Do not reload page after adding comments in Pull Request reviews (#13877)

Fixed #8861 
* use ajax on PR review page

* handle review comments

* extract duplicate code

FetchCodeCommentsByLine was initially more or less copied from fetchCodeCommentsByReview. Now they both use a common findCodeComments function instead

* use the Engine that was passed into the method

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

routers/repo/pull_review.go

@@ -9,11 +9,40 @@ import (
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/auth"
+	"code.gitea.io/gitea/modules/base"
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/log"
 	pull_service "code.gitea.io/gitea/services/pull"
 )
 
+const (
+	tplConversation base.TplName = "repo/diff/conversation"
+	tplNewComment   base.TplName = "repo/diff/new_comment"
+)
+
+// RenderNewCodeCommentForm will render the form for creating a new review comment
+func RenderNewCodeCommentForm(ctx *context.Context) {
+	issue := GetActionIssue(ctx)
+	if !issue.IsPull {
+		return
+	}
+	currentReview, err := models.GetCurrentReview(ctx.User, issue)
+	if err != nil && !models.IsErrReviewNotExist(err) {
+		ctx.ServerError("GetCurrentReview", err)
+		return
+	}
+	ctx.Data["PageIsPullFiles"] = true
+	ctx.Data["Issue"] = issue
+	ctx.Data["CurrentReview"] = currentReview
+	pullHeadCommitID, err := ctx.Repo.GitRepo.GetRefCommitID(issue.PullRequest.GetGitRefName())
+	if err != nil {
+		ctx.ServerError("GetRefCommitID", err)
+		return
+	}
+	ctx.Data["AfterCommitID"] = pullHeadCommitID
+	ctx.HTML(200, tplNewComment)
+}
+
 // CreateCodeComment will create a code comment including an pending review if required
 func CreateCodeComment(ctx *context.Context, form auth.CodeCommentForm) {
 	issue := GetActionIssue(ctx)
@@ -58,11 +87,17 @@ func CreateCodeComment(ctx *context.Context, form auth.CodeCommentForm) {
 	}
 
 	log.Trace("Comment created: %-v #%d[%d] Comment[%d]", ctx.Repo.Repository, issue.Index, issue.ID, comment.ID)
+
+	if form.Origin == "diff" {
+		renderConversation(ctx, comment)
+		return
+	}
 	ctx.Redirect(comment.HTMLURL())
 }
 
 // UpdateResolveConversation add or remove an Conversation resolved mark
 func UpdateResolveConversation(ctx *context.Context) {
+	origin := ctx.Query("origin")
 	action := ctx.Query("action")
 	commentID := ctx.QueryInt64("comment_id")
 
@@ -103,11 +138,38 @@ func UpdateResolveConversation(ctx *context.Context) {
 		return
 	}
 
+	if origin == "diff" {
+		renderConversation(ctx, comment)
+		return
+	}
 	ctx.JSON(200, map[string]interface{}{
 		"ok": true,
 	})
 }
 
+func renderConversation(ctx *context.Context, comment *models.Comment) {
+	comments, err := models.FetchCodeCommentsByLine(comment.Issue, ctx.User, comment.TreePath, comment.Line)
+	if err != nil {
+		ctx.ServerError("FetchCodeCommentsByLine", err)
+		return
+	}
+	ctx.Data["PageIsPullFiles"] = true
+	ctx.Data["comments"] = comments
+	ctx.Data["CanMarkConversation"] = true
+	ctx.Data["Issue"] = comment.Issue
+	if err = comment.Issue.LoadPullRequest(); err != nil {
+		ctx.ServerError("comment.Issue.LoadPullRequest", err)
+		return
+	}
+	pullHeadCommitID, err := ctx.Repo.GitRepo.GetRefCommitID(comment.Issue.PullRequest.GetGitRefName())
+	if err != nil {
+		ctx.ServerError("GetRefCommitID", err)
+		return
+	}
+	ctx.Data["AfterCommitID"] = pullHeadCommitID
+	ctx.HTML(200, tplConversation)
+}
+
 // SubmitReview creates a review out of the existing pending review or creates a new one if no pending review exist
 func SubmitReview(ctx *context.Context, form auth.SubmitReviewForm) {
 	issue := GetActionIssue(ctx)

routers/routes/macaron.go

@@ -856,6 +856,7 @@ func RegisterMacaronRoutes(m *macaron.Macaron) {
 			m.Group("/files", func() {
 				m.Get("", context.RepoRef(), repo.SetEditorconfigIfExists, repo.SetDiffViewStyle, repo.SetWhitespaceBehavior, repo.ViewPullFiles)
 				m.Group("/reviews", func() {
+					m.Get("/new_comment", repo.RenderNewCodeCommentForm)
 					m.Post("/comments", bindIgnErr(auth.CodeCommentForm{}), repo.CreateCodeComment)
 					m.Post("/submit", bindIgnErr(auth.SubmitReviewForm{}), repo.SubmitReview)
 				}, context.RepoMustNotBeArchived())