using System.Text;
using syntax.Tokenization;

namespace syntax.Diagnostics;

public static class ConsoleColors
{
    public const string Reset = "\e[0m";
    public const string Bold = "\e[1m";
    public const string Faint = "\e[2m";
    public const string Italic = "\e[3m";
    public const string Underline = "\e[4m";
    public const string SlowBlink = "\e[5m";
    public const string RapidBlink = "\e[6m";
    public const string SwapBgAndFg = "\e[7m";
    public const string Conceal = "\e[8m";
    public const string CrossedOut = "\e[9m";
    
    public const string DefaultFont = "\e[10m";
    public const string AltFont1 = "\e[11m";
    public const string AltFont2 = "\e[12m";
    public const string AltFont3 = "\e[13m";
    public const string AltFont4 = "\e[14m";
    public const string AltFont5 = "\e[15m";
    public const string AltFont6 = "\e[16m";
    public const string AltFont7 = "\e[17m";
    public const string AltFont8 = "\e[18m";
    public const string AltFont9 = "\e[19m";

    public const string Black = "\e[30m";
    public const string Red = "\e[31m";
    public const string Green = "\e[32m";
    public const string Yellow = "\e[33m";
    public const string Blue = "\e[34m";
    public const string Magenta = "\e[35m";
    public const string Cyan = "\e[36m";
    public const string White = "\e[37m";

    public const string BrightBlack = "\e[90m";
    public const string BrightRed = "\e[91m";
    public const string BrightGreen = "\e[92m";
    public const string BrightYellow = "\e[93m";
    public const string BrightBlue = "\e[94m";
    public const string BrightMagenta = "\e[95m";
    public const string BrightCyan = "\e[96m";
    public const string BrightWhite = "\e[97m";

    private static bool IsColorSupported()
    {
        var term = Environment.GetEnvironmentVariable("TERM");
        var colorTerm = Environment.GetEnvironmentVariable("COLORTERM");
        return !string.IsNullOrEmpty(term) || !string.IsNullOrEmpty(colorTerm) || !Console.IsOutputRedirected;
    }

    public static string Colorize(string text, string color)
    {
        return IsColorSupported() ? $"{color}{text}{Reset}" : text;
    }

    private static string GetTokenColor(Token token)
    {
        switch (token)
        {
            case DocumentationToken:
                return Faint;
            case IdentifierToken:
                return White;
            case LiteralToken literal:
                return literal.Kind switch
                {
                    LiteralKind.String => Green,
                    LiteralKind.Integer or LiteralKind.Float => BrightBlue,
                    LiteralKind.Bool => Blue,
                    _ => White
                };
            case ModifierToken:
                return White;
            case SymbolToken symbol:
                switch (symbol.Symbol)
                {
                    case Symbol.If:
                    case Symbol.Else:
                    case Symbol.While:
                    case Symbol.Break:
                    case Symbol.Continue:
                    case Symbol.Return:
                        return Magenta;
                    case Symbol.Func:
                    case Symbol.Struct:
                    case Symbol.Namespace:
                    case Symbol.Let:
                    case Symbol.Alloc:
                        return Blue;
                    case Symbol.Assign:
                    case Symbol.Bang:
                    case Symbol.Equal:
                    case Symbol.NotEqual:
                    case Symbol.LessThan:
                    case Symbol.LessThanOrEqual:
                    case Symbol.GreaterThan:
                    case Symbol.GreaterThanOrEqual:
                    case Symbol.Plus:
                    case Symbol.Minus:
                    case Symbol.Star:
                    case Symbol.ForwardSlash:
                    case Symbol.Caret:
                    case Symbol.Ampersand:
                        return White;
                    case Symbol.Semicolon:
                    case Symbol.Colon:
                    case Symbol.Comma:
                    case Symbol.Period:
                    case Symbol.DoubleColon:
                        return Faint;
                    case Symbol.OpenParen:
                    case Symbol.CloseParen:
                    case Symbol.OpenBrace:
                    case Symbol.CloseBrace:
                    case Symbol.OpenBracket:
                    case Symbol.CloseBracket:
                        return Yellow;
                    default:
                        return White;
                }
            default:
                return White;
        }
    }

    public static string ColorizeSource(string source)
    {
        var sourceText = new SourceText(string.Empty, source);
        var tokens = Tokenizer.Tokenize(sourceText).Value;
        var result = new StringBuilder();
        var lastCharIndex = 0;

        foreach (var token in tokens)
        {
            var tokenStartIndex = GetCharacterIndex(sourceText, token.Span.Start);
            var tokenEndIndex = GetCharacterIndex(sourceText, token.Span.End);

            if (tokenStartIndex > lastCharIndex)
            {
                var between = sourceText.Content.Substring(lastCharIndex, tokenStartIndex - lastCharIndex);
                result.Append(between);
            }

            var tokenText = sourceText.Content.Substring(tokenStartIndex, tokenEndIndex - tokenStartIndex);

            result.Append(Colorize(tokenText, GetTokenColor(token)));
            lastCharIndex = tokenEndIndex;
        }

        if (lastCharIndex < sourceText.Content.Length)
        {
            var remaining = sourceText.Content[lastCharIndex..];
            result.Append(Colorize(remaining, Faint));
        }

        return result.ToString();
    }

    private static int GetCharacterIndex(SourceText sourceText, SourceLocation location)
    {
        var lines = sourceText.Content.Split('\n');
        var index = 0;

        for (var i = 0; i < location.Line - 1 && i < lines.Length; i++)
        {
            index += lines[i].Length + 1;
        }

        index += location.Column - 1;

        return Math.Min(index, sourceText.Content.Length);
    }
}