import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.*;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class JavaFileExtractor {

    private static final int MAX_LINES = 3000;
    private static final String OUTPUT_FILE = "extracted_java_code.txt";

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入要扫描的绝对路径: ");
        String inputPath = scanner.nextLine().trim();
        scanner.close();

        Path rootPath = Paths.get(inputPath);
        if (!Files.exists(rootPath) || !Files.isDirectory(rootPath)) {
            System.err.println("错误：路径不存在或不是目录: " + inputPath);
            return;
        }

        List<Path> javaFiles = new ArrayList<>();
        try {
            Files.walkFileTree(rootPath, new SimpleFileVisitor<Path>() {
                @Override
                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
                    if (file.toString().endsWith(".java")) {
                        javaFiles.add(file);
                    }
                    return FileVisitResult.CONTINUE;
                }

                @Override
                public FileVisitResult visitFileFailed(Path file, IOException exc) {
                    return FileVisitResult.CONTINUE;
                }
            });
        } catch (IOException e) {
            System.err.println("遍历文件出错: " + e.getMessage());
            return;
        }

        System.out.println("找到 " + javaFiles.size() + " 个Java文件");

        // 拼接所有文件处理后的内容
        List<String> allLines = new ArrayList<>();
        int lineCount = 0;

        for (Path file : javaFiles) {
            if (lineCount >= MAX_LINES) {
                break;
            }

            try {
                List<String> processedLines = processJavaFile(file);
                int remaining = MAX_LINES - lineCount;
                if (processedLines.size() <= remaining) {
                    allLines.addAll(processedLines);
                    lineCount += processedLines.size();
                } else {
                    allLines.addAll(processedLines.subList(0, remaining));
                    lineCount = MAX_LINES;
                    break;
                }
            } catch (IOException e) {
                System.err.println("读取文件出错: " + file + " -> " + e.getMessage());
            }
        }

        Path outputPath = rootPath.resolve(OUTPUT_FILE);
        try (PrintWriter writer = new PrintWriter(
                new OutputStreamWriter(new FileOutputStream(outputPath.toFile()), StandardCharsets.UTF_8))) {

            writer.println("========== Java代码提取报告 ==========");
            writer.println("扫描路径: " + inputPath);
            writer.println("Java文件数: " + javaFiles.size());
            writer.println("输出行数: " + Math.min(lineCount, MAX_LINES));
            writer.println("限制行数: " + MAX_LINES);
            writer.println("======================================\n");

            for (String line : allLines) {
                writer.println(line);
            }
        } catch (IOException e) {
            System.err.println("写入输出文件出错: " + e.getMessage());
            return;
        }

        System.out.println("处理完成！输出 " + Math.min(lineCount, MAX_LINES) + " 行到: " + outputPath.toAbsolutePath());
    }

    /**
     * 处理单个Java文件：去除空行和注释，返回行列表
     */
    private static List<String> processJavaFile(Path filePath) throws IOException {
        List<String> result = new ArrayList<>();
        List<String> lines = Files.readAllLines(filePath, StandardCharsets.UTF_8);

        boolean inBlockComment = false;

        for (String line : lines) {
            String trimmed = line.trim();

            if (inBlockComment) {
                int endIndex = trimmed.indexOf("*/");
                if (endIndex != -1) {
                    inBlockComment = false;
                    String after = trimmed.substring(endIndex + 2).trim();
                    if (!after.isEmpty()) {
                        result.add(after);
                    }
                }
                continue;
            }

            if (trimmed.contains("/*")) {
                int startIdx = trimmed.indexOf("/*");
                int endIdx = trimmed.indexOf("*/", startIdx + 2);
                if (endIdx != -1) {
                    String before = trimmed.substring(0, startIdx).trim();
                    String after = trimmed.substring(endIdx + 2).trim();
                    String combined = (before + " " + after).trim();
                    if (!combined.isEmpty()) {
                        result.add(combined);
                    }
                } else {
                    inBlockComment = true;
                    String before = trimmed.substring(0, startIdx).trim();
                    if (!before.isEmpty()) {
                        result.add(before);
                    }
                }
                continue;
            }

            if (trimmed.startsWith("//")) {
                continue;
            }

            int commentIdx = trimmed.indexOf("//");
            if (commentIdx != -1) {
                trimmed = trimmed.substring(0, commentIdx).trim();
            }

            if (trimmed.isEmpty()) {
                continue;
            }

            result.add(trimmed);
        }

        return result;
    }
}