// 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.Generic;
using System.Collections.Immutable;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CSharp.Formatting;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Indentation;
using Microsoft.CodeAnalysis.Options;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.Razor
{
    /// <summary>
    /// Enables Razor to utilize Roslyn's C# formatting service.
    /// </summary>
    internal static class RazorCSharpFormattingInteractionService
    {
 
        /// <summary>
        /// Returns the text changes necessary to format the document after the user enters a 
        /// character.  The position provided is the position of the caret in the document after
        /// the character been inserted into the document.
        /// </summary>
        public static async Task<ImmutableArray<TextChange>> GetFormattingChangesAsync(
            Document document,
            char typedChar,
            int position,
            RazorIndentationOptions indentationOptions,
            RazorAutoFormattingOptions autoFormattingOptions,
            FormattingOptions.IndentStyle indentStyle,
            CancellationToken cancellationToken)
        {
            Contract.ThrowIfFalse(document.Project.Language is LanguageNames.CSharp);
            var formattingService = document.GetRequiredLanguageService<ISyntaxFormattingService>();
            var documentSyntax = await ParsedDocument.CreateAsync(document, cancellationToken).ConfigureAwait(false);
 
            if (!formattingService.ShouldFormatOnTypedCharacter(documentSyntax, typedChar, position, cancellationToken))
            {
                return ImmutableArray<TextChange>.Empty;
            }
 
            var formattingOptions = GetFormattingOptions(indentationOptions);
            var roslynIndentationOptions = new IndentationOptions(formattingOptions)
            {
                AutoFormattingOptions = autoFormattingOptions.UnderlyingObject,
                IndentStyle = (FormattingOptions2.IndentStyle)indentStyle
            };
 
            return formattingService.GetFormattingChangesOnTypedCharacter(documentSyntax, position, roslynIndentationOptions, cancellationToken);
        }
 
        public static IList<TextChange> GetFormattedTextChanges(
            HostWorkspaceServices services,
            SyntaxNode root,
            TextSpan span,
            RazorIndentationOptions indentationOptions,
            CancellationToken cancellationToken)
        {
            Contract.ThrowIfFalse(root.Language is LanguageNames.CSharp);
            return Formatter.GetFormattedTextChanges(root, span, services.SolutionServices, GetFormattingOptions(indentationOptions), cancellationToken);
        }
 
        public static SyntaxNode Format(
            HostWorkspaceServices services,
            SyntaxNode root,
            RazorIndentationOptions indentationOptions,
            CancellationToken cancellationToken)
        {
            Contract.ThrowIfFalse(root.Language is LanguageNames.CSharp);
            return Formatter.Format(root, services.SolutionServices, GetFormattingOptions(indentationOptions), cancellationToken: cancellationToken);
        }
 
        private static SyntaxFormattingOptions GetFormattingOptions(RazorIndentationOptions indentationOptions)
            => new CSharpSyntaxFormattingOptions()
            {
                LineFormatting = new()
                {
                    UseTabs = indentationOptions.UseTabs,
                    TabSize = indentationOptions.TabSize,
                    IndentationSize = indentationOptions.IndentationSize,
                    NewLine = CSharpSyntaxFormattingOptions.Default.NewLine
                }
            };
    }
}