using Godot;
using Godot.Collections;
using System;
using System.Text.RegularExpressions;

namespace ReEdit.Syntax
{
    public partial class Lua : SyntaxHighlighter
    {
        // Define Godot colors matching VS Code defaults
        private static readonly Color ColorKeyword = Color.FromHtml("#C586C0"); // Purple
        private static readonly Color ColorFunction = Color.FromHtml("#DCDCAA"); // Yellow
        private static readonly Color ColorString = Color.FromHtml("#CE9178"); // Peach
        private static readonly Color ColorLocal = Color.FromHtml("#CE7882"); // redish
        private static readonly Color ColorNumber = Color.FromHtml("#B5CEA8"); // Sage Green
        private static readonly Color ColorVariable = Color.FromHtml("#9CDCFE"); // Sky Blue
        private static readonly Color ColorConstant = Color.FromHtml("#4FC1FF"); // Cyan Blue
        private static readonly Color ColorComment = Color.FromHtml("#6A9955"); // Foliage Green
        private static readonly Color ColorOperator = Color.FromHtml("#D4D4D4"); // Light Gray

        // Token rule definition structure
        private struct TokenRule
        {
            public Regex Regex;
            public Color Color;

            public TokenRule(string pattern, Color color)
            {
                Regex = new Regex("^(" + pattern + ")", RegexOptions.Compiled);
                Color = color;
            }
        }

        private static readonly TokenRule[] Rules = new TokenRule[]
        {
            new TokenRule(@"--\[\[[\s\S]*?\]\]|--.*", ColorComment),
            new TokenRule(@"\[\[[\s\S]*?\]\]|""([^""\\]|\\.)*""|'([^'\\]|\\.)*'", ColorString),
            new TokenRule(@"\b(and|break|do|else|elseif|end|for|function|if|in|not|or|repeat|return|then|until|while)\b", ColorKeyword),
            new TokenRule(@"\b(local)\b", ColorLocal),
            new TokenRule(@"\b(true|false|nil)\b", ColorConstant),
            new TokenRule(@"\b[a-zA-Z_][a-zA-Z0-9_]*(?=\s*\()", ColorFunction),
            new TokenRule(@"\b0x[0-9a-fA-F]+\b|\b\d+(\.\d+)?\b", ColorNumber),
            new TokenRule(@"==|~=|<=|>=|\.\.|[.+\-*/%^#=<>(){}\[\];,:]", ColorOperator),
            new TokenRule(@"\b[a-zA-Z_][a-zA-Z0-9_]*\b", ColorVariable)
        };

        public override Godot.Collections.Dictionary _GetLineSyntaxHighlighting(int lineIdx)
        {
            var highlightingData = new Godot.Collections.Dictionary();
            string lineText = GetTextEdit().GetLine(lineIdx);

            int currentColumn = 0;
            int lineLength = lineText.Length;

            while (currentColumn < lineLength)
            {
                if (char.IsWhiteSpace(lineText[currentColumn]))
                {
                    currentColumn++;
                    continue;
                }

                string remainingText = lineText.Substring(currentColumn);
                bool matchFound = false;

                foreach (var rule in Rules)
                {
                    Match match = rule.Regex.Match(remainingText);

                    if (match.Success)
                    {
                        int tokenLength = match.Length;

                        var colorContainer = new Dictionary { { "color", rule.Color } };
                        highlightingData[currentColumn] = colorContainer;

                        currentColumn += tokenLength;
                        matchFound = true;
                        break;
                    }
                }

                if (!matchFound)
                {
                    var fallbackColor = new Dictionary { { "color", ColorVariable } };
                    highlightingData[currentColumn] = fallbackColor;
                    currentColumn++;
                }
            }

            return highlightingData;
        }
    }
}