// 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.CodeAnalysis;

namespace Microsoft.AspNetCore.Components.Forms
{
    /// <summary>
    /// Holds arbitrary key/value pairs associated with an <see cref="EditContext"/>.
    /// This can be used to track additional metadata for application-specific purposes.
    /// </summary>
    public sealed class EditContextProperties
    {
        // We don't want to expose any way of enumerating the underlying dictionary, because that would
        // prevent its usage to store private information. So we only expose an indexer and TryGetValue.
        private Dictionary<object, object>? _contents;

        /// <summary>
        /// Gets or sets a value in the collection.
        /// </summary>
        /// <param name="key">The key under which the value is stored.</param>
        /// <returns>The stored value.</returns>
        public object this[object key]
        {
            get => _contents is null ? throw new KeyNotFoundException() : _contents[key];
            set
            {
                _contents ??= new Dictionary<object, object>();
                _contents[key] = value;
            }
        }

        /// <summary>
        /// Gets the value associated with the specified key, if any.
        /// </summary>
        /// <param name="key">The key under which the value is stored.</param>
        /// <param name="value">The value, if present.</param>
        /// <returns>True if the value was present, otherwise false.</returns>
        public bool TryGetValue(object key, [NotNullWhen(true)] out object? value)
        {
            if (_contents is null)
            {
                value = default;
                return false;
            }
            else
            {
                return _contents.TryGetValue(key, out value);
            }
        }

        /// <summary>
        /// Removes the specified entry from the collection.
        /// </summary>
        /// <param name="key">The key of the entry to be removed.</param>
        /// <returns>True if the value was present, otherwise false.</returns>
        public bool Remove(object key)
        {
            return _contents?.Remove(key) ?? false;
        }
    }
}
