//---------------------------------------------------------------------
// <copyright file="ObjectItemCollection.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner       Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------

using System.Collections.Generic;
// Using an alias for this because a lot of names in this namespace conflicts with names in metadata
using System.Data.Entity;
using System.Diagnostics;
using System.Reflection;

namespace System.Data.Metadata.Edm
{
    /// <summary>
    /// Class for representing a collection of items for the object layer.
    /// Most of the implemetation for actual maintainance of the collection is
    /// done by ItemCollection
    /// </summary>
    [CLSCompliant(false)]
    public sealed partial class ObjectItemCollection : ItemCollection
    {
        #region Constructors

        /// <summary>
        /// The ObjectItemCollection that loads metadata from assemblies
        /// </summary>
        public ObjectItemCollection()
            : base(DataSpace.OSpace)
        {
            foreach (PrimitiveType type in ClrProviderManifest.Instance.GetStoreTypes())
            {
                AddInternal(type);
                _primitiveTypeMaps.Add(type);
            }
        }
        #endregion

        #region Fields

        // Cache for primitive type maps for Edm to provider
        private readonly CacheForPrimitiveTypes _primitiveTypeMaps = new CacheForPrimitiveTypes();

        // Used for tracking the loading of an assembly and its referenced assemblies. Though the value of an entry is bool, the logic represented
        // by an entry is tri-state, the third state represented by a "missing" entry. To summarize:
        // 1. The <value> associated with an <entry> is "true"  : Specified and all referenced assemblies have been loaded 
        // 2. The <value> associated with an <entry> is "false" : Specified assembly loaded. Its referenced assemblies may not be loaded
        // 3. The <entry> is missing                            : Specified assembly has not been loaded
        private KnownAssembliesSet _knownAssemblies = new KnownAssembliesSet();

        // Dictionary which keeps tracks of oc mapping information - the key is the conceptual name of the type
        // and the value is the reference to the ospace type
        private Dictionary<string, EdmType> _ocMapping = new Dictionary<string, EdmType>();

        private object _loaderCookie;
        private object _loadAssemblyLock = new object();

        internal object LoadAssemblyLock
        {
            get
            {
                return _loadAssemblyLock;
            }
        }

        internal static IList<Assembly> ViewGenerationAssemblies
        {
            get
            {
                return AssemblyCache.ViewGenerationAssemblies;
            }
        }

        #endregion

        #region Methods


        internal static bool IsCompiledViewGenAttributePresent(Assembly assembly)
        {
            return assembly.IsDefined(typeof(System.Data.Mapping.EntityViewGenerationAttribute), false /*inherit*/);
        }

        /// <summary>
        /// The method loads the O-space metadata for all the referenced assemblies starting from the given assembly 
        /// in a recursive way.
        /// The assembly should be from Assembly.GetCallingAssembly via one of our public API's.
        /// </summary>
        /// <param name="assembly">assembly whose dependency list we are going to traverse</param>
        internal void ImplicitLoadAllReferencedAssemblies(Assembly assembly, EdmItemCollection edmItemCollection)
        {
            if (!MetadataAssemblyHelper.ShouldFilterAssembly(assembly))
            {
                bool loadAllReferencedAssemblies = true;
                LoadAssemblyFromCache(this, assembly, loadAllReferencedAssemblies, edmItemCollection, null);
            }
        }

        internal void ImplicitLoadViewsFromAllReferencedAssemblies(Assembly assembly)
        {
            // we filter implicit loads
            if (MetadataAssemblyHelper.ShouldFilterAssembly(assembly))
            {
                return;
            }
            lock (this)
            {
                CollectIfViewGenAssembly(assembly);

                foreach (Assembly referenceAssembly in MetadataAssemblyHelper.GetNonSystemReferencedAssemblies(assembly))
                {
                    CollectIfViewGenAssembly(referenceAssembly);
                }
            }
        }

