package com.se.nsl.utils;

import org.springframework.http.*;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;

import java.util.Map;
import java.util.Optional;

/**
 * HTTP 请求工具类，支持带/不带 Token 的请求
 */
public class HttpRequestUtil {

    private static final RestTemplate restTemplate = new RestTemplate();

    /**
     * 发送 GET 请求（不带 Token）
     */
    public static <T> ResponseEntity<T> get(String url, Map<String, String> params, Class<T> responseType) {
        return get(url, params, responseType, null);
    }

    /**
     * 发送 GET 请求（带 Token）
     */
    public static <T> ResponseEntity<T> get(String url, Map<String, String> params, Class<T> responseType, String token) {
        HttpEntity<String> entity = new HttpEntity<>(null, createHeaders(token));

        // 构建带参数的 URL
        if (params != null && !params.isEmpty()) {
            StringBuilder urlBuilder = new StringBuilder(url).append("?");
            params.forEach((key, value) -> urlBuilder.append(key).append("=").append(value).append("&"));
            url = urlBuilder.substring(0, urlBuilder.length() - 1);
        }

        return restTemplate.exchange(url, HttpMethod.GET, entity, responseType);
    }

    /**
     * 发送 POST 请求（不带 Token）
     */
    public static <T, B> ResponseEntity<T> post(String url, B body, Class<T> responseType) {
        return post(url, body, responseType, null);
    }

    /**
     * 发送 POST 请求（带 Token）
     */
    public static <T, B> ResponseEntity<T> post(String url, B body, Class<T> responseType, String token) {
        HttpHeaders headers = createHeaders(token);
        headers.setContentType(MediaType.APPLICATION_JSON);
        HttpEntity<B> entity = new HttpEntity<>(body, headers);

        return restTemplate.exchange(url, HttpMethod.POST, entity, responseType);
    }

    /**
     * 发送表单 POST 请求（不带 Token）
     */
    public static <T> ResponseEntity<T> postForm(String url, Map<String, Object> formData, Class<T> responseType) {
        return postForm(url, formData, responseType, null);
    }

    /**
     * 发送表单 POST 请求（带 Token）
     */
    public static <T> ResponseEntity<T> postForm(String url, Map<String, Object> formData, Class<T> responseType, String token) {
        HttpHeaders headers = createHeaders(token);
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);

        MultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
        if (formData != null) {
            formData.forEach(map::add);
        }

        HttpEntity<MultiValueMap<String, Object>> entity = new HttpEntity<>(map, headers);

        return restTemplate.exchange(url, HttpMethod.POST, entity, responseType);
    }

    /**
     * 发送 PUT 请求（不带 Token）
     */
    public static <T, B> ResponseEntity<T> put(String url, B body, Class<T> responseType) {
        return put(url, body, responseType, null);
    }

    /**
     * 发送 PUT 请求（带 Token）
     */
    public static <T, B> ResponseEntity<T> put(String url, B body, Class<T> responseType, String token) {
        HttpHeaders headers = createHeaders(token);
        headers.setContentType(MediaType.APPLICATION_JSON);
        HttpEntity<B> entity = new HttpEntity<>(body, headers);

        return restTemplate.exchange(url, HttpMethod.PUT, entity, responseType);
    }

    /**
     * 发送 DELETE 请求（不带 Token）
     */
    public static <T> ResponseEntity<T> delete(String url, Class<T> responseType) {
        return delete(url, responseType, null);
    }

    /**
     * 发送 DELETE 请求（带 Token）
     */
    public static <T> ResponseEntity<T> delete(String url, Class<T> responseType, String token) {
        HttpEntity<String> entity = new HttpEntity<>(null, createHeaders(token));

        return restTemplate.exchange(url, HttpMethod.DELETE, entity, responseType);
    }

    /**
     * 创建 HTTP 头
     * @param token 认证 Token，可为 null
     * @return HTTP 头
     */
    private static HttpHeaders createHeaders(String token) {
        HttpHeaders headers = new HttpHeaders();
        headers.set("Accept", MediaType.APPLICATION_JSON_VALUE);

        // 如果提供了 Token，则添加到请求头
        Optional.ofNullable(token)
                .ifPresent(t -> headers.set("Authorization", "Bearer " + t));

        return headers;
    }
}