using System;

namespace VMdemo.Simulation
{
    public class StatsCollector
    {
        public int TotalAccess { get; private set; }
        public int TlbHit { get; private set; }
        public int PageTableHit { get; private set; }
        public int PageFault { get; private set; }
        public long TotalCost { get; private set; }

        public double TlbHitRate => TotalAccess > 0 ? (double)TlbHit / TotalAccess : 0.0;
        public double PageTableHitRate => TotalAccess > 0 ? (double)PageTableHit / TotalAccess : 0.0;
        public double AvgCost => TotalAccess > 0 ? (double)TotalCost / TotalAccess : 0.0;

        public void Reset()
        {
            TotalAccess = 0;
            TlbHit = 0;
            PageTableHit = 0;
            PageFault = 0;
            TotalCost = 0L;
        }

        public int CalculateCost(bool tlbHit, bool pageTableHit, bool pageFault, int pageFaultPenalty)
        {
            if (pageFaultPenalty <= 0)
            {
                throw new ArgumentOutOfRangeException(nameof(pageFaultPenalty), "pageFaultPenalty 必须是正整数。");
            }

            if (tlbHit)
            {
                return 1;
            }

            if (pageFault)
            {
                return 4 + pageFaultPenalty;
            }

            if (pageTableHit)
            {
                return 4;
            }

            throw new InvalidOperationException("访问结果无效：TLB miss 时必须是页表命中或缺页之一。");
        }

        public void RecordAccess(bool tlbHit, bool pageTableHit, bool pageFault, int cost)
        {
            if (cost < 0)
            {
                throw new ArgumentOutOfRangeException(nameof(cost), "cost 不能为负数。");
            }

            TotalAccess++;
            if (tlbHit)
            {
                TlbHit++;
            }

            if (pageTableHit)
            {
                PageTableHit++;
            }

            if (pageFault)
            {
                PageFault++;
            }

            TotalCost += cost;
        }
    }
}