//---------------------------------------------------------------------
// <copyright file="Perspective.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner       Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System.Diagnostics;
using System.Linq;

namespace System.Data.Metadata.Edm
{
    using System.Collections.Generic;

    /// <summary>
    /// Internal helper class for query
    /// </summary>
    internal abstract class Perspective
    {
        #region Constructors
        /// <summary>
        /// Creates a new instance of perspective class so that query can work
        /// ignorant of all spaces
        /// </summary>
        /// <param name="metadataWorkspace">runtime metadata container</param>
        /// <param name="targetDataspace">target dataspace for the perspective</param>
        internal Perspective(MetadataWorkspace metadataWorkspace,
                             DataSpace targetDataspace)
        {
            EntityUtil.CheckArgumentNull(metadataWorkspace, "metadataWorkspace");

            m_metadataWorkspace = metadataWorkspace;
            m_targetDataspace = targetDataspace;
        }
        #endregion

        #region Fields
        private MetadataWorkspace m_metadataWorkspace;
        private DataSpace m_targetDataspace;
        #endregion

        #region Methods

        /// <summary>
        /// Given the type in the target space and the member name in the source space,
        /// get the corresponding member in the target space
        /// For e.g.  consider a Conceptual Type 'Foo' with a member 'Bar' and a CLR type
        /// 'XFoo' with a member 'YBar'. If one has a reference to Foo one can
        /// invoke GetMember(Foo,"YBar") to retrieve the member metadata for bar
        /// </summary>
        /// <param name="type">The type in the target perspective</param>
        /// <param name="memberName">the name of the member in the source perspective</param>
        /// <param name="ignoreCase">Whether to do case-sensitive member look up or not</param>
        /// <param name="outMember">returns the member in target space, if a match is found</param>
        internal virtual bool TryGetMember(StructuralType type, String memberName, bool ignoreCase, out EdmMember outMember)
        {
            EntityUtil.CheckArgumentNull(type, "type");
            EntityUtil.CheckStringArgument(memberName, "memberName");
            outMember = null;
            return type.Members.TryGetValue(memberName, ignoreCase, out outMember);
        }
        internal bool TryGetEnumMember(EnumType type, String memberName, bool ignoreCase, out EnumMember outMember)
        {
            EntityUtil.CheckArgumentNull(type, "type");
            EntityUtil.CheckStringArgument(memberName, "memberName");
            outMember = null;
            return type.Members.TryGetValue(memberName, ignoreCase, out outMember);
        }

        /// <summary>
        /// Returns the extent in the target space, for the given entity container.
        /// </summary>
        /// <param name="entityContainer">name of the entity container in target space</param>
        /// <param name="extentName">name of the extent</param>
        /// <param name="ignoreCase">Whether to do case-sensitive member look up or not</param>
        /// <param name="outSet">extent in target space, if a match is found</param>
        /// <returns>returns true, if a match is found otherwise returns false</returns>
        internal bool TryGetExtent(EntityContainer entityContainer, String extentName, bool ignoreCase, out EntitySetBase outSet)
        {
            // There are no entity containers in the OSpace. So there is no mapping involved.
            // Hence the name should be a valid name in the CSpace.
            return entityContainer.BaseEntitySets.TryGetValue(extentName, ignoreCase, out outSet);
        }

        /// <summary>
        /// Returns the function import in the target space, for the given entity container.
        /// </summary>
        internal bool TryGetFunctionImport(EntityContainer entityContainer, String functionImportName, bool ignoreCase, out EdmFunction functionImport)
        {
            // There are no entity containers in the OSpace. So there is no mapping involved.
            // Hence the name should be a valid name in the CSpace.
            functionImport = null;
            if (ignoreCase)
            {
                functionImport = entityContainer.FunctionImports.Where(fi => String.Equals(fi.Name, functionImportName, StringComparison.OrdinalIgnoreCase)).SingleOrDefault();
            }
            else
            {
                functionImport = entityContainer.FunctionImports.Where(fi => fi.Name == functionImportName).SingleOrDefault();
            }
            return functionImport != null;
        }

        /// <summary>
        /// Get the default entity container
        /// returns null for any perspective other 
        /// than the CLR perspective
        /// </summary>
        /// <returns>The default container</returns>
        internal virtual EntityContainer GetDefaultContainer()
        {
            return null;
        }

