import SwiftUI

enum FileFilterType: String, Hashable, CaseIterable, Identifiable {
    case images
    case text
    case videos
    case other

    var text: String {
        switch self {
        case .images: return "Image"
        case .text: return "Text"
        case .videos: return "Video"
        case .other: return "Other"
        }
    }

    var id: String {
        rawValue
    }

    func matches(_ type: FileType) -> Bool {
        switch self {
        case .images: return type.isImage
        case .text: return type.isTextFile
        case .videos: return type.isVideo
        case .other: return type.isOtherFile
        }
    }
}

struct FileListView: View {

    @EnvironmentObject
    private var content: Content

    @Binding
    var selectedFile: FileResource?

    @State
    private var selectedFileType: FileFilterType

    @State
    private var searchString = ""

    let allowedType: FileFilterType?

    init(selectedFile: Binding<FileResource?>, allowedType: FileFilterType? = nil) {
        self._selectedFile = selectedFile
        self.allowedType = allowedType
        self.selectedFileType = allowedType ?? .images
    }

    var filesBySelectedType: [FileResource] {
        content.files.filter { selectedFileType.matches($0.type) }
    }

    var filteredFiles: [FileResource] {
        guard !searchString.isEmpty else {
            return filesBySelectedType
        }
        return filesBySelectedType.filter { $0.id.contains(searchString) }
    }

    var body: some View {
        VStack(alignment: .center) {
            Picker("", selection: $selectedFileType) {
                ForEach(FileFilterType.allCases) { type in
                    Text(type.text).tag(type)
                }
            }
            .pickerStyle(.segmented)
            .padding(.trailing, 7)
            .disabled(allowedType != nil)
            TextField("", text: $searchString, prompt: Text("Search"))
                .textFieldStyle(.roundedBorder)
                .padding(.horizontal, 8)
            List(filteredFiles, selection: $selectedFile) { file in
                Text(file.id).tag(file)
            }
            .onChange(of: selectedFileType) { oldValue, newValue in
                guard oldValue != newValue else {
                    return
                }
                let newFile = filteredFiles.first

                guard let selectedFile else {
                    if let newFile {
                        DispatchQueue.main.async {
                            selectedFile = newFile
                        }
                    }
                    return
                }

                if newValue.matches(selectedFile.type) {
                    return
                }
                DispatchQueue.main.async {
                    self.selectedFile = newFile
                }
            }
        }
        .onAppear {
            if selectedFile == nil {
                DispatchQueue.main.async {
                    selectedFile = content.files.first
                }
            }
        }
    }
}

#Preview {
    NavigationSplitView {
        FileListView(selectedFile: .constant(nil))
            .environmentObject(Content.mock)
            .navigationSplitViewColumnWidth(250)
    } detail: {
        Text("")
            .frame(width: 50)
    }
}