import SwiftUI

// MARK: - 简化的卡片组件
struct SimpleCardView: View {
    let content: AnyView
    let padding: EdgeInsets
    let cornerRadius: CGFloat
    let shadowColor: Color
    let shadowRadius: CGFloat
    let shadowOffset: CGSize
    let backgroundColor: Color
    
    init(
        padding: EdgeInsets = EdgeInsets(top: 16, leading: 16, bottom: 16, trailing: 16),
        cornerRadius: CGFloat = 12,
        shadowColor: Color = .black.opacity(0.1),
        shadowRadius: CGFloat = 8,
        shadowOffset: CGSize = CGSize(width: 0, height: 4),
        backgroundColor: Color = Color(.systemBackground),
        @ViewBuilder content: () -> some View
    ) {
        self.padding = padding
        self.cornerRadius = cornerRadius
        self.shadowColor = shadowColor
        self.shadowRadius = shadowRadius
        self.shadowOffset = shadowOffset
        self.backgroundColor = backgroundColor
        self.content = AnyView(content())
    }
    
    var body: some View {
        content
            .padding(padding)
            .background(backgroundColor)
            .cornerRadius(cornerRadius)
            .shadow(
                color: shadowColor,
                radius: shadowRadius,
                x: shadowOffset.width,
                y: shadowOffset.height
            )
    }
}

// MARK: - 预定义的卡片样式
extension SimpleCardView {
    static func standard<Content: View>(
        @ViewBuilder content: () -> Content
    ) -> SimpleCardView {
        SimpleCardView(content: content)
    }
    
    static func elevated<Content: View>(
        @ViewBuilder content: () -> Content
    ) -> SimpleCardView {
        SimpleCardView(
            shadowColor: .black.opacity(0.15),
            shadowRadius: 12,
            shadowOffset: CGSize(width: 0, height: 6),
            content: content
        )
    }
    
    static func subtle<Content: View>(
        @ViewBuilder content: () -> Content
    ) -> SimpleCardView {
        SimpleCardView(
            shadowColor: .black.opacity(0.05),
            shadowRadius: 4,
            shadowOffset: CGSize(width: 0, height: 2),
            content: content
        )
    }
    
    static func compact<Content: View>(
        @ViewBuilder content: () -> Content
    ) -> SimpleCardView {
        SimpleCardView(
            padding: EdgeInsets(top: 12, leading: 12, bottom: 12, trailing: 12),
            cornerRadius: 8,
            content: content
        )
    }
    
    static func large<Content: View>(
        @ViewBuilder content: () -> Content
    ) -> SimpleCardView {
        SimpleCardView(
            padding: EdgeInsets(top: 24, leading: 24, bottom: 24, trailing: 24),
            cornerRadius: 16,
            content: content
        )
    }
}

// MARK: - 信息卡片组件
struct InfoCard: View {
    let title: String
    let subtitle: String?
    let icon: String?
    let iconColor: Color
    let content: String
    let actionTitle: String?
    let action: (() -> Void)?
    
    init(
        title: String,
        subtitle: String? = nil,
        icon: String? = nil,
        iconColor: Color = .blue,
        content: String,
        actionTitle: String? = nil,
        action: (() -> Void)? = nil
    ) {
        self.title = title
        self.subtitle = subtitle
        self.icon = icon
        self.iconColor = iconColor
        self.content = content
        self.actionTitle = actionTitle
        self.action = action
    }
    
    var body: some View {
        SimpleCardView.standard {
            VStack(alignment: .leading, spacing: 12) {
                // 标题行
                HStack {
                    if let icon = icon {
                        Image(systemName: icon)
                            .font(.title2)
                            .foregroundColor(iconColor)
                    }
                    
                    VStack(alignment: .leading, spacing: 2) {
                        Text(title)
                            .font(.headline)
                            .foregroundColor(.primary)
                        
                        if let subtitle = subtitle {
                            Text(subtitle)
                                .font(.caption)
                                .foregroundColor(.secondary)
                        }
                    }
                    
                    Spacer()
                }
                
                // 内容
                Text(content)
                    .font(.body)
                    .foregroundColor(.primary)
                    .lineLimit(nil)
                
                // 操作按钮
                if let actionTitle = actionTitle, let action = action {
                    Button(action: action) {
                        Text(actionTitle)
                            .font(.subheadline)
                            .fontWeight(.medium)
                            .foregroundColor(iconColor)
                    }
                }
            }
        }
    }
}

// MARK: - 统计卡片组件
struct StatCard: View {
    let title: String
    let value: String
    let subtitle: String?
    let icon: String?
    let iconColor: Color
    let trend: Trend?
    
    enum Trend {
        case up(String)
        case down(String)
        case neutral(String)
    }
    
    init(
        title: String,
        value: String,
        subtitle: String? = nil,
        icon: String? = nil,
        iconColor: Color = .blue,
        trend: Trend? = nil
    ) {
        self.title = title
        self.value = value
        self.subtitle = subtitle
        self.icon = icon
        self.iconColor = iconColor
        self.trend = trend
    }
    
    var body: some View {
        SimpleCardView.standard {
            VStack(alignment: .leading, spacing: 12) {
                // 标题和图标
                HStack {
                    if let icon = icon {
                        Image(systemName: icon)
                            .font(.title2)
                            .foregroundColor(iconColor)
                    }
                    
                    Text(title)
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                    
                    Spacer()
                }
                
                // 数值
                Text(value)
                    .font(.title)
                    .fontWeight(.bold)
                    .foregroundColor(.primary)
                
                // 副标题和趋势
                HStack {
                    if let subtitle = subtitle {
                        Text(subtitle)
                            .font(.caption)
                            .foregroundColor(.secondary)
                    }
                    
                    Spacer()
                    
                    if trend != nil {
                        HStack(spacing: 4) {
                            Image(systemName: trendIcon)
                                .font(.caption)
                                .foregroundColor(trendColor)
                            
                            Text(trendValue)
                                .font(.caption)
                                .foregroundColor(trendColor)
                        }
                    }
                }
            }
        }
    }
    
    private var trendIcon: String {
        switch trend {
        case .up:
            return "arrow.up"
        case .down:
            return "arrow.down"
        case .neutral:
            return "minus"
        case .none:
            return ""
        }
    }
    
    private var trendColor: Color {
        switch trend {
        case .up:
            return .green
        case .down:
            return .red
        case .neutral:
            return .orange
        case .none:
            return .clear
        }
    }
    
    private var trendValue: String {
        switch trend {
        case .up(let value), .down(let value), .neutral(let value):
            return value
        case .none:
            return ""
        }
    }
}

#Preview {
    VStack(spacing: 20) {
        // 标准卡片
        SimpleCardView.standard {
            VStack(alignment: .leading, spacing: 12) {
                Text("标准卡片")
                    .font(.headline)
                Text("这是一个标准样式的卡片组件")
                    .font(.body)
            }
        }
        
        // 信息卡片
        InfoCard(
            title: "提示信息",
            subtitle: "重要提醒",
            icon: "info.circle",
            content: "这是一个信息卡片，用于显示重要的提示信息。",
            actionTitle: "了解更多",
            action: {}
        )
        
        // 统计卡片
        StatCard(
            title: "总用户数",
            value: "1,234",
            subtitle: "本月新增 123",
            icon: "person.3",
            trend: .up("+12%")
        )
        
        // 紧凑卡片
        SimpleCardView.compact {
            Text("紧凑卡片")
                .font(.headline)
        }
    }
    .padding()
}