using MongoDB.Bson;
using System;

namespace MongoDbGenericRepository.Utils
{
    /// <summary>
    /// The IdGenerator instance, used to generate Ids of different types.
    /// </summary>
    public static class IdGenerator
    {
        private static readonly Random Random = new Random();

        /// <summary>
        /// Generates a random value of a given type.
        /// </summary>
        /// <typeparam name="TKey">The type of the value to generate.</typeparam>
        /// <returns>A value of type TKey.</returns>
        public static TKey GetId<TKey>()
        {
            var idTypeName = typeof(TKey).Name;
            switch (idTypeName)
            {
                case "Guid":
                    return (TKey)(object)Guid.NewGuid();
                case "Int16":
                    return (TKey)(object)Random.Next(1, short.MaxValue);
                case "Int32":
                    return (TKey)(object)Random.Next(1, int.MaxValue);
                case "Int64":
                    return (TKey)(object)(Random.NextLong(1, long.MaxValue));
                case "String":
                    return (TKey)(object)Guid.NewGuid().ToString();
                case "ObjectId":
                    return (TKey)(object)ObjectId.GenerateNewId();
            }
            throw new ArgumentException($"{idTypeName} is not a supported Id type, the Id of the document cannot be set.");
        }
    }
}