import SwiftUI
import AppKit

/// A clickable field that records a keyboard shortcut when focused.
/// Click it, press a key combination, and it saves the binding.
struct HotkeyRecorderView: View {
    let label: String
    @Binding var binding: HotkeyBinding

    @State private var isRecording = false

    var body: some View {
        HStack {
            Text(label)
                .frame(width: 140, alignment: .leading)

            HotkeyRecorderField(binding: $binding, isRecording: $isRecording)
                .frame(width: 120, height: 24)
                .background(
                    RoundedRectangle(cornerRadius: 6)
                        .fill(isRecording ? Color.accentColor.opacity(0.15) : Color.secondary.opacity(0.1))
                )
                .overlay(
                    RoundedRectangle(cornerRadius: 6)
                        .stroke(isRecording ? Color.accentColor : Color.secondary.opacity(0.3), lineWidth: 1)
                )
        }
    }
}

/// NSViewRepresentable that captures key events when focused.
struct HotkeyRecorderField: NSViewRepresentable {
    @Binding var binding: HotkeyBinding
    @Binding var isRecording: Bool

    func makeNSView(context: Context) -> HotkeyNSView {
        let view = HotkeyNSView()
        view.onKeyRecorded = { newBinding in
            binding = newBinding
            isRecording = false
        }
        view.onFocusChanged = { focused in
            isRecording = focused
        }
        return view
    }

    func updateNSView(_ nsView: HotkeyNSView, context: Context) {
        nsView.currentLabel = binding.displayString
        nsView.showRecording = isRecording
        nsView.needsDisplay = true
    }
}

/// The actual NSView that handles key capture.
class HotkeyNSView: NSView {
    var currentLabel: String = ""
    var showRecording: Bool = false
    var onKeyRecorded: ((HotkeyBinding) -> Void)?
    var onFocusChanged: ((Bool) -> Void)?

    override var acceptsFirstResponder: Bool { true }

    override func draw(_ dirtyRect: NSRect) {
        let text = showRecording ? "Press keys…" : currentLabel
        let attrs: [NSAttributedString.Key: Any] = [
            .font: NSFont.monospacedSystemFont(ofSize: 12, weight: .medium),
            .foregroundColor: showRecording ? NSColor.controlAccentColor : NSColor.labelColor
        ]
        let str = NSAttributedString(string: text, attributes: attrs)
        let size = str.size()
        let point = NSPoint(
            x: (bounds.width - size.width) / 2,
            y: (bounds.height - size.height) / 2
        )
        str.draw(at: point)
    }

    override func mouseDown(with event: NSEvent) {
        window?.makeFirstResponder(self)
    }

    override func becomeFirstResponder() -> Bool {
        onFocusChanged?(true)
        return true
    }

    override func resignFirstResponder() -> Bool {
        onFocusChanged?(false)
        return true
    }

    override func keyDown(with event: NSEvent) {
        guard showRecording else {
            super.keyDown(with: event)
            return
        }

        let relevantFlags: NSEvent.ModifierFlags = [.command, .shift, .control, .option]
        let masked = event.modifierFlags.intersection(.deviceIndependentFlagsMask).intersection(relevantFlags)

        // Require at least one modifier key
        guard !masked.isEmpty else { return }

        let binding = HotkeyBinding(modifiers: masked.rawValue, keyCode: event.keyCode)
        onKeyRecorded?(binding)

        // Resign first responder after recording
        window?.makeFirstResponder(nil)
    }
}