namespace TarninaHub.Application.Matchmaking;

public static class VectorMath
{
    public static double CosineSimilarity(IReadOnlyList<float> a, IReadOnlyList<float> b)
    {
        if (a.Count == 0 || a.Count != b.Count)
        {
            return 0;
        }

        double dot = 0;
        double magnitudeA = 0;
        double magnitudeB = 0;

        for (var i = 0; i < a.Count; i++)
        {
            dot += (double)a[i] * b[i];
            magnitudeA += (double)a[i] * a[i];
            magnitudeB += (double)b[i] * b[i];
        }

        if (magnitudeA <= 0 || magnitudeB <= 0)
        {
            return 0;
        }

        return dot / (Math.Sqrt(magnitudeA) * Math.Sqrt(magnitudeB));
    }
}