// 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.
 
#nullable disable
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Immutable;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.UnitTests
{
    public class FileSet : IEnumerable<(string fileName, object content)>
    {
        private readonly IImmutableDictionary<string, object> _fileMap;
 
        private FileSet(IImmutableDictionary<string, object> fileMap)
        {
            _fileMap = fileMap ?? ImmutableDictionary<string, object>.Empty;
        }
 
        public FileSet(params (string fileName, object content)[] files)
        {
            var builder = ImmutableDictionary.CreateBuilder<string, object>(StringComparer.OrdinalIgnoreCase);
 
            foreach (var (fileName, fileContent) in files)
            {
                builder.Add(fileName, fileContent);
            }
 
            _fileMap = builder.ToImmutable();
        }
 
        public IEnumerator<(string fileName, object content)> GetEnumerator()
        {
            foreach (var (fileName, content) in _fileMap)
                yield return (fileName, content);
        }
 
        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
 
        public FileSet WithFile(string fileName, object content)
        {
            var newFileMap = _fileMap.SetItem(fileName, content);
 
            return new FileSet(newFileMap);
        }
 
        public FileSet ReplaceFileElement(string fileName, string elementName, string elementValue)
        {
            if (_fileMap.TryGetValue(fileName, out var content))
            {
                if (content is string textContent)
                {
                    var elementStartTag = "<" + elementName;
                    var elementEndTag = "</" + elementName;
                    var startTagStart = textContent.IndexOf(elementStartTag, StringComparison.Ordinal);
                    if (startTagStart >= -1)
                    {
                        var startTagEnd = textContent.IndexOf('>', startTagStart + 1);
                        if (startTagEnd >= startTagStart)
                        {
                            var endTagStart = textContent.IndexOf(elementEndTag, startTagEnd + 1, StringComparison.Ordinal);
                            if (endTagStart >= startTagEnd)
                            {
                                var newContent = textContent[..(startTagEnd + 1)] + elementValue + textContent[endTagStart..];
                                return this.WithFile(fileName, newContent);
                            }
                        }
                    }
                }
            }
 
            return this;
        }
    }
}