Display pull request head branch even the branch deleted or repository deleted (#10413)

* Display pull request head branch even the branch deleted or repository deleted

* Merge getHeadRepo/loadHeadRepo and getBaseRepo/loadBaseRepo on pull and fill repo when pr.Issue.Repo is available

* retrieve sha from pull head when pull request branch deleted and fix tests

* Fix test

* Ensure MustHeadRepoName returns empty string if no head repo

Co-authored-by: zeripath <art27@cantab.net>

3 files changed, 35 insertions, 27 deletions

diff --git a/routers/api/v1/repo/pull.go b/routers/api/v1/repo/pull.go
index d6d6918bb6..428f112633 100644
--- a/routers/api/v1/repo/pull.go
+++ b/routers/api/v1/repo/pull.go
@@ -101,12 +101,12 @@ func ListPullRequests(ctx *context.APIContext, form api.ListPullRequestsOptions)
 			ctx.Error(http.StatusInternalServerError, "LoadAttributes", err)
 			return
 		}
-		if err = prs[i].GetBaseRepo(); err != nil {
-			ctx.Error(http.StatusInternalServerError, "GetBaseRepo", err)
+		if err = prs[i].LoadBaseRepo(); err != nil {
+			ctx.Error(http.StatusInternalServerError, "LoadBaseRepo", err)
 			return
 		}
-		if err = prs[i].GetHeadRepo(); err != nil {
-			ctx.Error(http.StatusInternalServerError, "GetHeadRepo", err)
+		if err = prs[i].LoadHeadRepo(); err != nil {
+			ctx.Error(http.StatusInternalServerError, "LoadHeadRepo", err)
 			return
 		}
 		apiPrs[i] = convert.ToAPIPullRequest(prs[i])
@@ -156,12 +156,12 @@ func GetPullRequest(ctx *context.APIContext) {
 		return
 	}
 
-	if err = pr.GetBaseRepo(); err != nil {
-		ctx.Error(http.StatusInternalServerError, "GetBaseRepo", err)
+	if err = pr.LoadBaseRepo(); err != nil {
+		ctx.Error(http.StatusInternalServerError, "LoadBaseRepo", err)
 		return
 	}
-	if err = pr.GetHeadRepo(); err != nil {
-		ctx.Error(http.StatusInternalServerError, "GetHeadRepo", err)
+	if err = pr.LoadHeadRepo(); err != nil {
+		ctx.Error(http.StatusInternalServerError, "LoadHeadRepo", err)
 		return
 	}
 	ctx.JSON(http.StatusOK, convert.ToAPIPullRequest(pr))
@@ -579,8 +579,8 @@ func MergePullRequest(ctx *context.APIContext, form auth.MergePullRequestForm) {
 		return
 	}
 
-	if err = pr.GetHeadRepo(); err != nil {
-		ctx.ServerError("GetHeadRepo", err)
+	if err = pr.LoadHeadRepo(); err != nil {
+		ctx.ServerError("LoadHeadRepo", err)
 		return
 	}
 
diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index ca7be7bd96..a4cd184c15 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -910,8 +910,8 @@ func ViewIssue(ctx *context.Context) {
 		ctx.Data["AllowMerge"] = false
 
 		if ctx.IsSigned {
-			if err := pull.GetHeadRepo(); err != nil {
-				log.Error("GetHeadRepo: %v", err)
+			if err := pull.LoadHeadRepo(); err != nil {
+				log.Error("LoadHeadRepo: %v", err)
 			} else if pull.HeadRepo != nil && pull.HeadBranch != pull.HeadRepo.DefaultBranch {
 				perm, err := models.GetUserRepoPermission(pull.HeadRepo, ctx.User)
 				if err != nil {
@@ -929,8 +929,8 @@ func ViewIssue(ctx *context.Context) {
 				}
 			}
 
