Add utilities to detect and replace broken links. #1366

barsh404error · 2025-12-30T10:52:45Z

Thanks alot to @christolis for helping me out on making this pull request.
Added two utulity methods isLinkBroken and replaceDeadLinks

-isLinkBroken(String url) checks the link availability using a HEAD request
I used HEAD request instead of GET request to check link availability without downloading the response body, reducing bandwidth and improving the performance.

-replaceDeadLinks (String text, String replacement) replaces unreachable/broken links asynchronously.

This change does not have any behavior changes to the existing code.

Part of #1276, implements the mentioned utility but doesnt apply it.

CLAassistant · 2025-12-30T10:52:53Z

All committers have signed the CLA.

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

barsh404error · 2025-12-31T13:34:06Z

@tj-wazei I've added your request and fixed them
I’ve updated the implementation to avoid mutating shared state in async callbacks and now collect the results before doing replacements sequentially.
I also reuse a single HttpClient and added a GET fallback when HEAD is not supported.
Let me know if anything else should be adjusted ^^

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

Zabuzard

The added methods are utility methods and for those it is crucial that they have a proper Javadoc explaining what they do and give examples.

The isLinkBroken method needs to explain what it means for a link to be broken and how it behaves in edge case, for example if the given text isnt a url and so on.

The other method needs to explain in more detail what the two parameters are and how they work, maybe giving a concrete example in the javadoc.

barsh404error · 2026-01-06T16:29:53Z

The added methods are utility methods and for those it is crucial that they have a proper Javadoc explaining what they do and give examples.

The isLinkBroken method needs to explain what it means for a link to be broken and how it behaves in edge case, for example if the given text isnt a url and so on.

The other method needs to explain in more detail what the two parameters are and how they work, maybe giving a concrete example in the javadoc.

Yes, i got that solved made javadoc for isLinkBroken and replaceDeadLinks.
i explained what does it do step by step altho idk if i wrote to long

tj-wazei

LGTM

Zabuzard · 2026-01-07T08:13:23Z

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

+                int status = response.statusCode();
+                return status < 200 || status >= 400;
+            })
+            .exceptionally(ignored -> true)


the idiomatic name for something you ignore is _

Zabuzard · 2026-01-07T08:15:27Z

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

+
+            .toList();
+
+        return CompletableFuture.allOf(deadLinkFutures.toArray(new CompletableFuture[0]))


toArray(new Foo[0]) is an anti-pattern. use method references instead toArray(Foo[]::new)

Zabuzard · 2026-01-07T08:15:42Z

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

+            .distinct()
+            .map(link -> isLinkBroken(link)
+                .thenApply(isBroken -> Boolean.TRUE.equals(isBroken) ? link : null))
+


empty line in the middle of the flow

Zabuzard · 2026-01-07T08:16:10Z

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

+    private static final Set<LinkFilter> DEFAULT_FILTERS =
+            Set.of(LinkFilter.SUPPRESSED, LinkFilter.NON_HTTP_SCHEME);


improve name. what does this filter, what does it mean, what is it used for?

Zabuzard · 2026-01-07T08:17:12Z

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

+     * <p>
+     * A link is considered broken if:
+     * <ul>
+     * <li>The URL is invalid or malformed</li>


this is incorrect, isnt it? did you test it? URI.create(url) throws on malformed URLs, doesnt it. so your documentation for that edge case is wrong then.

Zabuzard · 2026-01-07T08:17:57Z

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

+     */
+
+    public static CompletableFuture<Boolean> isLinkBroken(String url) {
+        HttpRequest headRequest = HttpRequest.newBuilder(URI.create(url))


improve name headRequest documents the "how" not the "what/why". a better name would be checkLinkHeadRequest

Zabuzard · 2026-01-07T08:24:04Z

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

+        List<CompletableFuture<String>> deadLinkFutures = links.stream()
+            .distinct()
+            .map(link -> isLinkBroken(link)
+                .thenApply(isBroken -> Boolean.TRUE.equals(isBroken) ? link : null))


isBroken cant be null, so just isBroken ? link : null works and is easier to read

