RelativePath.cs

// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Collections.Generic;
using System.IO;

namespace Microsoft.DotNet.Interactive.CSharpProject;

public abstract class RelativePath
{
    private string _value;

    protected RelativePath(string value)
    {
        if (value == null)
        {
            throw new ArgumentNullException(nameof(value));
        }

        ThrowIfPathIsRooted(value);
    }

    private void ThrowIfPathIsRooted(string path)
    {
        if (IsPathRootedRegardlessOfOS(path))
        {
            throw new ArgumentException($"Path cannot be absolute: {path}");
        }
    }

    private static bool IsPathRootedRegardlessOfOS(string path)
    {
        return Path.IsPathRooted(path) ||
               path.StartsWith(@"/") ||
               path.StartsWith(@"\\") ||
               path.Substring(1).StartsWith(@":\");
    }

    public string Value
    {
        get => _value;
        protected set => _value = value ?? throw new ArgumentNullException(nameof(value));
    }

    public override string ToString() => Value;

    private static readonly HashSet<char> DisallowedPathChars = new HashSet<char>(
        new char[]
        {
            '|',
            '\0',
            '\u0001',
            '\u0002',
            '\u0003',
            '\u0004',
            '\u0005',
            '\u0006',
            '\a',
            '\b',
            '\t',
            '\n',
            '\v',
            '\f',
            '\r',
            '\u000e',
            '\u000f',
            '\u0010',
            '\u0011',
            '\u0012',
            '\u0013',
            '\u0014',
            '\u0015',
            '\u0016',
            '\u0017',
            '\u0018',
            '\u0019',
            '\u001a',
            '\u001b',
            '\u001c',
            '\u001d',
            '\u001e',
            '\u001f'
        });

    private static readonly HashSet<char> DisallowedFileNameChars = new HashSet<char>(
        new char[]
        {
            '"',
            '<',
            '>',
            '|',
            '\0',
            '\u0001',
            '\u0002',
            '\u0003',
            '\u0004',
            '\u0005',
            '\u0006',
            '\a',
            '\b',
            '\t',
            '\n',
            '\v',
            '\f',
            '\r',
            '\u000e',
            '\u000f',
            '\u0010',
            '\u0011',
            '\u0012',
            '\u0013',
            '\u0014',
            '\u0015',
            '\u0016',
            '\u0016',
            '\u0017',
            '\u0018',
            '\u0019',
            '\u001a',
            '\u001b',
            '\u001c',
            '\u001d',
            '\u001e',
            '\u001f',
            ':',
            '*',
            '?',
            '\\'
        });

    public static string NormalizeDirectory(string directoryPath)
    {
        directoryPath = directoryPath.Replace('\\', '/');

        if (string.IsNullOrWhiteSpace(directoryPath))
        {
            directoryPath = "./";
        }
        else
        {
            if (!IsPathRootedRegardlessOfOS(directoryPath) &&
                !directoryPath.StartsWith(".") &&
                !directoryPath.StartsWith("..") &&
                !directoryPath.StartsWith("/"))
            {
                directoryPath = $"./{directoryPath}";
            }

            directoryPath = directoryPath.TrimEnd('\\', '/') + '/';
        }

        ThrowIfContainsDisallowedDirectoryPathChars(directoryPath);

        return directoryPath;
    }

    protected static void ThrowIfContainsDisallowedDirectoryPathChars(string path)
    {
        for (var index = 0; index < path.Length; index++)
        {
            var ch = path[index];
            if (DisallowedPathChars.Contains(ch))
            {
                throw new ArgumentException($"The character {ch} is not allowed in the path");
            }
        }
    }

    protected static void ThrowIfContainsDisallowedFilePathChars(string filename)
    {
        for (var index = 0; index < filename.Length; index++)
        {
            var ch = filename[index];
            if (DisallowedFileNameChars.Contains(ch))
            {
                throw new ArgumentException($"The character {ch} is not allowed in the filename");
            }
        }
    }
}