//---------------------------------------------------------------------
// <copyright file="ReferentialConstraint.cs" company="Microsoft">
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
//
// @owner       Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
 
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Data.Common;
 
namespace System.Data.Metadata.Edm
{
    /// <summary>
    /// This class describes referential constraint on the relationships
    /// </summary>
    public sealed class ReferentialConstraint : MetadataItem
    {
        #region Constructors
        /// <summary>
        /// Constructs a new constraint on the relationship
        /// </summary>
        /// <param name="fromRole">role from which the relationship originates</param>
        /// <param name="toRole">role to which the relationship is linked/targeted to</param>
        /// <param name="toProperties">properties on entity type of from role which take part in the constraint</param>
        /// <param name="fromProperties">properties on entity type of to role which take part in the constraint</param>
        /// <exception cref="ArgumentNullException">Argument Null exception if any of the arguments is null</exception>
        internal ReferentialConstraint(RelationshipEndMember fromRole,
                                     RelationshipEndMember toRole,
                                     IEnumerable<EdmProperty> fromProperties,
                                     IEnumerable<EdmProperty> toProperties)
        {
            _fromRole = EntityUtil.GenericCheckArgumentNull(fromRole, "fromRole");
            _toRole = EntityUtil.GenericCheckArgumentNull(toRole, "toRole");
            _fromProperties = new ReadOnlyMetadataCollection<EdmProperty>(new MetadataCollection<EdmProperty>(
                EntityUtil.GenericCheckArgumentNull(fromProperties, "fromProperties")));
            _toProperties = new ReadOnlyMetadataCollection<EdmProperty>(new MetadataCollection<EdmProperty>(
                EntityUtil.GenericCheckArgumentNull(toProperties, "toProperties")));
        }
        #endregion
 
        #region Fields
        private RelationshipEndMember _fromRole;
        private RelationshipEndMember _toRole;
        private readonly ReadOnlyMetadataCollection<EdmProperty> _fromProperties;
        private readonly ReadOnlyMetadataCollection<EdmProperty> _toProperties;
        #endregion
 
        #region Properties
        /// <summary>
        /// Returns the kind of the type
        /// </summary>
        public override BuiltInTypeKind BuiltInTypeKind { get { return BuiltInTypeKind.ReferentialConstraint; } }
 
        /// <summary>
        /// Returns the identity for this constraint
        /// </summary>
        internal override string Identity
        {
            get
            {
                return this.FromRole.Name + "_" + this.ToRole.Name;
            }
        }
 
        /// <summary>
        /// Returns the FromRole which takes part in this referential constraint
        /// </summary>
        /// <exception cref="System.ArgumentNullException">Thrown if value passed into setter is null</exception>
        /// <exception cref="System.InvalidOperationException">Thrown if the ReferentialConstraint instance is in ReadOnly state</exception>
        [MetadataProperty(BuiltInTypeKind.RelationshipEndMember, false)]
        public RelationshipEndMember FromRole
        {
            get
            {
                return _fromRole;
            }
        }
 
        /// <summary>
        /// Returns the ToRole which takes part in this referential constraint
        /// </summary>
        /// <exception cref="System.ArgumentNullException">Thrown if value passed into setter is null</exception>
        /// <exception cref="System.InvalidOperationException">Thrown if the ReferentialConstraint instance is in ReadOnly state</exception>
        [MetadataProperty(BuiltInTypeKind.RelationshipEndMember, false)]
        public RelationshipEndMember ToRole
        {
            get
            {
                return _toRole;
            }
        }
 
        /// <summary>
        /// Returns the collection of properties on the from role on which the constraint is defined on
        /// </summary>
        [MetadataProperty(BuiltInTypeKind.EdmProperty, true)]
        public ReadOnlyMetadataCollection<EdmProperty> FromProperties
        {
            get
            {
                return _fromProperties;
            }
        }
 
        /// <summary>
        /// Returns the collection of properties on the ToRole on whose value the constraint is defined on
        /// </summary>
        [MetadataProperty(BuiltInTypeKind.EdmProperty, true)]
        public ReadOnlyMetadataCollection<EdmProperty> ToProperties
        {
            get
            {
                return _toProperties;
            }
        }
        #endregion
 
        #region Methods
        /// <summary>
        /// Overriding System.Object.ToString to provide better String representation 
        /// for this type.
        /// </summary>
        public override string ToString()
        {
            return this.FromRole.Name + "_" + this.ToRole.Name;
        }
 
        /// <summary>
        /// Sets this item to be read-only, once this is set, the item will never be writable again.
        /// </summary>
        internal override void SetReadOnly()
        {
            if (!IsReadOnly)
            {
                base.SetReadOnly();
 
                RelationshipEndMember fromRole = FromRole;
                if (fromRole != null)
                {
                    fromRole.SetReadOnly();
                }
 
                RelationshipEndMember toRole = ToRole;
                if (toRole != null)
                {
                    toRole.SetReadOnly();
                }
                this.FromProperties.Source.SetReadOnly();
                this.ToProperties.Source.SetReadOnly();
            }
        }
        #endregion
    }
}