// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.

// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;

using System.Linq;

using System.Linq.Expressions;

using System.Reflection;

using JetBrains.Annotations;

using Remotion.Linq.Clauses;

namespace Microsoft.Data.Entity.Query

{

public abstract class QuerySourceScope

{

private static readonly MethodInfo _createMethodInfo

= typeof(QuerySourceScope).GetTypeInfo()

.GetDeclaredMethods("Create").FirstOrDefault(m => m.IsStatic && !m.IsPublic);

public static readonly MethodInfo GetResultMethodInfo

= typeof(QuerySourceScope).GetTypeInfo()

.GetDeclaredMethods("GetResult").FirstOrDefault(m => !m.IsStatic && !m.IsPublic);

public static Expression Create(

[NotNull] IQuerySource querySource,

[NotNull] Expression result,

[NotNull] Expression parentScope)

{

return Expression.Call(

_createMethodInfo.MakeGenericMethod(result.Type),

Expression.Constant(querySource),

result,

parentScope);

}

public static Expression GetResult(

[NotNull] Expression querySourceScope,

[NotNull] IQuerySource querySource,

[NotNull] Type resultType)

{

return Expression.Call(

querySourceScope,

GetResultMethodInfo.MakeGenericMethod(resultType),

Expression.Constant(querySource));

}

private readonly QuerySourceScope _parentScope;

private readonly IQuerySource _querySource;

protected QuerySourceScope(IQuerySource querySource, QuerySourceScope parentScope)

{

_querySource = querySource;

_parentScope = parentScope;

}

[UsedImplicitly]

private static QuerySourceScope<TResult> Create<TResult>(

IQuerySource querySource, TResult result, QuerySourceScope parentScope)

{

return new QuerySourceScope<TResult>(querySource, result, parentScope);

}

[UsedImplicitly]

private TResult GetResult<TResult>(IQuerySource querySource)

{

return _querySource == querySource

? ((QuerySourceScope<TResult>)this)._result

: _parentScope.GetResult<TResult>(querySource);

}

}

}