import SwiftUI

struct MeasurementColumn: Identifiable {
    let id = UUID()
    let header: String
    let width: CGFloat
    let alignment: Alignment
}

struct MeasurementTable<Row: Identifiable>: View {
    let columns: [MeasurementColumn]
    let rows: [Row]
    let cellText: (Row, Int) -> String

    var body: some View {
        VStack(spacing: 0) {
            headerRow
            Divider().background(Color.gray.opacity(0.4))
            ScrollView {
                LazyVStack(spacing: 0) {
                    ForEach(Array(rows.enumerated()), id: \.element.id) { idx, row in
                        dataRow(row, even: idx % 2 == 0)
                    }
                }
            }
        }
        .font(.system(.caption, design: .monospaced))
        #if os(iOS)
        .background(Color(.systemBackground).opacity(0.05))
        #else
        .background(Color(white: 0.1).opacity(0.05))
        #endif
    }

    private var headerRow: some View {
        HStack(spacing: 0) {
            ForEach(Array(columns.enumerated()), id: \.element.id) { idx, col in
                Text(col.header)
                    .fontWeight(.semibold)
                    .frame(width: col.width, alignment: col.alignment)
                    .foregroundStyle(.secondary)
                if idx < columns.count - 1 {
                    Spacer(minLength: 4)
                }
            }
        }
        .padding(.vertical, 6)
        .padding(.horizontal, 8)
    }

    private func dataRow(_ row: Row, even: Bool) -> some View {
        HStack(spacing: 0) {
            ForEach(Array(columns.enumerated()), id: \.element.id) { idx, col in
                Text(cellText(row, idx))
                    .frame(width: col.width, alignment: col.alignment)
                if idx < columns.count - 1 {
                    Spacer(minLength: 4)
                }
            }
        }
        .padding(.vertical, 3)
        .padding(.horizontal, 8)
        .background(even ? Color.clear : Color.white.opacity(0.03))
    }
}