gui-cs.Terminal.Gui/Terminal.Gui/View/Layout/Dim.cs

using System.Diagnostics;

namespace Terminal.Gui;

/// <summary>
///     <para>
///         A Dim object describes the dimensions of a <see cref="View"/>. Dim is the type of the
///         <see cref="View.Width"/> and <see cref="View.Height"/> properties of <see cref="View"/>. Dim objects enable
///         Computed Layout (see <see cref="LayoutStyle.Computed"/>) to automatically manage the dimensions of a view.
///     </para>
///     <para>
///         Integer values are implicitly convertible to an absolute <see cref="Dim"/>. These objects are created using
///         the static methods described below. The <see cref="Dim"/> objects can be combined with the addition and
///         subtraction operators.
///     </para>
/// </summary>
/// <remarks>
///     <para>
///         <list type="table">
///             <listheader>
///                 <term>Dim Object</term> <description>Description</description>
///             </listheader>
///             <item>
///                 <term>
///                     <see cref="Dim.Auto"/>
///                 </term>
///                 <description>
///                     Creates a <see cref="Dim"/> object that automatically sizes the view to fit
///                     the view's Text, SubViews, or ContentArea.
///                 </description>
///             </item>
///             <item>
///                 <term>
///                     <see cref="Dim.Function(Func{int})"/>
///                 </term>
///                 <description>
///                     Creates a <see cref="Dim"/> object that computes the dimension by executing the provided
///                     function. The function will be called every time the dimension is needed.
///                 </description>
///             </item>
///             <item>
///                 <term>
///                     <see cref="Dim.Percent(float, bool)"/>
///                 </term>
///                 <description>
///                     Creates a <see cref="Dim"/> object that is a percentage of the width or height of the
///                     SuperView.
///                 </description>
///             </item>
///             <item>
///                 <term>
///                     <see cref="Dim.Fill(int)"/>
///                 </term>
///                 <description>
///                     Creates a <see cref="Dim"/> object that fills the dimension from the View's X position
///                     to the end of the super view's width, leaving the specified number of columns for a margin.
///                 </description>
///             </item>
///             <item>
///                 <term>
///                     <see cref="Dim.Width(View)"/>
///                 </term>
///                 <description>
///                     Creates a <see cref="Dim"/> object that tracks the Width of the specified
///                     <see cref="View"/>.
///                 </description>
///             </item>
///             <item>
///                 <term>
///                     <see cref="Dim.Height(View)"/>
///                 </term>
///                 <description>
///                     Creates a <see cref="Dim"/> object that tracks the Height of the specified
///                     <see cref="View"/>.
///                 </description>
///             </item>
///         </list>
///     </para>
///     <para></para>
/// </remarks>
public class Dim
{
    /// <summary>
    ///     Specifies how <see cref="Dim.Auto"/> will compute the dimension.
    /// </summary>
    [Flags]
    public enum DimAutoStyle
    {
        /// <summary>
        ///     The dimension will be computed using both the view's <see cref="View.Text"/> and
        ///     <see cref="View.Subviews"/> (whichever is larger).
        /// </summary>
        Auto = Content | Text,

        /// <summary>
        ///     The dimensions will be computed based on the View's non-Text content.
        /// <para>
        ///     If <see cref="View.ContentSize"/> is explicitly set (is not <see langword="null"/>) then <see cref="View.ContentSize"/>
        ///     will be used to determine the dimension.
        /// </para>
        /// <para>
        ///     Otherwise, the Subview in <see cref="View.Subviews"/> with the largest corresponding position plus dimension
        ///     will determine the dimension.
        /// </para>
        /// <para>
        ///     The corresponding dimension of the view's <see cref="View.Text"/> will be ignored.
        /// </para>
        /// </summary>
        Content = 1,

        /// <summary>
        /// <para>
        ///     The corresponding dimension of the view's <see cref="View.Text"/>, formatted using the
        ///     <see cref="View.TextFormatter"/> settings,
        ///     will be used to determine the dimension.
        /// </para>
        /// <para>
        ///     The corresponding dimensions of the <see cref="View.Subviews"/> will be ignored.
        /// </para>
        /// </summary>
        Text = 2
    }


    /// <summary>
    /// 
    /// </summary>
    public enum Dimension
    {
        /// <summary>
        /// No dimension specified.
        /// </summary>
        None = 0,

        /// <summary>
        /// The height dimension.
        /// </summary>
        Height = 1,

        /// <summary>
        /// The width dimension.
        /// </summary>
        Width = 2
    }


