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backend/src/main/java/com/example/demo/auth/JwtService.java

@@ -0,0 +1,59 @@
+package com.example.demo.auth;
+
+import com.auth0.jwt.JWT;
+import com.auth0.jwt.algorithms.Algorithm;
+import com.auth0.jwt.interfaces.DecodedJWT;
+import com.auth0.jwt.interfaces.JWTVerifier;
+import org.springframework.stereotype.Service;
+
+import java.time.Instant;
+import java.util.HashMap;
+import java.util.Map;
+
+@Service
+public class JwtService {
+    private final JwtProperties props;
+
+    public JwtService(JwtProperties props) {
+        this.props = props;
+    }
+
+    public String signToken(Long userId, Long shopId, String phone, String provider) {
+        Instant now = Instant.now();
+        Algorithm alg = Algorithm.HMAC256(props.getSecret() == null ? "dev-secret" : props.getSecret());
+        var jwt = JWT.create()
+                .withIssuer(props.getIssuer())
+                .withIssuedAt(java.util.Date.from(now))
+                .withExpiresAt(java.util.Date.from(now.plusSeconds(props.getTtlSeconds())))
+                .withClaim("userId", userId)
+                .withClaim("shopId", shopId)
+                .withClaim("provider", provider);
+        if (phone != null && !phone.isBlank()) jwt.withClaim("phone", phone);
+        return jwt.sign(alg);
+    }
+
+    public Map<String,Object> parseClaims(String authorizationHeader) {
+        Map<String,Object> out = new HashMap<>();
+        if (authorizationHeader == null || authorizationHeader.isBlank()) return out;
+        String prefix = "Bearer ";
+        if (!authorizationHeader.startsWith(prefix)) return out;
+        String token = authorizationHeader.substring(prefix.length()).trim();
+        try {
+            Algorithm alg = Algorithm.HMAC256(props.getSecret() == null ? "dev-secret" : props.getSecret());
+            JWTVerifier verifier = JWT.require(alg)
+                    .withIssuer(props.getIssuer())
+                    .acceptLeeway(props.getClockSkewSeconds())
+                    .build();
+            DecodedJWT jwt = verifier.verify(token);
+            Long userId = jwt.getClaim("userId").asLong();
+            Long shopId = jwt.getClaim("shopId").asLong();
+            String phone = jwt.getClaim("phone").asString();
+            if (userId != null) out.put("userId", userId);
+            if (shopId != null) out.put("shopId", shopId);
+            if (phone != null && !phone.isBlank()) out.put("phone", phone);
+        } catch (Exception ignore) { }
+        return out;
+    }
+}
+
+