Support displaying diff stats in PR tab bar (#25387)

Fix #25326

---------

Co-authored-by: silverwind <me@silverwind.io>

4 files changed, 94 insertions, 5 deletions

diff --git a/routers/web/repo/pull.go b/routers/web/repo/pull.go
index 950979a6ed..c543d90e19 100644
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@@ -356,12 +356,46 @@ func setMergeTarget(ctx *context.Context, pull *issues_model.PullRequest) {
 	ctx.Data["BaseBranchLink"] = pull.GetBaseBranchLink()
 }
 
-// PrepareMergedViewPullInfo show meta information for a merged pull request view page
-func PrepareMergedViewPullInfo(ctx *context.Context, issue *issues_model.Issue) *git.CompareInfo {
+// GetPullDiffStats get Pull Requests diff stats
+func GetPullDiffStats(ctx *context.Context) {
+	issue := checkPullInfo(ctx)
 	pull := issue.PullRequest
 
-	setMergeTarget(ctx, pull)
-	ctx.Data["HasMerged"] = true
+	mergeBaseCommitID := GetMergedBaseCommitID(ctx, issue)
+
+	if ctx.Written() {
+		return
+	} else if mergeBaseCommitID == "" {
+		ctx.NotFound("PullFiles", nil)
+		return
+	}
+
+	headCommitID, err := ctx.Repo.GitRepo.GetRefCommitID(pull.GetGitRefName())
+	if err != nil {
+		ctx.ServerError("GetRefCommitID", err)
+		return
+	}
+
+	diffOptions := &gitdiff.DiffOptions{
+		BeforeCommitID:     mergeBaseCommitID,
+		AfterCommitID:      headCommitID,
+		MaxLines:           setting.Git.MaxGitDiffLines,
+		MaxLineCharacters:  setting.Git.MaxGitDiffLineCharacters,
+		MaxFiles:           setting.Git.MaxGitDiffFiles,
+		WhitespaceBehavior: gitdiff.GetWhitespaceFlag(ctx.Data["WhitespaceBehavior"].(string)),
+	}
+
+	diff, err := gitdiff.GetPullDiffStats(ctx.Repo.GitRepo, diffOptions)
+	if err != nil {
+		ctx.ServerError("GetPullDiffStats", err)
+		return
+	}
+
+	ctx.Data["Diff"] = diff
+}
+
+func GetMergedBaseCommitID(ctx *context.Context, issue *issues_model.Issue) string {
+	pull := issue.PullRequest
 
 	var baseCommit string
 	// Some migrated PR won't have any Base SHA and lose history, try to get one
@@ -401,6 +435,18 @@ func PrepareMergedViewPullInfo(ctx *context.Context, issue *issues_model.Issue)
 		baseCommit = pull.MergeBase
 	}
 
+	return baseCommit
+}
+
+// PrepareMergedViewPullInfo show meta information for a merged pull request view page
+func PrepareMergedViewPullInfo(ctx *context.Context, issue *issues_model.Issue) *git.CompareInfo {
+	pull := issue.PullRequest
+
+	setMergeTarget(ctx, pull)
+	ctx.Data["HasMerged"] = true
+
+	baseCommit := GetMergedBaseCommitID(ctx, issue)
+
 	compareInfo, err := ctx.Repo.GitRepo.GetCompareInfo(ctx.Repo.Repository.RepoPath(),
 		baseCommit, pull.GetGitRefName(), false, false)
 	if err != nil {
diff --git a/routers/web/web.go b/routers/web/web.go
index 5dd7be120d..45c374e9c0 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -1277,9 +1277,10 @@ func registerRoutes(m *web.Route) {
 		})
 
