using System;
using System.Diagnostics.Contracts;
using System.Runtime.Caching;

namespace Kreta.Core
{
    public static class Cache
    {
        private static readonly MemoryCache DefaultCache = new MemoryCache("DefaultCache");

        private static readonly CacheItemPolicy DefaultPolicy = new CacheItemPolicy { SlidingExpiration = TimeSpan.FromSeconds(30) };

        [Pure]
        public static Guid Add(object value)
        {
            var guid = Guid.NewGuid();
            DefaultCache.Add(new CacheItem($"{guid}", value), DefaultPolicy);
            return guid;
        }

        public static bool Add(string key, object value, CacheItemPolicy cacheItemPolicy)
        {
            return DefaultCache.Add(new CacheItem(key, value), cacheItemPolicy);
        }

        public static T AddOrGetExisting<T>(string key, T value, CacheItemPolicy cacheItemPolicy)
        {
            object existingValue = DefaultCache.AddOrGetExisting(key, value, cacheItemPolicy);
            return (existingValue != null) ? (T)existingValue : value;
        }

        public static void Set(string key, object value, CacheItemPolicy cacheItemPolicy)
        {
            DefaultCache.Set(new CacheItem(key, value), cacheItemPolicy);
        }

        [Pure]
        public static object Get(Guid guid)
        {
            return DefaultCache.Get($"{guid}");
        }

        [Pure]
        public static object Get(string key)
        {
            return DefaultCache.Get(key);
        }

        [Pure]
        public static void Remove(string key)
        {
            try
            {
                DefaultCache.Remove(key);
            }
            catch
            {
                throw;
            }
        }
    }
}