// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Immutable;
using System.Composition;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.CodeFixes;

/// <summary>
/// Use this attribute to declare a <see cref="CodeFixProvider"/> implementation so that it can be discovered by the host.
/// </summary>
[MetadataAttribute]
[AttributeUsage(AttributeTargets.Class, Inherited = false)]
public sealed class ExportCodeFixProviderAttribute : ExportAttribute
{
    private static readonly string[] s_defaultDocumentKinds = [nameof(TextDocumentKind.Document)];
    private static readonly string[] s_documentKindNames = Enum.GetNames(typeof(TextDocumentKind));

    private string[] _documentKinds;

    /// <summary>
    /// Optional name of the <see cref="CodeFixProvider"/>.  
    /// </summary>
    [DisallowNull]
    public string? Name { get; set; }

    /// <summary>
    /// The source languages this provider can provide fixes for.  See <see cref="LanguageNames"/>.
    /// </summary>
    public string[] Languages { get; }

    /// <summary>
    /// The document kinds for which this provider can provide code fixes. See <see cref="TextDocumentKind"/>.
    /// By default, the provider supports code fixes only for source documents, <see cref="TextDocumentKind.Document"/>.
    /// Provide string representation of the documents kinds for this property, for example:
    ///     DocumentKinds = new[] { nameof(TextDocumentKind.AdditionalDocument) }
    /// </summary>
    public string[] DocumentKinds
    {
        get => _documentKinds;
        set
        {
            if (value == null)
                throw new ArgumentNullException(nameof(value));

            foreach (var kind in value)
            {
                if (kind == null || !s_documentKindNames.Contains(kind))
                {
                    var message = string.Format(WorkspacesResources.Unexpected_value_0_in_DocumentKinds_array,
                        arg0: kind?.ToString() ?? "null");
                    throw new ArgumentException(message);
                }
            }

            _documentKinds = value;
        }
    }

    /// <summary>
    /// The document extensions for which this provider can provide code fixes.
    /// Each extension string must include the leading period, for example, ".txt", ".xaml", ".editorconfig", etc.
    /// By default, this value is null and the document extension is not considered to determine applicability of code fixes.
    /// </summary>
    public string[]? DocumentExtensions { get; set; }

    /// <summary>
    /// Attribute constructor used to specify automatic application of a code fix provider.
    /// </summary>
    /// <param name="firstLanguage">One language to which the code fix provider applies.</param>
    /// <param name="additionalLanguages">Additional languages to which the code fix provider applies. See <see cref="LanguageNames"/>.</param>
    public ExportCodeFixProviderAttribute(
        string firstLanguage,
        params string[] additionalLanguages)
        : base(typeof(CodeFixProvider))
    {
        if (additionalLanguages == null)
        {
            throw new ArgumentNullException(nameof(additionalLanguages));
        }

        var languages = new string[additionalLanguages.Length + 1];
        languages[0] = firstLanguage ?? throw new ArgumentNullException(nameof(firstLanguage));
        for (var index = 0; index < additionalLanguages.Length; index++)
        {
            languages[index + 1] = additionalLanguages[index];
        }

        this.Languages = languages;
        this._documentKinds = s_defaultDocumentKinds;
        this.DocumentExtensions = null;
    }
}