 		m.Group("/pulls/{index}", func() {
+			m.Get("", repo.SetWhitespaceBehavior, repo.GetPullDiffStats, repo.ViewIssue)
 			m.Get(".diff", repo.DownloadPullDiff)
 			m.Get(".patch", repo.DownloadPullPatch)
-			m.Get("/commits", context.RepoRef(), repo.ViewPullCommits)
+			m.Get("/commits", context.RepoRef(), repo.SetWhitespaceBehavior, repo.GetPullDiffStats, repo.ViewPullCommits)
 			m.Post("/merge", context.RepoMustNotBeArchived(), web.Bind(forms.MergePullRequestForm{}), repo.MergePullRequest)
 			m.Post("/cancel_auto_merge", context.RepoMustNotBeArchived(), repo.CancelAutoMergePullRequest)
 			m.Post("/update", repo.UpdatePullRequest)
diff --git a/services/gitdiff/gitdiff.go b/services/gitdiff/gitdiff.go
index 9adf3b9400..38283680ae 100644
--- a/services/gitdiff/gitdiff.go
+++ b/services/gitdiff/gitdiff.go
@@ -1229,6 +1229,42 @@ func GetDiff(gitRepo *git.Repository, opts *DiffOptions, files ...string) (*Diff
 	return diff, nil
 }
 
+type PullDiffStats struct {
+	TotalAddition, TotalDeletion int
+}
+
+// GetPullDiffStats
+func GetPullDiffStats(gitRepo *git.Repository, opts *DiffOptions) (*PullDiffStats, error) {
+	repoPath := gitRepo.Path
+
+	diff := &PullDiffStats{}
+
+	separator := "..."
+	if opts.DirectComparison {
+		separator = ".."
+	}
+
+	diffPaths := []string{opts.BeforeCommitID + separator + opts.AfterCommitID}
+	if len(opts.BeforeCommitID) == 0 || opts.BeforeCommitID == git.EmptySHA {
+		diffPaths = []string{git.EmptyTreeSHA, opts.AfterCommitID}
+	}
+
+	var err error
+
+	_, diff.TotalAddition, diff.TotalDeletion, err = git.GetDiffShortStat(gitRepo.Ctx, repoPath, nil, diffPaths...)
+	if err != nil && strings.Contains(err.Error(), "no merge base") {
+		// git >= 2.28 now returns an error if base and head have become unrelated.
+		// previously it would return the results of git diff --shortstat base head so let's try that...
+		diffPaths = []string{opts.BeforeCommitID, opts.AfterCommitID}
+		_, diff.TotalAddition, diff.TotalDeletion, err = git.GetDiffShortStat(gitRepo.Ctx, repoPath, nil, diffPaths...)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	return diff, nil
+}
+
 // SyncAndGetUserSpecificDiff is like GetDiff, except that user specific data such as which files the given user has already viewed on the given PR will also be set
 // Additionally, the database asynchronously is updated if files have changed since the last review
 func SyncAndGetUserSpecificDiff(ctx context.Context, userID int64, pull *issues_model.PullRequest, gitRepo *git.Repository, opts *DiffOptions, files ...string) (*Diff, error) {
diff --git a/templates/repo/pulls/tab_menu.tmpl b/templates/repo/pulls/tab_menu.tmpl
index f44968c775..6c121bdd1f 100644
--- a/templates/repo/pulls/tab_menu.tmpl
+++ b/templates/repo/pulls/tab_menu.tmpl
@@ -14,4 +14,10 @@
 		{{$.locale.Tr "repo.pulls.tab_files"}}
 		<span class="ui small label">{{if .NumFiles}}{{.NumFiles}}{{else}}-{{end}}</span>
 	</a>
+	<span class="item gt-ml-auto gt-pr-0 gt-font-bold gt-df gt-ac gt-gap-3">
+		<span><span class="text green">{{if .Diff.TotalAddition}}+{{.Diff.TotalAddition}}{{end}}</span> <span class="text red">{{if .Diff.TotalDeletion}}-{{.Diff.TotalDeletion}}{{end}}</span></span>
+		<span class="diff-stats-bar">
+			<div class="diff-stats-add-bar" style="width: {{Eval 100 "*" .Diff.TotalAddition "/" "(" .Diff.TotalAddition "+" .Diff.TotalDeletion "+" 0.0 ")"}}%"></div>
+		</span>
+	</span>
 </div>