using System.Collections.Generic;
using System.Text;
using VMdemo.Simulation;

namespace VMdemo.UI
{
    public static class SimulationUIFormatter
    {
        private const string ColorVpn = "#4FC3F7";
        private const string ColorL1 = "#FFB74D";
        private const string ColorL2 = "#81C784";
        private const string ColorOffset = "#B0BEC5";

        public static string FormatStateSummary(
            SimulationState state,
            int machineBits,
            int vaBits,
            int pageSizeKB,
            int physicalMemoryMB,
            int tlbEntries)
        {
            var va = FormatAddressHex(state.CurrentVirtualAddress, vaBits);
            var pa = FormatAddressHex(state.CurrentPhysicalAddress, vaBits);
            var stepText = TranslationStepDisplay.ToChinese(state.CurrentStep);
            return
                $"系统规格：{machineBits}位机\n" +
                $"虚拟地址有效位：{vaBits}位\n" +
                $"页大小：{pageSizeKB}KB\n" +
                $"物理内存：{physicalMemoryMB}MB\n" +
                $"TLB：{tlbEntries}条全相联\n";
        }

        public static string FormatStats(StatsCollector stats)
        {
            return
                $"总访问={stats.TotalAccess}\n" +
                $"TLB命中率={stats.TlbHitRate:P2}\n" +
                $"页表命中率={stats.PageTableHitRate:P2}\n" +
                $"缺页次数={stats.PageFault}\n" +
                $"平均开销={stats.AvgCost:F2}";
        }

        public static string FormatTlbTable(
            IReadOnlyList<TlbEntry> entries,
            int vpnBits,
            int pfnBits)
        {
            if (entries == null || entries.Count == 0)
            {
                return "TLB：空";
            }

            var sb = new StringBuilder();
            sb.AppendLine("TLB（最近使用 -> 最久未用）");
            for (var i = 0; i < entries.Count; i++)
            {
                var entry = entries[i];
                sb.Append("#").Append(i + 1)
                    .Append("VPN=").Append(FormatBitWidthHex(entry.Vpn, vpnBits))
                    .Append(" -> PFN=").Append(FormatBitWidthHex(entry.Pfn, pfnBits))
                    .AppendLine();
            }

            return sb.ToString().TrimEnd();
        }

        public static string FormatCurrentPageTableEntry(
            SimulationState state,
            TwoLevelPageTable pageTable,
            EvictionInfo eviction)
        {
            if (state == null || pageTable == null)
            {
                return "页表：N/A";
            }

            var sb = new StringBuilder();
            sb.Append("当前页表项：");
            if (pageTable.TryGetEntry(state.CurrentAddressParts.L1Index, state.CurrentAddressParts.L2Index,
                    out var entry))
            {
                sb.Append("存在=").Append(entry.Present)
                    .Append(" 物理帧号PFN=").Append(FormatHex(entry.Pfn))
                    .Append(" 脏位=").Append(entry.Dirty);
            }
            else
            {
                sb.Append("（缺失）");
            }

            sb.AppendLine();
            if (eviction.HasEvicted)
            {
                sb.Append("最近淘汰：虚拟页号VPN=").Append(FormatHex(eviction.EvictedVpn))
                    .Append(" 物理帧号PFN=").Append(FormatHex(eviction.EvictedPfn));
            }
            else
            {
                sb.Append("最近淘汰：无");
            }

            return sb.ToString();
        }

        public static string FormatFifoQueue(IReadOnlyList<ulong> fifoOrder)
        {
            if (fifoOrder == null || fifoOrder.Count == 0)
            {
                return "FIFO：空";
            }

            var sb = new StringBuilder("FIFO（最早进入 -> 最新进入）：");
            for (var i = 0; i < fifoOrder.Count; i++)
            {
                if (i > 0)
                {
                    sb.Append(" -> ");
                }

                sb.Append(FormatHex(fifoOrder[i]));
            }

            return sb.ToString();
        }

        public static string FormatAddressHex(ulong value, int vaBits)
        {
            return FormatBitWidthHex(value, vaBits);
        }

        private static string FormatHex(ulong value)
        {
            return $"0x{value:X}";
        }

        public static string FormatBitWidthHex(ulong value, int bits)
        {
            var digits = bits switch
            {
                8 => 2,
                16 => 4,
                24 => 6,
                32 => 8,
                48 => 12,
                64 => 16,
                _ => bits > 0 ? (bits + 3) / 4 : 1
            };

            return $"0x{value.ToString($"X{digits}")}";
        }

        public static int ComputeBitsForCount(ulong count)
        {
            if (count <= 1UL)
            {
                return 1;
            }

            var maxValue = count - 1UL;
            var bits = 0;
            while (maxValue > 0UL)
            {
                bits++;
                maxValue >>= 1;
            }

            return bits;
        }

        public static string FormatAddressSplitTrace(
            SimulationState state,
            int vaBits,
            int offsetBits,
            int l1Bits,
            int l2Bits)
        {
            if (state == null)
            {
                return "地址拆分可视化：N/A";
            }

