Rework markup link rendering (#26745)

Fixes #26548

This PR refactors the rendering of markup links. The old code uses
`strings.Replace` to change some urls while the new code uses more
context to decide which link should be generated.

The added tests should ensure the same output for the old and new
behaviour (besides the bug).

We may need to refactor the rendering a bit more to make it clear how
the different helper methods render the input string. There are lots of
options (resolve links / images / mentions / git hashes / emojis / ...)
but you don't really know what helper uses which options. For example,
we currently support images in the user description which should not be
allowed I think:

<details>
  <summary>Profile</summary> 

https://try.gitea.io/KN4CK3R

![grafik](https://github.com/go-gitea/gitea/assets/1666336/109ae422-496d-4200-b52e-b3a528f553e5)

</details>

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

1 files changed, 18 insertions, 12 deletions

diff --git a/modules/markup/html_internal_test.go b/modules/markup/html_internal_test.go
index 7b7f6df701..5ba9561915 100644
--- a/modules/markup/html_internal_test.go
+++ b/modules/markup/html_internal_test.go
@@ -287,8 +287,8 @@ func TestRender_IssueIndexPattern_Document(t *testing.T) {
 }
 
 func testRenderIssueIndexPattern(t *testing.T, input, expected string, ctx *RenderContext) {
-	if ctx.URLPrefix == "" {
-		ctx.URLPrefix = TestAppURL
+	if ctx.Links.Base == "" {
+		ctx.Links.Base = TestRepoURL
 	}
 
 	var buf strings.Builder
@@ -303,19 +303,23 @@ func TestRender_AutoLink(t *testing.T) {
 	test := func(input, expected string) {
 		var buffer strings.Builder
 		err := PostProcess(&RenderContext{
-			Ctx:       git.DefaultContext,
-			URLPrefix: TestRepoURL,
-			Metas:     localMetas,
+			Ctx: git.DefaultContext,
+			Links: Links{
+				Base: TestRepoURL,
+			},
+			Metas: localMetas,
 		}, strings.NewReader(input), &buffer)
 		assert.Equal(t, err, nil)
 		assert.Equal(t, strings.TrimSpace(expected), strings.TrimSpace(buffer.String()))
 
 		buffer.Reset()
 		err = PostProcess(&RenderContext{
-			Ctx:       git.DefaultContext,
-			URLPrefix: TestRepoURL,
-			Metas:     localMetas,
-			IsWiki:    true,
+			Ctx: git.DefaultContext,
+			Links: Links{
+				Base: TestRepoURL,
+			},
+			Metas:  localMetas,
+			IsWiki: true,
 		}, strings.NewReader(input), &buffer)
 		assert.Equal(t, err, nil)
 		assert.Equal(t, strings.TrimSpace(expected), strings.TrimSpace(buffer.String()))
@@ -342,9 +346,11 @@ func TestRender_FullIssueURLs(t *testing.T) {
 	test := func(input, expected string) {
 		var result strings.Builder
 		err := postProcess(&RenderContext{
-			Ctx:       git.DefaultContext,
-			URLPrefix: TestRepoURL,
-			Metas:     localMetas,
+			Ctx: git.DefaultContext,
+			Links: Links{
+				Base: TestRepoURL,
+			},
+			Metas: localMetas,
 		}, []processor{fullIssuePatternProcessor}, strings.NewReader(input), &result)
 		assert.NoError(t, err)
 		assert.Equal(t, expected, result.String())