///////////////////////////////////////////////////////////////////////////////
//
//  Microsoft Research Singularity
//
//  Copyright (c) Microsoft Corporation.  All rights reserved.
//
//  File: Service\Test\Replace\GameTable.sg
//
//  Note:
//
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Text;
using System.Threading;
using Microsoft.SingSharp;
using Microsoft.Singularity;
using Microsoft.Singularity.Channels;
using Microsoft.Singularity.Resiliency;
using Microsoft.Singularity.ServiceManager;

namespace Microsoft.Singularity.Services.Replace
{
    internal sealed class GameTable
    {
        //private const String[]  Names = new String[4] {"Microsoft", "Google", "Yahoo", "Apple"};
        private readonly String[]! Names;
        private const String    ProtectionString = "PROTECTED";

        private const int       NumberOfNames = 4;
        private const int       ProtectionPeriod = 500;
        private const int       TableSize = 100;
        private String[]!       table;
        private ASCIIEncoding!  encoding;
        private Random!         random;

        private TRef<ServiceProxyContract.Imp:Ready>!   proxyRef;

        internal GameTable([Claims]ServiceProxyContract.Imp:Start! ep)
        {
            DebugStub.Print("Waiting for Success message\n");
            switch receive {
                case ep.Success():
                    break;
                case unsatisfiable:
                    new ArgumentException();
                    break;
            }
            DebugStub.Print("done\n");
            Names = new String[4] {"Microsoft", "Google", "Yahoo", "Apple"};
            this.table = new String[TableSize];
            this.proxyRef = new TRef<ServiceProxyContract.Imp:Ready>(ep);
            this.encoding = new ASCIIEncoding();
            Thread.Sleep(1);
            this.random = new Random();
        }

        internal void Initialize()
        {
            ServiceProxyContract.Imp:Ready! ep;

            ep = proxyRef.Acquire();
            DebugStub.Print("Downloading\n");
            ep.SendDownload();
            switch receive {
                case ep.AckDownload(buffer):
                {
                    Deserialize(buffer, table);
                    delete buffer;
                    break;
                }
                case ep.NakDownload():
                {
                    int j = 0;
                    for (int i = 0; i < TableSize; i++) {
                        table[i] = Names[j++];
                        if (j >= NumberOfNames) {
                            j = 0;
                        }
                    }
                    break;
                }
                case unsatisfiable:
                {
                    DebugStub.Break();
                    break;
                }
            }
            proxyRef.Release(ep);

            DebugStub.Print("-- Initial Score\n");
            Print();
            DebugStub.Break();
        }

        internal void Commit()
        {
            ServiceProxyContract.Imp:Ready! ep;
            byte[]! in ExHeap               buffer;

            DebugStub.Print("-- Commit\n");
            Print();

            Serialize(table, out buffer);

            ep = proxyRef.Acquire();
            ep.SendUpload(buffer);
            switch receive {
                case ep.AckUpload():
                    break;
                case unsatisfiable:
                    DebugStub.Break();
                    break;
            }
            proxyRef.Release(ep);
        }

        internal int Lookup(string! query)
        {
            int start;
            int current;

            start = random.Next(TableSize);

            assert 0 <= start && start < TableSize;

            if (table[start] == query) {
                return start;
            }

            current = start + 1;
            if (current >= TableSize) {
                current = 0;
            }

            while (current != start) {
                assert 0 <= current && current < TableSize;
                if (table[current] == query) {
                    break;
                }
                ++current;
                if (current >= TableSize) {
                    current = -1;
                }
            }

            if (current == start) {
                current = -1;
            }

            return current;
        }

        internal void Replace(string! query, int position)
        {
            //DebugStub.Print("-- Replace {0}\n", __arglist(position));
            if (position < 0 || TableSize <= position) {
                return;
            }

            lock (this) {
                if (!((!)table[position]).EndsWith(ProtectionString)) {
                    table[position] = query;
                }
                else {
                    DebugStub.Print("Protected!!\n");
                }
            }
        }

        internal void Lock(int position)
        {
            String! tmp;

            if (position < 0 || TableSize <= position) {
                return;
            }

            tmp = (!)table[position];
            lock (this) {
                table[position] += ProtectionString;
            }
            Thread.Sleep(ProtectionPeriod);
            lock (this) {
                table[position] = tmp;
            }
        }

        internal int Score(string! query)
        {
            int count = 0;
            lock (this) {
                foreach (String! str in table) {
                    if (str.StartsWith(query)) {
                        ++count;
                    }
                }
            }
            return count;
        }

        internal void Print()
        {
            foreach (String! player in Names) {
                DebugStub.Print("{0} : {1}\n",
                                __arglist(player, Score(player)));
            }
        }

        private void Serialize(string[]! src, out byte[]! in ExHeap dest)
        {
            byte[][]!           conversion = new byte[TableSize][];
            byte[]              buffer;
            byte[] in ExHeap    exBuffer;
            int                 size = 0;
            int                 offset = 0;

            //
            // Enumerate table elements
            //
            lock (this) {
                for (int i = 0; i < TableSize; i++) {
                    conversion[i] = encoding.GetBytes((!)src[i]);
                    if (conversion[i] != null) {
                        size += ((!)conversion[i]).Length + sizeof(int) * 2;
                    }
                    else {
                        throw new NullReferenceException();
                    }
                }
            }
            assert 0 <= size && size < Int32.MaxValue;

            //
            // Create a base buffer
            //
            buffer = new byte[size];
            offset = 0;
            for (int i = 0; i < TableSize; i++) {
                // length
                Buffer.BlockCopy(BitConverter.GetBytes(((!)conversion[i]).Length),
                                 0, buffer, offset, sizeof(int));
                offset += sizeof(int);

                // index
                Buffer.BlockCopy(BitConverter.GetBytes(i), 0,
                                 buffer, offset, sizeof(int));
                offset += sizeof(int);

                // contents
                Buffer.BlockCopy(conversion[i], 0, buffer, offset,
                                 ((!)conversion[i]).Length);
                offset += ((!)conversion[i]).Length;
            }

            // 
            // Copy to ExHeap
            //
            exBuffer = Bitter.FromByteArray(buffer);
            dest = exBuffer;
        }

        private void Deserialize(byte[]! in ExHeap src, string[]! dest)
        {
            byte[]! copyBuffer = Bitter.ToByteArray(src);
            byte[]  storeBuffer;
            int     length = src.Length;
            int     count;
            int     id;
            int     offset = 0;

            lock (this) {
                while (offset + 8 < length) {
                    // length
                    count = BitConverter.ToInt32(copyBuffer, offset);

                    offset += sizeof(int);
                    if (offset >= length) {
                        break;
                    }

                    // index
                    id = BitConverter.ToInt32(copyBuffer, offset);

                    offset += sizeof(int);
                    if (offset >= length) {
                        break;
                    }

                    // contents
                    storeBuffer = new byte[count];
                    Buffer.BlockCopy(copyBuffer, offset, storeBuffer, 0, count);
                    offset += count;
                    if (id < TableSize) {
                        dest[id] = encoding.GetString(storeBuffer);
                    }
                    else {
                        DebugStub.Break();
                        // throw new Exception();
                    }
                }
            }
        }
    } // class
}