tbd-station-14/Content.Shared/Random/Helpers/SharedRandomExtensions.cs

using System.Linq;
using Content.Shared.Dataset;
using Robust.Shared.Random;

namespace Content.Shared.Random.Helpers
{
    public static class SharedRandomExtensions
    {
        public static string Pick(this IRobustRandom random, DatasetPrototype prototype)
        {
            return random.Pick(prototype.Values);
        }

        public static string Pick(this WeightedRandomPrototype prototype, System.Random random)
        {
            var picks = prototype.Weights;
            var sum = picks.Values.Sum();
            var accumulated = 0f;

            var rand = random.NextFloat() * sum;

            foreach (var (key, weight) in picks)
            {
                accumulated += weight;

                if (accumulated >= rand)
                {
                    return key;
                }
            }

            // Shouldn't happen
            throw new InvalidOperationException($"Invalid weighted pick for {prototype.ID}!");
        }

        public static string Pick(this WeightedRandomPrototype prototype, IRobustRandom? random = null)
        {
            IoCManager.Resolve(ref random);
            var picks = prototype.Weights;
            var sum = picks.Values.Sum();
            var accumulated = 0f;

            var rand = random.NextFloat() * sum;

            foreach (var (key, weight) in picks)
            {
                accumulated += weight;

                if (accumulated >= rand)
                {
                    return key;
                }
            }

            // Shouldn't happen
            throw new InvalidOperationException($"Invalid weighted pick for {prototype.ID}!");
        }

        public static string Pick(this IRobustRandom random, Dictionary<string, float> weights)
        {
            var sum = weights.Values.Sum();
            var accumulated = 0f;

            var rand = random.NextFloat() * sum;

            foreach (var (key, weight) in weights)
            {
                accumulated += weight;

                if (accumulated >= rand)
                {
                    return key;
                }
            }

            throw new InvalidOperationException($"Invalid weighted pick");
        }
    }
}