package com.example.demo.Util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.FileSystemResource;
import org.springframework.http.*;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;

import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.Map;

/**
 * Excel文件上传工具类
 */
public class ExcelUploadUtil {
    private static final Logger logger = LoggerFactory.getLogger(ExcelUploadUtil.class);

    // 默认配置
    private static final int DEFAULT_CONNECT_TIMEOUT = 30000; // 30秒
    private static final int DEFAULT_READ_TIMEOUT = 60000;    // 60秒

    private final RestTemplate restTemplate;
    private final String uploadUrl;
    private final Map<String, String> defaultHeaders;
    private final Map<String, String> defaultParams;

    /**
     * 构造方法
     *
     * @param uploadUrl 上传接口URL
     */
    public ExcelUploadUtil(String uploadUrl) {
        this(uploadUrl, new HashMap<>(), new HashMap<>());
    }

    /**
     * 构造方法
     *
     * @param uploadUrl      上传接口URL
     * @param defaultHeaders 默认请求头
     * @param defaultParams  默认请求参数
     */
    public ExcelUploadUtil(String uploadUrl, Map<String, String> defaultHeaders, Map<String, String> defaultParams) {
        this.uploadUrl = uploadUrl;
        this.defaultHeaders = new HashMap<>(defaultHeaders);
        this.defaultParams = new HashMap<>(defaultParams);
        this.restTemplate = createRestTemplate(DEFAULT_CONNECT_TIMEOUT, DEFAULT_READ_TIMEOUT);
    }

    /**
     * 创建RestTemplate (Spring Boot 1.x 兼容版本)
     */
    private RestTemplate createRestTemplate(int connectTimeout, int readTimeout) {
        RestTemplate restTemplate = new RestTemplate();

        // 添加字符串消息转换器 (Spring 1.x 使用Charset而不是StandardCharsets)
        restTemplate.getMessageConverters().add(0, new StringHttpMessageConverter(Charset.forName("UTF-8")));

        // 设置超时 (Spring 1.x 方式)
        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
        factory.setConnectTimeout(connectTimeout);
        factory.setReadTimeout(readTimeout);
        restTemplate.setRequestFactory(factory);

        return restTemplate;
    }

    /**
     * 上传Excel文件
     *
     * @param excelFile Excel文件
     * @param targetDir 目标目录
     * @return 上传结果
     * @throws IOException     文件操作异常
     * @throws UploadException 上传异常
     */
    public String uploadExcel(File excelFile, String targetDir) throws IOException, UploadException {
        return uploadExcel(excelFile, targetDir, new HashMap<>(), new HashMap<>());
    }

    /**
     * 上传Excel文件（带自定义参数）
     *
     * @param excelFile     Excel文件
     * @param targetDir     目标目录
     * @param customHeaders 自定义请求头
     * @param customParams  自定义请求参数
     * @return 上传结果
     * @throws IOException     文件操作异常
     * @throws UploadException 上传异常
     */
    public String uploadExcel(File excelFile, String targetDir,
                              Map<String, String> customHeaders,
                              Map<String, String> customParams) throws IOException, UploadException {
        // 验证文件
        validateFile(excelFile);

        try {
            // 准备请求
            HttpEntity<MultiValueMap<String, Object>> requestEntity = prepareRequest(excelFile, targetDir, customHeaders, customParams);

            // 执行上传
            ResponseEntity<String> response = restTemplate.exchange(
                    uploadUrl,
                    HttpMethod.POST,
                    requestEntity,
                    String.class
            );

            // 处理响应
            return handleResponse(response, excelFile.getName());
        } catch (Exception e) {
            logger.error("Excel文件上传失败: {}", excelFile.getAbsolutePath(), e);
            throw new UploadException("文件上传失败: " + e.getMessage(), e);
        }
    }

    /**
     * 验证文件
     */
    private void validateFile(File file) throws IOException {
        if (file == null) {
            throw new IOException("文件不能为null");
        }
        if (!file.exists()) {
            throw new IOException("文件不存在: " + file.getAbsolutePath());
        }
        if (!file.isFile()) {
            throw new IOException("不是有效的文件: " + file.getAbsolutePath());
        }
        if (file.length() == 0) {
            throw new IOException("文件内容为空: " + file.getAbsolutePath());
        }
        if (!file.getName().toLowerCase().endsWith(".xlsx") &&
                !file.getName().toLowerCase().endsWith(".xls")) {
            throw new IOException("仅支持Excel文件(.xlsx, .xls)");
        }
    }

    /**
     * 准备请求
     */
    private HttpEntity<MultiValueMap<String, Object>> prepareRequest(File file, String targetDir,
                                                                     Map<String, String> customHeaders,
                                                                     Map<String, String> customParams) {
        // 设置请求头
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.MULTIPART_FORM_DATA);

        // 添加默认和自定义请求头
        defaultHeaders.forEach(headers::set);
        customHeaders.forEach(headers::set);

        // 准备请求体
        MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
        body.add("file", new FileSystemResource(file));
        body.add("dir", targetDir);

        // 添加默认和自定义参数
        defaultParams.forEach(body::add);
        customParams.forEach(body::add);

        return new HttpEntity<>(body, headers);
    }

    /**
     * 处理响应
     */
    private String handleResponse(ResponseEntity<String> response, String filename) throws UploadException {
        if (response.getStatusCode() == HttpStatus.OK) {
            logger.info("文件上传成功: {}", filename);
            return response.getBody();
        } else {
            String errorMsg = String.format("上传接口返回错误状态码: %d, 响应: %s",
                    response.getStatusCodeValue(), response.getBody());
            logger.error(errorMsg);
            throw new UploadException(errorMsg);
        }
    }

    /**
     * 自定义上传异常
     */
    public static class UploadException extends Exception {
        public UploadException(String message) {
            super(message);
        }

        public UploadException(String message, Throwable cause) {
            super(message, cause);
        }
    }
}