LootBoxGenerator/LootBoxSimulator/Program.cs

using LootBoxSimulator.Models.DAO;

RemoteDatabaseContext databaseContext = new RemoteDatabaseContext();

var result = RandomizeRate();
var item = RandomizeItem(result);
Console.WriteLine($"{item?.Name} {item?.Id}");

ItemDao? RandomizeItem(RateDao? rateDao){
    if(rateDao == null) return null;
    var items = databaseContext.Items
        .Where(item => 
            item.Rate.Id == rateDao.Id
            ).ToList();
    if(items.Count == 0) return null;
    Random random = new Random();
    int randomIndex = random.Next(0, items.Count);
    return items[randomIndex];
}


RateDao? RandomizeRate()
{
    var rates = databaseContext
        .Rates
        .OrderByDescending(item => item.Rate).ToList();
    if (rates.Count == 0) return null;    
    decimal start = 0;
    decimal end = rates[0].Rate;
    Random random = new Random();
    decimal number = Convert.ToDecimal(random.NextDouble());
    for (var i = 0; i < rates.Count; i++)
    {
        if (number >= start && number <= end)
        {
            Console.WriteLine($"{number} {start} {end}");
            return rates[i];
        }
        
        start = end;
        end += rates[i].Rate;
    }
    return null;
}