Refactor HangarVersionChecker to use HTTP client.

Replaced direct HangarClient with HTTP client and Gson for HangarVersionChecker. Introduced new records and enums to model version data. This enhances flexibility and modularity in handling version checks.

Author: david

version-checker/src/main/java/core/version/HangarVersionChecker.java

@@ -0,0 +1,7 @@
+package core.version.hangar;
+
+import java.util.List;
+import java.util.Map;
+
+public record HangarVersion(String name, String author, Map<Platform, List<String>> platformDependencies) {
+}

version-checker/src/main/java/core/version/hangar/HangarVersion.java

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+package core.version.hangar;
+
+import com.google.gson.Gson;
+import core.annotation.FieldsAreNotNullByDefault;
+import core.annotation.MethodsReturnNotNullByDefault;
+import core.annotation.ParametersAreNotNullByDefault;
+import core.annotation.TypesAreNotNullByDefault;
+import core.version.Version;
+import core.version.VersionChecker;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.jetbrains.annotations.Unmodifiable;
+
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
+
+/**
+ * The HangarVersionChecker class is an abstract class that provides methods
+ * for retrieving and checking the latest supported version of a specific component in a hangar project.
+ *
+ * @param <V> the type parameter for the version
+ */
+@Getter
+@RequiredArgsConstructor
+@TypesAreNotNullByDefault
+@FieldsAreNotNullByDefault
+@MethodsReturnNotNullByDefault
+@ParametersAreNotNullByDefault
+public abstract class HangarVersionChecker<V extends Version> implements VersionChecker<HangarVersion, V> {
+    private static final String API_URL = "https://hangar.papermc.io/api/v1";
+    private static final HttpClient client = HttpClient.newBuilder()
+            .version(HttpClient.Version.HTTP_1_1)
+            .build();
+    private static final Gson gson = new Gson();
+
+    /**
+     * The slug of the project.
+     */
+    private final String slug;
+
+    @Override
+    public CompletableFuture<V> retrieveLatestVersion() {
+        return get("/projects/" + getSlug() + "/latestrelease")
+                .thenApply(HttpResponse::body)
+                .thenApply(this::parseVersion);
+    }
+
+    @Override
+    public CompletableFuture<@Unmodifiable Set<V>> retrieveVersions() {
+        return retrieveHangarVersions().thenApply(versions -> versions.stream()
+                .map(this::parseVersion)
+                .collect(Collectors.toUnmodifiableSet()));
+    }
+
+    @Override
+    public CompletableFuture<V> retrieveLatestSupportedVersion() {
+        return retrieveHangarVersions().thenApply(versions -> versions.stream()
+                .filter(this::isSupported)
+                .map(this::parseVersion)
+                .max(Version::compareTo)
+                .orElseThrow());
+    }
+
+    @Override
+    public V parseVersion(HangarVersion version) {
+        return parseVersion(version.name());
+    }
+
+    public final CompletableFuture<Set<HangarVersion>> retrieveHangarVersions() {
+        return get("/projects/" + getSlug() + "/versions")
+                .thenApply(response -> gson.fromJson(response.body(), HangarVersions.class))
+                .thenApply(HangarVersions::result);
+    }
+
+    private CompletableFuture<HttpResponse<String>> get(String path) {
+        return client.sendAsync(HttpRequest.newBuilder()
+                        .uri(URI.create(API_URL + path))
+                        .build(),
+                HttpResponse.BodyHandlers.ofString());
+    }
+}

version-checker/src/main/java/core/version/hangar/HangarVersionChecker.java

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+package core.version.hangar;
+
+import java.util.Set;
+
+public record HangarVersions(Set<HangarVersion> result) {
+}

version-checker/src/main/java/core/version/hangar/HangarVersions.java

@@ -0,0 +1,7 @@
+package core.version.hangar;
+
+public enum Platform {
+    PAPER,
+    WATERFALL,
+    VELOCITY
+}