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

namespace CodePlay.Core.Converters;

public class JavaCodeGenerator : ICodeGenerator
{
    private readonly StringBuilder _output = new();
    private int _indentLevel;
    private bool _needCollectors;
    private bool _needCompletableFuture;
    
    public string Generate(Interfaces.SyntaxTree syntaxTree)
    {
        _output.Clear();
        _indentLevel = 0;
        _needCollectors = false;
        _needCompletableFuture = false;
        
        var root = syntaxTree.Root;
        
        // 如果根节点的 Text 已经包含处理后的内容，直接使用
        if (!string.IsNullOrEmpty(root.Text) && 
            (root.Text.Contains("package ") || root.Text.Contains("import ")))
        {
            var lines = root.Text.Split('\n');
            foreach (var line in lines)
            {
                var trimmed = line.Trim();
                if (!string.IsNullOrEmpty(trimmed))
                {
                    _output.AppendLine(trimmed);
                    
                    if (trimmed.Contains("Collectors.")) _needCollectors = true;
                    if (trimmed.Contains("CompletableFuture.")) _needCompletableFuture = true;
                }
            }
            
            // 添加缺失的导入
            var outputStr = _output.ToString();
            if (_needCollectors && !outputStr.Contains("import java.util.stream.Collectors"))
            {
                outputStr = outputStr.Replace("package ", "import java.util.stream.Collectors;\npackage ");
            }
            if (_needCompletableFuture && !outputStr.Contains("import java.util.concurrent.CompletableFuture"))
            {
                outputStr = outputStr.Replace("package ", "import java.util.concurrent.CompletableFuture;\npackage ");
            }
            
            return outputStr;
        }
        
        GenerateNode(root);
        
        var result = _output.ToString();
        
        // 添加 Stream API 需要的导入
        if (result.Contains(".filter(") || result.Contains(".map(") || result.Contains(".collect("))
        {
            _needCollectors = true;
        }
        
        // 在 package 后添加导入
        if (_output.Length > 0)
        {
            var finalOutput = new StringBuilder();
            var content = _output.ToString();
            var pkgIndex = content.IndexOf("package ");
            
            if (pkgIndex >= 0)
            {
                var endOfPkg = content.IndexOf(';', pkgIndex);
                if (endOfPkg >= 0)
                {
                    finalOutput.Append(content.Substring(0, endOfPkg + 1));
                    finalOutput.AppendLine();
                    
                    if (_needCollectors)
                    {
                        finalOutput.AppendLine("import java.util.ArrayList;");
                        finalOutput.AppendLine("import java.util.HashMap;");
                        finalOutput.AppendLine("import java.util.stream.Collectors;");
                    }
                    if (_needCompletableFuture)
                    {
                        finalOutput.AppendLine("import java.util.concurrent.CompletableFuture;");
                    }
                    
                    finalOutput.AppendLine();
                    finalOutput.Append(content.Substring(endOfPkg + 1));
                }
                else
                {
                    finalOutput.Append(content);
                }
            }
            else
            {
                finalOutput.Append(content);
            }
            
            return finalOutput.ToString();
        }
        
        return result;
    }
    
    private void GenerateNode(Interfaces.SyntaxNode node)
    {
        if (node == null) return;
        
        if (node.Type == Interfaces.SyntaxNodeType.Unknown)
        {
            if (!string.IsNullOrWhiteSpace(node.Text))
            {
                var lines = node.Text.Split('\n');
                foreach (var line in lines)
                {
                    var trimmed = line.Trim();
                    if (!string.IsNullOrEmpty(trimmed) && !trimmed.StartsWith("{") && !trimmed.StartsWith("}"))
                        _output.AppendLine(Indent(trimmed));
                }
            }
            return;
        }
        
        switch (node.Type)
        {
            case Interfaces.SyntaxNodeType.CompilationUnit:
                GenerateCompilationUnit(node);
                break;
            case Interfaces.SyntaxNodeType.Class:
                GenerateClass(node);
                break;
            case Interfaces.SyntaxNodeType.Method:
                GenerateMethod(node);
                break;
            case Interfaces.SyntaxNodeType.Property:
                GenerateProperty(node);
                break;
            case Interfaces.SyntaxNodeType.Field:
                GenerateField(node);
                break;
        }
    }
    
    private void GenerateCompilationUnit(Interfaces.SyntaxNode node)
    {
        foreach (var child in node.Children)
            GenerateNode(child);
    }
    
    private void GenerateClass(Interfaces.SyntaxNode node)
    {
        var classLine = node.Text?.Trim() ?? "";
        if (!classLine.Contains("class ") && !classLine.Contains("interface ")) return;
        
        var braceIndex = classLine.IndexOf('{');
        if (braceIndex > 0) classLine = classLine.Substring(0, braceIndex).Trim();
        
        _output.AppendLine(Indent($"public {classLine.Replace("public ", "")} {{"));
        _indentLevel++;
        
        foreach (var child in node.Children)
            GenerateNode(child);
        
        _indentLevel--;
        _output.AppendLine(Indent("}"));
    }
    
    private void GenerateMethod(Interfaces.SyntaxNode node)
    {
        if (string.IsNullOrEmpty(node.Text)) return;
        
        var lines = node.Text.Split('\n').Select(l => l.Trim()).Where(l => !string.IsNullOrEmpty(l)).ToList();
        if (lines.Count == 0) return;
        
        var sig = lines[0];
        if (sig.EndsWith("{")) sig = sig.Substring(0, sig.Length - 1).Trim();
        
        _output.AppendLine(Indent($"{sig} {{"));
        _indentLevel++;
        
        var inBody = false;
        foreach (var line in lines)
        {
            if (line == "{") { inBody = true; continue; }
            if (line == "}") continue;
            if (inBody) _output.AppendLine(Indent(line));
        }
        
        _indentLevel--;
        _output.AppendLine(Indent("}"));
    }
    
    private void GenerateProperty(Interfaces.SyntaxNode node)
    {
        if (!string.IsNullOrWhiteSpace(node.Text))
            _output.AppendLine(Indent(node.Text.Trim()));
    }
    
    private void GenerateField(Interfaces.SyntaxNode node)
    {
        if (!string.IsNullOrWhiteSpace(node.Text))
            _output.AppendLine(Indent(node.Text.Trim()));
    }
    
    private string Indent(string text) => new string(' ', _indentLevel * 4) + text;
}