        /// <summary>
        /// Load metadata from the given assembly
        /// </summary>
        /// <param name="assembly">The assembly from which to load metadata</param>
        /// <exception cref="System.ArgumentNullException">thrown if assembly argument is null</exception>
        public void LoadFromAssembly(Assembly assembly)
        {
            ExplicitLoadFromAssembly(assembly, null, null);
        }

        /// <summary>
        /// Load metadata from the given assembly
        /// </summary>
        /// <param name="assembly">The assembly from which to load metadata</param>
        /// <exception cref="System.ArgumentNullException">thrown if assembly argument is null</exception>
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "edm")]
        public void LoadFromAssembly(Assembly assembly, EdmItemCollection edmItemCollection, Action<String> logLoadMessage)
        {
            EntityUtil.CheckArgumentNull(assembly, "assembly");
            EntityUtil.CheckArgumentNull(edmItemCollection, "edmItemCollection");
            EntityUtil.CheckArgumentNull(logLoadMessage, "logLoadMessage");

            ExplicitLoadFromAssembly(assembly, edmItemCollection, logLoadMessage);
        }

        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "edm")]
        public void LoadFromAssembly(Assembly assembly, EdmItemCollection edmItemCollection)
        {
            EntityUtil.CheckArgumentNull(assembly, "assembly");
            EntityUtil.CheckArgumentNull(edmItemCollection, "edmItemCollection");

            ExplicitLoadFromAssembly(assembly, edmItemCollection, null);
        }
        /// <summary>
        /// Explicit loading means that the user specifically asked us to load this assembly.
        /// We won't do any filtering, they "know what they are doing"
        /// </summary>
        internal void ExplicitLoadFromAssembly(Assembly assembly, EdmItemCollection edmItemCollection, Action<String> logLoadMessage)
        {
            LoadAssemblyFromCache(this, assembly, false /*loadAllReferencedAssemblies*/, edmItemCollection, logLoadMessage);
            //Since User called LoadFromAssembly, so we should collect the generated views if present
            //even if the schema attribute is not present
            if (IsCompiledViewGenAttributePresent(assembly) && !ObjectItemAttributeAssemblyLoader.IsSchemaAttributePresent(assembly))
            {
                CollectIfViewGenAssembly(assembly);
            }
        }

        /// <summary>
        /// Implicit loading means that we are trying to help the user find the right 
        /// assembly, but they didn't explicitly ask for it. Our Implicit rules require that
        /// we filter out assemblies with the Ecma or MicrosoftPublic PublicKeyToken on them
        /// </summary>
        internal void ImplicitLoadFromAssembly(Assembly assembly, EdmItemCollection edmItemCollection)
        {
            if (!MetadataAssemblyHelper.ShouldFilterAssembly(assembly))
            {
                // it meets the Implicit rules Load it
                ExplicitLoadFromAssembly(assembly, edmItemCollection, null);
            }
        }
        
        /// <summary>
        /// Implicit loading means that we are trying to help the user find the right 
        /// assembly, but they didn't explicitly ask for it. Our Implicit rules require that
        /// we filter out assemblies with the Ecma or MicrosoftPublic PublicKeyToken on them
        /// 
        /// Load metadata from the type's assembly.
        /// </summary>
        /// <param name="type">The type's assembly is loaded into the OSpace ItemCollection</param>
        /// <returns>true if the type and all its generic arguments are filtered out (did not attempt to load assembly)</returns>
        internal bool ImplicitLoadAssemblyForType(Type type, EdmItemCollection edmItemCollection)
        {
            bool result;

            if (!MetadataAssemblyHelper.ShouldFilterAssembly(type.Assembly))
            {
                // InternalLoadFromAssembly will check _knownAssemblies
                result = LoadAssemblyFromCache(this, type.Assembly, false /*loadAllReferencedAssemblies*/, edmItemCollection, null);
            }
            else
            {
                result = false;
            }

            if (type.IsGenericType)
            {
                // recursively load all generic types
                // interesting code paths are ObjectQuery<Nullable<Int32>>, ObjectQuery<IEnumerable<Product>>
                foreach (Type t in type.GetGenericArguments())
                {
                    result |= ImplicitLoadAssemblyForType(t, edmItemCollection);
                }
            }
            return result;
        }

