using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Linq;
using System.Diagnostics.CodeAnalysis;

namespace System.Data.Linq.Mapping {
    /// <summary>
    /// A MetaModel is an abstraction representing the mapping between a database and domain objects
    /// </summary>
    public abstract class MetaModel {
        /// <summary>
        ///  The mapping source that originated this model.
        /// </summary>
        public abstract MappingSource MappingSource { get; }
        /// <summary>
        /// The type of DataContext type this model describes.
        /// </summary>
        public abstract Type ContextType { get; }
        /// <summary>
        /// The name of the database.
        /// </summary>
        public abstract string DatabaseName { get; }
        /// <summary>
        /// The CLR type that implements IProvider to use as a provider.
        /// </summary>
        public abstract Type ProviderType { get; }
        /// <summary>
        /// Gets the MetaTable associated with a given type.
        /// </summary>
        /// <param name="rowType">The CLR row type.</param>
        /// <returns>The MetaTable if one exists, otherwise null.</returns>
        public abstract MetaTable GetTable(Type rowType);
        /// <summary>
        /// Gets the MetaFunction corresponding to a database function: user-defined function, table-valued function or stored-procedure.
        /// </summary>
        /// <param name="method">The method defined on the DataContext or subordinate class that represents the database function.</param>
        /// <returns>The MetaFunction if one exists, otherwise null.</returns>
        public abstract MetaFunction GetFunction(MethodInfo method);
        /// <summary>
        /// Get an enumeration of all tables.
        /// </summary>
        /// <returns>An enumeration of all the MetaTables</returns>
        [SuppressMessage("Microsoft.Design", "CA1024:UsePropertiesWhereAppropriate", Justification="Non-trivial operations are not suitable for properties.")]
        public abstract IEnumerable<MetaTable> GetTables();
        /// <summary>
        /// Get an enumeration of all functions.
        /// </summary>
        /// <returns>An enumeration of all the MetaFunctions</returns>
        [SuppressMessage("Microsoft.Design", "CA1024:UsePropertiesWhereAppropriate", Justification="Non-trivial operations are not suitable for properties.")]
        public abstract IEnumerable<MetaFunction> GetFunctions();
        /// <summary>
        /// This method discovers the MetaType for the given Type.
        /// </summary>
        public abstract MetaType GetMetaType(Type type);
        /// <summary>
        /// Internal value used to determine a reference identity for comparing meta models
        /// without needing to keep track of the actual meta model reference.
        /// </summary>
        private object identity = new object();
        internal object Identity {
            get { return this.identity; }
        }
    }

    /// <summary>
    /// A MetaTable represents an abstraction of a database table (or view)
    /// </summary>
    public abstract class MetaTable {
        /// <summary>
        /// The MetaModel containing this MetaTable.
        /// </summary>
        public abstract MetaModel Model { get; }
        /// <summary>
        /// The name of the table as defined by the database.
        /// </summary>
        public abstract string TableName { get; }
        /// <summary>
        /// The MetaType describing the type of the rows of the table.
        /// </summary>
        public abstract MetaType RowType { get; }
        /// <summary>
        /// The DataContext method used to perform insert operations
        /// </summary>
        public abstract MethodInfo InsertMethod { get; }
        /// <summary>
        /// The DataContext method used to perform update operations
        /// </summary>
        public abstract MethodInfo UpdateMethod { get; }
        /// <summary>
        /// The DataContext method used to perform delete operations
        /// </summary>
        public abstract MethodInfo DeleteMethod { get; }
    }

