BloodType.cs

using System;
using System.Diagnostics;

namespace PopulationGenerator
{
	public enum BloodGroup
	{
		O,
		A,
		B,
		AB
	}

	public enum BloodRHFactor
	{
		Positive,
		Negative
	}

	public sealed class BloodType
	{
		public BloodGroup Group { get; private set; }
		public BloodRHFactor RHFactor { get; private set; }

		public BloodType(BloodGroup group, BloodRHFactor rhFactor)
		{
			Group = group;
			RHFactor = rhFactor;
		}

		public override string ToString()
		{
			return Group.ToString() + (RHFactor == BloodRHFactor.Negative ? '-' : '+');
		}

		public static bool AreGroups(BloodType mother, BloodType father, BloodGroup group1, BloodGroup group2)
		{
			return (mother.Group == group1 && father.Group == group2) || (mother.Group == group2 && father.Group == group1);
		}

		public static BloodType Derive(BloodType mother, BloodType father)
		{
			var rnd = new Random();

			BloodRHFactor rhFactor;

			if (mother.RHFactor == BloodRHFactor.Negative && father.RHFactor == BloodRHFactor.Negative)
			{
				rhFactor = BloodRHFactor.Negative;
			}
			else
			{
				rhFactor = Utils.Pick<BloodRHFactor>();
			}

			BloodGroup group;

			if (mother.Group == BloodGroup.O && father.Group == BloodGroup.O) // O and O
			{
				group = BloodGroup.O;
			}
			else if (AreGroups(mother, father, BloodGroup.O, BloodGroup.A)) // O and A
			{
				group = Utils.Pick(BloodGroup.O, BloodGroup.A);
			}
			else if (AreGroups(mother, father, BloodGroup.O, BloodGroup.B)) // O and B
			{
				group = Utils.Pick(BloodGroup.O, BloodGroup.B);
			}
			else if (AreGroups(mother, father, BloodGroup.O, BloodGroup.AB)) // O and AB
			{
				group = Utils.Pick(BloodGroup.A, BloodGroup.B);
			}
			else if (mother.Group == BloodGroup.A && father.Group == BloodGroup.A) // A and A
			{
				group = Utils.Pick(BloodGroup.O, BloodGroup.A);
			}
			else if (AreGroups(mother, father, BloodGroup.A, BloodGroup.B)) // A and B
			{
				if (rnd.Next(100) <= 50.0)
				{
					group = Utils.Pick(BloodGroup.O, BloodGroup.A);
				}
				else
				{
					group = (BloodGroup)rnd.Next((int)BloodGroup.B, (int)BloodGroup.AB + 1);
				}
			}
			else if (AreGroups(mother, father, BloodGroup.A, BloodGroup.AB)) // A and AB
			{
				if (rnd.Next(100) <= 33.0)
				{
					group = BloodGroup.A;
				}
				else if (rnd.Next(100) <= 33.0)
				{
					group = BloodGroup.B;
				}
				else
				{
					group = BloodGroup.AB;
				}
			}
			else if (mother.Group == BloodGroup.B && father.Group == BloodGroup.B) // B and B
			{
				group = Utils.Pick(BloodGroup.O, BloodGroup.B);
			}
			else if (AreGroups(mother, father, BloodGroup.B, BloodGroup.AB)) // B and AB
			{
				if (rnd.Next(100) <= 33.0)
				{
					group = BloodGroup.B;
				}
				else if (rnd.Next(100) <= 33.0)
				{
					group = BloodGroup.A;
				}
				else
				{
					group = BloodGroup.AB;
				}
			}
			else if (mother.Group == BloodGroup.AB && father.Group == BloodGroup.AB) // AB and AB
			{
				if (rnd.Next(100) <= 33.0)
				{
					group = BloodGroup.A;
				}
				else if (rnd.Next(100) <= 33.0)
				{
					group = BloodGroup.B;
				}
				else
				{
					group = BloodGroup.AB;
				}
			}
			else
			{
				group = BloodGroup.O;
				Debug.Assert(false);
			}

			return new BloodType(group, rhFactor);
		}
	}
}