// 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;
 
#nullable disable
 
namespace Microsoft.Build.Framework
{
    /// <summary>
    /// Provides a way to efficiently enumerate item metadata
    /// </summary>
    internal interface IMetadataContainer
    {
        /// <summary>
        /// Gets the backing metadata dictionary in a serializable wrapper.
        /// </summary>
        /// <remarks>
        /// If the implementation's backing dictionary does not support copy-on-write, it should return the default struct,
        /// allowing the caller to decide whether to take the reference.
        /// This can safely be used across AppDomain boundaries.
        /// </remarks>
        SerializableMetadata BackingMetadata { get; }
 
        /// <summary>
        /// Gets a value indicating whether indicates whether the item has any custom metadata.
        /// </summary>
        /// <remarks>
        /// Used to skip unnecessary enumerations when copying metadata between items, allowing copy-on-write cloning.
        /// This is independent of a Count property as items may have multiple backing collections that need to be deduped.
        /// </remarks>
        bool HasCustomMetadata { get; }
 
        /// <summary>
        /// Returns a list of metadata names and unescaped values, including
        /// metadata from item definition groups, but not including built-in
        /// metadata. Implementations should be low-overhead as the method
        /// is used for serialization (in node packet translator) as well as
        /// in the binary logger.
        /// </summary>
        IEnumerable<KeyValuePair<string, string>> EnumerateMetadata();
 
        /// <summary>
        /// Sets the given metadata. The operation is equivalent to calling
        /// <see cref="ITaskItem.SetMetadata"/> on all metadata, but takes
        /// advantage of a faster bulk-set operation where applicable. The
        /// implementation may not perform the same parameter validation
        /// as SetMetadata.
        /// </summary>
        /// <param name="metadata">The metadata to set. The keys are assumed
        /// to be unique and values are assumed to be escaped.
        /// </param>
        void ImportMetadata(IEnumerable<KeyValuePair<string, string>> metadata);
    }
}