    /// <summary>
    /// A MetaType represents the mapping of a domain object type onto a database table's columns.
    /// </summary>
    public abstract class MetaType {
        /// <summary>
        /// The MetaModel containing this MetaType.
        /// </summary>
        public abstract MetaModel Model { get; }
        /// <summary>
        /// The MetaTable using this MetaType for row definition.
        /// </summary>
        public abstract MetaTable Table { get; }
        /// <summary>
        /// The underlying CLR type.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1721:PropertyNamesShouldNotMatchGetMethods", Justification = "The contexts in which this is available are fairly specific.")]
        public abstract Type Type { get; }
        /// <summary>
        /// The name of the MetaType (same as the CLR type's name).
        /// </summary>
        public abstract string Name { get; }
        /// <summary>
        /// True if the MetaType is an entity type.
        /// </summary>
        public abstract bool IsEntity { get; }
        /// <summary>
        /// True if the underlying type can be instantiated as the result of a query.
        /// </summary>
        public abstract bool CanInstantiate { get; }
        /// <summary>
        /// The member that represents the auto-generated identity column, or null if there is none.
        /// </summary>
        public abstract MetaDataMember DBGeneratedIdentityMember { get; }
        /// <summary>
        /// The member that represents the row-version or timestamp column, or null if there is none.
        /// </summary>
        public abstract MetaDataMember VersionMember { get; }
        /// <summary>
        /// The member that represents the inheritance discriminator column, or null if there is none.
        /// </summary>
        public abstract MetaDataMember Discriminator { get; }
        /// <summary>
        /// True if the type has any persistent member with an UpdateCheck policy other than Never.
        /// </summary>
        public abstract bool HasUpdateCheck { get; }
        /// <summary>
        /// True if the type is part of a mapped inheritance hierarchy.
        /// </summary>
        public abstract bool HasInheritance { get; }
        /// <summary>
        /// True if this type defines an inheritance code.
        /// </summary>
        public abstract bool HasInheritanceCode { get; }
        /// <summary>
        /// The inheritance code defined by this type.
        /// </summary>
        public abstract object InheritanceCode { get; }
        /// <summary>
        /// True if this type is used as the default of an inheritance hierarchy.
        /// </summary>
        public abstract bool IsInheritanceDefault { get; }
        /// <summary>
        /// The root type of the inheritance hierarchy.
        /// </summary>
        public abstract MetaType InheritanceRoot { get; }
        /// <summary>
        /// The base metatype in the inheritance hierarchy.
        /// </summary>
        public abstract MetaType InheritanceBase { get; }
        /// <summary>
        /// The type that is the default of the inheritance hierarchy.
        /// </summary>
        public abstract MetaType InheritanceDefault { get; }
        /// <summary>
        /// Gets the MetaType for an inheritance sub type.
        /// </summary>
        /// <param name="type">The root or sub type of the inheritance hierarchy.</param>
        /// <returns>The MetaType.</returns>
        public abstract MetaType GetInheritanceType(Type type);
        /// <summary>
        /// Gets type associated with the specified inheritance code.
        /// </summary>
        /// <param name="code">The inheritance code</param>
        /// <returns>The MetaType.</returns>
        public abstract MetaType GetTypeForInheritanceCode(object code);
        /// <summary>
        /// Gets an enumeration of all types defined by an inheritance hierarchy.
        /// </summary>
        /// <returns>Enumeration of MetaTypes.</returns>
        public abstract ReadOnlyCollection<MetaType> InheritanceTypes { get; }
        /// <summary>
        /// Returns true if the MetaType or any base MetaType has an OnLoaded method.
        /// </summary>
        public abstract bool HasAnyLoadMethod { get; }
        /// <summary>
        /// Returns true if the MetaType or any base MetaType has an OnValidate method.
        /// </summary>
        public abstract bool HasAnyValidateMethod { get; }
        /// <summary>
        /// Gets an enumeration of the immediate derived types in an inheritance hierarchy.
        /// </summary>
        /// <returns>Enumeration of MetaTypes.</returns>
        public abstract ReadOnlyCollection<MetaType> DerivedTypes { get; }
        /// <summary>
        /// Gets an enumeration of all the data members (fields and properties).
        /// </summary>
        public abstract ReadOnlyCollection<MetaDataMember> DataMembers { get; }
        /// <summary>
        /// Gets an enumeration of all the persistent data members (fields and properties mapped into database columns).
        /// </summary>
        public abstract ReadOnlyCollection<MetaDataMember> PersistentDataMembers { get; }
        /// <summary>
        /// Gets an enumeration of all the data members that define up the unique identity of the type.
        /// </summary>
        public abstract ReadOnlyCollection<MetaDataMember> IdentityMembers { get; }
        /// <summary>
        /// Gets an enumeration of all the associations.
        /// </summary>
        public abstract ReadOnlyCollection<MetaAssociation> Associations { get; }
        /// <summary>
        /// Gets the MetaDataMember associated with the specified member.
        /// </summary>
        /// <param name="member">The CLR member.</param>
        /// <returns>The MetaDataMember if there is one, otherwise null.</returns>
        public abstract MetaDataMember GetDataMember(MemberInfo member);
        /// <summary>
        /// The method called when the entity is first loaded.
        /// </summary>
        public abstract MethodInfo OnLoadedMethod { get; }
        /// <summary>
        /// The method called to ensure the entity is in a valid state.
        /// </summary>
        public abstract MethodInfo OnValidateMethod { get; }
    }

