Feature/ratelimit refactor (#197)

CryptoExchange.Net/RateLimiting/LimitCheck.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace CryptoExchange.Net.RateLimiting
+{
+    /// <summary>
+    /// Limit check
+    /// </summary>
+    public readonly struct LimitCheck
+    {
+        /// <summary>
+        /// Is guard applicable
+        /// </summary>
+        public bool Applicable { get; }
+        /// <summary>
+        /// Delay needed
+        /// </summary>
+        public TimeSpan Delay { get; }
+        /// <summary>
+        /// Current counter
+        /// </summary>
+        public int Current { get; }
+        /// <summary>
+        /// Limit
+        /// </summary>
+        public int? Limit { get; }
+        /// <summary>
+        /// Time period
+        /// </summary>
+        public TimeSpan? Period { get; }
+
+        private LimitCheck(bool applicable, TimeSpan delay, int limit, TimeSpan period, int current)
+        {
+            Applicable = applicable;
+            Delay = delay;
+            Limit = limit;
+            Period = period;
+            Current = current;
+        }
+
+        /// <summary>
+        /// Not applicable
+        /// </summary>
+        public static LimitCheck NotApplicable { get; } = new LimitCheck(false, default, default, default, default);
+
+        /// <summary>
+        /// No wait needed
+        /// </summary>
+        public static LimitCheck NotNeeded { get; } = new LimitCheck(true, default, default, default, default);
+
+        /// <summary>
+        /// Wait needed
+        /// </summary>
+        /// <param name="delay">The delay needed</param>
+        /// <param name="limit">Limit per period</param>
+        /// <param name="period">Period the limit is for</param>
+        /// <param name="current">Current counter</param>
+        /// <returns></returns>
+        public static LimitCheck Needed(TimeSpan delay, int limit, TimeSpan period, int current) => new(true, delay, limit, period, current);
+    }
+}