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

namespace CodePlay.Core.Converters;

/// <summary>
/// Java 代码生成器
/// </summary>
public class JavaCodeGenerator : ICodeGenerator
{
    private readonly StringBuilder _output = new();
    private int _indentLevel;
    
    /// <summary>
    /// 从语法树生成 Java 代码
    /// </summary>
    public string Generate(Interfaces.SyntaxTree syntaxTree)
    {
        _output.Clear();
        _indentLevel = 0;
        
        // 生成 JavaDoc
        foreach (var doc in syntaxTree.Documentation)
        {
            _output.AppendLine("/**");
            _output.AppendLine($" * {doc.Content}");
            _output.AppendLine(" */");
        }
        
        // 生成代码
        GenerateNode(syntaxTree.Root);
        
        return _output.ToString();
    }
    
    private void GenerateNode(Interfaces.SyntaxNode node)
    {
        switch (node.Type)
        {
            case SyntaxNodeType.CompilationUnit:
                GenerateCompilationUnit(node);
                break;
            case SyntaxNodeType.Namespace:
                GenerateNamespace(node);
                break;
            case SyntaxNodeType.Class:
                GenerateClass(node);
                break;
            case SyntaxNodeType.Method:
                GenerateMethod(node);
                break;
            case SyntaxNodeType.Property:
                GenerateProperty(node);
                break;
            case SyntaxNodeType.Field:
                GenerateField(node);
                break;
            default:
                GenerateDefault(node);
                break;
        }
    }
    
    private void GenerateCompilationUnit(Interfaces.SyntaxNode node)
    {
        foreach (var child in node.Children)
        {
            GenerateNode(child);
        }
    }
    
    private void GenerateNamespace(Interfaces.SyntaxNode node)
    {
        // 提取 package 声明
        var packageLine = node.Text.StartsWith("package ") 
            ? node.Text.Split(';')[0] + ";" 
            : $"package com.codeplay.converted;";
        
        _output.AppendLine(packageLine);
        _output.AppendLine();
        
        foreach (var child in node.Children)
        {
            GenerateNode(child);
        }
    }
    
    private void GenerateClass(Interfaces.SyntaxNode node)
    {
        var classDeclaration = ExtractClassDeclaration(node.Text);
        _output.AppendLine(Indent(classDeclaration));
        _output.AppendLine(Indent("{"));
        _indentLevel++;
        
        foreach (var child in node.Children)
        {
            if (child.Type != SyntaxNodeType.Unknown)
            {
                GenerateNode(child);
            }
        }
        
        _indentLevel--;
        _output.AppendLine(Indent("}"));
        _output.AppendLine();
    }
    
    private void GenerateMethod(Interfaces.SyntaxNode node)
    {
        var methodSignature = ExtractMethodSignature(node.Text);
        _output.AppendLine(Indent(methodSignature));
        _output.AppendLine(Indent("{"));
        _indentLevel++;
        
        // 生成方法体（简化处理）
        var methodBody = ExtractMethodBody(node.Text);
        if (!string.IsNullOrWhiteSpace(methodBody))
        {
            _output.AppendLine(Indent(methodBody));
        }
        
        _indentLevel--;
        _output.AppendLine(Indent("}"));
        _output.AppendLine();
    }
    
    private void GenerateProperty(Interfaces.SyntaxNode node)
    {
        var propertyDeclaration = node.Text;
        _output.AppendLine(Indent(propertyDeclaration));
    }
    
    private void GenerateField(Interfaces.SyntaxNode node)
    {
        var fieldDeclaration = node.Text;
        _output.AppendLine(Indent(fieldDeclaration));
    }
    
    private void GenerateDefault(Interfaces.SyntaxNode node)
    {
        if (!string.IsNullOrWhiteSpace(node.Text))
        {
            _output.AppendLine(Indent(node.Text));
        }
        
        foreach (var child in node.Children)
        {
            GenerateNode(child);
        }
    }
    
    private string Indent(string text)
    {
        var indent = new string(' ', _indentLevel * 4);
        return indent + text;
    }
    
    private string ExtractClassDeclaration(string text)
    {
        // 简化处理：替换 class 修饰符
        return text.Replace("public class", "public class")
                  .Replace("abstract class", "public abstract class")
                  .Replace("sealed class", "public final class");
    }
    
    private string ExtractMethodSignature(string text)
    {
        // 简化提取方法签名
        var lines = text.Split('\n');
        return lines.FirstOrDefault(l => l.Trim().Length > 0 && !l.Trim().StartsWith("{"))?.Trim() ?? text;
    }
    
    private string ExtractMethodBody(string text)
    {
        var startIndex = text.IndexOf('{');
        var endIndex = text.LastIndexOf('}');
        
        if (startIndex >= 0 && endIndex > startIndex)
        {
            return text.Substring(startIndex + 1, endIndex - startIndex - 1).Trim();
        }
        
        return string.Empty;
    }
}