import SwiftUI
import CoreImage
import CoreImage.CIFilterBuiltins

// MARK: - 条形码预览组件
struct BarcodePreviewView: View {
    let content: String
    let barcodeType: BarcodeType
    
    var body: some View {
        Group {
            if let barcodeImage = generateBarcodeImage() {
                Image(uiImage: barcodeImage)
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    .frame(maxWidth: .infinity)
                    .background(Color.white)
                    .cornerRadius(8)
                    .shadow(color: .black.opacity(0.1), radius: 2, x: 0, y: 1)
            } else {
                // 生成失败时的占位符
                VStack(spacing: 8) {
                    Image(systemName: "barcode.viewfinder")
                        .font(.system(size: 32))
                        .foregroundColor(.gray)
                    
                    Text(NSLocalizedString("cannot_generate_barcode", comment: "Cannot generate barcode"))
                        .font(.caption)
                        .foregroundColor(.gray)
                    
                    Text(NSLocalizedString("check_input_format", comment: "Please check input content format"))
                        .font(.caption2)
                        .foregroundColor(.gray)
                }
                .frame(maxWidth: .infinity)
                .frame(height: 120)
                .background(Color(.systemGray5))
                .cornerRadius(8)
            }
        }
    }
    
    // MARK: - 生成条形码图片
    private func generateBarcodeImage() -> UIImage? {
        guard !content.isEmpty else { return nil }
        
        let context = CIContext()
        let filter: CIFilter?
        
        // 根据条形码类型选择相应的滤镜
        switch barcodeType {
        case .ean13, .ean8, .upce, .itf14:
            filter = CIFilter.code128BarcodeGenerator()
            filter?.setValue(content.data(using: .utf8), forKey: "inputMessage")
            
        case .code39:
            // Code 39 使用 Code 128 滤镜，因为 Core Image 不直接支持 Code 39
            filter = CIFilter.code128BarcodeGenerator()
            filter?.setValue(content.data(using: .utf8), forKey: "inputMessage")
            
        case .code128:
            filter = CIFilter.code128BarcodeGenerator()
            filter?.setValue(content.data(using: .utf8), forKey: "inputMessage")
            
        case .pdf417:
            filter = CIFilter.pdf417BarcodeGenerator()
            filter?.setValue(content.data(using: .utf8), forKey: "inputMessage")
        }
        
        guard let filter = filter,
              let outputImage = filter.outputImage else { return nil }
        
        // 设置条形码的尺寸和缩放
        let scale = CGAffineTransform(scaleX: 3, y: 3)
        let scaledImage = outputImage.transformed(by: scale)
        
        // 转换为UIImage
        guard let cgImage = context.createCGImage(scaledImage, from: scaledImage.extent) else {
            return nil
        }
        
        return UIImage(cgImage: cgImage)
    }
}

#Preview {
    VStack(spacing: 20) {
        BarcodePreviewView(content: "1234567890123", barcodeType: .ean13)
        BarcodePreviewView(content: "12345678", barcodeType: .ean8)
        BarcodePreviewView(content: "CODE39", barcodeType: .code39)
        BarcodePreviewView(content: "123456789012345678901234567890", barcodeType: .pdf417)
    }
    .padding()
}