.cs

using System;
using System.Reflection.Metadata.Ecma335;

namespace PracticalCSharp.Preliminaries.PatternMatch.Test
{
    namespace Case1
    {
        abstract class Shape { }
        class Rectangle : Shape
        {
            public int Width { get; set; }
            public int Height { get; set; }
        }

        class Circle : Shape
        {
            public int Radius { get; set; }
        }
        public class Demo
        {
            public void Run()
            {
                // Func<Shape, string> GetShapeDescription = (Shape shape) =>

                string GetShapeDescription1(Shape shape)
                {
                    if (shape is Circle)
                        return $"found a circle with radius {(shape as Circle).Radius}";
                    if (shape is Rectangle)
                        return $"Found {(shape as Rectangle).Height }x {(shape as Rectangle).Width} rectangle";

                    throw new System.Exception(nameof(shape));
                }


                string GetShapeDescription(Shape shape)
                {
                    switch (shape)
                    {
                        case Circle c:
                            return $"found a circle with radius {c.Radius}";
                        case Rectangle s:
                            return $"Found {s.Height }x {s.Width} rectangle";
                        default:
                            throw new System.Exception(nameof(shape));
                    }
                };

                Shape shape = new Rectangle
                {
                    Width = 100,
                    Height = 100,
                };

                var description = GetShapeDescription1(shape);
            }
        }

    }

    namespace Case2
    {
        abstract class Shape
        {
            public abstract string GetShapeDescription();
        }
        class Rectangle : Shape
        {
            public int Width { get; set; }
            public int Height { get; set; }

            public override string GetShapeDescription()
            {
                return $"Found { Height }x { Width} rectangle";
            }
        }

        class Circle : Shape
        {
            public int Radius { get; set; }
            public override string GetShapeDescription()
            {
                return $"found a circle with radius { Radius}";
            }
        }

        public class Demo
        {
            public void Run()
            {
                Shape shape = new Rectangle { Width = 100, Height = 100, };

                shape = new Circle { Radius = 30 };

                var result = shape switch
                {
                    Rectangle { Width: var w, Height: var h } => $"Found {h}x {w} rectangle",
                    Circle { Radius: var r } => $"found a circle with radius {r}",
                    _ => "Different, or null shape"
                };

            }
        }

    }

    namespace Case3
    {
        abstract class Shape
        {
            public abstract T MatchWith<T>(Func<Rectangle, T> rectangleCase, Func<Circle, T> circleCase);
        }
        class Rectangle : Shape
        {
            public int Width { get; set; }
            public int Height { get; set; }

            public override T MatchWith<T>(Func<Rectangle, T> rectangleCase, Func<Circle, T> circleCase)
            => rectangleCase(this);
        }

        class Circle : Shape
        {
            public int Radius { get; set; }
            public override T MatchWith<T>(Func<Rectangle, T> rectangleCase, Func<Circle, T> circleCase)
                => circleCase(this);
        }

        public class Demo
        {
            public void Run()
            {
                Shape shape = new Rectangle { Width = 100, Height = 100, };

                shape = new Circle { Radius = 30 };

                string GetShapeDescription(Shape shape)
                 => shape.MatchWith<string>(
                    rectangleCase: r => $"Found {r.Height}x {r.Width} rectangle",
                    circleCase: c => $"found a circle with radius {c.Radius}"
                );

                var description = GetShapeDescription(shape);

            }
        }

    }

    namespace Case4
    {
        abstract class Shape { }
        class Rectangle : Shape
        {
            public int Width { get; set; }
            public int Height { get; set; }
        }

        class Circle : Shape
        {
            public int Radius { get; set; }
        }
        public class Demo
        {
            public void Run()
            {
                // Func<Shape, string> GetShapeDescription = (Shape shape) =>
                //  case Circle c:
                //            return $"found a circle with radius {c.Radius}";
                //        case Rectangle s:
                //            return $"Found {s.Height }x {s.Width} rectangle";
                //default:
                //            throw new System.Exception(nameof(shape));

                string GetShapeDescription1(Shape shape) =>
                    shape switch
                    {
                        Rectangle { Height: var h, Width: var w } => $"Found {h }x {w} rectangle",
                        Circle { Radius: var r } => $"found a circle with radius {r}",
                    };


                Shape shape = new Rectangle
                {
                    Width = 100,
                    Height = 100,
                };

                var description = GetShapeDescription1(shape);
            }
        }

    }
}