import SwiftUI

struct RequestTabCloseAction {
    let perform: (UUID) -> Void
    func callAsFunction(_ id: UUID) { perform(id) }
}
private struct RequestTabCloseKey: EnvironmentKey {
    static let defaultValue = RequestTabCloseAction { _ in }
}
extension EnvironmentValues {
    var requestTabClose: RequestTabCloseAction {
        get { self[RequestTabCloseKey.self] }
        set { self[RequestTabCloseKey.self] = newValue }
    }
}

struct UnsavedChangesAlert: ViewModifier {
    @ObservedObject var editorState:  EditorState
    let buildService:                  BuildService
    @State private var pendingTabId:  UUID?
    @State private var showAlert = false

    func body(content: Content) -> some View {
        content
            .environment(\.requestTabClose, RequestTabCloseAction { tabId in
                if let tab = editorState.tabs.first(where: { $0.id == tabId }), tab.isDirty {
                    pendingTabId = tabId; showAlert = true
                } else {
                    editorState.closeTab(id: tabId)
                }
            })
            .alert("Unsaved Changes", isPresented: $showAlert) {
                Button("Save & Close") {
                    if let id = pendingTabId,
                       let tab = editorState.tabs.first(where: { $0.id == id }) {
                        Task {
                            await buildService.saveFile(path: tab.path, content: tab.content)
                            editorState.closeTab(id: id)
                        }
                    }
                }
                Button("Discard", role: .destructive) {
                    if let id = pendingTabId { editorState.closeTab(id: id) }
                }
                Button("Cancel", role: .cancel) { pendingTabId = nil }
            } message: {
                if let id = pendingTabId,
                   let name = editorState.tabs.first(where: { $0.id == id })?.fileName {
                    Text("\"\(name)\" has unsaved changes.")
                }
            }
    }
}

extension View {
    func unsavedChangesGuard(editorState: EditorState, buildService: BuildService) -> some View {
        modifier(UnsavedChangesAlert(editorState: editorState, buildService: buildService))
    }
}