    /// <summary>
    ///     Creates a <see cref="Dim"/> object that automatically sizes the view to fit all the view's SubViews and/or Text.
    /// </summary>
    /// <remarks>
    ///     <para>
    ///         See <see cref="DimAutoStyle"/>.
    ///     </para>
    /// </remarks>
    /// <example>
    ///     This initializes a <see cref="View"/> with two SubViews. The view will be automatically sized to fit the two
    ///     SubViews.
    /// <code>
    /// var button = new Button () { Text = "Click Me!", X = 1, Y = 1, Width = 10, Height = 1 };
    /// var textField = new TextField { Text = "Type here", X = 1, Y = 2, Width = 20, Height = 1 };
    /// var view = new Window () { Title = "MyWindow", X = 0, Y = 0, Width = Dim.Auto (), Height = Dim.Auto () };
    /// view.Add (button, textField);
    /// </code>
    /// </example>
    /// <returns>The <see cref="Dim"/> object.</returns>
    /// <param name="style">
    ///     Specifies how <see cref="Dim.Auto"/> will compute the dimension. The default is <see cref="DimAutoStyle.Auto"/>.
    /// </param>
    /// <param name="minimumContentDim">The minimum dimension the View's ContentSize will be constrained to.</param>
    /// <param name="maximumContentDim">The maximum dimension the View's ContentSize will be fit to. NOT CURRENTLY SUPPORTED.</param>
    public static Dim Auto (DimAutoStyle style = DimAutoStyle.Auto, Dim minimumContentDim = null, Dim maximumContentDim = null)
    {
        if (maximumContentDim != null)
        {
            throw new NotImplementedException (@"maximumContentDim is not implemented");
        }

        return new DimAuto (style, minimumContentDim, maximumContentDim);
    }

    /// <summary>Determines whether the specified object is equal to the current object.</summary>
    /// <param name="other">The object to compare with the current object. </param>
    /// <returns>
    ///     <see langword="true"/> if the specified object  is equal to the current object; otherwise,
    ///     <see langword="false"/>.
    /// </returns>
    public override bool Equals (object other) { return other is Dim abs && abs == this; }

    /// <summary>
    ///     Creates a <see cref="Dim"/> object that fills the dimension, leaving the specified number of columns for a
    ///     margin.
    /// </summary>
    /// <returns>The Fill dimension.</returns>
    /// <param name="margin">Margin to use.</param>
    public static Dim Fill (int margin = 0) { return new DimFill (margin); }

    /// <summary>
    ///     Creates a function <see cref="Dim"/> object that computes the dimension by executing the provided function.
    ///     The function will be called every time the dimension is needed.
    /// </summary>
    /// <param name="function">The function to be executed.</param>
    /// <returns>The <see cref="Dim"/> returned from the function.</returns>
    public static Dim Function (Func<int> function) { return new DimFunc (function); }

    /// <summary>Serves as the default hash function. </summary>
    /// <returns>A hash code for the current object.</returns>
    public override int GetHashCode () { return Anchor (0).GetHashCode (); }

    /// <summary>Creates a <see cref="Dim"/> object that tracks the Height of the specified <see cref="View"/>.</summary>
    /// <returns>The height <see cref="Dim"/> of the other <see cref="View"/>.</returns>
    /// <param name="view">The view that will be tracked.</param>
    public static Dim Height (View view) { return new DimView (view, Dimension.Height); }

    /// <summary>Adds a <see cref="Dim"/> to a <see cref="Dim"/>, yielding a new <see cref="Dim"/>.</summary>
    /// <param name="left">The first <see cref="Dim"/> to add.</param>
    /// <param name="right">The second <see cref="Dim"/> to add.</param>
    /// <returns>The <see cref="Dim"/> that is the sum of the values of <c>left</c> and <c>right</c>.</returns>
    public static Dim operator + (Dim left, Dim right)
    {
        if (left is DimAbsolute && right is DimAbsolute)
        {
            return new DimAbsolute (left.Anchor (0) + right.Anchor (0));
        }

        var newDim = new DimCombine (true, left, right);
        (left as DimView)?.Target.SetNeedsLayout ();

        return newDim;
    }

    /// <summary>Creates an Absolute <see cref="Dim"/> from the specified integer value.</summary>
    /// <returns>The Absolute <see cref="Dim"/>.</returns>
    /// <param name="n">The value to convert to the pos.</param>
    public static implicit operator Dim (int n) { return new DimAbsolute (n); }

