package com.imutil.service.impl;

import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.imutil.common.MsgKeys;
import com.imutil.entity.DistQueue;
import com.imutil.entity.GroupMapping;
import com.imutil.entity.ImMessage;
import com.imutil.entity.Tenant;
import com.imutil.mapper.DistQueueMapper;
import com.imutil.mapper.GroupMappingMapper;
import com.imutil.mapper.ImMessageMapper;
import com.imutil.mapper.PullWatermarkMapper;
import com.imutil.service.CallbackService;
import com.imutil.service.CrossTenantService;
import com.imutil.service.TenantService;
import lombok.extern.slf4j.Slf4j;
import org.noear.snack4.ONode;
import org.noear.solon.annotation.Component;
import org.noear.solon.annotation.Inject;
import org.noear.solon.data.annotation.Tran;

import java.time.Instant;
import java.time.OffsetDateTime;
import java.time.ZoneId;

/**
 * 腾讯回调处理服务实现
 * <p>
 * 流程：识别租户 → 消息类回调落 im_message（幂等）→ 所有回调写 dist_queue 分发业务系统。
 * {@code @Tran} 保证消息落库与分发入队同事务：要么同时成功，要么都不入库（避免半写）。
 *
 * @author imutil
 */
@Slf4j
@Component
public class CallbackServiceImpl implements CallbackService {

    /** 消息类回调命令关键字（命中则额外落 im_message） */
    private static final String[] MSG_COMMAND_KEYWORDS = {"SendMsg", "RecvMsg"};

    @Inject
    private ImMessageMapper imMessageMapper;

    @Inject
    private DistQueueMapper distQueueMapper;

    @Inject
    private GroupMappingMapper groupMappingMapper;

    @Inject
    private PullWatermarkMapper pullWatermarkMapper;

    @Inject
    private TenantService tenantService;

    @Inject
    private CrossTenantService crossTenantService;

    @Override
    @Tran
    public String handleCallback(String callbackCommand, String body) {
        if (callbackCommand == null || callbackCommand.isEmpty()) {
            return ok();
        }
        ONode node;
        try {
            node = ONode.ofJson(body == null ? "{}" : body);
        } catch (Exception e) {
            log.warn("回调 body 解析失败 command={} : {}", callbackCommand, e.getMessage());
            return ok();
        }

        // 1. 识别租户
        String tenantId = identifyTenant(callbackCommand, node);
        if (tenantId == null) {
            // 无法识别租户（如腾讯系统消息 administrator），不落库不分发
            log.debug("回调无法识别租户，跳过 command={} from={}", callbackCommand, node.get("FromAccount").getString());
            return ok();
        }

        // 2. 消息类回调落库 im_message（幂等：msg_key 存在则跳过）
        //    msg_key = command:from:convTarget:msgSeq:msgRandom，含 MsgSeq+MsgRandom 全局唯一，单独作幂等键；
        //    不依赖 MsgTimeStamp（避免腾讯回调时间戳偏差导致漏判）。
        //    DB 主键 (msg_key, msg_time) 因分区表约束保留 msg_time，作兜底防护。
        String msgKey = null;
        // 跨租户授权命中的对端账号（非空表示该消息为授权放行的跨租户消息，需额外分发+审计）
        String crossToImUser = null;
        Long crossGrantId = null;
        if (isMessageCallback(callbackCommand)) {
            ImMessage msg = parseMessage(callbackCommand, node, tenantId);
            if (msg != null) {
                msgKey = msg.getMsgKey();
                // 跨租户授权检查（仅 C2C；群消息跨租户语义为群成员维度，本设计不处理）
                if (msg.getConvType() != null && msg.getConvType() == 1) {
                    String toTenant = parsePrefix(msg.getConvId());
                    if (toTenant != null && !toTenant.equals(tenantId)) {
                        crossGrantId = crossTenantService.checkSendMsgGrant(
                                tenantId, msg.getFromAccount(), toTenant, msg.getConvId());
                        if (crossGrantId != null) {
                            msg.setIsCrossTenant(true);
                            crossToImUser = msg.getConvId();
                        }
                    }
                }
                long exists = imMessageMapper.selectCount(Wrappers.<ImMessage>lambdaQuery()
                        .eq(ImMessage::getMsgKey, msg.getMsgKey()));
                if (exists == 0) {
                    imMessageMapper.insert(msg);
                    // 推进补拉水位线：记录该会话最新消息位置，补拉任务据此增量拉取（兜底回调丢失）
                    pullWatermarkMapper.upsert(tenantId, msg.getConvId(), msg.getConvType(),
                            node.get("MsgSeq").getLong(), msg.getMsgTime(), OffsetDateTime.now());
                }
            }
        }

        // 3. 分发给 from 租户（payload=原始回调体，供业务系统消费）
        String convId = extractConvId(callbackCommand, node);
        enqueueIfConfigured(tenantId, msgKey, convId, body);

        // 4. 跨租户授权放行：额外分发给 to 租户 + 记录审计
        if (crossGrantId != null && crossToImUser != null) {
            String toTenant = parsePrefix(crossToImUser);
            enqueueIfConfigured(toTenant, msgKey, convId, body);
            crossTenantService.audit(crossGrantId, msgKey,
                    node.get("FromAccount").getString(), crossToImUser);
        }
        return ok();
    }

