// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Generic;
using System.Diagnostics;
 
namespace System.Composition.Hosting.Core
{
    internal sealed class CycleBreakingMetadataDictionary : IDictionary<string, object>
    {
        private readonly Lazy<ExportDescriptor> _exportDescriptor;
 
        public CycleBreakingMetadataDictionary(Lazy<ExportDescriptor> exportDescriptor)
        {
            _exportDescriptor = exportDescriptor;
        }
 
        private IDictionary<string, object> ActualMetadata
        {
            get
            {
                if (!_exportDescriptor.IsValueCreated)
                {
                    var ex = new NotImplementedException(SR.NotImplemented_MetadataCycles);
                    Debug.WriteLine(SR.Diagnostic_ThrowingException, ex.ToString());
                    throw ex;
                }
 
                return _exportDescriptor.Value.Metadata;
            }
        }
 
        public void Add(string key, object value)
        {
            ActualMetadata.Add(key, value);
        }
 
        public bool ContainsKey(string key)
        {
            return ActualMetadata.ContainsKey(key);
        }
 
        public ICollection<string> Keys
        {
            get { return ActualMetadata.Keys; }
        }
 
        public bool Remove(string key)
        {
            return ActualMetadata.Remove(key);
        }
 
        public bool TryGetValue(string key, out object value)
        {
            return ActualMetadata.TryGetValue(key, out value);
        }
 
        public ICollection<object> Values
        {
            get { return ActualMetadata.Values; }
        }
 
        public object this[string key]
        {
            get
            {
                return ActualMetadata[key];
            }
            set
            {
                ActualMetadata[key] = value;
            }
        }
 
        public void Add(KeyValuePair<string, object> item)
        {
            ActualMetadata.Add(item);
        }
 
        public void Clear()
        {
            ActualMetadata.Clear();
        }
 
        public bool Contains(KeyValuePair<string, object> item)
        {
            return ActualMetadata.Contains(item);
        }
 
        public void CopyTo(KeyValuePair<string, object>[] array, int arrayIndex)
        {
            ActualMetadata.CopyTo(array, arrayIndex);
        }
 
        public int Count
        {
            get { return ActualMetadata.Count; }
        }
 
        public bool IsReadOnly
        {
            get { return ActualMetadata.IsReadOnly; }
        }
 
        public bool Remove(KeyValuePair<string, object> item)
        {
            return ActualMetadata.Remove(item);
        }
 
        public IEnumerator<KeyValuePair<string, object>> GetEnumerator()
        {
            return ActualMetadata.GetEnumerator();
        }
 
        Collections.IEnumerator Collections.IEnumerable.GetEnumerator()
        {
            return ((Collections.IEnumerable)ActualMetadata).GetEnumerator();
        }
    }
}