// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.IO;
 
namespace Microsoft.Extensions.CommandLineUtils;
 
internal sealed class AnsiConsole
{
    private AnsiConsole(TextWriter writer, bool useConsoleColor)
    {
        Writer = writer;
 
        _useConsoleColor = useConsoleColor;
        if (_useConsoleColor)
        {
            OriginalForegroundColor = Console.ForegroundColor;
        }
    }
 
    private int _boldRecursion;
    private readonly bool _useConsoleColor;
 
    public static AnsiConsole GetOutput(bool useConsoleColor)
    {
        return new AnsiConsole(Console.Out, useConsoleColor);
    }
 
    public static AnsiConsole GetError(bool useConsoleColor)
    {
        return new AnsiConsole(Console.Error, useConsoleColor);
    }
 
    public TextWriter Writer { get; }
 
    public ConsoleColor OriginalForegroundColor { get; }
 
    private static void SetColor(ConsoleColor color)
    {
        Console.ForegroundColor = (ConsoleColor)(((int)Console.ForegroundColor & 0x08) | ((int)color & 0x07));
    }
 
    private void SetBold(bool bold)
    {
        _boldRecursion += bold ? 1 : -1;
        if (_boldRecursion > 1 || (_boldRecursion == 1 && !bold))
        {
            return;
        }
 
        Console.ForegroundColor = (ConsoleColor)((int)Console.ForegroundColor ^ 0x08);
    }
 
    public void WriteLine(string message)
    {
        if (!_useConsoleColor)
        {
            Writer.WriteLine(message);
            return;
        }
 
        var escapeScan = 0;
        for (; ; )
        {
            var escapeIndex = message.IndexOf("\x1b[", escapeScan, StringComparison.Ordinal);
            if (escapeIndex == -1)
            {
                var text = message.Substring(escapeScan);
                Writer.Write(text);
                break;
            }
            else
            {
                var startIndex = escapeIndex + 2;
                var endIndex = startIndex;
                while (endIndex != message.Length &&
                    message[endIndex] >= 0x20 &&
                    message[endIndex] <= 0x3f)
                {
                    endIndex += 1;
                }
 
                var text = message.Substring(escapeScan, escapeIndex - escapeScan);
                Writer.Write(text);
                if (endIndex == message.Length)
                {
                    break;
                }
 
                switch (message[endIndex])
                {
                    case 'm':
                        int value;
#if NETFRAMEWORK
                        if (int.TryParse(message.Substring(startIndex, endIndex - startIndex), out value))
#else
                        if (int.TryParse(message.AsSpan(startIndex, endIndex - startIndex), out value))
#endif
                        {
                            switch (value)
                            {
                                case 1:
                                    SetBold(true);
                                    break;
                                case 22:
                                    SetBold(false);
                                    break;
                                case 30:
                                    SetColor(ConsoleColor.Black);
                                    break;
                                case 31:
                                    SetColor(ConsoleColor.Red);
                                    break;
                                case 32:
                                    SetColor(ConsoleColor.Green);
                                    break;
                                case 33:
                                    SetColor(ConsoleColor.Yellow);
                                    break;
                                case 34:
                                    SetColor(ConsoleColor.Blue);
                                    break;
                                case 35:
                                    SetColor(ConsoleColor.Magenta);
                                    break;
                                case 36:
                                    SetColor(ConsoleColor.Cyan);
                                    break;
                                case 37:
                                    SetColor(ConsoleColor.Gray);
                                    break;
                                case 39:
                                    SetColor(OriginalForegroundColor);
                                    break;
                            }
                        }
                        break;
                }
 
                escapeScan = endIndex + 1;
            }
        }
        Writer.WriteLine();
    }
}