using System;

namespace SharpChat.RateLimiting {
    public class RateLimiter {
        private int Size { get; }
        private int WarnSize { get; }
        private int MinimumDelay { get; }
        private long[] Times { get; }

        public RateLimiter(int size, int warnSize, int minimumDelay) {
            if(size < 3)
                throw new ArgumentException(@"Size must be more than 1.", nameof(size));
            if(warnSize >= size && warnSize > 0)
                throw new ArgumentException(@"Warning Size must be less than Size, or less than 0 to be disabled.", nameof(warnSize));
            if(minimumDelay < 1000)
                throw new ArgumentException(@"Minimum Delay must be more than 999 milliseconds.", nameof(minimumDelay));
            Size = size;
            WarnSize = warnSize;
            MinimumDelay = minimumDelay;
            Times = new long[Size];
        }

        private bool IsSeeding
            => (Times[0] < 1 && Times[1] < 1);

        public bool ShouldKick
            => !IsSeeding && Times[0] + MinimumDelay >= Times[Size - 1]; 

        public bool ShouldWarn
            => WarnSize > 0 && !IsSeeding && Times[0] + MinimumDelay >= Times[WarnSize - 1];

        public void Update() {
            for(int i = 0; i < Size - 1; ++i)
                Times[i] = Times[i + 1];
            Times[Size - 1] = DateTimeOffset.Now.ToUnixTimeMilliseconds();
        }
    }
}