////////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File:   ByteContainers.sg
//
//  Helper class for abstracting over either byte[] or byte[] in ExHeap
//
using System;
using Microsoft.Singularity;
using Microsoft.SingSharp;
using Microsoft.Singularity.Channels;

public class ByteContainer {
    bool inSharedHeap;
    bool occupied;
    int length;
    byte[] normalBuf;
    VContainer<byte> sharedBuf;
    
    public ByteContainer() {sharedBuf = null;}
    public ByteContainer(byte[] newBuf) {
        inSharedHeap = false;
        occupied = true;
        normalBuf = newBuf;
        sharedBuf = null;
        length = newBuf.Length;
    }
    
    public ByteContainer([Claims]byte[]! in ExHeap newBuf) {
        inSharedHeap = true;
        occupied = true;
        normalBuf = null;
        length = newBuf.Length;
        sharedBuf = new VContainer<byte>(newBuf);
    }
    
    public bool InSharedHeap {get{return inSharedHeap;}}
    public int Length {
        get{
            if (!occupied) {
                DebugStub.Break();
                throw new Exception("Tried to get length of empty ByteContainer!");
            }
            else {
                return length;
            }
        }
    }
    
    public void CopyFrom(byte[] dest, int srcOff, int destOff, int len) {
        if (!occupied) {
            DebugStub.Break();
            throw new Exception("Trying to CopyFrom empty ByteContainer!");
        }
        else {
            if (inSharedHeap) {
                byte[]! in ExHeap src = sharedBuf.Acquire();
                for (int i = 0; i < len; i++) {
                    dest[destOff+i] = src[srcOff+i];
                }
                sharedBuf.Release(src);
            }
            else {
                for (int i = 0; i < len; i++) {
                    dest[destOff+i] = normalBuf[srcOff+i];
                }
            }
        }
    }
    
    public void CopyTo(byte[] src, int srcOff, int destOff, int len) {
        if (!occupied) {
            DebugStub.Break();
            throw new Exception("Trying to CopyTo empty ByteContainer!");
        }
        else {
            if (inSharedHeap) {
                byte[]! in ExHeap dest = sharedBuf.Acquire();
                for (int i = 0; i < len; i++) {
                    dest[destOff+i] = src[srcOff+i];
                }
                sharedBuf.Release(dest);
            }
            else {
                for (int i = 0; i < len; i++) {
                    normalBuf[destOff+i] = src[srcOff+i];
                }
            }
        }
    }
    
    public void Clear(long off, long amount) {
        if (!occupied) {
            throw new Exception("Trying to CopyFrom empty ByteContainer!");
        }
        else {
            if (inSharedHeap) {
                byte[]! in ExHeap buf = sharedBuf.Acquire();
                for (long i = 0; i < amount; i++) {
                    buf[off+i] = 0;
                }
                sharedBuf.Release(buf);
            }
            else {
                for (long i = 0; i < amount; i++) {
                    normalBuf[off+i] = 0;
                }
            }
        }
    }
    
    public byte[] GetArray() {
        if (inSharedHeap) {
            DebugStub.Break();
            throw new Exception("Tried to get vector as array!");
        }
        else if (!occupied) {
            DebugStub.Break();
            throw new Exception("Trying to get empty ByteContainer!");
        }
        else {
            occupied = false;
            return normalBuf;
        }
    }
    
    public void PutArray(byte[] buf) {
        if (occupied) {
            DebugStub.Break();
            throw new Exception("ByteContainer already occupied!");
        }
        else {
            inSharedHeap = false;
            occupied = true;
            normalBuf = buf;
            length = buf.Length;
        }
    }
    
    public byte[] in ExHeap ConvertToVector() {
        if (inSharedHeap) {
            DebugStub.Break();
            throw new Exception("Tried to convert a vector to a vector!");
        }
        else if (!occupied) {
            DebugStub.Break();
            throw new Exception("Trying to get empty ByteContainer!");
        }
        else {
            return Bitter.FromByteArray(normalBuf);
        }
    }
    
    public byte[] ConvertToArray() {
        if (!inSharedHeap) {
            return normalBuf;
        }
        else if (!occupied) {
            DebugStub.Break();
            throw new Exception("Trying to get empty ByteContainer!");
        }
        else {
            byte[]! in ExHeap temp = sharedBuf.Acquire();
            byte[] ret = Bitter.ToByteArray(temp);
            sharedBuf.Release(temp);
            return ret;
        }
    }
    
    public byte[]! in ExHeap GetVector() {
        if (!inSharedHeap) {
            DebugStub.Break();
            throw new Exception("Tried to get array as vector!");
        }
        else if (!occupied) {
            DebugStub.Break();
            throw new Exception("Trying to get empty ByteContainer!");
        }
        else {
            occupied = false;
            return sharedBuf.Acquire();
        }
    }
    
    public void PutVector([Claims]byte[]! in ExHeap buf) {
        if (occupied) {
            DebugStub.Break();
            throw new Exception("ByteContainer already occupied!");
        }
        else {
            occupied = true;
            inSharedHeap = true;
            if (sharedBuf == null) {
                length = buf.Length;
                sharedBuf = new VContainer<byte>(buf);
            }
            else {
                length = buf.Length;
                sharedBuf.Release(buf);
            }
        }
    }
}