using ChocolArm64;
using ChocolArm64.Memory;
using Ryujinx.Loaders;
using Ryujinx.Loaders.Executables;
using Ryujinx.OsHle.Handles;
using Ryujinx.OsHle.Svc;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;

namespace Ryujinx.OsHle
{
    class Process
    {
        private const int  MaxStackSize  = 8 * 1024 * 1024;

        private const int  TlsSize       = 0x200;
        private const int  TotalTlsSlots = 32;
        private const int  TlsTotalSize  = TotalTlsSlots * TlsSize;
        private const long TlsPageAddr   = (AMemoryMgr.AddrSize - TlsTotalSize) & ~AMemoryMgr.PageMask;

        private Switch Ns;

        public int ProcessId { get; private set; }

        public AMemory Memory { get; private set; }

        private SvcHandler SvcHandler;

        private AThread MainThread;

        private ConcurrentDictionary<int, AThread> TlsSlots;

        private List<Executable> Executables;

        private long ImageBase;

        public Process(Switch Ns, AMemoryAlloc Allocator, int ProcessId)
        {
            this.Ns        = Ns;
            this.ProcessId = ProcessId;

            Memory      = new AMemory(Ns.Ram, Allocator);
            SvcHandler  = new SvcHandler(Ns, Memory);
            TlsSlots    = new ConcurrentDictionary<int, AThread>();
            Executables = new List<Executable>();

            ImageBase = 0x8000000;

            Memory.Manager.MapPhys(
                TlsPageAddr,
                TlsTotalSize,
                (int)MemoryType.ThreadLocal,
                AMemoryPerm.RW);
        }

        public void LoadProgram(IElf Program)
        {
            Executable Executable = new Executable(Program, Memory, ImageBase);

            Executables.Add(Executable);

            ImageBase = AMemoryHelper.PageRoundUp(Executable.ImageEnd);
        }

        public void SetEmptyArgs()
        {
            ImageBase += AMemoryMgr.PageSize;
        }

        public void InitializeHeap()
        {
            Memory.Manager.SetHeapAddr((ImageBase + 0x3fffffff) & ~0x3fffffff);
        }

        public bool Run()
        {
            if (Executables.Count == 0)
            {
                return false;
            }

            long StackBot = TlsPageAddr - MaxStackSize;

            Memory.Manager.MapPhys(StackBot, MaxStackSize, (int)MemoryType.Normal, AMemoryPerm.RW);

            int Handle = MakeThread(Executables[0].ImageBase, TlsPageAddr, 0, 48, 0);

            if (Handle == -1)
            {
                return false;
            }

            MainThread = Ns.Os.Handles.GetData<HThread>(Handle).Thread;

            MainThread.Execute();

            return true;
        }

        public void StopAllThreads()
        {
            if (MainThread != null)
            {
                while (MainThread.IsAlive)
                {
                    MainThread.StopExecution();
                }
            }

            foreach (AThread Thread in TlsSlots.Values)
            {
                while (Thread.IsAlive)
                {
                    Thread.StopExecution();
                }
            }
        }

        public int MakeThread(
            long EntryPoint,
            long StackTop,
            long ArgsPtr,
            int  Priority,
            int  ProcessorId)
        {
            AThread Thread = new AThread(Memory, EntryPoint, Priority);

            int TlsSlot = GetFreeTlsSlot(Thread);

            int Handle = Ns.Os.Handles.GenerateId(new HThread(Thread));

            if (TlsSlot == -1 || Handle  == -1)
            {
                return -1;
            }

            Thread.Registers.SvcCall  += SvcHandler.SvcCall;
            Thread.Registers.ProcessId = ProcessId;
            Thread.Registers.ThreadId  = Ns.Os.IdGen.GenerateId();
            Thread.Registers.Tpidr   = TlsPageAddr + TlsSlot * TlsSize;
            Thread.Registers.X0        = (ulong)ArgsPtr;
            Thread.Registers.X1        = (ulong)Handle;
            Thread.Registers.X31       = (ulong)StackTop;

            Thread.WorkFinished += ThreadFinished;

            return Handle;
        }

        private int GetFreeTlsSlot(AThread Thread)
        {
            for (int Index = 1; Index < TotalTlsSlots; Index++)
            {
                if (TlsSlots.TryAdd(Index, Thread))
                {
                    return Index;
                }
            }

            return -1;
        }

        private void ThreadFinished(object sender, EventArgs e)
        {
            if (sender is AThread Thread)
            {
                TlsSlots.TryRemove(GetTlsSlot(Thread.Registers.Tpidr), out _);

                Ns.Os.IdGen.DeleteId(Thread.ThreadId);
            }
        }

        private int GetTlsSlot(long Position)
        {
            return (int)((Position - TlsPageAddr) / TlsSize);
        }
    }
}