// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
 
namespace Microsoft.Extensions.VectorData;
 
/// <summary>
/// Defines an attribute to mark a property on a record class as the key under which the record is stored in a vector store.
/// </summary>
/// <remarks>
/// The characteristics defined here influence how the property is treated by the vector store.
/// </remarks>
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public sealed class VectorStoreKeyAttribute : Attribute
{
    /// <summary>
    /// Gets an optional name to use for the property in storage, if different from the property name.
    /// </summary>
    /// <remarks>
    /// For example, the property name might be "MyProperty" and the storage name might be "my_property".
    /// </remarks>
    public string? StorageName { get; init; }
 
    /// <summary>
    /// Gets or sets a value indicating whether this key property's value is auto-generated or not.
    /// </summary>
    /// <remarks>
    /// The availability of auto-generated properties - as well as the .NET types supported for them - varies across provider implementations.
    /// </remarks>
    public bool IsAutoGenerated
    {
        // The getter returns GetValueOrDefault() rather than throwing, as a workaround for a C# compiler limitation:
        // Nullable<bool> cannot be used as a compile-time attribute argument, so the public property must be bool.
        get => IsAutoGeneratedNullable.GetValueOrDefault();
        set => IsAutoGeneratedNullable = value;
    }
 
    /// <summary>
    /// Gets whether this key property's value is auto-generated or not, or <see langword="null" /> if not set.
    /// </summary>
    internal bool? IsAutoGeneratedNullable { get; private set; }
}