Add calendar control

Closes #101

src/Spectre.Console/Widgets/Calendar.cs

@@ -0,0 +1,274 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using Spectre.Console.Internal;
+using Spectre.Console.Internal.Collections;
+using Spectre.Console.Rendering;
+
+namespace Spectre.Console
+{
+    /// <summary>
+    /// A renderable calendar.
+    /// </summary>
+    public sealed class Calendar : Renderable, IHasCulture, IHasTableBorder
+    {
+        private const int NumberOfWeekDays = 7;
+        private const int ExpectedRowCount = 6;
+
+        private readonly ListWithCallback<CalendarEvent> _calendarEvents;
+
+        private int _year;
+        private int _month;
+        private int _day;
+        private IRenderable? _table;
+        private TableBorder _border;
+        private bool _useSafeBorder;
+        private Style? _borderStyle;
+        private bool _dirty;
+        private CultureInfo _culture;
+        private Style _highlightStyle;
+
+        /// <summary>
+        /// Gets or sets the calendar year.
+        /// </summary>
+        public int Year
+        {
+            get => _year;
+            set => MarkAsDirty(() => _year = value);
+        }
+
+        /// <summary>
+        /// Gets or sets the calendar month.
+        /// </summary>
+        public int Month
+        {
+            get => _month;
+            set => MarkAsDirty(() => _month = value);
+        }
+
+        /// <summary>
+        /// Gets or sets the calendar day.
+        /// </summary>
+        public int Day
+        {
+            get => _day;
+            set => MarkAsDirty(() => _day = value);
+        }
+
+        /// <inheritdoc/>
+        public TableBorder Border
+        {
+            get => _border;
+            set => MarkAsDirty(() => _border = value);
+        }
+
+        /// <inheritdoc/>
+        public bool UseSafeBorder
+        {
+            get => _useSafeBorder;
+            set => MarkAsDirty(() => _useSafeBorder = value);
+        }
+
+        /// <inheritdoc/>
+        public Style? BorderStyle
+        {
+            get => _borderStyle;
+            set => MarkAsDirty(() => _borderStyle = value);
+        }
+
+        /// <summary>
+        /// Gets or sets the calendar's <see cref="CultureInfo"/>.
+        /// </summary>
+        public CultureInfo Culture
+        {
+            get => _culture;
+            set => MarkAsDirty(() => _culture = value);
+        }
+
+        /// <summary>
+        /// Gets or sets the calendar's highlight <see cref="Style"/>.
+        /// </summary>
+        public Style HightlightStyle
+        {
+            get => _highlightStyle;
+            set => MarkAsDirty(() => _highlightStyle = value);
+        }
+
+        /// <summary>
+        /// Gets a list containing all calendar events.
+        /// </summary>
+        public IList<CalendarEvent> CalendarEvents => _calendarEvents;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Calendar"/> class.
+        /// </summary>
+        /// <param name="date">The calendar date.</param>
+        public Calendar(DateTime date)
+            : this(date.Year, date.Month, date.Day)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Calendar"/> class.
+        /// </summary>
+        /// <param name="year">The calendar year.</param>
+        /// <param name="month">The calendar month.</param>
+        public Calendar(int year, int month)
+            : this(year, month, 1)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Calendar"/> class.
+        /// </summary>
+        /// <param name="year">The calendar year.</param>
+        /// <param name="month">The calendar month.</param>
+        /// <param name="day">The calendar day.</param>
+        public Calendar(int year, int month, int day)
+        {
+            _year = year;
+            _month = month;
+            _day = day;
+            _table = null;
+            _border = TableBorder.Square;
+            _useSafeBorder = true;
+            _borderStyle = null;
+            _dirty = true;
+            _culture = CultureInfo.InvariantCulture;
+            _highlightStyle = new Style(foreground: Color.Blue);
+            _calendarEvents = new ListWithCallback<CalendarEvent>(() => _dirty = true);
+        }
+
+        /// <inheritdoc/>
+        protected override Measurement Measure(RenderContext context, int maxWidth)
+        {
+            var table = GetTable();
+            return table.Measure(context, maxWidth);
+        }
+
+        /// <inheritdoc/>
+        protected override IEnumerable<Segment> Render(RenderContext context, int maxWidth)
+        {
+            return GetTable().Render(context, maxWidth);
+        }
+
+        private IRenderable GetTable()
+        {
+            // Table needs to be built?
+            if (_dirty || _table == null)
+            {
+                _table = BuildTable();
+                _dirty = false;
+            }
+
+            return _table;
+        }
+
+        private IRenderable BuildTable()
+        {
+            var culture = Culture ?? CultureInfo.InvariantCulture;
+
+            var table = new Table
+            {
+                Border = _border,
+                UseSafeBorder = _useSafeBorder,
+                BorderStyle = _borderStyle,
+            };
+
+            // Add columns
+            foreach (var order in GetWeekdays())
+            {
+                table.AddColumn(new TableColumn(order.GetAbbreviatedDayName(culture)));
+            }
+
+            var row = new List<IRenderable>();
+
+            var currentDay = 1;
+            var weekday = culture.DateTimeFormat.FirstDayOfWeek;
+            var weekdays = BuildWeekDayTable();
+
+            var daysInMonth = DateTime.DaysInMonth(Year, Month);
+            while (currentDay <= daysInMonth)
+            {
+                if (weekdays[currentDay - 1] == weekday)
+                {
+                    if (_calendarEvents.Any(e => e.Month == Month && e.Day == currentDay))
+                    {
+                        row.Add(new Markup(currentDay.ToString(CultureInfo.InvariantCulture) + "*", _highlightStyle));
+                    }
+                    else
+                    {
+                        row.Add(new Text(currentDay.ToString(CultureInfo.InvariantCulture)));
+                    }
+
+                    currentDay++;
+                }
+                else
+                {
+                    // Add empty cell
+                    row.Add(Text.Empty);
+                }
+
+                if (row.Count == NumberOfWeekDays)
+                {
+                    // Flush row
+                    table.AddRow(row.ToArray());
+                    row.Clear();
+                }
+
+                weekday = weekday.GetNextWeekDay();
+            }
+
+            if (row.Count > 0)
+            {
+                // Flush row
+                table.AddRow(row.ToArray());
+                row.Clear();
+            }
+
+            // We want all calendars to have the same height.
+            if (table.RowCount < ExpectedRowCount)
+            {
+                var diff = Math.Max(0, ExpectedRowCount - table.RowCount);
+                for (var i = 0; i < diff; i++)
+                {
+                    table.AddEmptyRow();
+                }
+            }
+
+            return table;
+        }
+
+        private void MarkAsDirty(Action action)
+        {
+            action();
+            _dirty = true;
+        }
+
+        private DayOfWeek[] GetWeekdays()
+        {
+            var culture = Culture ?? CultureInfo.InvariantCulture;
+
+            var days = new DayOfWeek[7];
+            days[0] = culture.DateTimeFormat.FirstDayOfWeek;
+            for (var i = 1; i < 7; i++)
+            {
+                days[i] = days[i - 1].GetNextWeekDay();
+            }
+
+            return days;
+        }
+
+        private DayOfWeek[] BuildWeekDayTable()
+        {
+            var result = new List<DayOfWeek>();
+            for (var day = 0; day < DateTime.DaysInMonth(Year, Month); day++)
+            {
+                result.Add(new DateTime(Year, Month, day + 1).DayOfWeek);
+            }
+
+            return result.ToArray();
+        }
+    }
+}

