SentenceGenerator.cs

using BytecodeApi.Extensions;
using System.Text;

namespace BytecodeApi.LanguageGenerator;

/// <summary>
/// Class that generates random sentences that match the pattern of real language.
/// A <see cref="LanguageGenerator.WordGenerator" /> is used to generate the words that generated sentences are composed of.
/// </summary>
public class SentenceGenerator : ILanguageStringGenerator
{
	/// <summary>
	/// Gets or sets the <see cref="LanguageGenerator.WordGenerator" /> that is used to generate words.
	/// </summary>
	public WordGenerator WordGenerator { get; set; }
	/// <summary>
	/// Gets or sets the minimum number of words used to build sentences.
	/// <para>The default value is 3</para>
	/// </summary>
	public int MinWords { get; set; }
	/// <summary>
	/// Gets or sets the maximum number of words used to build sentences.
	/// <para>The default value is 10</para>
	/// </summary>
	public int MaxWords { get; set; }
	/// <summary>
	/// Gets or sets a <see cref="double" /> value that specifies the chance of a comma being inserted after a word, where 0.0 means no commas and 1.0 means a comma between every word.
	/// <para>The default value is 0.2</para>
	/// </summary>
	public double CommaChance { get; set; }
	/// <summary>
	/// Gets or sets the characters that are used for punctuation after a sentence. Including a character multiple times increases the chance for this character. For example, this can be used to increase the likelihood of a period over a question mark or exclamation mark. Character order is not relevant.
	/// <para>The default value is "...?!"</para>
	/// </summary>
	public char[] FinishPunctuation { get; set; }

	/// <summary>
	/// Initializes a new instance of the <see cref="SentenceGenerator" /> class with default values.
	/// </summary>
	public SentenceGenerator() : this(new())
	{
	}
	/// <summary>
	/// Initializes a new instance of the <see cref="SentenceGenerator" /> class with the specified <see cref="LanguageGenerator.WordGenerator" /> and with default values (<see cref="MinWords" /> = 3, <see cref="MaxWords" /> = 10, <see cref="CommaChance" /> = 0.2, <see cref="FinishPunctuation" /> = "...?!").
	/// </summary>
	/// <param name="wordGenerator">The <see cref="WordGenerator" /> to use for word generation.</param>
	public SentenceGenerator(WordGenerator wordGenerator)
	{
		Check.ArgumentNull(wordGenerator);

		WordGenerator = wordGenerator;
		MinWords = 3;
		MaxWords = 10;
		CommaChance = .2;
		FinishPunctuation = "...?!".ToCharArray();
	}

	/// <summary>
	/// Generates a random sentence using the specified parameters of this <see cref="SentenceGenerator" /> instance.
	/// </summary>
	/// <returns>
	/// A new <see cref="string" /> with a dynamically generated sentence.
	/// </returns>
	public string Generate()
	{
		Check.ArgumentNull(WordGenerator);
		Check.ArgumentOutOfRangeEx.GreaterEqual0(MinWords);
		Check.ArgumentOutOfRangeEx.GreaterEqual0(MaxWords);
		Check.ArgumentOutOfRangeEx.GreaterEqualValue(MaxWords, MinWords);
		Check.ArgumentOutOfRangeEx.Between0And1(CommaChance);
		Check.ArgumentNull(FinishPunctuation);
		Check.ArgumentEx.ArrayElementsRequired(FinishPunctuation);

		StringBuilder stringBuilder = new();
		int words = Random.Shared.Next(MinWords, MaxWords + 1);

		for (int i = 0; i < words; i++)
		{
			stringBuilder.Append(WordGenerator.Generate(i == 0 ? StringCasing.CamelCase : StringCasing.Lower));

			if (i < words - 1)
			{
				if (Random.Shared.NextDouble() < CommaChance)
				{
					stringBuilder.Append(',');
				}
				stringBuilder.Append(' ');
			}
		}

		return stringBuilder.Append(Random.Shared.GetObject(FinishPunctuation)).ToString();
	}
}