    /// <summary>
    /// A MetaDataMember represents the mapping between a domain object's field or property into a database table's column.
    /// </summary>
    [SuppressMessage("Microsoft.Naming", "CA1702:CompoundWordsShouldBeCasedCorrectly", MessageId = "MetaData", Justification = "The capitalization was deliberately chosen.")]
    public abstract class MetaDataMember {
        /// <summary>
        /// The MetaType containing this data member.
        /// </summary>
        public abstract MetaType DeclaringType { get; }
        /// <summary>
        /// The underlying MemberInfo.
        /// </summary>
        public abstract MemberInfo Member { get; }
        /// <summary>
        /// The member that actually stores this member's data.
        /// </summary>
        public abstract MemberInfo StorageMember { get; }
        /// <summary>
        /// The name of the member, same as the MemberInfo name.
        /// </summary>
        public abstract string Name { get; }
        /// <summary>
        /// The name of the column (or constraint) in the database.
        /// </summary>
        public abstract string MappedName { get; }
        /// <summary>
        /// The oridinal position of this member in the default layout of query results.
        /// </summary>
        public abstract int Ordinal { get; }
        /// <summary>
        /// The type of this member.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1721:PropertyNamesShouldNotMatchGetMethods", Justification = "The contexts in which this is available are fairly specific.")]
        public abstract Type Type { get; }
        /// <summary>
        /// True if this member is declared by the specified type.
        /// </summary>
        /// <param name="type">Type to check.</param>
        public abstract bool IsDeclaredBy(MetaType type);
        /// <summary>
        /// The accessor used to get/set the value of this member.
        /// </summary>
        public abstract MetaAccessor MemberAccessor { get; }
        /// <summary>
        /// The accessor used to get/set the storage value of this member.
        /// </summary>
        public abstract MetaAccessor StorageAccessor { get; }
        /// <summary>
        /// The accessor used to get/set the deferred value of this member (without causing fetch).
        /// </summary>
        public abstract MetaAccessor DeferredValueAccessor { get; }
        /// <summary>
        /// The accessor used to get/set the deferred source of this member.
        /// </summary>
        public abstract MetaAccessor DeferredSourceAccessor { get; }
        /// <summary>
        /// True if this member is defer-loaded by default.
        /// </summary>
        public abstract bool IsDeferred { get; }
        /// <summary>
        /// True if this member is mapped to a column (or constraint).
        /// </summary>
        public abstract bool IsPersistent { get; }
        /// <summary>
        /// True if this member defines an association relationship.
        /// </summary>
        public abstract bool IsAssociation { get; }
        /// <summary>
        /// True if this member is part of the type's identity.
        /// </summary>
        public abstract bool IsPrimaryKey { get; }
        /// <summary>
        /// True if this member is automatically generated by the database.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db", Justification = "Conforms to legacy spelling.")]
        public abstract bool IsDbGenerated { get; }
        /// <summary>
        /// True if this member represents the row version or timestamp.
        /// </summary>
        public abstract bool IsVersion { get; }
        /// <summary>
        /// True if this member represents the inheritance discriminator.
        /// </summary>
        public abstract bool IsDiscriminator { get; }
        /// <summary>
        /// True if this member's value can be assigned the null value.
        /// </summary>
        public abstract bool CanBeNull { get; }
        /// <summary>
        /// The type of the database column.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db", Justification = "Conforms to legacy spelling.")]
        public abstract string DbType { get; }
        /// <summary>
        /// Expression defining a computed column.
        /// </summary>
        public abstract string Expression { get; }
        /// <summary>
        /// The optimistic concurrency check policy for this member.
        /// </summary>
        public abstract UpdateCheck UpdateCheck { get; }
        /// <summary>
        /// Specifies for inserts and updates when this member should be read back after the
        /// operation completes.
        /// </summary>
        public abstract AutoSync AutoSync { get; }
        /// <summary>
        /// The MetaAssociation corresponding to this member, or null if there is none.
        /// </summary>
        public abstract MetaAssociation Association { get; }
        /// <summary>
        /// The DataContext method used to perform load operations
        /// </summary>
        public abstract MethodInfo LoadMethod { get; }
    }