        /// <summary>
        /// Get an entity container based upon the strong name of the container
        /// If no entity container is found, returns null, else returns the first one/// </summary>
        /// <param name="name">name of the entity container</param>
        /// <param name="ignoreCase">true for case-insensitive lookup</param>
        /// <param name="entityContainer">returns the entity container if a match is found</param>
        /// <returns>returns true if a match is found, otherwise false</returns>
        internal virtual bool TryGetEntityContainer(string name, bool ignoreCase, out EntityContainer entityContainer)
        {
            return MetadataWorkspace.TryGetEntityContainer(name, ignoreCase, TargetDataspace, out entityContainer);
        }

        /// <summary>
        /// Gets a type with the given name in the target space.
        /// </summary>
        /// <param name="fullName">full name of the type</param>
        /// <param name="ignoreCase">true for case-insensitive lookup</param>
        /// <param name="typeUsage">TypeUsage for the type</param>
        /// <returns>returns true if a match was found, otherwise false</returns>
        internal abstract bool TryGetTypeByName(string fullName, bool ignoreCase, out TypeUsage typeUsage);

        /// <summary>
        /// Returns overloads of a function with the given name in the target space.
        /// </summary>
        /// <param name="namespaceName">namespace of the function</param>
        /// <param name="functionName">name of the function</param>
        /// <param name="ignoreCase">true for case-insensitive lookup</param>
        /// <param name="functionOverloads">function overloads</param>
        /// <returns>returns true if a match was found, otherwise false</returns>
        internal bool TryGetFunctionByName(string namespaceName, string functionName, bool ignoreCase, out IList<EdmFunction> functionOverloads)
        {
            EntityUtil.CheckStringArgument(namespaceName, "namespaceName");
            EntityUtil.CheckStringArgument(functionName, "functionName");

            var fullName = namespaceName + "." + functionName;

            // First look for a model-defined function in the target space.
            ItemCollection itemCollection = m_metadataWorkspace.GetItemCollection(m_targetDataspace);
            IList<EdmFunction> overloads =
                m_targetDataspace == DataSpace.SSpace ?
                ((StoreItemCollection)itemCollection).GetCTypeFunctions(fullName, ignoreCase) :
                itemCollection.GetFunctions(fullName, ignoreCase);

            if (m_targetDataspace == DataSpace.CSpace)
            {
                // Then look for a function import.
                if (overloads == null || overloads.Count == 0)
                {
                    EntityContainer entityContainer;
                    if (this.TryGetEntityContainer(namespaceName, /*ignoreCase:*/ false, out entityContainer))
                    {
                        EdmFunction functionImport;
                        if (this.TryGetFunctionImport(entityContainer, functionName, /*ignoreCase:*/ false, out functionImport))
                        {
                            overloads = new EdmFunction[] { functionImport };
                        }
                    }
                }

                // Last, look in SSpace.
                if (overloads == null || overloads.Count == 0)
                {
                    ItemCollection storeItemCollection;
                    if (m_metadataWorkspace.TryGetItemCollection(DataSpace.SSpace, out storeItemCollection))
                    {
                        overloads = ((StoreItemCollection)storeItemCollection).GetCTypeFunctions(fullName, ignoreCase);
                    }
                }
            }

            functionOverloads = (overloads != null && overloads.Count > 0) ? overloads : null;
            return functionOverloads != null;
        }

        /// <summary>
        /// Return the metadata workspace
        /// </summary>
        internal MetadataWorkspace MetadataWorkspace
        {
            get
            {
                return m_metadataWorkspace;
            }
        }

        /// <summary>
        /// returns the primitive type for a given primitive type kind.
        /// </summary>
        /// <param name="primitiveTypeKind"></param>
        /// <param name="primitiveType"></param>
        /// <returns></returns>
        internal virtual bool TryGetMappedPrimitiveType(PrimitiveTypeKind primitiveTypeKind, out PrimitiveType primitiveType)
        {
            primitiveType = m_metadataWorkspace.GetMappedPrimitiveType(primitiveTypeKind, DataSpace.CSpace);

            return (null != primitiveType);
        }

        //
        // This property will be needed to construct keys for transient types
        //
        /// <summary>
        /// Returns the target dataspace for this perspective
        /// </summary>
        internal DataSpace TargetDataspace
        {
            get
            {
                return m_targetDataspace;
            }
        }
        #endregion
    }
}