import SwiftUI
import RealityKit
import RealityKitContent

struct GlobalData {
    var currNr: Int = 0
    var images: [String] = ["view0","view1","view2","view3","view4"]
    var matX: ShaderGraphMaterial!
    var currImage: TextureResource!
}

class ContentViewModel: ObservableObject {
    @Published var globalData: GlobalData

    init() {
        self.globalData = GlobalData(
            currNr: 0
        )
    }
}

struct ImmersiveView: View {
    @EnvironmentObject var vm: ContentViewModel
    @State var updating: Bool = false

    var body: some View {
        HStack {
            Button(action: {
                if !updating && vm.globalData.currNr < vm.globalData.images.count-1 {
                    vm.globalData.currNr += 1
                    updating = true
                } else {
                    vm.globalData.currNr = 0
                }
            }) {
                Text(String(vm.globalData.currNr))
            }
        }
        .offset(x: 0, y: -300)
        .scaleEffect(x: 2, y: 2)
        
        RealityView { content in
            do {
                vm.globalData.matX = try await ShaderGraphMaterial(named: "/Root/Mat_Stereo360",
                                                     from: "360Stereo.usda",
                                                     in: realityKitContentBundle)
            } catch {
                print("Error loading material: \(error)")
            }
                
            do {
                vm.globalData.currImage = try await TextureResource(named: vm.globalData.images[vm.globalData.currNr])
                try vm.globalData.matX.setParameter(name: "imageFile", value: .textureResource(vm.globalData.currImage))

            } catch {
                print("Error loading texture: \(error)")
            }
                
            let sphere = MeshResource.generateSphere(radius:1000)
            let entity = ModelEntity()
            entity.components.set(ModelComponent(mesh: sphere, materials: [vm.globalData.matX]))
            content.add(entity)
            
        } update: { content in
            Task {
                if updating { do {
                    vm.globalData.currImage = nil
                    vm.globalData.currImage =  try await TextureResource(named: vm.globalData.images[vm.globalData.currNr])
                    try vm.globalData.matX.setParameter(name: "imageFile", value: .textureResource(vm.globalData.currImage))
                    updating = false;
                } catch {
                    print("Error loading texture: \(error)")
                    updating = false;
                }
                }
            }
            
        }
    }
}