import SwiftUI
import CoreImage
import CoreImage.CIFilterBuiltins

// MARK: - QR 码生成器（macOS + iOS 通用）

/// 把任意文本编码成 QR 码图片。
public enum QRCodeGenerator {
    private static let context = CIContext()

    /// 生成 QR 码位图。返回 nil 表示编码失败。
    public static func image(from string: String, size: CGFloat = 260) -> PlatformImage? {
        guard !string.isEmpty else { return nil }
        let data = Data(string.utf8)

        let filter = CIFilter.qrCodeGenerator()
        filter.message = data
        // 容错等级 H：即使二维码中间叠 logo 也能扫出，同时更耐屏幕反光/压缩
        filter.correctionLevel = "H"

        guard let output = filter.outputImage else { return nil }

        // 原始 QR 码每模块 1px，放大到目标尺寸
        let scale = size / output.extent.width
        let scaled = output.transformed(by: CGAffineTransform(scaleX: scale, y: scale))

        #if os(macOS)
        guard let cg = context.createCGImage(scaled, from: scaled.extent) else { return nil }
        return NSImage(cgImage: cg, size: NSSize(width: size, height: size))
        #else
        guard let cg = context.createCGImage(scaled, from: scaled.extent) else { return nil }
        return UIImage(cgImage: cg)
        #endif
    }
}

#if os(macOS)
public typealias PlatformImage = NSImage
#else
public typealias PlatformImage = UIImage
#endif

// MARK: - 二维码弹窗内容视图（macOS 窗口 / iOS sheet 共用）

public struct QRDisplayView: View {
    let urlString: String          // 实际编码进二维码的内容（可能是 JSON 载荷）
    let displayText: String?       // 界面上给用户看的明文（通常是纯 URL）
    let onDismiss: () -> Void

    @State private var copied = false

    public init(urlString: String, displayText: String? = nil, onDismiss: @escaping () -> Void) {
        self.urlString = urlString
        self.displayText = displayText
        self.onDismiss = onDismiss
    }

    /// 界面上展示的文本：优先用明文 URL，没有则展示编码内容
    private var shownText: String { displayText ?? urlString }

    public var body: some View {
        VStack(spacing: 18) {
            Text(L.showQRCode)
                .font(.headline)

            Group {
                if let img = QRCodeGenerator.image(from: urlString, size: 260) {
                    #if os(macOS)
                    Image(nsImage: img)
                        .interpolation(.none)
                        .resizable()
                        .frame(width: 260, height: 260)
                        .padding(10)
                        .background(Color.white)
                        .cornerRadius(8)
                    #else
                    Image(uiImage: img)
                        .interpolation(.none)
                        .resizable()
                        .frame(width: 260, height: 260)
                        .padding(10)
                        .background(Color.white)
                        .cornerRadius(8)
                    #endif
                } else {
                    Text(L.qrGenFailed)
                        .foregroundColor(.red)
                        .frame(width: 260, height: 260)
                }
            }

            // URL 明文：方便长按/复制/手动核对
            Text(shownText)
                .font(.system(size: 12, design: .monospaced))
                .multilineTextAlignment(.center)
                .lineLimit(4)
                .truncationMode(.middle)
                .textSelection(.enabled)
                .frame(maxWidth: 300)

            HStack(spacing: 12) {
                Button(copied ? L.copied : L.copyURL) {
                    copyToClipboard(shownText)
                    copied = true
                    DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) { copied = false }
                }
                Button(L.done, action: onDismiss)
                    .keyboardShortcut(.defaultAction)
            }
        }
        .padding(24)
        .frame(minWidth: 340)
    }

    private func copyToClipboard(_ s: String) {
        #if os(macOS)
        let pb = NSPasteboard.general
        pb.clearContents()
        pb.setString(s, forType: .string)
        #else
        UIPasteboard.general.string = s
        #endif
    }
}

#if os(macOS)
/// macOS：独立窗口控制器，复用与扫码窗口一致的 NSWindow 模式
public final class QRDisplayWindowController {
    private var window: NSWindow?
    private let onClose: () -> Void

    public init(onClose: @escaping () -> Void = {}) {
        self.onClose = onClose
    }

    public func show(urlString: String, displayText: String? = nil) {
        if let win = window, win.isVisible {
            win.makeKeyAndOrderFront(nil)
            return
        }
        let win = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 380, height: 460),
            styleMask: [.titled, .closable],
            backing: .buffered,
            defer: false
        )
        win.title = L.showQRCode
        win.isReleasedWhenClosed = false
        win.center()
        win.contentView = NSHostingView(rootView: QRDisplayView(urlString: urlString, displayText: displayText) { [weak self] in
            self?.close()
        })
        win.makeKeyAndOrderFront(nil)
        NSApp.activate(ignoringOtherApps: true)
        self.window = win
    }

    public func close() {
        window?.close()
        window = nil
        onClose()
    }
}
#endif