    /// <summary>
    ///     Subtracts a <see cref="Dim"/> from a <see cref="Dim"/>, yielding a new
    ///     <see cref="Dim"/>.
    /// </summary>
    /// <param name="left">The <see cref="Dim"/> to subtract from (the minuend).</param>
    /// <param name="right">The <see cref="Dim"/> to subtract (the subtrahend).</param>
    /// <returns>The <see cref="Dim"/> that is the <c>left</c> minus <c>right</c>.</returns>
    public static Dim operator - (Dim left, Dim right)
    {
        if (left is DimAbsolute && right is DimAbsolute)
        {
            return new DimAbsolute (left.Anchor (0) - right.Anchor (0));
        }

        var newDim = new DimCombine (false, left, right);
        (left as DimView)?.Target.SetNeedsLayout ();

        return newDim;
    }

    /// <summary>Creates a percentage <see cref="Dim"/> object that is a percentage of the width or height of the SuperView.</summary>
    /// <returns>The percent <see cref="Dim"/> object.</returns>
    /// <param name="percent">A value between 0 and 100 representing the percentage.</param>
    /// <param name="usePosition">
    ///     If <see langword="true"/> the dimension is computed using the View's position (<see cref="View.X"/> or
    ///     <see cref="View.Y"/>).
    ///     If <see langword="false"/> the dimension is computed using the View's <see cref="View.ContentSize"/>.
    /// </param>
    /// <example>
    ///     This initializes a <see cref="TextField"/> that will be centered horizontally, is 50% of the way down, is 30% the
    ///     height,
    ///     and is 80% the width of the SuperView.
    ///     <code>
    ///  var textView = new TextField {
    ///     X = Pos.Center (),
    ///     Y = Pos.Percent (50),
    ///     Width = Dim.Percent (80),
    ///     Height = Dim.Percent (30),
    ///  };
    ///  </code>
    /// </example>
    public static Dim Percent (float percent, bool usePosition = false)
    {
        if (percent is < 0 or > 100)
        {
            throw new ArgumentException ("Percent value must be between 0 and 100");
        }

        return new DimFactor (percent / 100, usePosition);
    }

    /// <summary>Creates an Absolute <see cref="Dim"/> from the specified integer value.</summary>
    /// <returns>The Absolute <see cref="Dim"/>.</returns>
    /// <param name="n">The value to convert to the <see cref="Dim"/>.</param>
    public static Dim Sized (int n) { return new DimAbsolute (n); }

    /// <summary>Creates a <see cref="Dim"/> object that tracks the Width of the specified <see cref="View"/>.</summary>
    /// <returns>The width <see cref="Dim"/> of the other <see cref="View"/>.</returns>
    /// <param name="view">The view that will be tracked.</param>
    public static Dim Width (View view) { return new DimView (view, Dimension.Width); }

    /// <summary>
    ///     Gets a dimension that is anchored to a certain point in the layout.
    ///     This method is typically used internally by the layout system to determine the size of a View.
    /// </summary>
    /// <param name="width">The width of the area where the View is being sized (Superview.ContentSize).</param>
    /// <returns>
    ///     An integer representing the calculated dimension. The way this dimension is calculated depends on the specific
    ///     subclass of Dim that is used. For example, DimAbsolute returns a fixed dimension, DimFactor returns a
    ///     dimension that is a certain percentage of the super view's size, and so on.
    /// </returns>
    internal virtual int Anchor (int width) { return 0; }

    /// <summary>
    ///     Calculates and returns the dimension of a <see cref="View"/> object. It takes into account the location of the
    ///     <see cref="View"/>, it's SuperView's ContentSize, and whether it should automatically adjust its size based on its content.
    /// </summary>
    /// <param name="location">
    ///     The starting point from where the size calculation begins. It could be the left edge for width calculation or the
    ///     top edge for height calculation.
    /// </param>
    /// <param name="superviewContentSize">The size of the SuperView's content. It could be width or height.</param>
    /// <param name="us">The View that holds this Pos object.</param>
    /// <param name="dimension">Width or Height</param>
    /// <returns>
    ///     The calculated size of the View. The way this size is calculated depends on the specific subclass of Dim that
    ///     is used.
    /// </returns>
    internal virtual int Calculate (int location, int superviewContentSize, View us, Dimension dimension)
    {
        return Math.Max (Anchor (superviewContentSize - location), 0);
    }