        /// <summary>
        /// internal static method to get the relationship name
        /// </summary>
        /// <param name="clrType"></param>
        /// <param name="relationshipName"></param>
        /// <returns></returns>
        internal AssociationType GetRelationshipType(Type entityClrType, string relationshipName)
        {
            AssociationType associationType;
            if (TryGetItem<AssociationType>(relationshipName, out associationType))
            {
                return associationType;
            }
            return null;
        }

        /// <summary>
        /// Loads the OSpace types in the assembly and returns them as a dictionary
        /// </summary>
        /// <param name="assembly">The assembly to load</param>
        /// <returns>A mapping from names to OSpace EdmTypes</returns>
        internal static Dictionary<string, EdmType> LoadTypesExpensiveWay(Assembly assembly)
        {
            Dictionary<string, EdmType> typesInLoading = null;
                
            List<EdmItemError> errors;
            KnownAssembliesSet knownAssemblies = new KnownAssembliesSet();

            AssemblyCache.LoadAssembly(assembly, false /*loadAllReferencedAssemblies*/,
                knownAssemblies, out typesInLoading, out errors);

            // Check for errors
            if (errors.Count != 0)
            {
                throw EntityUtil.InvalidSchemaEncountered(Helper.CombineErrorMessage(errors));
            }

            return typesInLoading;
        }

        /// <summary>
        /// internal static method to get the relationship name
        /// </summary>
        /// <param name="clrType"></param>
        /// <param name="relationshipName"></param>
        /// <returns></returns>
        internal static AssociationType GetRelationshipTypeExpensiveWay(Type entityClrType, string relationshipName)
        {
            Dictionary<string, EdmType> typesInLoading = LoadTypesExpensiveWay(entityClrType.Assembly);
            if (typesInLoading != null)
            {
                EdmType edmType;
                // Look in typesInLoading for relationship type
                if (typesInLoading.TryGetValue(relationshipName, out edmType) && Helper.IsRelationshipType(edmType))
                {
                    return (AssociationType)edmType;
                }
            }
            return null;
        }

        /// <summary>
        /// internal static method to get all the AssociationTypes from an assembly 
        /// </summary>
        /// <param name="assembly">The assembly from which to load relationship types</param>
        /// <returns>An enumeration of OSpace AssociationTypes that are present in this assembly</returns>
        internal static IEnumerable<AssociationType> GetAllRelationshipTypesExpensiveWay(Assembly assembly)
        {
            Dictionary<string, EdmType> typesInLoading = LoadTypesExpensiveWay(assembly);
            if (typesInLoading != null)
            {
                // Iterate through the EdmTypes looking for AssociationTypes
                foreach (EdmType edmType in typesInLoading.Values)
                {
                    if (Helper.IsAssociationType(edmType))
                    {
                        yield return (AssociationType)edmType;
                    }
                }
            }
            yield break;
        }
        
        private static bool LoadAssemblyFromCache(ObjectItemCollection objectItemCollection, Assembly assembly,
            bool loadReferencedAssemblies, EdmItemCollection edmItemCollection, Action<String> logLoadMessage)
        {
            // Check if its loaded in the cache - if the call is for loading referenced assemblies, make sure that all referenced
            // assemblies are also loaded
            KnownAssemblyEntry entry;
            if (objectItemCollection._knownAssemblies.TryGetKnownAssembly(assembly, objectItemCollection._loaderCookie, edmItemCollection, out entry))
            {
                // Proceed if only we need to load the referenced assemblies and they are not loaded
                if (loadReferencedAssemblies == false)
                {
                    // don't say we loaded anything, unless we actually did before
                    return entry.CacheEntry.TypesInAssembly.Count != 0;
                }
                else if (entry.ReferencedAssembliesAreLoaded == true)
                {
                    // this assembly was part of a all hands reference search
                    return true;
                }
            }

            lock (objectItemCollection.LoadAssemblyLock)
            {
                // Check after acquiring the lock, since the known assemblies might have got modified
                // Check if the assembly is already loaded. The reason we need to check if the assembly is already loaded, is that 
                if (objectItemCollection._knownAssemblies.TryGetKnownAssembly(assembly, objectItemCollection._loaderCookie, edmItemCollection, out entry))
                {
                    // Proceed if only we need to load the referenced assemblies and they are not loaded
                    if (loadReferencedAssemblies == false || entry.ReferencedAssembliesAreLoaded == true)
                    {
                        return true;
                    }
                }

