import OrgSwift
import SwiftUI

/// A table, in a `Grid` that scrolls sideways when it is wider than the screen.
///
/// Column alignment comes from org's `|---+:---:+---|` separator row. `Grid` takes it from
/// one cell per column, so it is set on the first row and inherited down.
struct OrgTableView: View {
    let table: OrgTableLayout
    @Environment(\.orgMath) private var math

    var body: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            Grid(alignment: .topLeading, horizontalSpacing: 14, verticalSpacing: 7) {
                ForEach(Array(table.rows.enumerated()), id: \.element.id) { index, row in
                    GridRow {
                        ForEach(0 ..< table.columnCount, id: \.self) { column in
                            cell(row, column: column, isHeader: index < table.headerRowCount)
                        }
                    }
                    // The rule row separating the header band from the body.
                    if index + 1 == table.headerRowCount {
                        Divider().gridCellColumns(table.columnCount)
                    }
                }
            }
            .padding(.vertical, 2)
        }
    }

    @ViewBuilder
    private func cell(_ row: OrgTableLayout.Row, column: Int, isHeader: Bool) -> some View {
        // Org tolerates ragged rows; a missing cell is empty, not a crash.
        let text = column < row.cells.count ? row.cells[column].text : AttributedString()
        orgText(text, math: math)
            .fontWeight(isHeader ? .semibold : .regular)
            .multilineTextAlignment(Self.textAlignment(table.alignment(column: column)))
            .fixedSize(horizontal: false, vertical: true)
            .gridColumnAlignment(Self.gridAlignment(table.alignment(column: column)))
    }

    private static func gridAlignment(_ alignment: OrgAlignment?) -> HorizontalAlignment {
        switch alignment {
        case .center: .center
        case .right: .trailing
        case .left, nil: .leading
        }
    }

    private static func textAlignment(_ alignment: OrgAlignment?) -> TextAlignment {
        switch alignment {
        case .center: .center
        case .right: .trailing
        case .left, nil: .leading
        }
    }
}