import SwiftUI

struct NutritionSection: View {
    let product: Product
    @State private var isExpanded = false

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            Button {
                withAnimation {
                    isExpanded.toggle()
                }
            } label: {
                HStack {
                    Image(systemName: "chart.bar.fill")
                        .foregroundColor(.green)
                    Text("Nutrition Facts")
                        .font(.headline)
                        .foregroundColor(.primary)
                    Spacer()
                    Text(product.servingSize)
                        .font(.caption)
                        .foregroundColor(.secondary)
                    Image(systemName: isExpanded ? "chevron.up" : "chevron.down")
                        .foregroundColor(.secondary)
                }
            }

            if isExpanded {
                VStack(spacing: 0) {
                    NutritionRow(label: "Calories", value: "\(Int(product.calories))", unit: "kcal", isHeader: true)
                    Divider()
                    NutritionRow(label: "Total Fat", value: formatGrams(product.fat), unit: "g")
                    NutritionRow(label: "  Saturated Fat", value: formatGrams(product.saturatedFat), unit: "g", isIndented: true)
                    Divider()
                    NutritionRow(label: "Carbohydrates", value: formatGrams(product.carbs), unit: "g")
                    NutritionRow(label: "  Sugar", value: formatGrams(product.sugar), unit: "g", isIndented: true)
                    NutritionRow(label: "  Fiber", value: formatGrams(product.fiber), unit: "g", isIndented: true)
                    Divider()
                    NutritionRow(label: "Protein", value: formatGrams(product.protein), unit: "g")
                    Divider()
                    NutritionRow(label: "Sodium", value: formatMg(product.sodium), unit: "mg")
                }
                .padding()
                .background(Color(.systemGray6))
                .cornerRadius(12)
            }
        }
        .padding()
        .background(Color(.secondarySystemBackground))
        .cornerRadius(16)
    }

    private func formatGrams(_ value: Double) -> String {
        if value < 1 {
            return String(format: "%.1f", value)
        }
        return String(format: "%.0f", value)
    }

    private func formatMg(_ value: Double) -> String {
        return String(format: "%.0f", value)
    }
}

struct NutritionRow: View {
    let label: String
    let value: String
    let unit: String
    var isHeader: Bool = false
    var isIndented: Bool = false

    var body: some View {
        HStack {
            Text(label)
                .font(isHeader ? .headline : .subheadline)
                .foregroundColor(isIndented ? .secondary : .primary)
            Spacer()
            Text("\(value) \(unit)")
                .font(isHeader ? .headline : .subheadline)
                .foregroundColor(isHeader ? .primary : .secondary)
        }
        .padding(.vertical, 4)
    }
}