package com.sinata.appointment.integration;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.sinata.appointment.config.WechatMiniAppProperties;
import com.sinata.appointment.constants.BizErrorCode;
import com.sinata.appointment.exception.BizException;
import java.util.concurrent.locks.ReentrantLock;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;

/**
 * 微信小程序服务端：js_code → openId；access_token + phoneCode → 手机号。
 *
 * <p>官方文档：code2session、getAccessToken(client_credential)、getuserphonenumber。
 */
@Slf4j
@Service
public class WechatMiniGateway {

    private static final String JSCODE2SESSION =
            "https://api.weixin.qq.com/sns/jscode2session";
    private static final String CGI_BIN_TOKEN =
            "https://api.weixin.qq.com/cgi-bin/token";
    private static final String GET_USER_PHONE =
            "https://api.weixin.qq.com/wxa/business/getuserphonenumber";

    private final WechatMiniAppProperties props;
    private final RestTemplate restTemplate;
    private final ObjectMapper objectMapper;

    private final ReentrantLock tokenLock = new ReentrantLock();
    private volatile String cachedAccessToken;
    private volatile long accessTokenExpireAtEpochMs;

    public WechatMiniGateway(
            WechatMiniAppProperties props,
            @Qualifier("wechatRestTemplate") RestTemplate restTemplate,
            ObjectMapper objectMapper) {
        this.props = props;
        this.restTemplate = restTemplate;
        this.objectMapper = objectMapper;
    }

    public WxCode2SessionResult code2Session(String jsCode) {
        if (jsCode == null || jsCode.isBlank()) {
            throw new BizException(BizErrorCode.AUTH_INVALID_CREDENTIALS, "wxCode 不能为空");
        }
        if (props.useStub()) {
            log.debug("Wechat mini stub: code2Session");
            return WxCode2SessionResult.stub(jsCode);
        }
        String url =
                UriComponentsBuilder.fromHttpUrl(JSCODE2SESSION)
                        .queryParam("appid", props.getAppId())
                        .queryParam("secret", props.getAppSecret())
                        .queryParam("js_code", jsCode)
                        .queryParam("grant_type", "authorization_code")
                        .build()
                        .toUriString();
        try {
            String body = restTemplate.getForObject(url, String.class);
            JsonNode root = objectMapper.readTree(body);
            int err = root.path("errcode").asInt(0);
            if (err != 0) {
                String msg = root.path("errmsg").asText("wx error");
                log.warn("code2session errcode={} msg={}", err, msg);
                throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "微信登录失败: " + msg);
            }
            String openId = root.path("openid").asText(null);
            if (openId == null || openId.isBlank()) {
                throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "微信未返回 openid");
            }
            return WxCode2SessionResult.builder()
                    .openId(openId)
                    .unionId(root.path("unionid").asText(null))
                    .sessionKey(root.path("session_key").asText(null))
                    .build();
        } catch (BizException e) {
            throw e;
        } catch (Exception e) {
            log.error("code2session http error", e);
            throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "微信接口调用异常");
        }
    }

    /**
     * @param phoneCode 前端 button open-type=getPhoneNumber 回调中的 code（非手机号明文）
     */
    public String getPhoneNumber(String phoneCode) {
        if (phoneCode == null || phoneCode.isBlank()) {
            throw new BizException(BizErrorCode.AUTH_INVALID_CREDENTIALS, "phoneCode 不能为空");
        }
        if (props.useStub()) {
            int h = Math.abs(phoneCode.hashCode() % 100_000_000);
            String stubPhone = "138" + String.format("%08d", h);
            log.debug("Wechat mini stub: phoneCode -> {}", stubPhone);
            return stubPhone;
        }
        String token = getAccessToken();
        String url =
                UriComponentsBuilder.fromHttpUrl(GET_USER_PHONE)
                        .queryParam("access_token", token)
                        .build()
                        .toUriString();
        try {
            String reqJson = objectMapper.createObjectNode().put("code", phoneCode).toString();
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.APPLICATION_JSON);
            String body =
                    restTemplate.postForObject(url, new HttpEntity<>(reqJson, headers), String.class);
            JsonNode root = objectMapper.readTree(body);
            int err = root.path("errcode").asInt(-1);
            if (err != 0) {
                String msg = root.path("errmsg").asText("wx error");
                log.warn("getuserphonenumber errcode={} msg={}", err, msg);
                throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "获取手机号失败: " + msg);
            }
            String phone = root.path("phone_info").path("purePhoneNumber").asText(null);
            if (phone == null || phone.isBlank()) {
                phone = root.path("phone_info").path("phoneNumber").asText(null);
            }
            if (phone == null || phone.isBlank()) {
                throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "微信未返回手机号");
            }
            return phone;
        } catch (BizException e) {
            throw e;
        } catch (Exception e) {
            log.error("getuserphonenumber http error", e);
            throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "微信手机号接口异常");
        }
    }

    private String getAccessToken() {
        tokenLock.lock();
        try {
            long now = System.currentTimeMillis();
            if (cachedAccessToken != null && now < accessTokenExpireAtEpochMs - 120_000) {
                return cachedAccessToken;
            }
            String url =
                    UriComponentsBuilder.fromHttpUrl(CGI_BIN_TOKEN)
                            .queryParam("grant_type", "client_credential")
                            .queryParam("appid", props.getAppId())
                            .queryParam("secret", props.getAppSecret())
                            .build()
                            .toUriString();
            String body = restTemplate.getForObject(url, String.class);
            JsonNode root = objectMapper.readTree(body);
            int err = root.path("errcode").asInt(0);
            if (err != 0) {
                throw new BizException(
                        BizErrorCode.MINI_WX_API_ERROR,
                        "获取 access_token 失败: " + root.path("errmsg").asText());
            }
            String token = root.path("access_token").asText(null);
            int expiresIn = root.path("expires_in").asInt(7200);
            if (token == null || token.isBlank()) {
                throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "微信未返回 access_token");
            }
            cachedAccessToken = token;
            accessTokenExpireAtEpochMs = now + expiresIn * 1000L;
            return token;
        } catch (BizException e) {
            throw e;
        } catch (Exception e) {
            log.error("getAccessToken error", e);
            throw new BizException(BizErrorCode.MINI_WX_API_ERROR, "获取 access_token 异常");
        } finally {
            tokenLock.unlock();
        }
    }
}