add submodule diff links (#33097)

This adds links to submodules in diffs, similar to the existing link
when viewing a repo at a specific commit. It does this by expanding diff
parsing to recognize changes to submodules, and find the specific refs
that are added, deleted or changed.

Related #25888

---------

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

modules/git/url/url_test.go

@@ -4,9 +4,15 @@
 package url
 
 import (
+	"context"
+	"net/http"
 	"net/url"
 	"testing"
 
+	"code.gitea.io/gitea/modules/httplib"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -164,3 +170,98 @@ func TestParseGitURLs(t *testing.T) {
 		})
 	}
 }
+
+func TestParseRepositoryURL(t *testing.T) {
+	defer test.MockVariableValue(&setting.AppURL, "https://localhost:3000")()
+	defer test.MockVariableValue(&setting.SSH.Domain, "try.gitea.io")()
+
+	ctxURL, _ := url.Parse("https://gitea")
+	ctxReq := &http.Request{URL: ctxURL, Header: http.Header{}}
+	ctxReq.Host = ctxURL.Host
+	ctxReq.Header.Add("X-Forwarded-Proto", ctxURL.Scheme)
+	ctx := context.WithValue(context.Background(), httplib.RequestContextKey, ctxReq)
+	cases := []struct {
+		input                          string
+		ownerName, repoName, remaining string
+	}{
+		{input: "/user/repo"},
+
+		{input: "https://localhost:3000/user/repo", ownerName: "user", repoName: "repo"},
+		{input: "https://external:3000/user/repo"},
+
+		{input: "https://localhost:3000/user/repo.git/other", ownerName: "user", repoName: "repo", remaining: "/other"},
+
+		{input: "https://gitea/user/repo", ownerName: "user", repoName: "repo"},
+		{input: "https://gitea:3333/user/repo"},
+
+		{input: "ssh://try.gitea.io:2222/user/repo", ownerName: "user", repoName: "repo"},
+		{input: "ssh://external:2222/user/repo"},
+
+		{input: "git+ssh://user@try.gitea.io/user/repo.git", ownerName: "user", repoName: "repo"},
+		{input: "git+ssh://user@external/user/repo.git"},
+
+		{input: "root@try.gitea.io:user/repo.git", ownerName: "user", repoName: "repo"},
+		{input: "root@gitea:user/repo.git", ownerName: "user", repoName: "repo"},
+		{input: "root@external:user/repo.git"},
+	}
+
+	for _, c := range cases {
+		t.Run(c.input, func(t *testing.T) {
+			ret, _ := ParseRepositoryURL(ctx, c.input)
+			assert.Equal(t, c.ownerName, ret.OwnerName)
+			assert.Equal(t, c.repoName, ret.RepoName)
+			assert.Equal(t, c.remaining, ret.RemainingPath)
+		})
+	}
+
+	t.Run("WithSubpath", func(t *testing.T) {
+		defer test.MockVariableValue(&setting.AppURL, "https://localhost:3000/subpath")()
+		defer test.MockVariableValue(&setting.AppSubURL, "/subpath")()
+		cases = []struct {
+			input                          string
+			ownerName, repoName, remaining string
+		}{
+			{input: "https://localhost:3000/user/repo"},
+			{input: "https://localhost:3000/subpath/user/repo.git/other", ownerName: "user", repoName: "repo", remaining: "/other"},
+
+			{input: "ssh://try.gitea.io:2222/user/repo", ownerName: "user", repoName: "repo"},
+			{input: "ssh://external:2222/user/repo"},
+
+			{input: "git+ssh://user@try.gitea.io/user/repo.git", ownerName: "user", repoName: "repo"},
+			{input: "git+ssh://user@external/user/repo.git"},
+
+			{input: "root@try.gitea.io:user/repo.git", ownerName: "user", repoName: "repo"},
+			{input: "root@external:user/repo.git"},
+		}
+
+		for _, c := range cases {
+			t.Run(c.input, func(t *testing.T) {
+				ret, _ := ParseRepositoryURL(ctx, c.input)
+				assert.Equal(t, c.ownerName, ret.OwnerName)
+				assert.Equal(t, c.repoName, ret.RepoName)
+				assert.Equal(t, c.remaining, ret.RemainingPath)
+			})
+		}
+	})
+}
+
+func TestMakeRepositoryBaseLink(t *testing.T) {
+	defer test.MockVariableValue(&setting.AppURL, "https://localhost:3000/subpath")()
+	defer test.MockVariableValue(&setting.AppSubURL, "/subpath")()
+
+	u, err := ParseRepositoryURL(context.Background(), "https://localhost:3000/subpath/user/repo.git")
+	assert.NoError(t, err)
+	assert.Equal(t, "/subpath/user/repo", MakeRepositoryWebLink(u))
+
+	u, err = ParseRepositoryURL(context.Background(), "https://github.com/owner/repo.git")
+	assert.NoError(t, err)
+	assert.Equal(t, "https://github.com/owner/repo", MakeRepositoryWebLink(u))
+
+	u, err = ParseRepositoryURL(context.Background(), "git@github.com:owner/repo.git")
+	assert.NoError(t, err)
+	assert.Equal(t, "https://github.com/owner/repo", MakeRepositoryWebLink(u))
+
+	u, err = ParseRepositoryURL(context.Background(), "git+ssh://other:123/owner/repo.git")
+	assert.NoError(t, err)
+	assert.Equal(t, "https://other/owner/repo", MakeRepositoryWebLink(u))
+}