import SwiftUI

struct GalleryView: View {
    @EnvironmentObject var store: AttachmentsStore
    @Binding var selectedItems: [String]

    var body: some View {
        Group {
            if store.galleryAccessGranted {
                ForEach(store.galleryItems) { item in
                    GridViewItem(item: item, selected: $selectedItems)
                }
            } 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)
                    }
                }
            }
        }
        .task {
            await store.checkGalleryAuthorization()
        }
        .onChange(of: store.galleryAccessGranted) { flag in
            if flag {
                Task {
                    await store.fetchGalleryItems()
                }
            }
        }
    }
}

private struct GridViewItem: View {
    @State var item: GalleryItem
    @Binding var selected: [String]

    var body: some View {
        if let img = item.thumbnail {
            ZStack {
                img
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .frame(width: Const.galleryGridSize, height: Const.galleryGridSize)
                    .clipped()
                if let duration = item.duration {
                    VStack {
                        Spacer()
                        HStack {
                            Spacer()
                            Text(duration)
                                .foregroundColor(.Material.Text.white)
                                .font(.sub1)
                                .shadow(color: .black, radius: 2)
                                .padding(4)
                        }
                    }
                }
                if isSelected {
                    VStack {
                        HStack {
                            Spacer()
                            Circle()
                                .frame(width: 30, height: 30)
                                .shadow(color: .black, radius: 2)
                                .foregroundColor(.Material.Shape.white)
                                .overlay {
                                    Image(systemName: "checkmark")
                                        .foregroundColor(.Material.Elements.active)
                                        .font(.body3)
                                }
                                .padding(4)
                        }
                        Spacer()
                    }
                }
            }
            .onTapGesture {
                if isSelected {
                    selected.removeAll { $0 == item.id }
                } else {
                    selected.append(item.id)
                }
            }
        } else {
            ZStack {
                Rectangle()
                    .fill(Color.Material.Background.light)
                    .overlay {
                        ProgressView()
                            .foregroundColor(.Material.Elements.active)
                    }
                    .frame(width: Const.galleryGridSize, height: Const.galleryGridSize)
            }
            .task {
                if item.thumbnail == nil {
                    try? await item.fetchThumbnail()
                }
            }
        }
    }

    private var isSelected: Bool {
        selected.contains(item.id)
    }
}