Zabuzard · 2026-01-07T08:25:25Z

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

+        List<CompletableFuture<String>> deadLinkFutures = links.stream()
+            .distinct()
+            .map(link -> isLinkBroken(link)
+                .thenApply(isBroken -> Boolean.TRUE.equals(isBroken) ? link : null))


better: instead of map(foo -> ...thenApply(...)), use .map(foo -> ...).filter(...) then you also dont have all these null items in ur list, polluting it

Zabuzard · 2026-01-07T08:25:46Z

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

+        return CompletableFuture.allOf(deadLinkFutures.toArray(new CompletableFuture[0]))
+            .thenApply(ignored -> deadLinkFutures.stream()
+                .map(CompletableFuture::join)
+                .filter(Objects::nonNull)


.filter(Objects::nonNull) that one isnt needed anymore with the above fix

Zabuzard · 2026-01-07T08:26:00Z

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

+            .toList();
+
+        return CompletableFuture.allOf(deadLinkFutures.toArray(new CompletableFuture[0]))
+            .thenApply(ignored -> deadLinkFutures.stream()


(_ instead of ignored)

Zabuzard · 2026-01-07T08:26:54Z

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

+            .thenApply(deadLinks -> {
+                String result = text;
+                for (String deadLink : deadLinks) {
+                    result = result.replace(deadLink, replacement);


performance trap. have a quick check if StringBuilder provides replace. if not, u can keep it, its not that big of a deal in this case, i guess.

barsh404error · 2026-01-09T11:41:04Z

I focused primarily on improving the Javadocs as requested @Zabuzard
While doing so, I slightly refactored the internal stream to use Optional instead of null to better match the documented behavior and avoid null handling
No external behavior was changed.

Zabuzard · 2026-01-09T11:47:43Z

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

+     * 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.


implementation detail like that goes into a comment inside the method, not in the javadoc 👍

Zabuzard · 2026-01-09T11:49:41Z

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

+     * @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})


u dont need to write that as ur params are all (implicitly) annotated with @NonNull already :)

Zabuzard · 2026-01-09T11:50:35Z

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

            .map(link -> isLinkBroken(link)
-                .thenApply(isBroken -> Boolean.TRUE.equals(isBroken) ? link : null))
-
+                .thenApply(isBroken -> isBroken ? Optional.of(link) : Optional.<String>empty()))


u misunderstood me. its better if u simply filter out these, skip them here instead of later.
.filter(...) so they are not even part of the list

Add utilities to detect and replace broken links.

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barsh404error requested a review from a team as a code owner December 30, 2025 10:52

tj-wazei requested changes Dec 30, 2025

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Add utilities to detect and replace broken links V2

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barsh404error requested a review from tj-wazei January 2, 2026 10:22

christolis requested changes Jan 2, 2026

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Add utilities to detect and replace broken links V2

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barsh404error requested a review from christolis January 2, 2026 19:14

Add utilities to detect and replace broken links V2

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barsh404error changed the title ~~Add utilities to detect and replace broken links.~~ Add utilities to detect and replace broken links. Fixed #1276 Jan 3, 2026

christolis changed the title ~~Add utilities to detect and replace broken links. Fixed #1276~~ Add utilities to detect and replace broken links. Jan 4, 2026

Zabuzard self-requested a review January 4, 2026 15:37

Zabuzard requested changes Jan 4, 2026

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Add utilities to detect and replace broken links V2

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barsh404error requested a review from Zabuzard January 6, 2026 16:30

tj-wazei previously approved these changes Jan 6, 2026

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Zabuzard reviewed Jan 7, 2026

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Add utilities to detect and replace broken links V2

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barsh404error dismissed tj-wazei’s stale review via 66b8d6e January 9, 2026 11:39

Zabuzard requested changes Jan 9, 2026

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		.toList();

		return CompletableFuture.allOf(deadLinkFutures.toArray(new CompletableFuture[0]))

		private static final Set<LinkFilter> DEFAULT_FILTERS =
		Set.of(LinkFilter.SUPPRESSED, LinkFilter.NON_HTTP_SCHEME);

		* 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.

		* @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})

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Add utilities to detect and replace broken links. #1366

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barsh404error commented Jan 9, 2026

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barsh404error commented Dec 30, 2025 •

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