            var vpnBits = vaBits - offsetBits;
            var vaHex = FormatAddressHex(state.CurrentVirtualAddress, vaBits);
            var vaBin = FormatBinary(state.CurrentVirtualAddress, vaBits);
            var vaBinColored = FormatVaBinaryWithFieldColors(state.CurrentVirtualAddress, vaBits, l1Bits, l2Bits, offsetBits);
            var vpnBin = FormatBinary(state.CurrentAddressParts.Vpn, vpnBits);
            var l1Bin = FormatBinary(state.CurrentAddressParts.L1Index, l1Bits);
            var l2Bin = FormatBinary(state.CurrentAddressParts.L2Index, l2Bits);
            var offBin = FormatBinary(state.CurrentAddressParts.Offset, offsetBits);

            var sb = new StringBuilder();
            sb.AppendLine("地址拆分可视化");
            sb.AppendLine($"{vaHex})");
            sb.AppendLine($"{vaBinColored}");
            sb.AppendLine(
                $"{WrapColor("VPN", ColorVpn)} = {WrapColor("L1+L2", ColorVpn)}，" +
                $"{WrapColor("L1", ColorL1)}，{WrapColor("L2", ColorL2)}，{WrapColor("Offset", ColorOffset)}");
            sb.AppendLine($"VPN({vpnBits}) = L1({l1Bits}) + L2({l2Bits}) | Offset({offsetBits})");
            sb.AppendLine($"VPN：{FormatBitWidthHex(state.CurrentAddressParts.Vpn, vpnBits)} ({WrapColor(vpnBin, ColorVpn)})");
            sb.AppendLine($"L1 索引：{FormatBitWidthHex(state.CurrentAddressParts.L1Index, l1Bits)} ({WrapColor(l1Bin, ColorL1)})");
            sb.AppendLine($"L2 索引：{FormatBitWidthHex(state.CurrentAddressParts.L2Index, l2Bits)} ({WrapColor(l2Bin, ColorL2)})");
            sb.Append($"Offset：{FormatBitWidthHex(state.CurrentAddressParts.Offset, offsetBits)} ({WrapColor(offBin, ColorOffset)})");
            return sb.ToString();
        }

        public static string FormatPageTableWalkTrace(SimulationState state, TwoLevelPageTable pageTable)
        {
            if (state == null || pageTable == null)
            {
                return "页表访问路径：N/A";
            }

            var probe = pageTable.Probe(state.CurrentAddressParts.L1Index, state.CurrentAddressParts.L2Index);
            var sb = new StringBuilder();
            sb.AppendLine("多级页表查询可视化");
            sb.AppendLine(
                $"1) 先按 VPN 拆分：L1={state.CurrentAddressParts.L1Index}, L2={state.CurrentAddressParts.L2Index}");
            switch (probe.Status)
            {
                case PageTableProbeStatus.MissingL1Table:
                    sb.Append("2) L1 未命中：对应二级页表不存在。");
                    break;
                case PageTableProbeStatus.MissingL2Entry:
                    sb.Append("2) L1 命中，L2 未命中：页表项不存在。");
                    break;
                case PageTableProbeStatus.NotPresentEntry:
                    sb.Append($"2) L1/L2 命中，但 present=false（PFN={FormatHex(probe.Entry.Pfn)}）。");
                    break;
                case PageTableProbeStatus.PresentEntry:
                    sb.Append($"2) L1/L2 命中，present=true，得到 PFN={FormatHex(probe.Entry.Pfn)}。");
                    break;
            }

            return sb.ToString();
        }

        private static string FormatBinary(ulong value, int bits)
        {
            if (bits <= 0)
            {
                return "0";
            }

            var sb = new StringBuilder(bits + (bits / 4));
            for (var i = bits - 1; i >= 0; i--)
            {
                var bit = (value >> i) & 1UL;
                sb.Append(bit == 1UL ? '1' : '0');
                if (i > 0 && i % 4 == 0)
                {
                    sb.Append('_');
                }
            }

            return sb.ToString();
        }

        private static string FormatVaBinaryWithFieldColors(
            ulong value,
            int vaBits,
            int l1Bits,
            int l2Bits,
            int offsetBits)
        {
            if (vaBits <= 0)
            {
                return "0";
            }

            var sb = new StringBuilder(vaBits * 10);
            string currentColor = null;

            for (var i = vaBits - 1; i >= 0; i--)
            {
                var bitColor = ResolveBitColor(i, l1Bits, l2Bits, offsetBits);
                if (currentColor != bitColor)
                {
                    if (currentColor != null)
                    {
                        sb.Append("</color>");
                    }

                    sb.Append("<color=").Append(bitColor).Append(">");
                    currentColor = bitColor;
                }

                var bit = (value >> i) & 1UL;
                sb.Append(bit == 1UL ? '1' : '0');
                if (i > 0 && i % 4 == 0)
                {
                    sb.Append('_');
                }
            }

            if (currentColor != null)
            {
                sb.Append("</color>");
            }

            return sb.ToString();
        }

        private static string ResolveBitColor(int bitIndex, int l1Bits, int l2Bits, int offsetBits)
        {
            var l1Start = offsetBits + l2Bits;
            if (bitIndex >= l1Start)
            {
                return ColorL1;
            }

            if (bitIndex >= offsetBits)
            {
                return ColorL2;
            }

            return ColorOffset;
        }

        private static string WrapColor(string text, string colorHex)
        {
            return $"<color={colorHex}>{text}</color>";
        }
    }
}