using Ryujinx.Common;
using Ryujinx.Common.Logging;
using Ryujinx.Graphics.Gpu.Memory;
using Ryujinx.Memory;
using System;
using System.Collections.Concurrent;

namespace Ryujinx.HLE.HOS.Services.Nv.NvDrvServices.NvMap
{
    internal class NvMapDeviceFile : NvDeviceFile
    {
        private const int FlagNotFreedYet = 1;

        private static ConcurrentDictionary<long, IdDictionary> _maps = new ConcurrentDictionary<long, IdDictionary>();

        public NvMapDeviceFile(ServiceCtx context, IVirtualMemoryManager memory, long owner) : base(context, owner)
        {
            IdDictionary dict = _maps.GetOrAdd(Owner, (key) => new IdDictionary());

            dict.Add(0, new NvMapHandle());
        }

        public override NvInternalResult Ioctl(NvIoctl command, Span<byte> arguments)
        {
            NvInternalResult result = NvInternalResult.NotImplemented;

            if (command.Type == NvIoctl.NvMapCustomMagic)
            {
                switch (command.Number)
                {
                    case 0x01:
                        result = CallIoctlMethod<NvMapCreate>(Create, arguments);
                        break;
                    case 0x03:
                        result = CallIoctlMethod<NvMapFromId>(FromId, arguments);
                        break;
                    case 0x04:
                        result = CallIoctlMethod<NvMapAlloc>(Alloc, arguments);
                        break;
                    case 0x05:
                        result = CallIoctlMethod<NvMapFree>(Free, arguments);
                        break;
                    case 0x09:
                        result = CallIoctlMethod<NvMapParam>(Param, arguments);
                        break;
                    case 0x0e:
                        result = CallIoctlMethod<NvMapGetId>(GetId, arguments);
                        break;
                    case 0x02:
                    case 0x06:
                    case 0x07:
                    case 0x08:
                    case 0x0a:
                    case 0x0c:
                    case 0x0d:
                    case 0x0f:
                    case 0x10:
                    case 0x11:
                        result = NvInternalResult.NotSupported;
                        break;
                }
            }

            return result;
        }

        private NvInternalResult Create(ref NvMapCreate arguments)
        {
            if (arguments.Size == 0)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid size 0x{arguments.Size:x8}!");

                return NvInternalResult.InvalidInput;
            }

            int size = BitUtils.AlignUp(arguments.Size, (int)MemoryManager.PageSize);

            arguments.Handle = CreateHandleFromMap(new NvMapHandle(size));

            Logger.Info?.Print(LogClass.ServiceNv, $"Created map {arguments.Handle} with size 0x{size:x8}!");

            return NvInternalResult.Success;
        }

        private NvInternalResult FromId(ref NvMapFromId arguments)
        {
            NvMapHandle map = GetMapFromHandle(Owner, arguments.Id);

            if (map == null)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid handle 0x{arguments.Handle:x8}!");

                return NvInternalResult.InvalidInput;
            }

            map.IncrementRefCount();

            arguments.Handle = arguments.Id;

            return NvInternalResult.Success;
        }

        private NvInternalResult Alloc(ref NvMapAlloc arguments)
        {
            NvMapHandle map = GetMapFromHandle(Owner, arguments.Handle);

            if (map == null)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid handle 0x{arguments.Handle:x8}!");

                return NvInternalResult.InvalidInput;
            }

            if ((arguments.Align & (arguments.Align - 1)) != 0)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid alignment 0x{arguments.Align:x8}!");

                return NvInternalResult.InvalidInput;
            }

            if ((uint)arguments.Align < MemoryManager.PageSize)
            {
                arguments.Align = (int)MemoryManager.PageSize;
            }

