Support open compare page directly (#17975)

* Support open compare page directly

* simple code

* Some improvements

Co-authored-by: 6543 <6543@obermui.de>

routers/web/repo/compare.go

@@ -215,21 +215,19 @@ func ParseCompareInfo(ctx *context.Context) *CompareInfo {
 	)
 
 	infoPath = ctx.Params("*")
-	infos := strings.SplitN(infoPath, "...", 2)
-
+	var infos []string
+	if infoPath == "" {
+		infos = []string{baseRepo.DefaultBranch, baseRepo.DefaultBranch}
+	} else {
+		infos = strings.SplitN(infoPath, "...", 2)
 		if len(infos) != 2 {
-		infos = []string{baseRepo.DefaultBranch, infoPath}
-		if strings.Contains(infoPath, "..") {
-			infos = strings.SplitN(infoPath, "..", 2)
+			if infos = strings.SplitN(infoPath, "..", 2); len(infos) == 2 {
 				ci.DirectComparison = true
 				ctx.Data["PageIsComparePull"] = false
+			} else {
+				infos = []string{baseRepo.DefaultBranch, infoPath}
 			}
 		}
-
-	if len(infos) != 2 {
-		log.Trace("ParseCompareInfo[%d]: not enough compared branches information %s", baseRepo.ID, infos)
-		ctx.NotFound("CompareAndPullRequest", nil)
-		return nil
 	}
 
 	ctx.Data["BaseName"] = baseRepo.OwnerName

routers/web/web.go

@@ -702,6 +702,7 @@ func RegisterRoutes(m *web.Route) {
 		m.Group("/milestone", func() {
 			m.Get("/{id}", repo.MilestoneIssuesAndPulls)
 		}, reqRepoIssuesOrPullsReader, context.RepoRef())
+		m.Get("/compare", repo.MustBeNotEmpty, reqRepoCodeReader, repo.SetEditorconfigIfExists, ignSignIn, repo.SetDiffViewStyle, repo.SetWhitespaceBehavior, repo.CompareDiff)
 		m.Combo("/compare/*", repo.MustBeNotEmpty, reqRepoCodeReader, repo.SetEditorconfigIfExists).
 			Get(ignSignIn, repo.SetDiffViewStyle, repo.SetWhitespaceBehavior, repo.CompareDiff).
 			Post(reqSignIn, context.RepoMustNotBeArchived(), reqRepoPullsReader, repo.MustAllowPulls, bindIgnErr(forms.CreateIssueForm{}), repo.SetWhitespaceBehavior, repo.CompareAndPullRequestPost)