using System;
using System.Diagnostics;

namespace BlueWest.Core
{
    public class TimerTick
    {
        private long startRawTime;
        private long lastRawTime;
        private int pauseCount;
        private long pauseStartTime;
        private long timePaused;
        private static decimal speedFactor = 1.0m;

        public TimeSpan StartTime { get; private set; }

        public TimeSpan TotalTime { get; private set; }

        public TimeSpan TotalTimeWithPause { get; private set; }

        public TimeSpan ElapsedTime { get; private set; }

        public TimeSpan ElapsedTimeWithPause { get; private set; }

        public void Reset()
        {
            Reset(TimeSpan.Zero);
        }

        public void Reset(TimeSpan startTime)
        {
            StartTime = startTime;
            TotalTime = startTime;
            startRawTime = Stopwatch.GetTimestamp();
            lastRawTime = startRawTime;
            timePaused = 0;
            pauseStartTime = 0;
            pauseCount = 0;
        }

        
        public void Resume()
        {
            pauseCount--;
            if (pauseCount <= 0)
            {
                timePaused += Stopwatch.GetTimestamp() - pauseStartTime;
                pauseStartTime = 0L;
            }
        }

        public void Tick()
        {
            var rawTime = Stopwatch.GetTimestamp();
            TotalTime = StartTime + new TimeSpan((long)Math.Round(ConvertRawToTimestamp(rawTime - timePaused - startRawTime).Ticks * speedFactor));
            TotalTimeWithPause = StartTime + new TimeSpan((long)Math.Round(ConvertRawToTimestamp(rawTime - startRawTime).Ticks * speedFactor));

            ElapsedTime = ConvertRawToTimestamp(rawTime - timePaused - lastRawTime);
            ElapsedTimeWithPause = ConvertRawToTimestamp(rawTime - lastRawTime);

            if (ElapsedTime < TimeSpan.Zero)
            {
                ElapsedTime = TimeSpan.Zero;
            }

            lastRawTime = rawTime;
        }

        public TimeSpan ConvertRawToTimestamp(long delta)
        {
            return new TimeSpan(delta == 0 ? 0 : (delta * TimeSpan.TicksPerSecond) / Stopwatch.Frequency);
        }

        public void Pause()
        {
            pauseCount++;
            if (pauseCount == 1)
            {
                pauseStartTime = Stopwatch.GetTimestamp();
            }
        }
    }
}