import AppKit
import Foundation

/// Native menu fallback for the paths where there is no drag to follow: the
/// menu bar's "Konvert Files…" item and the Finder Quick Action.
enum QuickMenu {
    private final class Choice: NSObject {
        let handler: () -> Void

        init(_ handler: @escaping () -> Void) {
            self.handler = handler
        }

        @objc func fire() {
            handler()
        }
    }

    /// The menu items hold their target weakly, so the choices are retained
    /// here for the duration of the (synchronous) popup.
    private static var retained: [Choice] = []

    static func show(urls: [URL], at point: CGPoint) {
        guard !urls.isEmpty else { return }
        retained.removeAll()

        let menu = NSMenu()
        menu.autoenablesItems = false

        let header = NSMenuItem(
            title: WheelBuilder.summary(for: urls),
            action: nil,
            keyEquivalent: ""
        )
        header.isEnabled = false
        menu.addItem(header)
        menu.addItem(.separator())

        let category = FileKind.category(of: urls[0])

        if ConversionCatalog.outputs(for: urls.map { FileKind.category(of: $0) }).isEmpty {
            let item = NSMenuItem(title: "No conversions for this selection", action: nil, keyEquivalent: "")
            item.isEnabled = false
            menu.addItem(item)
        } else {
            let convert = NSMenu()
            for item in WheelBuilder.items(kind: .convert, urls: urls) {
                let entry = NSMenuItem(title: item.title, action: #selector(Choice.fire), keyEquivalent: "")
                entry.target = makeChoice {
                    JobStore.shared.submit(urls: urls, target: .format(format(from: item)))
                }
                entry.isEnabled = item.isEnabled
                if let reason = item.availability.reason { entry.toolTip = reason }
                convert.addItem(entry)
            }
            let submenu = NSMenuItem(title: "Convert", action: nil, keyEquivalent: "")
            submenu.submenu = convert
            menu.addItem(submenu)
        }

        let tools = WheelBuilder.items(kind: .tools, urls: urls)
        if category != .unknown, !tools.isEmpty {
            let submenu = NSMenu()
            for item in tools {
                guard case .tool(let tool) = item.payload else { continue }
                let entry = NSMenuItem(title: tool.title, action: #selector(Choice.fire), keyEquivalent: "")
                entry.target = makeChoice {
                    if tool.fields.isEmpty {
                        JobStore.shared.submit(urls: urls, target: .tool(tool))
                    } else {
                        OptionsWindowController.shared.present(tool: tool, urls: urls, origin: point)
                    }
                }
                entry.isEnabled = item.isEnabled
                if let reason = item.availability.reason { entry.toolTip = reason }
                submenu.addItem(entry)
            }
            let wrapper = NSMenuItem(title: "Tools", action: nil, keyEquivalent: "")
            wrapper.submenu = submenu
            menu.addItem(wrapper)
        }

        let actions = NSMenu()
        for item in WheelBuilder.items(kind: .actions, urls: urls) {
            guard case .action(let action) = item.payload else { continue }
            let entry = NSMenuItem(title: action.title, action: #selector(Choice.fire), keyEquivalent: "")
            entry.target = makeChoice {
                JobStore.shared.submit(urls: urls, target: .action(action))
            }
            actions.addItem(entry)
        }
        let actionsWrapper = NSMenuItem(title: "Actions", action: nil, keyEquivalent: "")
        actionsWrapper.submenu = actions
        menu.addItem(actionsWrapper)

        menu.popUp(positioning: nil, at: point, in: nil)
        retained.removeAll()
    }

    private static func makeChoice(_ handler: @escaping () -> Void) -> Choice {
        let choice = Choice(handler)
        retained.append(choice)
        return choice
    }

    private static func format(from item: WheelItem) -> Format {
        if case .format(let format) = item.payload { return format }
        return .png
    }
}