                Dictionary<string, EdmType> typesInLoading;
                List<EdmItemError> errors;
                KnownAssembliesSet knownAssemblies;

                if (objectItemCollection != null)
                {
                    knownAssemblies = new KnownAssembliesSet(objectItemCollection._knownAssemblies);
                }
                else
                {
                    knownAssemblies = new KnownAssembliesSet();
                }

                // Load the assembly from the cache
                AssemblyCache.LoadAssembly(assembly, loadReferencedAssemblies, knownAssemblies, edmItemCollection, logLoadMessage, ref objectItemCollection._loaderCookie, out typesInLoading, out errors);

                // Throw if we have encountered errors
                if (errors.Count != 0)
                {
                    throw EntityUtil.InvalidSchemaEncountered(Helper.CombineErrorMessage(errors));
                }

                // We can encounter new assemblies, but they may not have any time in them
                if (typesInLoading.Count != 0)
                {
                    // No errors, so go ahead and add the types and make them readonly
                    // The existence of the loading lock tells us whether we should be thread safe or not, if we need
                    // to be thread safe, then we need to use AtomicAddRange. We don't need to actually use the lock
                    // because the caller should have done it already
                    // Recheck the assemblies added, another list is created just to match up the collection type
                    // taken in by AtomicAddRange()
                    List<GlobalItem> globalItems = new List<GlobalItem>();
                    foreach (EdmType edmType in typesInLoading.Values)
                    {
                        globalItems.Add(edmType);

                        string cspaceTypeName = "";
                        try
                        {
                            // Also populate the ocmapping information
                            if (Helper.IsEntityType(edmType))
                            {
                                cspaceTypeName = ((ClrEntityType)edmType).CSpaceTypeName;
                                objectItemCollection._ocMapping.Add(cspaceTypeName, edmType);
                            }
                            else if (Helper.IsComplexType(edmType))
                            {
                                cspaceTypeName = ((ClrComplexType)edmType).CSpaceTypeName;
                                objectItemCollection._ocMapping.Add(cspaceTypeName, edmType);
                            }
                            else if (Helper.IsEnumType(edmType))
                            {
                                cspaceTypeName = ((ClrEnumType)edmType).CSpaceTypeName;
                                objectItemCollection._ocMapping.Add(cspaceTypeName, edmType);
                            }
                            // for the rest of the types like a relationship type, we do not have oc mapping, 
                            // so we don't keep that information
                        }
                        catch (ArgumentException e)
                        {
                            throw new MappingException(Strings.Mapping_CannotMapCLRTypeMultipleTimes(cspaceTypeName), e);
                        }
                    }

                    // Create a new ObjectItemCollection and add all the global items to it. 
                    // Also copy all the existing items from the existing collection
                    objectItemCollection.AtomicAddRange(globalItems);
                }
                
                
                // Update the value of known assemblies
                objectItemCollection._knownAssemblies = knownAssemblies;

                foreach (Assembly loadedAssembly in knownAssemblies.Assemblies)
                {
                    CollectIfViewGenAssembly(loadedAssembly);
                }

                return typesInLoading.Count != 0;
            }
        }

        /// <summary>
        /// Check to see if the assembly has the custom view generation attribute AND
        /// collect the assembly into the local list if it has cutom attribute.
        /// </summary>
        /// <param name="assembly"></param>
        /// <param name="viewGenAssemblies"></param>
        private static void CollectIfViewGenAssembly(Assembly assembly) 
        {
            if (assembly.IsDefined(typeof(System.Data.Mapping.EntityViewGenerationAttribute), false /*inherit*/))
            {
                if (!AssemblyCache.ViewGenerationAssemblies.Contains(assembly))
                {
                    AssemblyCache.ViewGenerationAssemblies.Add(assembly);
                }
            }
        }

