Support for creating tables

[sveinungf]

API proposal

namespace SpreadCheetah.Tables;

public sealed class Table
{
    public Table(TableStyle style, string? name = null);

    public bool BandedColumns { get; set; }
    public bool BandedRows { get; set; } = true;

    // If not set, then the call to AddHeaderRowAsync determines the number of columns.
    public int? NumberOfColumns { get; set; }

    public TableColumnOptions Column(int columnNumber);
}

public sealed class TableColumnOptions
{
    public string? TotalRowLabel { get; set; }
    public TableTotalRowFunction? TotalRowFunction { get; set; }
}

public enum TableStyle
{
    None,
    Light1,
    // Light2 .. Light21
    Medium1,
    // Medium2 .. Medium28
    Dark1,
    // Dark2 .. Dark11
}

public enum TableTotalRowFunction
{
    Average = 1,
    Count,
    CountNumbers,
    Max,
    Min,
    Sum,
    StdDev,
    Var
}

public sealed class Spreadsheet
{
    // Starts the table from the next row. Doesn't write anything to the file, so it doesn't need to be async.
    public void StartTable(Table table, string firstColumnName = "A");

    public ValueTask AddHeaderRowAsync(IList<string> headerNames, StyleId? styleId = null, CancellationToken token = default);

    // Finishes the table at the current row.
    // May also add a total row, depending on what options have been set on the Table instance.
    // The total row will be written to the file asynchronously.
    public ValueTask FinishTableAsync(CancellationToken token = default);
}

API usage

await using var spreadsheet = await Spreadsheet.CreateNewAsync(stream);
await spreadsheet.StartWorksheetAsync("Sheet");

var table = new Table(TableStyle.Light9);
table.Column(1).TotalRowLabel = "Total";
table.Column(4).TotalRowFunction = TableTotalRowFunction.Sum;
spreadsheet.StartTable(table);

await spreadsheet.AddHeaderRowAsync(headerNames);
await spreadsheet.AddRowAsync(row1);
await spreadsheet.AddRowAsync(row2);

await spreadsheet.FinishAsync();