Added expert field mirror flow

src/common/auth/guards/auth.guard.ts

@@ -0,0 +1,35 @@
+import {
+  CanActivate,
+  ExecutionContext,
+  Injectable,
+  UnauthorizedException,
+} from "@nestjs/common";
+import { JwtService } from "@nestjs/jwt";
+import { Request } from "express";
+import { JwtPayload } from "../types/payload.types";
+
+@Injectable()
+export class AuthGuard implements CanActivate {
+  constructor(private readonly jwtService: JwtService) {}
+
+  async canActivate(context: ExecutionContext): Promise<boolean> {
+    const request = context.switchToHttp().getRequest<Request>();
+    const token = this.extractTokenFromHeader(request);
+    if (!token) {
+      throw new UnauthorizedException("No token provided");
+    }
+    try {
+      const payload: JwtPayload =
+        await this.jwtService.verifyAsync<JwtPayload>(token);
+      request["user"] = payload;
+    } catch {
+      throw new UnauthorizedException("Invalid or expired token");
+    }
+    return true;
+  }
+
+  private extractTokenFromHeader(request: Request): string | undefined {
+    const [type, token] = request.headers.authorization?.split(" ") ?? [];
+    return type === "Bearer" ? token : undefined;
+  }
+}