NaivePatternSearch.cs

namespace AlgorithmsAndDataStructures.Algorithms.Strings.Search;

public class NaivePatternSearch : IStringPatternSearchAlgorithm
{
    public int Search(string input, string pattern)
    {
        if (string.IsNullOrEmpty(input) || string.IsNullOrEmpty(pattern)) return -1;

        const int negativeResult = -1;

        if (pattern.Length > input.Length) return negativeResult;

        for (var i = 0; i <= input.Length - pattern.Length; i++)
            if (input[i] == pattern[0])
            {
                var originalPosition = i + 1;
                var isMatch = true;

                for (var j = 1; j < pattern.Length; j++)
                {
                    if (input[originalPosition] != pattern[j])
                    {
                        isMatch = false;
                        break;
                    }

                    originalPosition++;
                }

                if (isMatch) return i;
            }

        return negativeResult;
    }
}