import SwiftData
import SwiftUI

/// A view for creating new todo tasks with an intuitive form interface.
///
/// This view presents a modal sheet that allows users to create new todo tasks by providing
/// task details through a structured form. The view integrates with SwiftData for persistence
/// and implements smart keyboard focus management for an enhanced input experience.
struct NewTaskView: View {

    // MARK: Properties

    /// Environment value for dismissing this view.
    @Environment(\.dismiss)
    private var dismiss

    /// SwiftData model context for saving todo tasks.
    @Environment(\.modelContext)
    private var modelContext

    /// Tracks which text field currently has keyboard focus.
    @FocusState
    private var inputFocus: InputFieldFocus?

    /// The view model managing the state and logic for this view.
    @State
    private var viewModel: ViewModel

    // MARK: Initialization

    /// Initializes a new task view with a fresh view model instance.
    ///
    /// Creates a new `NewTaskViewModel` with default values:
    /// - Empty title
    /// - Empty note
    /// - Due date set to current date
    ///
    /// The view model is stored as `@State` to ensure it persists across view updates
    /// and maintains its state throughout the view's lifecycle.
    init() {
        _viewModel = State(initialValue: .init())
    }

    // MARK: Body

    /// The content and behavior of the view.
    ///
    /// Constructs a form interface wrapped in the custom content container that provides
    /// tap-to-dismiss keyboard functionality.
    var body: some View {
        Content(inputFocus: $inputFocus) {
            Form {
                Section("view.new-task.section.task") {
                    TextField(
                        "view.new-task.placeholder.title",
                        text: $viewModel.title,
                        axis: .vertical
                    )
                    .focused(
                        $inputFocus,
                        equals: .title
                    )
                    .onNewlineFocus(
                        $viewModel.title,
                        to: .note,
                        on: $inputFocus
                    )

                    TextField(
                        "view.new-task.placeholder.note",
                        text: $viewModel.note,
                        axis: .vertical
                    )
                    .focused(
                        $inputFocus,
                        equals: .note
                    )
                    .onEmptyNewlineResignFocus(
                        text: $viewModel.note,
                        from: $inputFocus
                    )
                }
                .autocapitalization(.sentences)
                .autocorrectionDisabled(false)
                .keyboardType(.default)

                Section("view.new-task.section.due-date") {
                    DatePicker(
                        "view.new-task.placeholder.due-date",
                        selection: $viewModel.due,
                        displayedComponents: [.date]
                    )
                    .datePickerStyle(.graphical)
                }
            }
        }
        .navigationTitle("view.new-task.navigation.title")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .cancellationAction) {
                Button(role: .cancel) {
                    dismiss()
                }
            }

            ToolbarItem(placement: .confirmationAction) {
                Button(role: .confirm) {
                    viewModel.save(to: modelContext)
                    dismiss()
                }
                .disabled(!viewModel.canConfirm)
            }
        }
    }

}

// MARK: - Previews

#Preview(
    "New todo task",
    traits: .emptyContainer
) {
    NavigationStack {
        NewTaskView()
    }
}