fix(icon): implement better handling of relative icon URLs within a subfolder

internal/reader/icon/finder.go

@@ -64,13 +64,17 @@ func (f *iconFinder) findIcon() (*model.Icon, error) {
 		}
 	}
 
-	if icon, err := f.fetchIconsFromHTMLDocument(); err != nil {
-		slog.Debug("Unable to fetch icons from HTML document",
-			slog.String("website_url", f.websiteURL),
-			slog.Any("error", err),
-		)
-	} else if icon != nil {
-		return icon, nil
+	// Try the website URL first, then fall back to the root URL if no icon is found.
+	// The website URL may include a subdirectory (e.g., https://example.org/subfolder/), and icons can be referenced relative to that path.
+	for _, documentURL := range []string{f.websiteURL, urllib.RootURL(f.websiteURL)} {
+		if icon, err := f.fetchIconsFromHTMLDocument(documentURL); err != nil {
+			slog.Debug("Unable to fetch icons from HTML document",
+				slog.String("document_url", documentURL),
+				slog.Any("error", err),
+			)
+		} else if icon != nil {
+			return icon, nil
+		}
 	}
 
 	return f.fetchDefaultIcon()
@@ -94,14 +98,12 @@ func (f *iconFinder) fetchDefaultIcon() (*model.Icon, error) {
 	return icon, nil
 }
 
-func (f *iconFinder) fetchIconsFromHTMLDocument() (*model.Icon, error) {
+func (f *iconFinder) fetchIconsFromHTMLDocument(documentURL string) (*model.Icon, error) {
 	slog.Debug("Searching icons from HTML document",
-		slog.String("website_url", f.websiteURL),
+		slog.String("document_url", documentURL),
 	)
 
-	rootURL := urllib.RootURL(f.websiteURL)
-
-	responseHandler := fetcher.NewResponseHandler(f.requestBuilder.ExecuteRequest(rootURL))
+	responseHandler := fetcher.NewResponseHandler(f.requestBuilder.ExecuteRequest(documentURL))
 	defer responseHandler.Close()
 
 	if localizedError := responseHandler.LocalizedError(); localizedError != nil {
@@ -109,6 +111,7 @@ func (f *iconFinder) fetchIconsFromHTMLDocument() (*model.Icon, error) {
 	}
 
 	iconURLs, err := findIconURLsFromHTMLDocument(
+		documentURL,
 		responseHandler.Body(config.Opts.HTTPClientMaxBodySize()),
 		responseHandler.ContentType(),
 	)
@@ -117,32 +120,27 @@ func (f *iconFinder) fetchIconsFromHTMLDocument() (*model.Icon, error) {
 	}
 
 	slog.Debug("Searched icon from HTML document",
-		slog.String("website_url", f.websiteURL),
+		slog.String("document_url", documentURL),
 		slog.String("icon_urls", strings.Join(iconURLs, ",")),
 	)
 
 	for _, iconURL := range iconURLs {
 		if strings.HasPrefix(iconURL, "data:") {
 			slog.Debug("Found icon with data URL",
-				slog.String("website_url", f.websiteURL),
+				slog.String("document_url", documentURL),
 			)
 			return parseImageDataURL(iconURL)
 		}
 
-		iconURL, err = urllib.AbsoluteURL(f.websiteURL, iconURL)
-		if err != nil {
-			return nil, fmt.Errorf(`icon: unable to convert icon URL to absolute URL: %w`, err)
-		}
-
 		if icon, err := f.downloadIcon(iconURL); err != nil {
 			slog.Debug("Unable to download icon from HTML document",
-				slog.String("website_url", f.websiteURL),
+				slog.String("document_url", documentURL),
 				slog.String("icon_url", iconURL),
 				slog.Any("error", err),
 			)
 		} else if icon != nil {
 			slog.Debug("Downloaded icon from HTML document",
-				slog.String("website_url", f.websiteURL),
+				slog.String("document_url", documentURL),
 				slog.String("icon_url", iconURL),
 			)
 			return icon, nil
@@ -195,7 +193,7 @@ func resizeIcon(icon *model.Icon) *model.Icon {
 	}
 
 	if !slices.Contains([]string{"image/jpeg", "image/png", "image/gif", "image/webp"}, icon.MimeType) {
-		slog.Info("Icon resize skipped: unsupported MIME type", slog.String("mime_type", icon.MimeType))
+		slog.Debug("Icon resize skipped: unsupported MIME type", slog.String("mime_type", icon.MimeType))
 		return icon
 	}
 
