forge: add method PullRequest.diff

bots/tester/src/test/java/org/openjdk/skara/bots/tester/InMemoryPullRequest.java

@@ -295,4 +295,9 @@ public Optional<ZonedDateTime> labelAddedAt(String label) {
     public URI headUrl() {
         return null;
     }
+
+    @Override
+    public Diff diff() {
+        return null;
+    }
 }

forge/src/main/java/org/openjdk/skara/forge/PullRequest.java

@@ -23,6 +23,7 @@
 package org.openjdk.skara.forge;
 
 import org.openjdk.skara.issuetracker.Issue;
+import org.openjdk.skara.vcs.Diff;
 import org.openjdk.skara.vcs.Hash;
 
 import java.net.URI;
@@ -120,6 +121,11 @@ public interface PullRequest extends Issue {
      */
     URI diffUrl();
 
+    /** Returns a diff of the changes between PR HEAD and target branch.
+     * @return
+     */
+    Diff diff();
+
     /**
      * Creates a new check.
      * @param check

forge/src/main/java/org/openjdk/skara/forge/github/GitHubPullRequest.java

@@ -27,6 +27,7 @@
 import org.openjdk.skara.issuetracker.*;
 import org.openjdk.skara.json.*;
 import org.openjdk.skara.network.*;
+import org.openjdk.skara.vcs.Diff;
 import org.openjdk.skara.vcs.Hash;
 
 import java.net.URI;
@@ -662,4 +663,10 @@ public Optional<ZonedDateTime> labelAddedAt(String label) {
     public URI headUrl() {
         return URI.create(webUrl() + "/commits/" + headHash().hex());
     }
+
+    @Override
+    public Diff diff() {
+        var files = request.get("pulls/" + json.get("number").toString() + "/files").execute();
+        return host.toDiff(targetHash(), headHash(), files);
+    }
 }

forge/src/main/java/org/openjdk/skara/forge/gitlab/GitLabMergeRequest.java

@@ -27,6 +27,7 @@
 import org.openjdk.skara.issuetracker.*;
 import org.openjdk.skara.json.*;
 import org.openjdk.skara.network.*;
+import org.openjdk.skara.vcs.Diff;
 import org.openjdk.skara.vcs.Hash;
 
 import java.net.URI;
@@ -42,12 +43,14 @@ public class GitLabMergeRequest implements PullRequest {
     private final RestRequest request;
     private final Logger log = Logger.getLogger("org.openjdk.skara.host");;
     private final GitLabRepository repository;
+    private final GitLabHost host;
 
     private Hash targetHash = null;
     private List<String> labels;
 
-    GitLabMergeRequest(GitLabRepository repository, JSONValue jsonValue, RestRequest request) {
+    GitLabMergeRequest(GitLabRepository repository, GitLabHost host, JSONValue jsonValue, RestRequest request) {
         this.repository = repository;
+        this.host = host;
         this.json = jsonValue;
         this.request = request.restrict("merge_requests/" + json.get("iid").toString() + "/");
 
@@ -736,4 +739,10 @@ public Optional<ZonedDateTime> labelAddedAt(String label) {
     public URI headUrl() {
         return URI.create(webUrl() + "/diffs?commit_id=" + headHash().hex());
     }
+
+    @Override
+    public Diff diff() {
+        var changes = request.get("changes").execute();
+        return host.toDiff(targetHash(), headHash(), changes.get("changes"));
+    }
 }

forge/src/main/java/org/openjdk/skara/forge/gitlab/GitLabRepository.java

@@ -104,21 +104,21 @@ public PullRequest createPullRequest(HostedRepository target,
                         .execute();
 
         var targetRepo = (GitLabRepository) target;
-        return new GitLabMergeRequest(targetRepo, pr, targetRepo.request);
+        return new GitLabMergeRequest(targetRepo, gitLabHost, pr, targetRepo.request);
     }
 
     @Override
     public PullRequest pullRequest(String id) {
         var pr = request.get("merge_requests/" + id).execute();
-        return new GitLabMergeRequest(this, pr, request);
+        return new GitLabMergeRequest(this, gitLabHost, pr, request);
     }
 
     @Override
     public List<PullRequest> pullRequests() {
         return request.get("merge_requests")
                       .param("state", "opened")
                       .execute().stream()
-                      .map(value -> new GitLabMergeRequest(this, value, request))
+                      .map(value -> new GitLabMergeRequest(this, gitLabHost, value, request))
                       .collect(Collectors.toList());
     }
 
@@ -128,7 +128,7 @@ public List<PullRequest> pullRequests(ZonedDateTime updatedAfter) {
                       .param("order_by", "updated_at")
                       .param("updated_after", updatedAfter.format(DateTimeFormatter.ISO_DATE_TIME))
                       .execute().stream()
-                      .map(value -> new GitLabMergeRequest(this, value, request))
+                      .map(value -> new GitLabMergeRequest(this, gitLabHost, value, request))
                       .collect(Collectors.toList());
     }
 

test/src/main/java/org/openjdk/skara/test/TestPullRequest.java

@@ -26,6 +26,7 @@
 import org.openjdk.skara.host.*;
 import org.openjdk.skara.issuetracker.IssueProject;
 import org.openjdk.skara.network.URIBuilder;
+import org.openjdk.skara.vcs.Diff;
 import org.openjdk.skara.vcs.Hash;
 
 import java.io.*;
@@ -232,4 +233,22 @@ public Optional<ZonedDateTime> labelAddedAt(String label) {
     public URI headUrl() {
         return URI.create(webUrl().toString() + "/commits/" + headHash().hex());
     }
+
+    @Override
+    public Diff diff() {
+        try {
+            var targetLocalRepository = targetRepository.localRepository();
+            var sourceLocalRepository = sourceRepository.localRepository();
+            if (targetLocalRepository.root().equals(sourceLocalRepository.root())) {
+                // same target and source repo, must contain both commits
+                return targetLocalRepository.diff(targetHash(), headHash());
+            } else {
+                var uri = URI.create("file://" + sourceLocalRepository.root().toString());
+                var fetchHead = targetLocalRepository.fetch(uri, sourceRef);
+                return targetLocalRepository.diff(targetHash(), fetchHead);
+            }
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
 }