        /// <summary>
        /// Get the list of primitive types for the given space
        /// </summary>
        /// <returns></returns> 
        public IEnumerable<PrimitiveType> GetPrimitiveTypes()
        {
            return _primitiveTypeMaps.GetTypes();
        }

        /// <summary>
        /// The method returns the underlying CLR type for the specified OSpace type argument.
        /// If the DataSpace of the parameter is not OSpace, an ArgumentException is thrown.
        /// </summary>
        /// <param name="objectSpaceType">The OSpace type to look up</param>
        /// <returns>The CLR type of the OSpace argument</returns>
        public Type GetClrType(StructuralType objectSpaceType)
        {
            return ObjectItemCollection.GetClrType((EdmType)objectSpaceType);
        }

        /// <summary>
        /// The method returns the underlying CLR type for the specified OSpace type argument.
        /// If the DataSpace of the parameter is not OSpace, the method returns false and sets
        /// the out parameter to null.
        /// </summary>
        /// <param name="objectSpaceType">The OSpace type to look up</param>
        /// <param name="clrType">The CLR type of the OSpace argument</param>
        /// <returns>true on success, false on failure</returns>
        public bool TryGetClrType(StructuralType objectSpaceType, out Type clrType)
        {
            return ObjectItemCollection.TryGetClrType((EdmType)objectSpaceType, out clrType);
        }

        /// <summary>
        /// The method returns the underlying CLR type for the specified OSpace type argument.
        /// If the DataSpace of the parameter is not OSpace, an ArgumentException is thrown.
        /// </summary>
        /// <param name="objectSpaceType">The OSpace type to look up</param>
        /// <returns>The CLR type of the OSpace argument</returns>
        public Type GetClrType(EnumType objectSpaceType)
        {
            return ObjectItemCollection.GetClrType((EdmType)objectSpaceType);
        }

        /// <summary>
        /// The method returns the underlying CLR type for the specified OSpace enum type argument.
        /// If the DataSpace of the parameter is not OSpace, the method returns false and sets
        /// the out parameter to null.
        /// </summary>
        /// <param name="objectSpaceType">The OSpace enum type to look up</param>
        /// <param name="clrType">The CLR enum type of the OSpace argument</param>
        /// <returns>true on success, false on failure</returns>
        public bool TryGetClrType(EnumType objectSpaceType, out Type clrType)
        {
            return ObjectItemCollection.TryGetClrType((EdmType)objectSpaceType, out clrType);
        }

        /// <summary>
        /// A helper method returning the underlying CLR type for the specified OSpace Enum or Structural type argument.
        /// If the DataSpace of the parameter is not OSpace, an ArgumentException is thrown.
        /// </summary>
        /// <param name="objectSpaceType">The OSpace type to look up</param>
        /// <returns>The CLR type of the OSpace argument</returns>
        private static Type GetClrType(EdmType objectSpaceType)
        {
            Debug.Assert(objectSpaceType == null || objectSpaceType is StructuralType || objectSpaceType is EnumType,
                "Only enum or structural type expected");

            Type clrType;
            if (!ObjectItemCollection.TryGetClrType(objectSpaceType, out clrType))
            {
                throw EntityUtil.Argument(Strings.FailedToFindClrTypeMapping(objectSpaceType.Identity));
            }

            return clrType;
        }

        /// <summary>
        /// A helper method returning the underlying CLR type for the specified OSpace enum or structural type argument.
        /// If the DataSpace of the parameter is not OSpace, the method returns false and sets
        /// the out parameter to null.
        /// </summary>
        /// <param name="objectSpaceType">The OSpace enum type to look up</param>
        /// <param name="clrType">The CLR enum type of the OSpace argument</param>
        /// <returns>true on success, false on failure</returns>
        private static bool TryGetClrType(EdmType objectSpaceType, out Type clrType)
        {
            Debug.Assert(objectSpaceType == null || objectSpaceType is StructuralType || objectSpaceType is EnumType, 
                "Only enum or structural type expected");

