using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace Cosmos.Compiler.Assembler
{
    public class ElementReference
    {
        private static Dictionary<string, ElementReference> mLookup = new Dictionary<string, ElementReference>( StringComparer.InvariantCultureIgnoreCase );
        public static ElementReference New( string aName, int aOffset )
        {
            ElementReference xResult;
            if( aName.StartsWith( "." ) )
            {
                aName = Label.LastFullLabel + aName;
            }
            string xId = String.Intern( aName + "@@" + aOffset );
            if( mLookup.TryGetValue( xId, out xResult ) )
            {
                return xResult;
            }
            if( aOffset == 0 )
            {
                xResult = new ElementReference( aName );
            }
            else
            {
                xResult = new ElementReference( aName, aOffset );
            }
            mLookup.Add( xId, xResult );
            return xResult;
        }

        public static ElementReference New( string aName )
        {
            return New( aName, 0 );
        }

        private ElementReference( string aName, int aOffset )
            : this( aName )
        {
            Offset = aOffset;
        }

        private ElementReference( string aName )
        {
            if( String.IsNullOrEmpty( aName ) )
            {
                throw new ArgumentNullException( "aName" );
            }
            if( aName == "00h" )
            {
                Console.Write( "" );
            }
            if( aName.StartsWith( "." ) )
            {
                Name = Label.LastFullLabel + aName;
            }
            else
            {
                Name = aName;
            }
        }

        private ulong? mActualAddress;

        private static ReaderWriterLockSlim mCacheLocker = new ReaderWriterLockSlim( LockRecursionPolicy.NoRecursion );
        private static Dictionary<string, BaseAssemblerElement> mCache;// = new SortedList<string, BaseAssemblerElement>(StringComparer.InvariantCultureIgnoreCase);
        private static int? mThreadId = null;

        private static BaseAssemblerElement DoResolve( Assembler aAssembler, string aName )
        {
            if( !mThreadId.HasValue )
            {
                mThreadId = Thread.CurrentThread.ManagedThreadId;
            }
            else
            {
                if( mThreadId.Value != Thread.CurrentThread.ManagedThreadId )
                {
                    throw new Exception( "Called from multiple threads" );
                }
            }
            mCacheLocker.EnterReadLock();
            try
            {
                if( mCache != null )
                {
                    BaseAssemblerElement xTempResult;
                    if( mCache.TryGetValue( aName, out xTempResult ) )
                    {
                        return xTempResult;
                    }
                }
            }
            finally
            {
                mCacheLocker.ExitReadLock();
            }
            mCacheLocker.EnterWriteLock();
            try
            {
                if( mCache == null )
                {
                    mCache = new Dictionary<string, BaseAssemblerElement>( StringComparer.InvariantCultureIgnoreCase );
                    int xMax = aAssembler.AllAssemblerElementCount;
                    for( int i = 0; i < xMax; i++ )
                    {
                        var xInstruction = aAssembler.GetAssemblerElement( i );
                        var xLabel = xInstruction as Label;
                        if( xLabel != null )
                        {
                            mCache.Add( xLabel.QualifiedName, xLabel );
                        }
                        var xDataMember = xInstruction as DataMember;
                        if( xDataMember != null )
                        {
                            if( mCache.ContainsKey( xDataMember.Name ) )
                            {
                                Console.Write( "" );
                            }
                            mCache.Add( xDataMember.Name, xDataMember );
                        }
                    }
                }
                BaseAssemblerElement xTempResult;
                if( mCache.TryGetValue( aName, out xTempResult ) )
                {
                    return xTempResult;
                }
                throw new Exception( "Cannot resolve ElementReference to '" + aName + "'!" );
                //foreach(var xInstruction in aAssembler.Instructions ) {
                //    var xLabel = xInstruction as Label;
                //    if(xLabel!=null) {
                //        if(aName.Equals(xLabel.Name, StringComparison.InvariantCultureIgnoreCase)) {
                //            xTempResult = xLabel;
                //            break;
                //        }
                //    }
                //}
                //if (xTempResult == null) {
                //    foreach (var xDataMember in aAssembler.DataMembers) {
                //        if (aName.Equals(xDataMember.Name, StringComparison.InvariantCultureIgnoreCase)) {
                //            xTempResult = xDataMember;
                //            break;
                //        }
                //    }
                //}
            }
            finally
            {
                mCacheLocker.ExitWriteLock();
            }
        }

        public bool Resolve( Assembler aAssembler, out ulong aAddress )
        {
            //
            if( mActualAddress != null )
            {
                aAddress = mActualAddress.Value;
                return true;
            }
            var xElement = DoResolve( aAssembler, Name );
            if( xElement != null )
            {
                if( xElement.ActualAddress.HasValue )
                {
                    mActualAddress = ( ulong )( ( long )xElement.ActualAddress.Value + Offset );
                    aAddress = mActualAddress.Value;
                    return true;
                }
            }

            aAddress = 0;
            return false;
        }

        public int Offset
        {
            get;
            set;
        }

        public string Name
        {
            get;
            set;
        }

        public override string ToString()
        {
            if( Offset != 0 )
            {
                return Label.FilterStringForIncorrectChars( Name ) + " + " + Offset;
            }
            else
            {
                return Label.FilterStringForIncorrectChars( Name );
            }
        }
    }
}