Add utilities to detect and replace broken links V2

Author: barsh404error

application/src/main/java/org/togetherjava/tjbot/features/utils/LinkDetection.java

@@ -9,7 +9,6 @@
 import java.net.http.HttpRequest;
 import java.net.http.HttpResponse;
 import java.util.List;
-import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
@@ -65,7 +64,7 @@ public static List<String> extractLinks(String content, Set<LinkFilter> filter)
      * @return true if the content contains at least one link
      */
     public static boolean containsLink(String content) {
-        return !(new UrlDetector(content, UrlDetectorOptions.BRACKET_MATCH).detect().isEmpty());
+        return !new UrlDetector(content, UrlDetectorOptions.BRACKET_MATCH).detect().isEmpty();
     }
 
     /**
@@ -74,39 +73,46 @@ public static boolean containsLink(String content) {
      * <p>
      * A link is considered broken if:
      * <ul>
-     * <li>The URL is invalid or malformed</li>
      * <li>An HTTP request fails</li>
      * <li>The HTTP response status code is outside the 200–399 range</li>
      * </ul>
      *
      * <p>
+     * The method first performs an HTTP {@code HEAD} request and falls back to an HTTP {@code GET}
+     * request if the {@code HEAD} request indicates a failure.
+     * </p>
+     *
+     * <p>
      * Notes:
      * <ul>
      * <li>Status code {@code 200} is considered valid, even if the response body is empty</li>
      * <li>The response body content is not inspected</li>
      * </ul>
      *
-     * @param url the URL to check
+     * @param url the URL to check (must be a valid {@link URI})
      * @return a future completing with {@code true} if the link is broken
+     * @throws IllegalArgumentException if the given URL is not a valid URI
      */
 
     public static CompletableFuture<Boolean> isLinkBroken(String url) {
-        HttpRequest headRequest = HttpRequest.newBuilder(URI.create(url))
+        HttpRequest headCheckRequest = HttpRequest.newBuilder(URI.create(url))
             .method("HEAD", HttpRequest.BodyPublishers.noBody())
             .build();
 
-        return HTTP_CLIENT.sendAsync(headRequest, HttpResponse.BodyHandlers.discarding())
+        return HTTP_CLIENT.sendAsync(headCheckRequest, HttpResponse.BodyHandlers.discarding())
             .thenApply(response -> {
                 int status = response.statusCode();
                 return status < 200 || status >= 400;
             })
             .exceptionally(ignored -> true)
             .thenCompose(result -> {
-                if (!Boolean.TRUE.equals(result)) {
+                if (!result) {
                     return CompletableFuture.completedFuture(false);
                 }
-                HttpRequest getRequest = HttpRequest.newBuilder(URI.create(url)).GET().build();
-                return HTTP_CLIENT.sendAsync(getRequest, HttpResponse.BodyHandlers.discarding())
+                HttpRequest getFallbackRequest =
+                        HttpRequest.newBuilder(URI.create(url)).GET().build();
+                return HTTP_CLIENT
+                    .sendAsync(getFallbackRequest, HttpResponse.BodyHandlers.discarding())
                     .thenApply(resp -> resp.statusCode() >= 400)
                     .exceptionally(ignored -> true); // still never null
             });
@@ -116,6 +122,10 @@ public static CompletableFuture<Boolean> isLinkBroken(String url) {
      * Replaces all broken links in the given text with the provided replacement string.
      *
      * <p>
+     * The link checks are performed asynchronously.
+     * </p>
+     *
+     * <p>
      * Example:
      * 
      * <pre>{@code
@@ -135,29 +145,28 @@ public static CompletableFuture<Boolean> isLinkBroken(String url) {
      * http://workinglink/1
      * }</pre>
      *
-     * @param text the input text containing URLs
-     * @param replacement the string to replace broken links with
+     * @param text the input text containing URLs (must not be {@code null})
+     * @param replacement the string to replace broken links with (must not be {@code null})
      * @return a future containing the modified text
      */
-
     public static CompletableFuture<String> replaceDeadLinks(String text, String replacement) {
         List<String> links = extractLinks(text, DEFAULT_FILTERS);
 
         if (links.isEmpty()) {
             return CompletableFuture.completedFuture(text);
         }
 
-        List<CompletableFuture<String>> deadLinkFutures = links.stream()
+        List<CompletableFuture<Optional<String>>> deadLinkFutures = links.stream()
             .distinct()
             .map(link -> isLinkBroken(link)
-                .thenApply(isBroken -> Boolean.TRUE.equals(isBroken) ? link : null))
-
+                .thenApply(isBroken -> isBroken ? Optional.of(link) : Optional.<String>empty()))
             .toList();
 
-        return CompletableFuture.allOf(deadLinkFutures.toArray(new CompletableFuture[0]))
+
+        return CompletableFuture.allOf(deadLinkFutures.toArray(CompletableFuture[]::new))
             .thenApply(ignored -> deadLinkFutures.stream()
                 .map(CompletableFuture::join)
-                .filter(Objects::nonNull)
+                .flatMap(Optional::stream)
                 .toList())
             .thenApply(deadLinks -> {
                 String result = text;