            EntityUtil.CheckArgumentNull(objectSpaceType, "objectSpaceType");

            if (objectSpaceType.DataSpace != DataSpace.OSpace)
            {
                throw EntityUtil.Argument(Strings.ArgumentMustBeOSpaceType, "objectSpaceType");
            }

            clrType = null;

            if (Helper.IsEntityType(objectSpaceType) || Helper.IsComplexType(objectSpaceType) || Helper.IsEnumType(objectSpaceType))
            {
                Debug.Assert(objectSpaceType is ClrEntityType || objectSpaceType is ClrComplexType || objectSpaceType is ClrEnumType,
                    "Unexpected OSpace object type.");

                clrType = objectSpaceType.ClrType;

                Debug.Assert(clrType != null, "ClrType property of ClrEntityType/ClrComplexType/ClrEnumType objects must not be null");
            }

            return clrType != null;
        }

        /// <summary>
        /// Given the canonical primitive type, get the mapping primitive type in the given dataspace
        /// </summary>
        /// <param name="modelType">canonical primitive type</param>
        /// <returns>The mapped scalar type</returns>
        internal override PrimitiveType GetMappedPrimitiveType(PrimitiveTypeKind modelType)
        {
            if (Helper.IsGeometricTypeKind(modelType))
            {
                modelType = PrimitiveTypeKind.Geometry;
            }
            else if (Helper.IsGeographicTypeKind(modelType))
            {
                modelType = PrimitiveTypeKind.Geography;
            }

            PrimitiveType type = null;
            _primitiveTypeMaps.TryGetType(modelType, null, out type);
            return type;
        }

        /// <summary>
        /// Get the OSpace type given the CSpace typename
        /// </summary>
        /// <param name="cspaceTypeName"></param>
        /// <param name="ignoreCase"></param>
        /// <param name="edmType"></param>
        /// <returns></returns>
        internal bool TryGetOSpaceType(EdmType cspaceType, out EdmType edmType)
        {
            Debug.Assert(DataSpace.CSpace == cspaceType.DataSpace, "DataSpace should be CSpace");

            // check if there is an entity, complex type or enum type mapping with this name
            if (Helper.IsEntityType(cspaceType) || Helper.IsComplexType(cspaceType) || Helper.IsEnumType(cspaceType))
            {
                return _ocMapping.TryGetValue(cspaceType.Identity, out edmType);
            }

            return TryGetItem<EdmType>(cspaceType.Identity, out edmType);
        }

        /// <summary>
        /// Given the ospace type, returns the fullname of the mapped cspace type.
        /// Today, since we allow non-default mapping between entity type and complex type,
        /// this is only possible for entity and complex type.
        /// </summary>
        /// <param name="edmType"></param>
        /// <returns></returns>
        internal static string TryGetMappingCSpaceTypeIdentity(EdmType edmType)
        {
            Debug.Assert(DataSpace.OSpace == edmType.DataSpace, "DataSpace must be OSpace");

            if (Helper.IsEntityType(edmType))
            {
                return ((ClrEntityType)edmType).CSpaceTypeName;
            }
            else if (Helper.IsComplexType(edmType))
            {
                return ((ClrComplexType)edmType).CSpaceTypeName;
            }
            else if (Helper.IsEnumType(edmType))
            {
                return ((ClrEnumType)edmType).CSpaceTypeName;
            }

            return edmType.Identity;
        }

        public override System.Collections.ObjectModel.ReadOnlyCollection<T> GetItems<T>()
        {
            return base.InternalGetItems(typeof(T)) as System.Collections.ObjectModel.ReadOnlyCollection<T>;
        }
        #endregion
    }
}