import SwiftUI
import AVFoundation

#if os(macOS)
import AppKit

// MARK: - 扫码窗口控制器（独立 NSWindow）
class QRScannerWindowController: NSObject, AVCaptureMetadataOutputObjectsDelegate {
    var window: NSWindow?
    var session: AVCaptureSession?
    weak var bridge: PlayerBridge?
    
    private var lastDetected: String?
    private var lastDetectedTime: Date = .distantPast
    private weak var resultLabel: NSTextField?
    private weak var previewHost: NSView?
    private weak var loadingLabel: NSTextField?
    
    init(bridge: PlayerBridge) {
        self.bridge = bridge
        super.init()
    }
    
    func show() {
        if let win = window, win.isVisible {
            win.makeKeyAndOrderFront(nil)
            return
        }
        
        let win = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 400, height: 380),
            styleMask: [.titled, .closable],
            backing: .buffered,
            defer: false
        )
        win.title = L.scanQRCode
        win.isReleasedWhenClosed = false
        win.center()
        
        let container = NSView(frame: win.contentView!.bounds)
        container.autoresizingMask = [.width, .height]
        container.wantsLayer = true
        container.layer?.backgroundColor = NSColor.black.cgColor
        
        // 摄像头预览区域（占位）
        let previewHost = NSView(frame: NSRect(x: 20, y: 80, width: 360, height: 240))
        previewHost.wantsLayer = true
        previewHost.layer?.backgroundColor = NSColor.darkGray.cgColor
        previewHost.autoresizingMask = [.width, .height]
        container.addSubview(previewHost)
        self.previewHost = previewHost
        
        // "正在初始化摄像头..." 提示
        let loadingLabel = NSTextField(labelWithString: "Initializing camera...")
        loadingLabel.font = NSFont.systemFont(ofSize: 12)
        loadingLabel.textColor = .secondaryLabelColor
        loadingLabel.frame = NSRect(x: 0, y: 100, width: 360, height: 40)
        loadingLabel.alignment = .center
        previewHost.addSubview(loadingLabel)
        self.loadingLabel = loadingLabel
        
        // 提示文字
        let hintLabel = NSTextField(wrappingLabelWithString: L.scanHint)
        hintLabel.font = NSFont.systemFont(ofSize: 11)
        hintLabel.textColor = .secondaryLabelColor
        hintLabel.frame = NSRect(x: 20, y: 20, width: 360, height: 40)
        hintLabel.alignment = .center
        container.addSubview(hintLabel)
        
        // 检测结果
        let resultLabel = NSTextField(labelWithString: "")
        resultLabel.font = NSFont.monospacedSystemFont(ofSize: 12, weight: .regular)
        resultLabel.textColor = .labelColor
        resultLabel.frame = NSRect(x: 20, y: 330, width: 360, height: 30)
        resultLabel.alignment = .center
        resultLabel.lineBreakMode = .byTruncatingMiddle
        resultLabel.tag = 100
        container.addSubview(resultLabel)
        self.resultLabel = resultLabel
        
        win.contentView = container
        win.makeKeyAndOrderFront(nil)
        NSApp.activate(ignoringOtherApps: true)
        self.window = win
        
        // 后台初始化摄像头（不阻塞主线程）
        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            self?.setupCaptureOnBackground(previewHost: previewHost)
        }
    }
    
    func close() {
        session?.stopRunning()
        DispatchQueue.main.async { [weak self] in
            self?.window?.close()
        }
    }
    
    // 在后台线程初始化摄像头
    private func setupCaptureOnBackground(previewHost: NSView) {
        let session = AVCaptureSession()
        
        guard let device = AVCaptureDevice.default(for: .video) else {
            DispatchQueue.main.async { [weak self] in
                self?.showError("No camera available")
            }
            return
        }
        
        guard let input = try? AVCaptureDeviceInput(device: device) else {
            DispatchQueue.main.async { [weak self] in
                self?.showError("Cannot access camera")
            }
            return
        }
        
        if session.canAddInput(input) {
            session.addInput(input)
        }
        
        let output = AVCaptureMetadataOutput()
        if session.canAddOutput(output) {
            session.addOutput(output)
            output.setMetadataObjectsDelegate(self, queue: .main)
            output.metadataObjectTypes = [.qr]
        }
        
        let previewLayer = AVCaptureVideoPreviewLayer(session: session)
        previewLayer.videoGravity = .resizeAspectFill
        
        self.session = session
        
        // 回到主线程更新 UI
        DispatchQueue.main.async { [weak self] in
            guard let self = self, previewHost.window != nil else {
                // 窗口已关闭，停止
                session.stopRunning()
                return
            }
            
            // 移除 loading 提示
            self.loadingLabel?.removeFromSuperview()
            
            // 添加预览层
            previewLayer.frame = previewHost.bounds
            previewHost.layer?.addSublayer(previewLayer)
            
            // 启动会话（后台启动避免阻塞）
            DispatchQueue.global(qos: .userInitiated).async {
                session.startRunning()
            }
        }
    }
    
    private func showError(_ msg: String) {
        resultLabel?.stringValue = msg
        resultLabel?.textColor = .systemRed
    }
    
    // MARK: - AVCaptureMetadataOutputObjectsDelegate
    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        guard let metadata = metadataObjects.first as? AVMetadataMachineReadableCodeObject,
              let code = metadata.stringValue else { return }
        
        let now = Date()
        if code == lastDetected, now.timeIntervalSince(lastDetectedTime) < 3 {
            return
        }
        lastDetected = code
        lastDetectedTime = now
        
        // 显示检测结果
        resultLabel?.stringValue = code
        resultLabel?.textColor = .systemGreen
        
        // 有效 URL → 添加并播放
        if let url = URL(string: code), (url.scheme == "http" || url.scheme == "https") {
            DispatchQueue.main.async { [weak self] in
                self?.bridge?.addURL(code)
            }
            DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) { [weak self] in
                self?.close()
            }
        }
    }
    
    deinit {
        session?.stopRunning()
    }
}

#endif