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

using System;
using System.Collections.Generic;
using System.Data.Common;
using System.Diagnostics;
using System.Reflection;

namespace System.Data.Metadata.Edm
{
    /// <summary>
    /// Class representing a metadata attribute for an item
    /// </summary>
    public sealed class MetadataProperty : MetadataItem
    {
        #region Constructors
        /// <summary>
        /// The constructor for MetadataProperty taking in a name, a TypeUsage object, and a value for the attribute
        /// </summary>
        /// <param name="name">The name of this MetadataProperty</param>
        /// <param name="typeUsage">The TypeUsage describing the type of this MetadataProperty</param>
        /// <param name="value">The value for this attribute</param>
        /// <exception cref="System.ArgumentNullException">Thrown if typeUsage argument is null</exception>
        internal MetadataProperty(string name, TypeUsage typeUsage, object value)
        {
            EntityUtil.GenericCheckArgumentNull(typeUsage, "typeUsage");

            _name = name;
            _value = value;
            _typeUsage = typeUsage;
            _propertyKind = PropertyKind.Extended;
        }

        /// <summary>
        /// The constructor for MetadataProperty taking in all the ingredients for creating TypeUsage and the actual value
        /// </summary>
        /// <param name="name">The name of the attribute</param>
        /// <param name="edmType">The edm type of the attribute</param>
        /// <param name="isCollectionType">Whether the collection type of the given edm type should be used</param>
        /// <param name="value">The value of the attribute</param>
        internal MetadataProperty(string name, EdmType edmType, bool isCollectionType, object value)
        {
            EntityUtil.CheckArgumentNull(edmType, "edmType");

            _name = name;
            _value = value;
            if (isCollectionType)
            {
                _typeUsage = TypeUsage.Create(edmType.GetCollectionType());
            }
            else
            {
                _typeUsage = TypeUsage.Create(edmType);
            }
            _propertyKind = PropertyKind.System;
        }
        #endregion

        #region Fields
        private string _name;
        private PropertyKind _propertyKind;
        private object _value;
        private TypeUsage _typeUsage;
        #endregion

        #region Properties
        /// <summary>
        /// Returns the kind of the type
        /// </summary>
        public override BuiltInTypeKind BuiltInTypeKind { get { return BuiltInTypeKind.MetadataProperty; } }

        /// <summary>
        /// Gets the identity of this item
        /// </summary>
        internal override string Identity
        {
            get
            {
                return Name;
            }
        }

        /// <summary>
        /// Gets/Sets the name of this MetadataProperty
        /// </summary>
        [MetadataProperty(PrimitiveTypeKind.String, false)]
        public string Name
        {
            get
            {
                // The name is immutable, so it should be safe to always get it from the field
                return _name;
            }
        }

        /// <summary>
        /// Gets/Sets the value of this MetadataProperty
        /// </summary>
        /// <exception cref="System.InvalidOperationException">Thrown if the MetadataProperty instance is in readonly state</exception>
        [MetadataProperty(typeof(Object), false)]
        public object Value
        {
            get
            {
                // Check if we're redirecting to an MetadataItem system property
                MetadataPropertyValue redirectValue = _value as MetadataPropertyValue;
                if (null != redirectValue)
                {
                    return redirectValue.GetValue();
                }

                // If not, return the actual stored value
                return _value;
            }
        }

        /// <summary>
        /// Gets/Sets the TypeUsage object describing the type of this attribute
        /// </summary>
        /// <exception cref="System.ArgumentNullException">Thrown if value passed into setter is null</exception>
        /// <exception cref="System.InvalidOperationException">Thrown if the MetadataProperty instance is in readonly state</exception>
        [MetadataProperty(BuiltInTypeKind.TypeUsage, false)]
        public TypeUsage TypeUsage
        {
            get
            {
                return _typeUsage;
            }
        }
        #endregion

        #region Methods
        /// <summary>
        /// Sets this item to be readonly, once this is set, the item will never be writable again.
        /// </summary>
        internal override void SetReadOnly()
        {
            if (!IsReadOnly)
            {
                base.SetReadOnly();

                // TypeUsage is always readonly, no need to set _typeUsage
            }
        }

        /// <summary>
        /// Returns the kind of the attribute
        /// </summary>
        public PropertyKind PropertyKind
        {
            get
            {
                return _propertyKind;
            }
        }
        #endregion
    }
}