///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   PacketFragment.sg
//

namespace Microsoft.Singularity.Io.Net
{
    using System;
    using System.Runtime.InteropServices;
    using Microsoft.Contracts;
    using Microsoft.SingSharp;
    using Microsoft.Singularity;
    using Microsoft.Singularity.Io;
    using Microsoft.Singularity.Channels;

    public enum FromDeviceFlags : ushort
    {
        TransmitSuccess  = 0x001,
        TransmitError    = 0x002,
        ReceiveSuccess   = 0x004,
        ReceiveError     = 0x008,
        BadIp4Checksum   = 0x010,
        BadUdp4Checksum  = 0x020,
        BadTcp4Checksum  = 0x040,
        GoodUdp4Checksum = 0x080,
        GoodTcp4Checksum = 0x100,
    };

    public enum ToDeviceFlags : ushort
    {
        RequestIp4Checksum  = 1,
        RequestUdp4Checksum = 2,
        RequestTcp4Checksum = 4,
    };

    public rep struct Packet : ITracked
    {
        private PacketFragment[]! in ExHeap fragments;
        private ToDeviceFlags   toDeviceFlags;
        private FromDeviceFlags fromDeviceFlags;

        public Packet(int fragments)
        {
            this.toDeviceFlags   = 0;
            this.fromDeviceFlags = 0;

            this.fragments = new [ExHeap] PacketFragment[fragments];
        }

        public Packet(byte[]! packetBytes)
            : this(1)
        {
            expose (this.fragments[0]) {
                this.fragments[0].Set(packetBytes, 0, packetBytes.Length);
            }
        }

        public Packet([Claims] byte[]! in ExHeap thePacket)
            : this(1)
        {
            expose (this.fragments[0]) {
                this.fragments[0].Set(thePacket, 0, thePacket.Length);
            }
        }

        public ToDeviceFlags ToDeviceFlags
        {
            get { return toDeviceFlags; }
            set { toDeviceFlags = value; }
        }

        public FromDeviceFlags FromDeviceFlags
        {
            get { return fromDeviceFlags; }
            set { fromDeviceFlags = value; }
        }

        [Pure]
        public int GetLength()
        {
            int total = 0;
            expose (this) {
                for (int i = 0; i < this.fragments.Length; i++) {
                    expose (this.fragments[i]) {
                        total += this.fragments[i].Length;
                    }
                }
            }
            return total;
        }

        [Pure]
        public byte[]! ToByteArray()
        {
            byte[]! buffer = new byte[this.GetLength()];
            this.ToByteArray(buffer);
            return buffer;
        }

        public void ToByteArray(byte[]! buffer)
        {
            expose (this) {
                int done = 0;
                for (int i = 0; i < this.FragmentCount; i++) {
                    expose (this.fragments[i]) {
                        done += this.fragments[i].Copy(buffer, done);
                    }
                }
            }
        }

        public void Dispose()
        {
            delete this.fragments;
        }

        //        [Pure]
        public int FragmentCount
        {
            get {
                expose (this) {
                    return this.fragments.Length;
                }
            }
        }

        //        [Pure]
        public void GetFragmentRange(int         fragment,
                                     out UIntPtr virtualAddr,
                                     out int     lengthBytes)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].GetFragmentRange(out virtualAddr,
                                                              out lengthBytes);
                }
            }
        }

        public UIntPtr GetFragmentVirtualAddress(int fragment)
        {
            UIntPtr virtualAddress;
            int     length;
            GetFragmentRange(fragment, out virtualAddress, out length);
            return virtualAddress;
        }

        public void SetFragmentLength(int fragment, int length)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    assert (length >= 0 &&
                            length <= this.fragments[fragment].Capacity);
                    this.fragments[fragment].Length = length;
                }
            }
        }

        public void UnsetFragmentLength(int fragment)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].Length =
                        this.fragments[fragment].Capacity;
                }
            }
        }

        public void UnsetFragmentLengths()
        {
            expose (this) {
                for (int i = 0; i < this.FragmentCount; i++) {
                    UnsetFragmentLength(i);
                }
            }
        }

        public void SetFragment(int fragment,
                                [Claims] byte []! in ExHeap buffer,
                                int bufferStart,
                                int bufferLength)
            requires fragment >= 0 && fragment <= this.FragmentCount;
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].Set(buffer,
                                                 bufferStart,
                                                 bufferLength);
                }
            }
        }

        public void SetFragment(int fragment,
                                [Claims] byte []! in ExHeap buffer)
            requires fragment >= 0 && fragment < this.FragmentCount;
        {
            SetFragment(fragment, buffer, 0, buffer.Length);
        }

        public void SetFragment(int fragment, byte []! buffer)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].Set(buffer, 0, buffer.Length);
                }
            }
        }

        public void SetFragment(int      fragment,
                                byte []! buffer,
                                int      offset,
                                int      length)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].Set(buffer, offset, length);
                }
            }
        }

        public void SetFragment(int fragment,
                                IoMemory! region,
                                UIntPtr offset,
                                UIntPtr length)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].Set(region, offset, length);
                }
            }
        }

        public void AppendToFragment(int fragment, byte value)
        {
            expose (this) {
                expose (this.fragments[fragment]) {
                    this.fragments[fragment].Append(value);
                }
            }
        }
    }
}