Refactor render system (#32492)

There were too many patches to the Render system, it's really difficult
to make further improvements.

This PR clears the legacy problems and fix TODOs.

1. Rename `RenderContext.Type` to `RenderContext.MarkupType` to clarify
its usage.
2. Use `ContentMode` to replace `meta["mode"]` and `IsWiki`, to clarify
the rendering behaviors.
3. Use "wiki" mode instead of "mode=gfm + wiki=true"
4. Merge `renderByType` and `renderByFile`
5. Add more comments

----

The problem of "mode=document": in many cases it is not set, so many
non-comment places use comment's hard line break incorrectly

routers/web/feed/convert.go

@@ -56,7 +56,6 @@ func renderMarkdown(ctx *context.Context, act *activities_model.Action, content
 		Links: markup.Links{
 			Base: act.GetRepoLink(ctx),
 		},
-		Type: markdown.MarkupName,
 		Metas: map[string]string{
 			"user": act.GetRepoUserName(ctx),
 			"repo": act.GetRepoName(ctx),

routers/web/misc/markup.go

@@ -6,6 +6,7 @@ package misc
 
 import (
 	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers/common"
 	"code.gitea.io/gitea/services/context"
@@ -14,5 +15,6 @@ import (
 // Markup render markup document to HTML
 func Markup(ctx *context.Context) {
 	form := web.GetForm(ctx).(*api.MarkupOption)
-	common.RenderMarkup(ctx.Base, ctx.Repo, form.Mode, form.Text, form.Context, form.FilePath, form.Wiki)
+	mode := util.Iif(form.Wiki, "wiki", form.Mode) //nolint:staticcheck
+	common.RenderMarkup(ctx.Base, ctx.Repo, mode, form.Text, form.Context, form.FilePath)
 }

routers/web/repo/view.go

@@ -312,6 +312,7 @@ func renderReadmeFile(ctx *context.Context, subfolder string, readmeFile *git.Tr
 
 		ctx.Data["EscapeStatus"], ctx.Data["FileContent"], err = markupRender(ctx, &markup.RenderContext{
 			Ctx:          ctx,
+			MarkupType:   markupType,
 			RelativePath: path.Join(ctx.Repo.TreePath, readmeFile.Name()), // ctx.Repo.TreePath is the directory not the Readme so we must append the Readme filename (and path).
 			Links: markup.Links{
 				Base:       ctx.Repo.RepoLink,
@@ -502,28 +503,20 @@ func renderFile(ctx *context.Context, entry *git.TreeEntry) {
 		ctx.Data["ReadmeExist"] = readmeExist
 
 		markupType := markup.DetectMarkupTypeByFileName(blob.Name())
-		// If the markup is detected by custom markup renderer it should not be reset later on
-		// to not pass it down to the render context.
-		detected := false
 		if markupType == "" {
-			detected = true
 			markupType = markup.DetectRendererType(blob.Name(), bytes.NewReader(buf))
 		}
 		if markupType != "" {
 			ctx.Data["HasSourceRenderedToggle"] = true
 		}
-
 		if markupType != "" && !shouldRenderSource {
 			ctx.Data["IsMarkup"] = true
 			ctx.Data["MarkupType"] = markupType
-			if !detected {
-				markupType = ""
-			}
 			metas := ctx.Repo.Repository.ComposeDocumentMetas(ctx)
 			metas["BranchNameSubURL"] = ctx.Repo.BranchNameSubURL()
 			ctx.Data["EscapeStatus"], ctx.Data["FileContent"], err = markupRender(ctx, &markup.RenderContext{
 				Ctx:          ctx,
-				Type:         markupType,
+				MarkupType:   markupType,
 				RelativePath: ctx.Repo.TreePath,
 				Links: markup.Links{
 					Base:       ctx.Repo.RepoLink,
@@ -615,6 +608,7 @@ func renderFile(ctx *context.Context, entry *git.TreeEntry) {
 			ctx.Data["MarkupType"] = markupType
 			ctx.Data["EscapeStatus"], ctx.Data["FileContent"], err = markupRender(ctx, &markup.RenderContext{
 				Ctx:          ctx,
+				MarkupType:   markupType,
 				RelativePath: ctx.Repo.TreePath,
 				Links: markup.Links{
 					Base:       ctx.Repo.RepoLink,

routers/web/repo/wiki.go

@@ -289,12 +289,12 @@ func renderViewPage(ctx *context.Context) (*git.Repository, *git.TreeEntry) {
 	}
 
 	rctx := &markup.RenderContext{
-		Ctx:   ctx,
-		Metas: ctx.Repo.Repository.ComposeDocumentMetas(ctx),
+		Ctx:         ctx,
+		ContentMode: markup.RenderContentAsWiki,
+		Metas:       ctx.Repo.Repository.ComposeDocumentMetas(ctx),
 		Links: markup.Links{
 			Base: ctx.Repo.RepoLink,
 		},
-		IsWiki: true,
 	}
 	buf := &strings.Builder{}
 

routers/web/user/profile.go

@@ -258,7 +258,6 @@ func prepareUserProfileTabData(ctx *context.Context, showPrivate bool, profileDb
 					Base:       profileDbRepo.Link(),
 					BranchPath: path.Join("branch", util.PathEscapeSegments(profileDbRepo.DefaultBranch)),
 				},
-				Metas: map[string]string{"mode": "document"},
 			}, bytes); err != nil {
 				log.Error("failed to RenderString: %v", err)
 			} else {