    /// <summary>
    /// Diagnostics API to determine if this Dim object references other views.
    /// </summary>
    /// <returns></returns>
    internal virtual bool ReferencesOtherViews ()
    {
        return false;
    }

    internal class DimAbsolute (int n) : Dim
    {
        private readonly int _n = n;
        public override bool Equals (object other) { return other is DimAbsolute abs && abs._n == _n; }
        public override int GetHashCode () { return _n.GetHashCode (); }
        public override string ToString () { return $"Absolute({_n})"; }
        internal override int Anchor (int width) { return _n; }

        internal override int Calculate (int location, int superviewContentSize, View us, Dimension dimension)
        {
            // DimAbsolute.Anchor (int width) ignores width and returns n
            return Math.Max (Anchor (0), 0);
        }
    }

    /// <summary>
    ///     A <see cref="Dim"/> object that automatically sizes the view to fit all the view's SubViews and/or Text.
    /// </summary>
    /// <remarks>
    ///     <para>
    ///         See <see cref="Dim.DimAutoStyle"/>.
    ///     </para>
    /// </remarks>
    /// <param name="style">
    ///     Specifies how <see cref="Dim.DimAuto"/> will compute the dimension. The default is <see cref="Dim.DimAutoStyle.Auto"/>.
    /// </param>
    /// <param name="minimumContentDim">The minimum dimension the View's ContentSize will be constrained to.</param>
    /// <param name="maximumContentDim">The maximum dimension the View's ContentSize will be fit to. NOT CURRENTLY SUPPORTED.</param>
    public class DimAuto (DimAutoStyle style, Dim minimumContentDim, Dim maximumContentDim) : Dim
    {
        internal readonly Dim _minContentDim = minimumContentDim;
        internal readonly Dim _maxContentDim = maximumContentDim;
        internal readonly DimAutoStyle _style = style;
        internal int _size;

        /// <inheritdoc />
        public override bool Equals (object other) { return other is DimAuto auto && auto._minContentDim == _minContentDim && auto._maxContentDim == _maxContentDim && auto._style == _style; }
        /// <inheritdoc />
        public override int GetHashCode () { return HashCode.Combine (base.GetHashCode (), _minContentDim, _maxContentDim, _style); }
        /// <inheritdoc />
        public override string ToString () { return $"Auto({_style},{_minContentDim},{_maxContentDim})"; }

        internal override int Calculate (int location, int superviewContentSize, View us, Dimension dimension)
        {
            if (us == null)
            {
                return _maxContentDim?.Anchor (0) ?? 0;
            }

            var textSize = 0;
            var subviewsSize = 0;

            int autoMin = _minContentDim?.Anchor (superviewContentSize) ?? 0;

            if (superviewContentSize < autoMin)
            {
                Debug.WriteLine ($"WARNING: DimAuto specifies a min size ({autoMin}), but the SuperView's bounds are smaller ({superviewContentSize}).");

                return superviewContentSize;
            }

            if (_style.HasFlag (Dim.DimAutoStyle.Text))
            {
                textSize = int.Max (autoMin, dimension == Dimension.Width ? us.TextFormatter.Size.Width : us.TextFormatter.Size.Height);
            }

            if (_style.HasFlag (DimAutoStyle.Content))
            {
                if (us._contentSize is { })
                {
                    subviewsSize = dimension == Dimension.Width ? us.ContentSize.Width : us.ContentSize.Height;
                }
                else
                {
                    // TODO: AnchorEnd needs work
                    // TODO: If _min > 0 we can SetRelativeLayout for the subviews?
                    subviewsSize = 0;
                    if (us.Subviews.Count > 0)
                    {
                        for (int i = 0; i < us.Subviews.Count; i++)
                        {
                            var v = us.Subviews [i];
                            bool isNotPosAnchorEnd = dimension == Dim.Dimension.Width ? v.X is not Pos.PosAnchorEnd : v.Y is not Pos.PosAnchorEnd;

                            //if (!isNotPosAnchorEnd)
                            //{
                            //    v.SetRelativeLayout(dimension == Dim.Dimension.Width ? (new Size (autoMin, 0)) : new Size (0, autoMin));
                            //}

                            if (isNotPosAnchorEnd)
                            {
                                int size = dimension == Dim.Dimension.Width ? v.Frame.X + v.Frame.Width : v.Frame.Y + v.Frame.Height;
                                if (size > subviewsSize)
                                {
                                    subviewsSize = size;
                                }
                            }
                        }
                    }

                }
            }

            // All sizes here are content-relative; ignoring adornments.
            // We take the larger of text and content.
            int max = int.Max (textSize, subviewsSize);

            // And, if min: is set, it wins if larger
            max = int.Max (max, autoMin);

