// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.DotNet.Cli.Utils;

public class AnsiConsole
{
    private const int Light = 0x08;
    private readonly bool _ansiEnabled;

    private AnsiConsole(TextWriter writer)
    {
        Writer = writer;

        OriginalForegroundColor = Console.ForegroundColor;
        _boldRecursion = ((int)OriginalForegroundColor & Light) != 0 ? 1 : 0;

        _ansiEnabled = string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable("NO_COLOR"));
    }

    private int _boldRecursion;

    public static AnsiConsole GetOutput()
    {
        return new AnsiConsole(Console.Out);
    }

    public static AnsiConsole GetError()
    {
        return new AnsiConsole(Console.Error);
    }

    public TextWriter Writer { get; }

    public ConsoleColor OriginalForegroundColor { get; }

    private void SetColor(ConsoleColor color)
    {
        if (!_ansiEnabled)
        {
            return;
        }

        int c = (int)color;

        Console.ForegroundColor =
            c < 0 ? color :                                   // unknown, just use it
            _boldRecursion > 0 ? (ConsoleColor)(c | Light) :  // ensure color is light
            (ConsoleColor)(c & ~Light);                       // ensure color is dark
    }

    private void SetBold(bool bold)
    {
        if (!_ansiEnabled)
        {
            return;
        }

        _boldRecursion += bold ? 1 : -1;
        if (_boldRecursion > 1 || (_boldRecursion == 1 && !bold))
        {
            return;
        }

        // switches on _boldRecursion to handle boldness
        SetColor(Console.ForegroundColor);
    }

    public void WriteLine(string message)
    {
        Write(message);
        Writer.WriteLine();
    }

    public void Write(string message)
    {
        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':
                        if (int.TryParse(message.Substring(startIndex, endIndex - startIndex), out int value))
                        {
                            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:
                                    Console.ForegroundColor = OriginalForegroundColor;
                                    break;
                            }
                        }
                        break;
                }

                escapeScan = endIndex + 1;
            }
        }
    }
}