package com.skyversation.poiaddr.util;

import java.io.FileWriter;
import java.io.IOException;
import java.util.*;

public class CsvWriter {
    /**
     * 将 List<Map<String, Object>> 类型的数据写入 CSV 文件
     * @param data 要写入的数据
     * @param filePath CSV 文件的保存路径
     * @throws IOException 如果写入文件时发生 I/O 错误
     */
    public static void writeToCsv(List<Map<String, Object>> data, String filePath) throws IOException {
        if (data == null || data.isEmpty()) {
            return;
        }

        // 获取所有的列名
        Set<String> headers = new LinkedHashSet<>();
        for (Map<String, Object> row : data) {
            headers.addAll(row.keySet());
        }

        // 将列名写入 CSV 文件
        try (FileWriter writer = new FileWriter(filePath)) {
            writeLine(writer, new ArrayList<>(headers));

            // 遍历数据，将每一行写入 CSV 文件
            for (Map<String, Object> row : data) {
                List<String> values = new ArrayList<>();
                for (String header : headers) {
                    Object value = row.get(header);
                    values.add(value != null ? value.toString() : "");
                }
                writeLine(writer, values);
            }
        }
    }

    /**
     * 将一行数据写入 CSV 文件
     * @param writer 文件写入器
     * @param values 一行数据的值
     * @throws IOException 如果写入文件时发生 I/O 错误
     */
    private static void writeLine(FileWriter writer, List<String> values) throws IOException {
        boolean firstValue = true;
        for (String value : values) {
            if (!firstValue) {
                writer.append(",");
            }
            writer.append(escapeCsv(value));
            firstValue = false;
        }
        writer.append("\n");
    }

    /**
     * 转义 CSV 中的特殊字符
     * @param value 要转义的值
     * @return 转义后的字符串
     */
    private static String escapeCsv(String value) {
        if (value == null) {
            return "";
        }
        boolean needsQuotes = value.contains(",") || value.contains("\"") || value.contains("\n");
        if (needsQuotes) {
            value = value.replace("\"", "\"\"");
            return "\"" + value + "\"";
        }
        return value;
    }

    public static void main(String[] args) {
        List<Map<String, Object>> data = new ArrayList<>();
        Map<String,Object> item = new HashMap<>();
        item.put("列名1","test00");
        item.put("列名3","test02");
        Map<String,Object> item2 = new HashMap<>();
        item2.put("列名2","test11");
        item2.put("列名3","test12");
        data.add(item);
        data.add(item2);
        // 这里可以添加测试数据
        try {
            writeToCsv(data, "C:\\Users\\Liumouren\\Desktop\\outputTest.csv");
            System.out.println("CSV 文件写入成功！");
        } catch (IOException e) {
            System.err.println("写入 CSV 文件时发生错误：" + e.getMessage());
        }
    }
}