(false))))

                @unknown default:
                    promise(.success(.sharingAction(.setGalleryAccess(false))))
                }
            }
            .eraseToAnyPublisher()

        case .sharingAction(.fetchGallery):
            return Future<AppAction, Never> { promise in
                let fetchOptions = PHFetchOptions()
                fetchOptions.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: false)]
                let assets = PHAsset.fetchAssets(with: fetchOptions)
                var items: [SharingGalleryItem] = []
                assets.enumerateObjects { asset, _, _ in
                    if asset.mediaType == .image {
                        items.append(.init(id: asset.localIdentifier, type: .photo))
                    } else if asset.mediaType == .video {
                        items.append(.init(id: asset.localIdentifier, type: .video))
                    }
                }
                promise(.success(.sharingAction(.galleryFetched(items))))
            }
            .eraseToAnyPublisher()

        case .sharingAction(.galleryFetched(let items)):
            DispatchQueue.global(qos: .background).async {
                // for item in items {
                //     switch item.type {
                //     case .photo:
                //         self.makePhotoThumbnail(assetId: PHAsset.fetchAssets(withLocalIdentifiers: [item.id], options: nil).firstObject!) { data in
                //             if let data {
                //                 DispatchQueue.main.async {
                //                     store.dispatch(.sharingAction(.thumbnailUpdated(data, item.id)))
                //                 }
                //             }
                //         }
                //
                //     case .video:
                //         self.fetchVideo(asset: PHAsset.fetchAssets(withLocalIdentifiers: [item.id], options: nil).firstObject!) { newItem in
                //             if let newItem {
                //                 newItems.append(newItem)
                //             }
                //         }
                //     }
                // }
            }
            return Empty().eraseToAnyPublisher()

        default:
            return Empty().eraseToAnyPublisher()
        }
    }
}

private extension SharingMiddleware {
    func makePhotoThumbnail(asset: PHAsset, completion: @escaping (Data?) -> Void) {
        PHImageManager.default().requestImage(
            for: asset,
            targetSize: PHImageManagerMaximumSize,
            contentMode: .aspectFill,
            options: nil
        ) { _, _ in
            // guard let image = image?.scaleAndCropImage(toExampleSize: CGSize(width: Const.galleryGridSize, height: Const.galleryGridSize)) else {
            //     completion(nil)
            //     return
            // }
            // let data = image.jpegData(compressionQuality: 1.0) ?? Data()
            // completion(.init(id: asset.localIdentifier, type: .photo, thumbnail: data))
            completion(.init(id: asset.localIdentifier, type: .photo, thumbnail: Data()))
        }
    }

    func fetchVideo(asset: PHAsset, completion: @escaping (SharingGalleryItem?) -> Void) {
        PHImageManager.default().requestAVAsset(forVideo: asset, options: nil) { _, _, _ 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)
            //         guard let image = thumbnail.scaleAndCropImage(toExampleSize: CGSize(width: Const.galleryGridSize, height: Const.galleryGridSize)) else {
            //             completion(nil)
            //             return
            //         }
            //         let data = image.jpegData(compressionQuality: 1.0) ?? Data()
            //         completion(.init(id: asset.localIdentifier, type: .video, thumbnail: data, duration: asset.duration.minAndSec))
            //     } catch {
            //         print("Failed to create thumbnail image")
            //         completion(nil)
            //     }
            // } else {
            //     completion(nil)
            // }
            completion(.init(id: asset.localIdentifier, type: .photo, thumbnail: Data()))
        }
    }
}

// case .sharingAction(.fetchGallery):
//     return Future<AppAction, Never> { promise in
//         DispatchQueue.global(qos: .background).async {
//             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
//
//             var items: [SharingGalleryItem] = []
//             let group = DispatchGroup()
//             assets.enumerateObjects { asset, _, _ in
//                 if asset.mediaType == .image {
//                     group.enter()
//                     manager.requestImage(
//                         for: asset,
//                         targetSize: PHImageManagerMaximumSize,
//                         contentMode: .aspectFill,
//                         options: option
//                     ) { image, _ in
//                         if image != nil {
//                             items.append(.init(id: asset.localIdentifier, type: .photo))
//                             group.leave()
//                         }
//                     }
//                 } else if asset.mediaType == .video {
//                     group.enter()
//                     manager.requestAVAsset(forVideo: asset, options: nil) { avAsset, _, _ in
//                         if avAsset != nil {
//                             items.append(.init(id: asset.localIdentifier, type: .video, duration: asset.duration.minAndSec))
//                             group.leave()
//                         }
//                     }
//                 }
//             }
//             group.notify(queue: .main) {
//                 promise(.success(.sharingAction(.galleryFetched(items))))
//             }
//         }
//     }
//     .eraseToAnyPublisher()
//
// case .sharingAction(.galleryFetched(let items)):
//     return Future<AppAction, Never> { promise in
//         DispatchQueue.global(qos: .background).async {
//             let ids = items
//                 .filter { $0.thumbnail == nil }
//                 .map { $0.id }
//             let assets = PHAsset.fetchAssets(withLocalIdentifiers: ids, options: nil)
//
//             var newItems: [SharingGalleryItem] = []
//             let group = DispatchGroup()
//
//             assets.enumerateObjects { asset, _, _ in
//                 let manager = PHImageManager.default()
//                 group.enter()
//                 if asset.mediaType == .image {
//                     manager.requestImage(
//                         for: asset,
//                         targetSize: PHImageManagerMaximumSize,
//                         contentMode: .aspectFill,
//                         options: nil
//                     ) { image, _ in
//                         image?.scaleAndCropImage(toExampleSize: CGSize(width: Const.galleryGridSize, height: Const.galleryGridSize)) { image in
//                             if let image {
//                                 let data = image.jpegData(compressionQuality: 1.0) ?? Data()
//                                 newItems.append(.init(id: asset.localIdentifier, type: .photo, thumbnail: data))
//                             }
//                             group.leave()
//                         }
//                     }
//                 } 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: Const.galleryGridSize, height: Const.galleryGridSize), completion: { image in
//                                     if let image {
//                                         let data = image.jpegData(compressionQuality: 1.0) ?? Data()
//                                         newItems.append(.init(id: asset.localIdentifier, type: .video, thumbnail: data, duration: asset.duration.minAndSec))
//                                     }
//                                     group.leave()
//                                 })
//                             } catch {
//                                 print("Failed to create thumbnail image")
//                                 group.leave()
//                             }
//                         } else {
//                             group.leave()
//                         }
//                     }
//                 } else {
//                     group.leave()
//                 }
//             }
//             group.notify(queue: .main) {
//                 promise(.success(.sharingAction(.thumbnailUpdated(newItems))))
//             }
//         }
//     }
//     .eraseToAnyPublisher()