//
//  ImmersiveView.swift
//  TestVideoLeakOneImmersiveView
//

import AVKit
import OSLog
import SwiftUI
import RealityKit
import RealityKitContent

struct ImmersiveView: View {
    let logger = Logger(subsystem: SUBSYSTEM, category: "ImmersiveView")
    @Environment(\.scenePhase) var scenePhase
    @Environment(\.dismissImmersiveSpace) var dismissImmersiveSpace
    
    var videoViewModel: Immersive180VideoViewModel? = {
        guard let url = Bundle.main.url(forResource: "a_large_650mb_video_file", withExtension: "mov") else {
            assertionFailure("missing video")
            return nil
        }
        return Immersive180VideoViewModel(url: url)
    }()
    
    private let rootEntity = Entity()
    private let immersiveS3180VideoEntity = Entity()
    @State private var isShowImmsersiveVideo = false
    
    var body: some View {
        RealityView { content, attachments in
            logger.info("\(#function) \(#line) `content, attachments in`")
            updateScene(content: content, attachments: attachments)
            
        } update: { content, attachments in
            
            logger.info("\(#function) \(#line) `update: { content, attachments in`")
            updateScene(content: content, attachments: attachments)

        } placeholder: {
            
            let _ = logger.info("\(#function) \(#line) `placeholder`")
            ProgressView()
            
        } attachments: {
            
            let _ = logger.info("\(#function) \(#line) `attachments`")
            
            Attachment(id: "closeImmersiveSpaceButton") {
                Button {
                    // show hide immsersive video
                    isShowImmsersiveVideo.toggle()
                } label: {
                    Text(isShowImmsersiveVideo ? "Hide Immersive Video" : "Show Immersive Video")
                }
            }
        }
        .onChange(of: scenePhase, { oldValue, newValue in
            logger.info("\(#function) \(#line) `onChange(of: scenePhase` scenePhase oldValue \(String(describing: oldValue)) scenePhase newValue \(String(describing: newValue))")
            switch newValue {
            case .active:
                logger.info("\(#function) \(#line) scenePhase newValue \(String(describing: newValue))")
            case .background:
                logger.info("\(#function) \(#line) scenePhase newValue \(String(describing: newValue))")
                unloadScenes()
            case .inactive:
                logger.info("\(#function) \(#line) scenePhase newValue \(String(describing: newValue))")
            @unknown default:
                logger.warning("\(#function) \(#line) scenePhase newValue \(String(describing: newValue))")
            }
        })
    }
    
    func updateScene(content: RealityViewContent, attachments: RealityViewAttachments) {
        logger.info("\(#function) \(#line)")
        guard scenePhase == .active else {
            logger.info("\(#function) \(#line) escaping since app backgrounded")
            return
        }

        if rootEntity.children.isEmpty {
            Task{
                await loadScenes(content: content, attachments: attachments)
            }
        } else {
            controlScene(content: content, attachments: attachments)
        }
    }
    
    func loadScenes(content: RealityViewContent, attachments: RealityViewAttachments) async {
        logger.info("\(#function) \(#line)")
        
        guard let closeImmersiveSpaceButton = attachments.entity(for: "closeImmersiveSpaceButton") else {
            logger.error("\(#function) \(#line) missing attachment")
            assertionFailure("missing attachment")
            return
        }
        closeImmersiveSpaceButton.position = [0.0, 0.1, -2.5]
        closeImmersiveSpaceButton.scale = scaleForAttachements
        rootEntity.addChild(closeImmersiveSpaceButton)
        content.add(rootEntity)
        loadS3180Video(content: content)
    }
    
    func unloadScenes() {
        logger.info("\(#function) \(#line)")
        if let videoViewModel {
            videoViewModel.reset()
        }
        immersiveS3180VideoEntity.children.removeAll()
        rootEntity.children.removeAll()
        Task {
            await dismissImmersiveSpace()
        }
    }

    func loadS3180Video(content: RealityViewContent) {
        logger.info("\(#function) \(#line)")
        guard let videoViewModel else {
            logger.error("\(#function) \(#line) missing model")
            assertionFailure("missing view model")
            return
        }
        let entity = videoViewModel.setupContentEntity()
        immersiveS3180VideoEntity.addChild(entity)
        immersiveS3180VideoEntity.isEnabled = false
        rootEntity.addChild(immersiveS3180VideoEntity)
    }

    func hideVideo() {
        logger.info("\(#function) \(#line)")
        guard let videoViewModel else {
            logger.error("\(#function) \(#line) missing model")
            assertionFailure("missing model")
            return
        }
        immersiveS3180VideoEntity.isEnabled = false
        videoViewModel.stop()
    }
    
    func showVideo() {
        logger.info("\(#function) \(#line)")
        guard let videoViewModel else {
            logger.error("\(#function) \(#line) missing model")
            assertionFailure("missing model")
            return
        }
        immersiveS3180VideoEntity.isEnabled = true
        videoViewModel.play()
    }

    func controlScene(content: RealityViewContent, attachments: RealityViewAttachments) {
        logger.info("\(#function) \(#line)")
        if isShowImmsersiveVideo {
            showVideo()
        } else {
            hideVideo()
        }
    }
}

#Preview(immersionStyle: .mixed) {
    ImmersiveView()
        .environment(AppModel())
}