using System.Text;
using CodePlay.Core.Interfaces;
using CodePlay.Core.Common;

namespace CodePlay.Core.Converters;

public class CppCodeGenerator : ICodeGenerator
{
    private StringBuilder _out = new();
    private int _indent;
    
    public string Generate(SyntaxTree tree)
    {
        _out.Clear(); _indent = 0;
        
        _out.AppendLine("#include <iostream>");
        _out.AppendLine("#include <string>");
        _out.AppendLine("#include <vector>");
        _out.AppendLine("#include <map>");
        _out.AppendLine("#include <memory>");
        _out.AppendLine("#include <future>");
        _out.AppendLine();
        
        GenNode(tree.Root);
        return _out.ToString();
    }
    
    void GenNode(SyntaxNode n)
    {
        if (n.Type == SyntaxNodeType.Unknown && !string.IsNullOrWhiteSpace(n.Text))
        {
            foreach (var line in n.Text.Split('\n'))
            {
                var t = line.Trim();
                if (!string.IsNullOrEmpty(t) && !t.StartsWith("{") && !t.StartsWith("}"))
                    _out.AppendLine(IndentLine(t));
            }
            return;
        }
        
        switch (n.Type)
        {
            case SyntaxNodeType.CompilationUnit:
                foreach (var c in n.Children) GenNode(c);
                break;
            case SyntaxNodeType.Namespace:
                var ns = System.Text.RegularExpressions.Regex.Match(n.Text, @"namespace\s+([\w.]+)").Groups[1].Value;
                _out.AppendLine($"namespace {ns} {{"); _indent++;
                foreach (var c in n.Children) GenNode(c);
                _indent--; _out.AppendLine("}");
                break;
            case SyntaxNodeType.Class:
                var cls = n.Text.Trim();
                var brace = cls.IndexOf('{'); if (brace > 0) cls = cls.Substring(0, brace);
                _out.AppendLine(IndentLine($"class {cls.Replace("public ", "")} {{"));
                _out.AppendLine(IndentLine("public:"));
                _indent++;
                foreach (var c in n.Children) GenNode(c);
                _indent--;
                _out.AppendLine(IndentLine("};")); _out.AppendLine();
                break;
            case SyntaxNodeType.Method:
                var sig = n.Text.Split('\n').First().Trim();
                if (sig.EndsWith("{")) sig = sig[..^1].Trim();
                _out.AppendLine(IndentLine($"{sig} {{"));
                _indent++;
                var body = string.Join('\n', n.Text.Split('{', '}').Skip(1)).Trim();
                foreach (var l in body.Split('\n')) if (!string.IsNullOrWhiteSpace(l)) _out.AppendLine(IndentLine(l.Trim()));
                _indent--;
                _out.AppendLine(IndentLine("}")); _out.AppendLine();
                break;
            case SyntaxNodeType.Field:
            case SyntaxNodeType.Property:
                if (!string.IsNullOrWhiteSpace(n.Text)) _out.AppendLine(IndentLine(n.Text.Trim()));
                break;
            default:
                if (!string.IsNullOrWhiteSpace(n.Text))
                    _out.AppendLine(IndentLine(n.Text.Trim()));
                foreach (var c in n.Children) GenNode(c);
                break;
        }
    }
    
    string IndentLine(string t)
    {
        var spaces = string.Concat(Enumerable.Repeat(" ", _indent * 2));
        return spaces + t;
    }
}