revised includes edited user entity

src/main/java/com/safeqr/app/qrcode/service/SafeBrowsingService.java

@@ -0,0 +1,101 @@
+package com.safeqr.app.qrcode.service;
+
+import com.safeqr.app.qrcode.dto.SafeBrowsingRequest;
+import com.safeqr.app.qrcode.dto.SafeBrowsingResponse;
+import com.safeqr.app.qrcode.entity.SafeBrowsingCache;
+import com.safeqr.app.qrcode.repository.SafeBrowsingCacheRepository;
+
+import jakarta.annotation.PostConstruct;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.stereotype.Service;
+import org.springframework.web.reactive.function.client.WebClient;
+import reactor.core.publisher.Mono;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Base64;
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+
+@Service
+public class SafeBrowsingService {
+
+    @Value("${google.safebrowsing.api.key}")
+    private String apiKey;
+
+    private final WebClient webClient;
+    private final SafeBrowsingCacheRepository cacheRepository;
+
+    public SafeBrowsingService(WebClient.Builder webClientBuilder, SafeBrowsingCacheRepository cacheRepository) {
+        this.webClient = webClientBuilder.baseUrl("https://safebrowsing.googleapis.com/v4/threatMatches:find").build();
+        this.cacheRepository = cacheRepository;
+    }
+
+    @PostConstruct
+    public void initializeCache() {
+        // Fetch the full list of hashes from Google and store them in the local database.
+        // This is a placeholder method. You need to implement the logic to fetch and store the hashes.
+        fetchAndStoreFullHashes();
+    }
+
+    public Mono<Boolean> isSafeUrl(String url) throws NoSuchAlgorithmException {
+        String hashPrefix = getHashPrefix(url);
+
+        Optional<SafeBrowsingCache> cachedResult = cacheRepository.findByHashPrefix(hashPrefix);
+        if (cachedResult.isPresent()) {
+            return Mono.just(cachedResult.get().getFullHash().isEmpty());
+        }
+
+        // If not in cache, call Google Safe Browsing API
+        String requestUrl = "?key=" + apiKey;
+
+        SafeBrowsingRequest request = new SafeBrowsingRequest(
+                new SafeBrowsingRequest.Client("safeqr-fyp-24", "1.0"),
+                new SafeBrowsingRequest.ThreatInfo(
+                        List.of("MALWARE", "SOCIAL_ENGINEERING"),
+                        List.of("WINDOWS"),
+                        List.of("URL"),
+                        List.of(new SafeBrowsingRequest.ThreatInfo.ThreatEntry(url))
+                )
+        );
+
+        return webClient.post()
+                .uri(requestUrl)
+                .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
+                .bodyValue(request)
+                .retrieve()
+                .bodyToMono(SafeBrowsingResponse.class)
+                .map(response -> {
+                    boolean isSafe = response.getMatches() == null || response.getMatches().isEmpty();
+                    if (!isSafe) {
+                        SafeBrowsingResponse.ThreatMatch match = response.getMatches().get(0);
+                        SafeBrowsingCache cache = new SafeBrowsingCache();
+                        cache.setId(UUID.randomUUID());
+                        cache.setHashPrefix(hashPrefix);
+                        cache.setThreatType(match.getThreatType());
+                        cache.setPlatformType(match.getPlatformType());
+                        cache.setThreatEntryType(match.getThreatEntryType());
+                        cache.setFullHash(match.getThreat().getHash());
+                        cacheRepository.save(cache);
+                    }
+                    return isSafe;
+                });
+    }
+
+    private String getHashPrefix(String url) throws NoSuchAlgorithmException {
+        // Compute hash prefix of the URL (first 4 bytes of SHA-256)
+        MessageDigest digest = MessageDigest.getInstance("SHA-256");
+        byte[] hash = digest.digest(url.getBytes(StandardCharsets.UTF_8));
+        return Base64.getEncoder().encodeToString(hash).substring(0, 4);
+    }
+
+    private void fetchAndStoreFullHashes() {
+        // Implement the logic to fetch and store the full list of hashes from Google Safe Browsing API
+        // This could involve using the threatListUpdates:fetch endpoint
+    }
+}