///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  Note: CachedFile is intended to hold copies of Custom.Ads
//  and User.Profiles in memory.
//

using System;
using System.Collections;
using System.Diagnostics;
using Microsoft.SingSharp;
using Microsoft.SingSharp.Runtime;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Directory;
using Microsoft.Singularity.WebApps;
using Microsoft.Singularity.WebApps.Contracts;
using System.Io;
using System.Text;
using System.Threading;
using System.Web;
using FileSystem.Utils;
using System.Net.IP;
using Microsoft.Singularity.V1.Services;

namespace Microsoft.Singularity.WebApps
{
    public class CachedFile
    {
        string  filename;
        byte[]  filedata;
        uint    fileMaxBytes;

        internal CachedFile(string! theFilename, uint maxBytes)
        {
            this.filename      = theFilename;
            this.fileMaxBytes  = maxBytes;
        }

        public bool Refresh()
        {
            lock (this) {
                FileContract.Imp conn;
                conn = FileUtils.OpenFile(filename);

                if (conn == null) {
                    Console.WriteLine("CachedFile: Failed to open {0}", filename);
                    return false;
                }

                try {
                    byte[]! in ExHeap bytes = new [ExHeap] byte [fileMaxBytes];
                    long bytesRead;
                    int  error;
                    conn.SendRead(bytes,
                                  /* buffer offset */0,
                                  /* file offset */0,
                                  bytes.Length);
                    conn.RecvAckRead(out bytes, out bytesRead, out error);

                    if (error != 0) {
                        delete bytes;
                        return false;
                    }

                    filedata = Bitter.ToByteArray(bytes);
                    delete bytes;
                    return true;
                }
                finally {
                    delete conn;
                }
            }
        }

        // Caller should not hold onto this outside of method of use.
        // "borrows"
        public byte[] FileData
        {
            get { lock (this) { return filedata; } }
        }
    }
}