            // Factor in adornments
            Thickness thickness = us.GetAdornmentsThickness ();
            if (dimension == Dimension.Width)
            {
                max += thickness.Horizontal;
            }
            else
            {
                max += thickness.Vertical;
            }

            // If max: is set, clamp the return - BUGBUG: Not tested
            return int.Min (max, _maxContentDim?.Anchor (superviewContentSize) ?? superviewContentSize);
        }

        /// <summary>
        /// Diagnostics API to determine if this Dim object references other views.
        /// </summary>
        /// <returns></returns>
        internal override bool ReferencesOtherViews ()
        {
            // BUGBUG: This is not correct. _contentSize may be null.
            return false;//_style.HasFlag (Dim.DimAutoStyle.Content);
        }

    }
    internal class DimCombine (bool add, Dim left, Dim right) : Dim
    {
        internal bool _add = add;
        internal Dim _left = left, _right = right;

        public override string ToString () { return $"Combine({_left}{(_add ? '+' : '-')}{_right})"; }

        internal override int Anchor (int width)
        {
            int la = _left.Anchor (width);
            int ra = _right.Anchor (width);

            if (_add)
            {
                return la + ra;
            }

            return la - ra;
        }

        internal override int Calculate (int location, int superviewContentSize, View us, Dimension dimension)
        {
            int leftNewDim = _left.Calculate (location, superviewContentSize, us, dimension);
            int rightNewDim = _right.Calculate (location, superviewContentSize, us, dimension);

            int newDimension;

            if (_add)
            {
                newDimension = leftNewDim + rightNewDim;
            }
            else
            {
                newDimension = Math.Max (0, leftNewDim - rightNewDim);
            }

            return newDimension;
        }


        /// <summary>
        /// Diagnostics API to determine if this Dim object references other views.
        /// </summary>
        /// <returns></returns>
        internal override bool ReferencesOtherViews ()
        {
            if (_left.ReferencesOtherViews ())
            {
                return true;
            }

            if (_right.ReferencesOtherViews ())
            {
                return true;
            }

            return false;
        }
    }

    internal class DimFactor (float factor, bool remaining = false) : Dim
    {
        private readonly float _factor = factor;
        private readonly bool _remaining = remaining;

        public override bool Equals (object other) { return other is DimFactor f && f._factor == _factor && f._remaining == _remaining; }
        public override int GetHashCode () { return _factor.GetHashCode (); }
        public bool IsFromRemaining () { return _remaining; }
        public override string ToString () { return $"Factor({_factor},{_remaining})"; }
        internal override int Anchor (int width) { return (int)(width * _factor); }

        internal override int Calculate (int location, int superviewContentSize, View us, Dimension dimension)
        {
            return _remaining ? Math.Max (Anchor (superviewContentSize - location), 0) : Anchor (superviewContentSize);
        }
    }

    internal class DimFill (int margin) : Dim
    {
        private readonly int _margin = margin;
        public override bool Equals (object other) { return other is DimFill fill && fill._margin == _margin; }
        public override int GetHashCode () { return _margin.GetHashCode (); }
        public override string ToString () { return $"Fill({_margin})"; }
        internal override int Anchor (int width) { return width - _margin; }
    }

    // Helper class to provide dynamic value by the execution of a function that returns an integer.
    internal class DimFunc (Func<int> n) : Dim
    {
        private readonly Func<int> _function = n;
        public override bool Equals (object other) { return other is DimFunc f && f._function () == _function (); }
        public override int GetHashCode () { return _function.GetHashCode (); }
        public override string ToString () { return $"DimFunc({_function ()})"; }
        internal override int Anchor (int width) { return _function (); }
    }

    internal class DimView : Dim
    {
        private readonly Dimension _side;

        internal DimView (View view, Dimension side)
        {
            Target = view;
            _side = side;
        }

        public View Target { get; init; }
        public override bool Equals (object other) { return other is DimView abs && abs.Target == Target; }
        public override int GetHashCode () { return Target.GetHashCode (); }

        public override string ToString ()
        {
            if (Target == null)
            {
                throw new NullReferenceException ();
            }

            string sideString = _side switch
            {
                Dimension.Height => "Height",
                Dimension.Width => "Width",
                _ => "unknown"
            };

            return $"View({sideString},{Target})";
        }

        internal override int Anchor (int width)
        {
            return _side switch
            {
                Dimension.Height => Target.Frame.Height,
                Dimension.Width => Target.Frame.Width,
                _ => 0
            };
        }

        internal override bool ReferencesOtherViews ()
        {
            return true;
        }
    }
}