Allow following file renames in commit history activity

Fixes #1419

app/src/main/java/com/gh4a/activities/CommitHistoryActivity.java

@@ -3,6 +3,10 @@
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
+
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 
@@ -27,6 +31,7 @@ public static Intent makeIntent(Context context, String repoOwner, String repoNa
     private String mRef;
     private String mFilePath;
     private boolean mSupportBaseSelection;
+    private boolean mFollowRenames;
 
     @Nullable
     @Override
@@ -52,14 +57,47 @@ protected void onInitExtras(Bundle extras) {
 
     @Override
     protected Fragment onCreateFragment() {
-        return CommitListFragment.newInstance(mRepoOwner, mRepoName, mRef, mFilePath);
+        CommitListFragment f = CommitListFragment.newInstance(mRepoOwner, mRepoName, mRef, mFilePath);
+        f.setFollowFileRenames(mFollowRenames);
+        return f;
     }
 
     @Override
     protected Intent navigateUp() {
         return RepositoryActivity.makeIntent(this, mRepoOwner, mRepoName, mRef);
     }
 
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        MenuInflater inflater = getMenuInflater();
+        inflater.inflate(R.menu.commit_history_menu, menu);
+        return super.onCreateOptionsMenu(menu);
+    }
+
+    @Override
+    public boolean onPrepareOptionsMenu(Menu menu) {
+        MenuItem followItem = menu.findItem(R.id.follow_renames);
+        if (followItem != null) {
+            followItem.setChecked(mFollowRenames);
+        }
+        return super.onPrepareOptionsMenu(menu);
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == R.id.follow_renames) {
+            mFollowRenames = !mFollowRenames;
+            item.setChecked(mFollowRenames);
+            CommitListFragment f = (CommitListFragment) getFragment();
+            if (f != null) {
+                f.setFollowFileRenames(mFollowRenames);
+            }
+            return true;
+        }
+
+        return super.onOptionsItemSelected(item);
+    }
+
     @Override
     public boolean baseSelectionAllowed() {
         return mSupportBaseSelection;

app/src/main/java/com/gh4a/fragment/CommitListFragment.java

@@ -43,7 +43,10 @@
 import com.meisolsson.githubsdk.service.repositories.RepositoryCommitService;
 
 import java.net.HttpURLConnection;
+import java.util.List;
+import java.util.Optional;
 
+import io.reactivex.Maybe;
 import io.reactivex.Single;
 import retrofit2.Response;
 
@@ -57,6 +60,8 @@ public interface ContextSelectionCallback {
     private String mRepoName;
     private String mRef;
     private String mFilePath;
+    private boolean mFollowRenames;
+    private RenameFollowData mRenameFollowData;
 
     private CommitAdapter mAdapter;
     private ContextSelectionCallback mCallback;
@@ -85,6 +90,13 @@ public static CommitListFragment newInstance(String repoOwner, String repoName,
         return f;
     }
 
+    public void setFollowFileRenames(boolean followRenames) {
+        if (mFollowRenames != followRenames) {
+            mFollowRenames = followRenames;
+            onRefresh();
+        }
+    }
+
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -155,7 +167,29 @@ public boolean onContextItemSelected(MenuItem item) {
     protected Single<Response<Page<Commit>>> loadPage(int page, boolean bypassCache) {
         final RepositoryCommitService service =
                 ServiceFactory.get(RepositoryCommitService.class, bypassCache);
-        return service.getCommits(mRepoOwner, mRepoName, mRef, mFilePath, page)
+        final String ref = mRenameFollowData != null ? mRenameFollowData.ref : mRef;
+        final String filePath = mRenameFollowData != null ? mRenameFollowData.fileName : mFilePath;
+
+        return service.getCommits(mRepoOwner, mRepoName, ref, filePath, page)
+                .flatMap(response -> {
+                    Page<Commit> commits = response.isSuccessful() ? response.body() : null;
+                    if (commits != null && commits.next() == null && mFollowRenames) {
+                        final List<Commit> items = commits.items();
+                        final Commit last = items.get(items.size() - 1);
+                        return determineFollowData(last, filePath)
+                                .map(data -> {
+                                    mRenameFollowData = data;
+                                    return Response.success(Page.<Commit>builder()
+                                            .items(items)
+                                            .next(1)
+                                            .prev(commits.prev())
+                                            .build());
+                                })
+                                .defaultIfEmpty(response)
+                                .toSingle();
+                    }
+                    return Single.just(response);
+                })
                 .map(response -> {
                     // 409 is returned for empty repos
                     if (response.code() == HttpURLConnection.HTTP_CONFLICT) {
@@ -164,4 +198,40 @@ protected Single<Response<Page<Commit>>> loadPage(int page, boolean bypassCache)
                     return response;
                 });
     }
+
+    @Override
+    protected void resetSubject() {
+        super.resetSubject();
+        mRenameFollowData = null;
+    }
+
+    private Maybe<RenameFollowData> determineFollowData(Commit commit, String currentFileName) {
+        final RepositoryCommitService service =
+                ServiceFactory.get(RepositoryCommitService.class, false);
+        return service.getCommit(mRepoOwner, mRepoName, commit.sha())
+                .filter(Response::isSuccessful)
+                .map(Response::body)
+                .map(actualCommit -> {
+                    if (actualCommit != null && actualCommit.files() != null) {
+                        return actualCommit.files().stream()
+                                .filter(f -> f.filename().equals(currentFileName) &&
+                                        f.previousFilename() != null)
+                                .findFirst()
+                                .map(f -> {
+                                    RenameFollowData data = new RenameFollowData();
+                                    data.fileName = f.previousFilename();
+                                    data.ref = actualCommit.parents().get(0).sha();
+                                    return data;
+                                });
+                    }
+                    return Optional.<RenameFollowData>empty();
+                })
+                .filter(Optional::isPresent)
+                .map(Optional::get);
+    }
+
+    private static class RenameFollowData {
+        String ref;
+        String fileName;
+    }
 }

app/src/main/res/menu/commit_history_menu.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+    <item
+        android:id="@+id/follow_renames"
+        android:checkable="true"
+        android:title="@string/follow_renames" />
+</menu>

app/src/main/res/values/strings.xml

@@ -79,6 +79,7 @@
     <string name="no_browser_found">The link could not be opened: no browser was found on your device</string>
     <string name="link_copied">Link copied</string>
     <string name="wrap_lines">Wrap lines</string>
+    <string name="follow_renames">Follow renames</string>
     <string name="unknown">unknown</string>
     <string name="history">History</string>
     <string name="download">Download</string>