// 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.
 
namespace Microsoft.CodeAnalysis.BannedApiAnalyzers
{
    /// <summary>
    /// Stripped down port of the code in roslyn.  Responsible only for determining the <see cref="ISymbol.Name"/> and
    /// name of the <see cref="ISymbol.ContainingSymbol"/> for a given xml doc comment symbol id.
    /// </summary>
    internal static class DocumentationCommentIdParser
    {
        private static readonly char[] s_nameDelimiters = { ':', '.', '(', ')', '{', '}', '[', ']', ',', '\'', '@', '*', '`', '~' };
 
        public static (string ParentName, string SymbolName)? ParseDeclaredSymbolId(string id)
        {
            if (id == null)
                return null;
 
            if (id.Length < 2)
                return null;
 
            int index = 0;
            return ParseDeclaredId(id, ref index);
        }
 
        private static (string ParentName, string SymbolName)? ParseDeclaredId(string id, ref int index)
        {
            var kindChar = PeekNextChar(id, index);
 
            switch (kindChar)
            {
                case 'E': // Events
                case 'F': // Fields
                case 'M': // Methods
                case 'P': // Properties
                case 'T': // Types
                case 'N': // Namespaces
                    break;
                default:
                    // Documentation comment id must start with E, F, M, N, P or T.
                    return null;
            }
 
            index++;
            if (PeekNextChar(id, index) == ':')
                index++;
 
            string parentName = "";
 
            // process dotted names
            while (true)
            {
                var symbolName = ParseName(id, ref index);
 
                // has type parameters?
                if (PeekNextChar(id, index) == '`')
                {
                    index++;
 
                    // method type parameters?
                    if (PeekNextChar(id, index) == '`')
                        index++;
 
                    ReadNextInteger(id, ref index);
                }
 
                if (PeekNextChar(id, index) == '.')
                {
                    index++;
                    parentName = symbolName;
                    continue;
                }
                else
                {
                    return (parentName, symbolName);
                }
            }
        }
 
        private static char PeekNextChar(string id, int index)
            => index >= id.Length ? '\0' : id[index];
 
        private static string ParseName(string id, ref int index)
        {
            string name;
 
            int delimiterOffset = id.IndexOfAny(s_nameDelimiters, index);
            if (delimiterOffset >= 0)
            {
                name = id[index..delimiterOffset];
                index = delimiterOffset;
            }
            else
            {
                name = id[index..];
                index = id.Length;
            }
 
            return name.Replace('#', '.');
        }
 
        private static void ReadNextInteger(string id, ref int index)
        {
            while (index < id.Length && char.IsDigit(id[index]))
                index++;
        }
    }
}