import AppKit
import OrgApp
import SwiftUI

/// Window-level requests the menu bar makes.
@MainActor
@Observable
final class AppCommands {
    var showingQuickOpen = false
    var showingFolderPicker = false
    var focusSearch = false
    var showingConflict = false
}

@MainActor
final class AppDelegate: NSObject, NSApplicationDelegate {
    var session: DocumentSession?

    func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool { true }

    func applicationShouldTerminate(_ sender: NSApplication) -> NSApplication.TerminateReply {
        guard let session else { return .terminateNow }
        return UnsavedChanges.resolve(session) ? .terminateNow : .terminateCancel
    }
}

/// Unsaved edits when leaving a file or quitting.
@MainActor
enum UnsavedChanges {
    /// Whether the open file can be left: saved in automatic mode, or as the user chooses in
    /// explicit mode. A save that fails or conflicts keeps the file open.
    static func resolve(_ session: DocumentSession) -> Bool {
        guard session.isDirty else { return true }
        if session.saveMode == .automatic { return session.save() }
        let alert = NSAlert()
        alert.messageText = "Save changes to \(session.path.map { ($0 as NSString).lastPathComponent } ?? "this file")?"
        alert.informativeText = "Your changes will be lost if you don't save them."
        alert.addButton(withTitle: "Save")
        alert.addButton(withTitle: "Don't Save")
        alert.addButton(withTitle: "Cancel")
        switch alert.runModal() {
        case .alertFirstButtonReturn: return session.save()
        case .alertSecondButtonReturn: return true
        default: return false
        }
    }
}

@main
struct OrgstarApp: App {
    @NSApplicationDelegateAdaptor private var delegate: AppDelegate
    @State private var workspace = Result { try WorkspaceModel(directory: WorkspaceModel.defaultDirectory) }
    @State private var commands = AppCommands()
    @State private var session = DocumentSession()

    var body: some Scene {
        Window("Orgstar", id: "main") {
            switch workspace {
            case .success(let model):
                ContentView(workspace: model, session: session, commands: commands)
                    .onAppear { delegate.session = session }
            case .failure(let error):
                ContentUnavailableView("Can't open the index", systemImage: "exclamationmark.triangle", description: Text(error.localizedDescription))
            }
        }
        .defaultSize(width: 1280, height: 860)
        .commands {
            CommandGroup(after: .newItem) {
                Button("Add Folder…") { commands.showingFolderPicker = true }
                    .keyboardShortcut("o", modifiers: [.command, .shift])
                Button("Quick Open…") { commands.showingQuickOpen = true }
                    .keyboardShortcut("p")
            }
            CommandGroup(replacing: .saveItem) {
                Button("Save") {
                    if !session.save(), session.conflict != nil { commands.showingConflict = true }
                }
                .keyboardShortcut("s")
                .disabled(session.path == nil || session.isReadOnly)
            }
            CommandGroup(after: .textEditing) {
                Button("Search Notes") { commands.focusSearch = true }
                    .keyboardShortcut("f", modifiers: [.command, .shift])
            }
        }
        Settings {
            SettingsView()
        }
    }
}

struct SettingsView: View {
    @AppStorage("saveMode") private var saveMode = SaveMode.automatic

    var body: some View {
        Form {
            Picker("Save files:", selection: $saveMode) {
                Text("Automatically, when typing stops").tag(SaveMode.automatic)
                Text("Only with File ▸ Save (⌘S)").tag(SaveMode.explicit)
            }
            .pickerStyle(.radioGroup)
        }
        .padding(20)
        .frame(width: 420)
    }
}