src/Spectre.Console/Widgets/CalendarEvent.cs

@@ -0,0 +1,54 @@
+namespace Spectre.Console
+{
+    /// <summary>
+    /// Represents a calendar event.
+    /// </summary>
+    public sealed class CalendarEvent
+    {
+        /// <summary>
+        /// Gets the description of the calendar event.
+        /// </summary>
+        public string Description { get; }
+
+        /// <summary>
+        /// Gets the year of the calendar event.
+        /// </summary>
+        public int Year { get; }
+
+        /// <summary>
+        /// Gets the month of the calendar event.
+        /// </summary>
+        public int Month { get; }
+
+        /// <summary>
+        /// Gets the day of the calendar event.
+        /// </summary>
+        public int Day { get; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CalendarEvent"/> class.
+        /// </summary>
+        /// <param name="year">The year of the calendar event.</param>
+        /// <param name="month">The month of the calendar event.</param>
+        /// <param name="day">The day of the calendar event.</param>
+        public CalendarEvent(int year, int month, int day)
+            : this(string.Empty, year, month, day)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CalendarEvent"/> class.
+        /// </summary>
+        /// <param name="description">The calendar event description.</param>
+        /// <param name="year">The year of the calendar event.</param>
+        /// <param name="month">The month of the calendar event.</param>
+        /// <param name="day">The day of the calendar event.</param>
+        public CalendarEvent(string description, int year, int month, int day)
+        {
+            Description = description ?? string.Empty;
+            Year = year;
+            Month = month;
+            Day = day;
+        }
+    }
+}

src/Spectre.Console/Widgets/Columns.cs

@@ -50,6 +50,29 @@ namespace Spectre.Console
             _items = new List<IRenderable>(items.Select(item => new Markup(item)));
         }
 
+        /// <inheritdoc/>
+        protected override Measurement Measure(RenderContext context, int maxWidth)
+        {
+            var maxPadding = Math.Max(Padding.Left, Padding.Right);
+
+            var itemWidths = _items.Select(item => item.Measure(context, maxWidth).Max).ToArray();
+            var columnCount = CalculateColumnCount(maxWidth, itemWidths, _items.Count, maxPadding);
+
+            var rows = _items.Count / columnCount;
+            var greatestWidth = 0;
+            for (var row = 0; row < rows; row += columnCount)
+            {
+                var widths = itemWidths.Skip(row * columnCount).Take(columnCount).ToList();
+                var totalWidth = widths.Sum() + (maxPadding * (widths.Count - 1));
+                if (totalWidth > greatestWidth)
+                {
+                    greatestWidth = totalWidth;
+                }
+            }
+
+            return new Measurement(greatestWidth, greatestWidth);
+        }
+
         /// <inheritdoc/>
         protected override IEnumerable<Segment> Render(RenderContext context, int maxWidth)
         {