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

1 files changed, 24 insertions, 3 deletions

diff --git a/tests/integration/markup_external_test.go b/tests/integration/markup_external_test.go
index e50f5c1356..2d713b0eb9 100644
--- a/tests/integration/markup_external_test.go
+++ b/tests/integration/markup_external_test.go
@@ -10,6 +10,8 @@ import (
 	"strings"
 	"testing"
 
+	"code.gitea.io/gitea/modules/markup"
+	"code.gitea.io/gitea/modules/markup/external"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/tests"
 
@@ -23,10 +25,9 @@ func TestExternalMarkupRenderer(t *testing.T) {
 		return
 	}
 
-	const repoURL = "user30/renderer"
-	req := NewRequest(t, "GET", repoURL+"/src/branch/master/README.html")
+	req := NewRequest(t, "GET", "/user30/renderer/src/branch/master/README.html")
 	resp := MakeRequest(t, req, http.StatusOK)
-	assert.EqualValues(t, "text/html; charset=utf-8", resp.Header()["Content-Type"][0])
+	assert.EqualValues(t, "text/html; charset=utf-8", resp.Header().Get("Content-Type"))
 
 	bs, err := io.ReadAll(resp.Body)
 	assert.NoError(t, err)
@@ -36,4 +37,24 @@ func TestExternalMarkupRenderer(t *testing.T) {
 	data, err := div.Html()
 	assert.NoError(t, err)
 	assert.EqualValues(t, "<div>\n\ttest external renderer\n</div>", strings.TrimSpace(data))
+
+	r := markup.GetRendererByFileName("a.html").(*external.Renderer)
+	r.RenderContentMode = setting.RenderContentModeIframe
+
+	req = NewRequest(t, "GET", "/user30/renderer/src/branch/master/README.html")
+	resp = MakeRequest(t, req, http.StatusOK)
+	assert.EqualValues(t, "text/html; charset=utf-8", resp.Header().Get("Content-Type"))
+	bs, err = io.ReadAll(resp.Body)
+	assert.NoError(t, err)
+	doc = NewHTMLParser(t, bytes.NewBuffer(bs))
+	iframe := doc.Find("iframe")
+	assert.EqualValues(t, "/user30/renderer/render/branch/master/README.html", iframe.AttrOr("src", ""))
+
+	req = NewRequest(t, "GET", "/user30/renderer/render/branch/master/README.html")
+	resp = MakeRequest(t, req, http.StatusOK)
+	assert.EqualValues(t, "text/html; charset=utf-8", resp.Header().Get("Content-Type"))
+	bs, err = io.ReadAll(resp.Body)
+	assert.NoError(t, err)
+	assert.EqualValues(t, "frame-src 'self'; sandbox allow-scripts", resp.Header().Get("Content-Security-Policy"))
+	assert.EqualValues(t, "<div>\n\ttest external renderer\n</div>\n", string(bs))
 }