package com.ruoyi.cms.service;

import cn.hutool.http.HttpRequest;
import cn.hutool.http.HttpResponse;
import cn.hutool.http.HttpUtil;
import com.alibaba.fastjson2.JSONObject;
import com.ruoyi.common.exception.ServiceException;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;

import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

/**
 * 微信小程序服务端接口客户端。
 *
 * <p>该客户端只负责单次远程调用，不记录 appSecret、access token 或微信响应中的敏感内容。</p>
 */
@Component
public class WeChatMiniProgramApiClient
{
    private static final String ACCESS_TOKEN_URL = "https://api.weixin.qq.com/cgi-bin/token";
    private static final String UNLIMITED_QR_CODE_URL =
            "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token=";
    private static final int HTTP_TIMEOUT_MILLIS = 15000;

    public AccessTokenResult getAccessToken(String appId, String appSecret)
    {
        Map<String, Object> params = new HashMap<>();
        params.put("grant_type", "client_credential");
        params.put("appid", appId);
        params.put("secret", appSecret);
        String body = HttpUtil.get(ACCESS_TOKEN_URL, params, HTTP_TIMEOUT_MILLIS);
        JSONObject json = parseJson(body, "获取微信 access token 失败");
        String accessToken = json.getString("access_token");
        Integer expiresIn = json.getInteger("expires_in");
        if (accessToken == null || accessToken.trim().isEmpty()) {
            throw weChatError("获取微信 access token 失败", json);
        }
        return new AccessTokenResult(accessToken, expiresIn == null ? 7200 : expiresIn);
    }

    public QrCodeImage getUnlimitedQrCode(String accessToken, String scene, String page)
    {
        JSONObject requestBody = new JSONObject();
        requestBody.put("scene", scene);
        requestBody.put("page", page);
        // 新页面尚未随小程序版本发布时也允许先生成码；扫码仍会进入正式版小程序。
        requestBody.put("check_path", false);
        requestBody.put("env_version", "release");
        requestBody.put("width", 430);

        HttpResponse response = null;
        try {
            response = HttpRequest.post(UNLIMITED_QR_CODE_URL + accessToken)
                    .timeout(HTTP_TIMEOUT_MILLIS)
                    .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
                    .body(requestBody.toJSONString())
                    .execute();
            byte[] body = response.bodyBytes();
            String contentType = response.header(HttpHeaders.CONTENT_TYPE);
            if (response.isOk() && body != null && body.length > 0
                    && isImageResponse(contentType, body)) {
                return new QrCodeImage(body, normalizeImageContentType(contentType, body));
            }
            String errorBody = body == null ? "" : new String(body, StandardCharsets.UTF_8);
            JSONObject errorJson = parseJson(errorBody, "生成微信小程序码失败");
            throw weChatError("生成微信小程序码失败", errorJson);
        } finally {
            if (response != null) {
                response.close();
            }
        }
    }

    private boolean isImageResponse(String contentType, byte[] body)
    {
        return (contentType != null && contentType.toLowerCase().startsWith("image/"))
                || isPng(body) || isJpeg(body);
    }

    private String normalizeImageContentType(String contentType, byte[] body)
    {
        if (contentType != null && contentType.toLowerCase().startsWith("image/")) {
            int separator = contentType.indexOf(';');
            return separator > 0 ? contentType.substring(0, separator) : contentType;
        }
        return isJpeg(body) ? MediaType.IMAGE_JPEG_VALUE : MediaType.IMAGE_PNG_VALUE;
    }

    private boolean isPng(byte[] body)
    {
        return body.length >= 8
                && (body[0] & 0xff) == 0x89
                && body[1] == 0x50
                && body[2] == 0x4e
                && body[3] == 0x47;
    }

    private boolean isJpeg(byte[] body)
    {
        return body.length >= 3
                && (body[0] & 0xff) == 0xff
                && (body[1] & 0xff) == 0xd8
                && (body[2] & 0xff) == 0xff;
    }

    private JSONObject parseJson(String body, String action)
    {
        try {
            JSONObject json = JSONObject.parseObject(body);
            if (json == null) {
                throw new IllegalArgumentException("empty json");
            }
            return json;
        } catch (Exception exception) {
            throw new ServiceException(action + "，微信接口返回了无法识别的响应");
        }
    }

    private ServiceException weChatError(String action, JSONObject json)
    {
        Integer errorCode = json.getInteger("errcode");
        String errorMessage = json.getString("errmsg");
        StringBuilder message = new StringBuilder(action);
        if (errorCode != null) {
            message.append("（错误码：").append(errorCode).append('）');
        }
        if (errorMessage != null && !errorMessage.trim().isEmpty()) {
            message.append("：").append(errorMessage);
        }
        return new ServiceException(message.toString());
    }

    public static class AccessTokenResult
    {
        private final String accessToken;
        private final int expiresIn;

        public AccessTokenResult(String accessToken, int expiresIn)
        {
            this.accessToken = accessToken;
            this.expiresIn = expiresIn;
        }

        public String getAccessToken()
        {
            return accessToken;
        }

        public int getExpiresIn()
        {
            return expiresIn;
        }
    }

    public static class QrCodeImage
    {
        private final byte[] content;
        private final String contentType;

        public QrCodeImage(byte[] content, String contentType)
        {
            this.content = content;
            this.contentType = contentType;
        }

        public byte[] getContent()
        {
            return content;
        }

        public String getContentType()
        {
            return contentType;
        }
    }
}