    /// <summary>
    /// A MetaFunction represents the mapping between a context method and a database function.
    /// </summary>
    public abstract class MetaFunction {
        /// <summary>
        /// The MetaModel containing this function.
        /// </summary>
        public abstract MetaModel Model { get; }
        /// <summary>
        /// The underlying context method.
        /// </summary>
        public abstract MethodInfo Method { get; }
        /// <summary>
        /// The name of the method (same as the MethodInfo's name).
        /// </summary>
        public abstract string Name { get; }
        /// <summary>
        /// The name of the database function or procedure.
        /// </summary>
        public abstract string MappedName { get; }
        /// <summary>
        /// True if the function can be composed within a query
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Composable", Justification="Spelling is correct.")]
        public abstract bool IsComposable { get; }
        /// <summary>
        /// Gets an enumeration of the function parameters.
        /// </summary>
        /// <returns></returns>
        public abstract ReadOnlyCollection<MetaParameter> Parameters { get; }
        /// <summary>
        /// The return parameter
        /// </summary>
        public abstract MetaParameter ReturnParameter { get; }
        /// <summary>
        /// True if the stored procedure has multiple result types.
        /// </summary>
        public abstract bool HasMultipleResults { get; }
        /// <summary>
        /// An enumeration of all the known result row types of a stored-procedure.
        /// </summary>
        /// <returns>Enumeration of possible result row types.</returns>
        public abstract ReadOnlyCollection<MetaType> ResultRowTypes { get; }
    }

    /// <summary>
    /// A MetaParameter represents the mapping between a method parameter and a database function parameter.
    /// </summary>
    public abstract class MetaParameter {
        /// <summary>
        /// The underlying method parameter.
        /// </summary>
        public abstract ParameterInfo Parameter { get; }
        /// <summary>
        /// The name of the parameter (same as the ParameterInfo's name).
        /// </summary>
        public abstract string Name { get; }
        /// <summary>
        /// The name of the database function's parameter.
        /// </summary>
        public abstract string MappedName { get; }
        /// <summary>
        /// The CLR type of the parameter.
        /// </summary>
        public abstract Type ParameterType { get; }
        /// <summary>
        /// The database type of the parameter.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "Db", Justification = "Conforms to legacy spelling.")]
        public abstract string DbType { get; }
    }

