feat: 实现实时匿名会话

apps/api/src/conversation/chat-rate-limiter.ts

@@ -0,0 +1,22 @@
+import { Inject, Injectable } from "@nestjs/common";
+import { RedisService } from "../redis/redis.service.js";
+
+@Injectable()
+export class ChatRateLimiter {
+  constructor(@Inject(RedisService) private readonly redis: RedisService) {}
+  async consume(accountId: string, sessionId: string): Promise<boolean> {
+    await this.redis.ensureConnected();
+    const prefix = process.env.REDIS_KEY_PREFIX ?? "drift:auth:";
+    const max = Number(process.env.CHAT_MESSAGE_RATE_LIMIT ?? 30);
+    const ttl = Number(process.env.CHAT_MESSAGE_RATE_WINDOW_SECONDS ?? 60);
+    const keys = [
+      `${prefix}chat:account:${accountId}`,
+      `${prefix}chat:session:${sessionId}`,
+    ];
+    const result = await this.redis.client.eval(
+      `for _,k in ipairs(KEYS) do if tonumber(redis.call('GET',k) or '0')+1>tonumber(ARGV[1]) then return 0 end end; for _,k in ipairs(KEYS) do local n=redis.call('INCR',k); if n==1 then redis.call('EXPIRE',k,ARGV[2]) end end; return 1`,
+      { keys, arguments: [String(max), String(ttl)] },
+    );
+    return Number(result) === 1;
+  }
+}