            NvInternalResult result = NvInternalResult.Success;

            if (!map.Allocated)
            {
                map.Allocated = true;

                map.Align =       arguments.Align;
                map.Kind  = (byte)arguments.Kind;

                int size = BitUtils.AlignUp(map.Size, (int)MemoryManager.PageSize);

                ulong address = arguments.Address;

                if (address == 0)
                {
                    // When the address is zero, we need to allocate
                    // our own backing memory for the NvMap.
                    // TODO: Is this allocation inside the transfer memory?
                    result = NvInternalResult.OutOfMemory;
                }

                if (result == NvInternalResult.Success)
                {
                    map.Size    = size;
                    map.Address = address;
                }
            }

            return result;
        }

        private NvInternalResult Free(ref NvMapFree arguments)
        {
            NvMapHandle map = GetMapFromHandle(Owner, arguments.Handle);

            if (map == null)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid handle 0x{arguments.Handle:x8}!");

                return NvInternalResult.InvalidInput;
            }

            if (DecrementMapRefCount(Owner, arguments.Handle))
            {
                arguments.Address = map.Address;
                arguments.Flags   = 0;
            }
            else
            {
                arguments.Address = 0;
                arguments.Flags   = FlagNotFreedYet;
            }

            arguments.Size = map.Size;

            return NvInternalResult.Success;
        }

        private NvInternalResult Param(ref NvMapParam arguments)
        {
            NvMapHandle map = GetMapFromHandle(Owner, arguments.Handle);

            if (map == null)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid handle 0x{arguments.Handle:x8}!");

                return NvInternalResult.InvalidInput;
            }

            switch (arguments.Param)
            {
                case NvMapHandleParam.Size:  arguments.Result = map.Size;   break;
                case NvMapHandleParam.Align: arguments.Result = map.Align;  break;
                case NvMapHandleParam.Heap:  arguments.Result = 0x40000000; break;
                case NvMapHandleParam.Kind:  arguments.Result = map.Kind;   break;
                case NvMapHandleParam.Compr: arguments.Result = 0;          break;

                // Note: Base is not supported and returns an error.
                // Any other value also returns an error.
                default: return NvInternalResult.InvalidInput;
            }

            return NvInternalResult.Success;
        }

        private NvInternalResult GetId(ref NvMapGetId arguments)
        {
            NvMapHandle map = GetMapFromHandle(Owner, arguments.Handle);

            if (map == null)
            {
                Logger.Warning?.Print(LogClass.ServiceNv, $"Invalid handle 0x{arguments.Handle:x8}!");

                return NvInternalResult.InvalidInput;
            }

            arguments.Id = arguments.Handle;

            return NvInternalResult.Success;
        }

        public override void Close()
        {
            // TODO: refcount NvMapDeviceFile instances and remove when closing
            // _maps.TryRemove(GetOwner(), out _);
        }

        private int CreateHandleFromMap(NvMapHandle map)
        {
            IdDictionary dict = _maps.GetOrAdd(Owner, (key) =>
            {
                IdDictionary newDict = new IdDictionary();

                newDict.Add(0, new NvMapHandle());

                return newDict;
            });

            return dict.Add(map);
        }

        private static bool DeleteMapWithHandle(long pid, int handle)
        {
            if (_maps.TryGetValue(pid, out IdDictionary dict))
            {
                return dict.Delete(handle) != null;
            }

            return false;
        }

        public static void IncrementMapRefCount(long pid, int handle, bool allowHandleZero = false)
        {
            GetMapFromHandle(pid, handle, allowHandleZero)?.IncrementRefCount();
        }

        public static bool DecrementMapRefCount(long pid, int handle)
        {
            NvMapHandle map = GetMapFromHandle(pid, handle, false);

            if (map == null)
            {
                return false;
            }

            if (map.DecrementRefCount() <= 0)
            {
                DeleteMapWithHandle(pid, handle);

                Logger.Info?.Print(LogClass.ServiceNv, $"Deleted map {handle}!");

                return true;
            }
            else
            {
                return false;
            }
        }

        public static NvMapHandle GetMapFromHandle(long pid, int handle, bool allowHandleZero = false)
        {
            if ((allowHandleZero || handle != 0) && _maps.TryGetValue(pid, out IdDictionary dict))
            {
                return dict.GetData<NvMapHandle>(handle);
            }

            return null;
        }
    }
}