import AppKit
import Carbon.HIToolbox
import SwiftUI

/// Invisible NSView overlay that becomes first responder while recording
/// and reports the next key combo (key code + modifiers) it sees.
final class KeyCaptureView: NSView {
    var onCapture: ((UInt32, UInt32) -> Void)?
    var onCancel: (() -> Void)?

    override var acceptsFirstResponder: Bool { true }

    override func keyDown(with event: NSEvent) {
        if Int(event.keyCode) == kVK_Escape {
            onCancel?()
            return
        }

        var modifiers: UInt32 = 0
        if event.modifierFlags.contains(.control) { modifiers |= UInt32(controlKey) }
        if event.modifierFlags.contains(.option) { modifiers |= UInt32(optionKey) }
        if event.modifierFlags.contains(.shift) { modifiers |= UInt32(shiftKey) }
        if event.modifierFlags.contains(.command) { modifiers |= UInt32(cmdKey) }

        // Require at least one modifier so plain letters still work normally elsewhere.
        guard modifiers != 0 else { return }
        onCapture?(UInt32(event.keyCode), modifiers)
    }
}

struct KeyCaptureRepresentable: NSViewRepresentable {
    @Binding var isRecording: Bool
    let onCapture: (UInt32, UInt32) -> Void

    func makeNSView(context: Context) -> KeyCaptureView {
        let view = KeyCaptureView()
        view.onCapture = { keyCode, modifiers in
            onCapture(keyCode, modifiers)
            isRecording = false
        }
        view.onCancel = {
            isRecording = false
        }
        return view
    }

    func updateNSView(_ nsView: KeyCaptureView, context: Context) {
        if isRecording {
            DispatchQueue.main.async {
                nsView.window?.makeFirstResponder(nsView)
            }
        }
    }
}