// src/main/java/com/llm/analysis/ExcelExporter.java
package com.llm.analysis;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.Map;

public class ExcelExporter {

    /**
     * 将词频统计结果写入XLSX文件。
     * @param topWords Top N 词语列表
     * @param filename 输出文件名
     */
    public static void exportToXLSX(List<Map.Entry<String, Long>> topWords, String filename) {
        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet("LLM应用案例词频");

        // 创建表头
        Row headerRow = sheet.createRow(0);
        headerRow.createCell(0).setCellValue("排名");
        headerRow.createCell(1).setCellValue("词语/LLM应用案例");
        headerRow.createCell(2).setCellValue("词频 (总数)");

        // 填充数据
        int rowNum = 1;
        for (int i = 0; i < topWords.size(); i++) {
            Map.Entry<String, Long> entry = topWords.get(i);
            Row row = sheet.createRow(rowNum++);
            
            row.createCell(0).setCellValue(i + 1); // 排名
            row.createCell(1).setCellValue(entry.getKey()); // 词语
            row.createCell(2).setCellValue(entry.getValue()); // 词频
        }

        // 自动调整列宽
        for (int i = 0; i < 3; i++) {
            sheet.autoSizeColumn(i);
        }

        // 写入文件
        try (FileOutputStream fileOut = new FileOutputStream(filename)) {
            workbook.write(fileOut);
            System.out.println("✅ 数据成功导出到 " + filename);
        } catch (IOException e) {
            System.err.println("导出Excel失败：" + e.getMessage());
        } finally {
            try {
                workbook.close();
            } catch (IOException e) {
                // Ignore
            }
        }
    }
}