-			if err := pull.GetBaseRepo(); err != nil {
-				log.Error("GetBaseRepo: %v", err)
+			if err := pull.LoadBaseRepo(); err != nil {
+				log.Error("LoadBaseRepo: %v", err)
 			}
 			perm, err := models.GetUserRepoPermission(pull.BaseRepo, ctx.User)
 			if err != nil {
diff --git a/routers/repo/pull.go b/routers/repo/pull.go
index 92538945b0..e4fd19ee49 100644
--- a/routers/repo/pull.go
+++ b/routers/repo/pull.go
@@ -273,8 +273,8 @@ func checkPullInfo(ctx *context.Context) *models.Issue {
 		return nil
 	}
 
-	if err = issue.PullRequest.GetHeadRepo(); err != nil {
-		ctx.ServerError("GetHeadRepo", err)
+	if err = issue.PullRequest.LoadHeadRepo(); err != nil {
+		ctx.ServerError("LoadHeadRepo", err)
 		return nil
 	}
 
@@ -313,7 +313,7 @@ func PrepareMergedViewPullInfo(ctx *context.Context, issue *models.Issue) *git.C
 	if err != nil {
 		if strings.Contains(err.Error(), "fatal: Not a valid object name") {
 			ctx.Data["IsPullRequestBroken"] = true
-			ctx.Data["BaseTarget"] = "deleted"
+			ctx.Data["BaseTarget"] = pull.BaseBranch
 			ctx.Data["NumCommits"] = 0
 			ctx.Data["NumFiles"] = 0
 			return nil
@@ -332,13 +332,13 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 	repo := ctx.Repo.Repository
 	pull := issue.PullRequest
 
-	if err := pull.GetHeadRepo(); err != nil {
-		ctx.ServerError("GetHeadRepo", err)
+	if err := pull.LoadHeadRepo(); err != nil {
+		ctx.ServerError("LoadHeadRepo", err)
 		return nil
 	}
 
-	if err := pull.GetBaseRepo(); err != nil {
-		ctx.ServerError("GetBaseRepo", err)
+	if err := pull.LoadBaseRepo(); err != nil {
+		ctx.ServerError("LoadBaseRepo", err)
 		return nil
 	}
 
@@ -432,7 +432,15 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 
 	if pull.HeadRepo == nil || !headBranchExist || headBranchSha != sha {
 		ctx.Data["IsPullRequestBroken"] = true
-		ctx.Data["HeadTarget"] = "deleted"
+		if pull.IsSameRepo() {
+			ctx.Data["HeadTarget"] = pull.HeadBranch
+		} else {
+			if pull.HeadRepo == nil {
+				ctx.Data["HeadTarget"] = "<deleted>:" + pull.HeadBranch
+			} else {
+				ctx.Data["HeadTarget"] = pull.HeadRepo.OwnerName + ":" + pull.HeadBranch
+			}
+		}
 	}
 
 	compareInfo, err := baseGitRepo.GetCompareInfo(pull.BaseRepo.RepoPath(),
@@ -440,7 +448,7 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 	if err != nil {
 		if strings.Contains(err.Error(), "fatal: Not a valid object name") {
 			ctx.Data["IsPullRequestBroken"] = true
-			ctx.Data["BaseTarget"] = "deleted"
+			ctx.Data["BaseTarget"] = pull.BaseBranch
 			ctx.Data["NumCommits"] = 0
 			ctx.Data["NumFiles"] = 0
 			return nil
@@ -976,15 +984,15 @@ func CleanUpPullRequest(ctx *context.Context) {
 		return
 	}
 
-	if err := pr.GetHeadRepo(); err != nil {
-		ctx.ServerError("GetHeadRepo", err)
+	if err := pr.LoadHeadRepo(); err != nil {
+		ctx.ServerError("LoadHeadRepo", err)
 		return
 	} else if pr.HeadRepo == nil {
 		// Forked repository has already been deleted
 		ctx.NotFound("CleanUpPullRequest", nil)
 		return
-	} else if err = pr.GetBaseRepo(); err != nil {
-		ctx.ServerError("GetBaseRepo", err)
+	} else if err = pr.LoadBaseRepo(); err != nil {
+		ctx.ServerError("LoadBaseRepo", err)
 		return
 	} else if err = pr.HeadRepo.GetOwner(); err != nil {
 		ctx.ServerError("HeadRepo.GetOwner", err)