    /// <summary>
    /// A MetaAssociation represents an association relationship between two entity types.
    /// </summary>
    public abstract class MetaAssociation {
        /// <summary>
        /// The type on the other end of the association.
        /// </summary>
        public abstract MetaType OtherType { get; }
        /// <summary>
        /// The member on this side that represents the association.
        /// </summary>
        public abstract MetaDataMember ThisMember { get; }
        /// <summary>
        /// The member on the other side of this association that represents the reverse association (may be null).
        /// </summary>
        public abstract MetaDataMember OtherMember { get; }
        /// <summary>
        /// A list of members representing the values on this side of the association.
        /// </summary>
        public abstract ReadOnlyCollection<MetaDataMember> ThisKey { get; }
        /// <summary>
        /// A list of members representing the values on the other side of the association.
        /// </summary>
        public abstract ReadOnlyCollection<MetaDataMember> OtherKey { get; }
        /// <summary>
        /// True if the association is OneToMany.
        /// </summary>
        public abstract bool IsMany { get; }
        /// <summary>
        /// True if the other type is the parent of this type.
        /// </summary>
        public abstract bool IsForeignKey { get; }
        /// <summary>
        /// True if the association is unique (defines a uniqueness constraint).
        /// </summary>
        public abstract bool IsUnique { get; }
        /// <summary>
        /// True if the association may be null (key values).
        /// </summary>
        public abstract bool IsNullable { get; }
        /// <summary>
        /// True if the ThisKey forms the identity (primary key) of the this type.
        /// </summary>
        public abstract bool ThisKeyIsPrimaryKey { get; }
        /// <summary>
        /// True if the OtherKey forms the identity (primary key) of the other type.
        /// </summary>
        public abstract bool OtherKeyIsPrimaryKey { get; }
        /// <summary>
        /// Specifies the behavior when the child is deleted (e.g. CASCADE, SET NULL).
        /// Returns null if no action is specified on delete.
        /// </summary>
        public abstract string DeleteRule { get; }
        /// <summary>
        /// Specifies whether the object should be deleted when this association
        /// is set to null.
        /// </summary>
        public abstract bool DeleteOnNull { get; }
    }

    /// <summary>
    /// A MetaAccessor
    /// </summary>
    public abstract class MetaAccessor {
        /// <summary>
        /// The type of the member accessed by this accessor.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1721:PropertyNamesShouldNotMatchGetMethods", Justification = "The contexts in which this is available are fairly specific.")]
        public abstract Type Type { get; }
        /// <summary>
        /// Gets the value as an object.
        /// </summary>
        /// <param name="instance">The instance to get the value from.</param>
        /// <returns>Value.</returns>
        public abstract object GetBoxedValue(object instance);
        /// <summary>
        /// Sets the value as an object.
        /// </summary>
        /// <param name="instance">The instance to set the value into.</param>
        /// <param name="value">The value to set.</param>
        [SuppressMessage("Microsoft.Design", "CA1007:UseGenericsWhereAppropriate", Justification="[....]: Needs to handle classes and structs.")]
        [SuppressMessage("Microsoft.Design", "CA1045:DoNotPassTypesByReference", Justification="Unknown reason.")]
        public abstract void SetBoxedValue(ref object instance, object value);
        /// <summary>
        /// True if the instance has a loaded or assigned value.
        /// </summary>
        public virtual bool HasValue(object instance) {
            return true;
        }
        /// <summary>
        /// True if the instance has an assigned value.
        /// </summary>
        public virtual bool HasAssignedValue(object instance) {
            return true;
        }
        /// <summary>
        /// True if the instance has a value loaded from a deferred source.
        /// </summary>
        public virtual bool HasLoadedValue(object instance) {
            return false;
        }
    }

    /// <summary>
    /// A strongly-typed MetaAccessor. Used for reading from and writing to
    /// CLR objects.
    /// </summary>
    /// <typeparam name="T">The type of the object</typeparam>
    /// <typeparam name="V">The type of the accessed member</typeparam>
    public abstract class MetaAccessor<TEntity, TMember> : MetaAccessor {
        /// <summary>
        /// The underlying CLR type.
        /// </summary>
        public override Type Type {
            get { return typeof(TMember); }
        }
        /// <summary>
        /// Set the boxed value on an instance.
        /// </summary>
        public override void SetBoxedValue(ref object instance, object value) {
            TEntity tInst = (TEntity)instance;
            this.SetValue(ref tInst, (TMember)value);
            instance = tInst;
        }
        /// <summary>
        /// Retrieve the boxed value.
        /// </summary>
        public override object GetBoxedValue(object instance) {
            return this.GetValue((TEntity)instance);
        }
        /// <summary>
        /// Gets the strongly-typed value.
        /// </summary>
        public abstract TMember GetValue(TEntity instance);
        /// <summary>
        /// Sets the strongly-typed value
        /// </summary>
        [SuppressMessage("Microsoft.Design", "CA1045:DoNotPassTypesByReference", MessageId = "0#", Justification = "Unknown reason.")]
        public abstract void SetValue(ref TEntity instance, TMember value);
    }
}