    /**
     * 租户配置了回调地址则入队分发
     *
     * @param tenantId 目标租户
     * @param msgKey   消息键（非消息类回调可为 null）
     * @param convId   会话ID（保序分桶用）
     * @param payload  分发载荷（原始回调体）
     */
    private void enqueueIfConfigured(String tenantId, String msgKey, String convId, String payload) {
        Tenant tenant = tenantService.getById(tenantId);
        if (tenant == null || tenant.getCallbackUrl() == null || tenant.getCallbackUrl().isEmpty()) {
            return;
        }
        DistQueue q = new DistQueue();
        q.setMsgKey(msgKey);
        q.setTenantId(tenantId);
        q.setConvId(convId);
        q.setTargetUrl(tenant.getCallbackUrl());
        q.setPayload(payload);
        q.setStatus(0);
        q.setRetryCount(0);
        q.setNextRetryAt(OffsetDateTime.now());
        distQueueMapper.insert(q);
    }

    /**
     * 识别租户：优先 FromAccount 前缀，群回调用 GroupId 查 group_mapping
     *
     * @return 租户ID，识别失败返回 null
     */
    private String identifyTenant(String command, ONode node) {
        String from = node.get("FromAccount").getString();
        if (from != null && !from.isEmpty()) {
            String tenantId = parsePrefix(from);
            if (tenantId != null && tenantService.getById(tenantId) != null) {
                return tenantId;
            }
        }
        // 群回调：GroupId 查映射
        String groupId = node.get("GroupId").getString();
        if (groupId != null && !groupId.isEmpty()) {
            GroupMapping gm = groupMappingMapper.selectOne(Wrappers.<GroupMapping>lambdaQuery()
                    .eq(GroupMapping::getImGroupId, groupId).last("LIMIT 1"));
            if (gm != null) {
                return gm.getTenantId();
            }
            // 群ID也带前缀
            String tid = parsePrefix(groupId);
            if (tid != null && tenantService.getById(tid) != null) {
                return tid;
            }
        }
        return null;
    }

    /**
     * 从带前缀的 IM 标识提取租户码（第一个下划线前部分）
     */
    private String parsePrefix(String imId) {
        if (imId == null || imId.isEmpty()) {
            return null;
        }
        int idx = imId.indexOf('_');
        if (idx <= 0) {
            return null;
        }
        return imId.substring(0, idx);
    }

    /**
     * 是否为消息类回调（需落 im_message）
     */
    private boolean isMessageCallback(String command) {
        for (String kw : MSG_COMMAND_KEYWORDS) {
            if (command.contains(kw)) {
                return true;
            }
        }
        return false;
    }

    /**
     * 解析消息体，构造 ImMessage（含幂等键 msg_key）
     */
    private ImMessage parseMessage(String command, ONode node, String tenantId) {
        String from = node.get("FromAccount").getString();
        String to = node.get("ToAccount").getString();
        if (to == null || to.isEmpty()) {
            to = node.get("ToPlayerId").getString();
        }
        String groupId = node.get("GroupId").getString();
        long msgSeq = node.get("MsgSeq").getLong();
        long msgRandom = node.get("MsgRandom").getLong();
        long msgTs = node.get("MsgTimeStamp").getLong();

        if (msgTs == 0) {
            msgTs = System.currentTimeMillis() / 1000L;
        }
        OffsetDateTime msgTime = OffsetDateTime.ofInstant(Instant.ofEpochSecond(msgTs), ZoneId.systemDefault());

        // msg_key 组合保证全局唯一与幂等（与补拉路径共享 MsgKeys 算法，跨路径去重）
        String convTarget = (groupId != null && !groupId.isEmpty()) ? groupId : (to != null ? to : "");
        String msgKey = MsgKeys.build(from, convTarget, msgSeq, msgRandom);

        ImMessage msg = new ImMessage();
        msg.setMsgKey(msgKey);
        msg.setTenantId(tenantId);
        msg.setMsgTime(msgTime);
        msg.setConvType(groupId != null && !groupId.isEmpty() ? 2 : 1);
        msg.setConvId(groupId != null && !groupId.isEmpty() ? groupId : (to != null ? to : ""));
        msg.setFromAccount(from);
        msg.setToAccount(groupId != null && !groupId.isEmpty() ? null : to);
        msg.setGroupId(groupId);
        msg.setMsgType(node.get("MsgType").getString());
        msg.setMsgBody(node.get("MsgBody").toString());
        msg.setSource("CALLBACK");
        msg.setIsCrossTenant(false);
        msg.setDistStatus(0);
        return msg;
    }

    /**
     * 提取会话ID（用于 dist_queue 保序分桶）
     */
    private String extractConvId(String command, ONode node) {
        String groupId = node.get("GroupId").getString();
        if (groupId != null && !groupId.isEmpty()) {
            return groupId;
        }
        String to = node.get("ToAccount").getString();
        if (to == null || to.isEmpty()) {
            to = node.get("ToPlayerId").getString();
        }
        return to;
    }

    /**
     * 返回腾讯回调成功响应
     */
    private String ok() {
        return "{\"ActionStatus\":\"OK\",\"ErrorCode\":0,\"ErrorInfo\":\"\"}";
    }
}