@@ -244,7 +242,7 @@ func resizeIcon(icon *model.Icon) *model.Icon {
 	return icon
 }
 
-func findIconURLsFromHTMLDocument(body io.Reader, contentType string) ([]string, error) {
+func findIconURLsFromHTMLDocument(documentURL string, body io.Reader, contentType string) ([]string, error) {
 	htmlDocumentReader, err := encoding.NewCharsetReader(body, contentType)
 	if err != nil {
 		return nil, fmt.Errorf("icon: unable to create charset reader: %w", err)
@@ -268,11 +266,20 @@ func findIconURLsFromHTMLDocument(body io.Reader, contentType string) ([]string,
 
 		for _, s := range doc.Find(query).EachIter() {
 			href, _ := s.Attr("href")
-			if iconURL := strings.TrimSpace(href); iconURL != "" {
-				iconURLs = append(iconURLs, iconURL)
+			href = strings.TrimSpace(href)
+			if href == "" {
+				continue
+			}
+
+			if absoluteIconURL, err := urllib.AbsoluteURL(documentURL, href); err != nil {
+				slog.Warn("Unable to convert icon URL to absolute URL", slog.Any("error", err), slog.String("icon_href", href))
+			} else {
+				iconURLs = append(iconURLs, absoluteIconURL)
 				slog.Debug("Found icon URL in HTML document",
 					slog.String("query", query),
-					slog.String("icon_url", iconURL))
+					slog.String("icon_href", href),
+					slog.String("absolute_icon_url", absoluteIconURL),
+				)
 			}
 		}
 	}

internal/reader/icon/finder_test.go

@@ -123,16 +123,16 @@ func TestFindIconURLsFromHTMLDocument_MultipleIcons(t *testing.T) {
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	expected := []string{
-		"/favicon.ico",
-		"/shortcut-favicon.ico",
-		"/icon-shortcut.ico",
-		"/apple-touch-icon.png",
+		"https://example.org/favicon.ico",
+		"https://example.org/shortcut-favicon.ico",
+		"https://example.org/icon-shortcut.ico",
+		"https://example.org/apple-touch-icon.png",
 	}
 
 	if len(iconURLs) != len(expected) {
@@ -155,22 +155,22 @@ func TestFindIconURLsFromHTMLDocument_CaseInsensitiveRel(t *testing.T) {
 	<link rel="SHORTCUT ICON" href="/favicon3.ico">
 	<link rel="Shortcut Icon" href="/favicon4.ico">
 	<link rel="ICON SHORTCUT" href="/favicon5.ico">
-	<link rel="Icon Shortcut" href="/favicon6.ico">
+	<link rel="Icon Shortcut" href="favicon6.ico">
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org/folder/", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	expected := []string{
-		"/favicon1.ico",
-		"/favicon2.ico",
-		"/favicon3.ico",
-		"/favicon4.ico",
-		"/favicon5.ico",
-		"/favicon6.ico",
+		"https://example.org/favicon1.ico",
+		"https://example.org/favicon2.ico",
+		"https://example.org/favicon3.ico",
+		"https://example.org/favicon4.ico",
+		"https://example.org/favicon5.ico",
+		"https://example.org/folder/favicon6.ico",
 	}
 
 	if len(iconURLs) != len(expected) {
@@ -194,7 +194,7 @@ func TestFindIconURLsFromHTMLDocument_NoIcons(t *testing.T) {
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -215,12 +215,12 @@ func TestFindIconURLsFromHTMLDocument_EmptyHref(t *testing.T) {
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	expected := []string{"/valid-icon.ico"}
+	expected := []string{"https://example.org/valid-icon.ico"}
 
 	if len(iconURLs) != len(expected) {
 		t.Fatalf("Expected %d icon URLs, got %d", len(expected), len(iconURLs))
@@ -241,7 +241,7 @@ func TestFindIconURLsFromHTMLDocument_DataURLs(t *testing.T) {
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org/folder", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -250,7 +250,7 @@ func TestFindIconURLsFromHTMLDocument_DataURLs(t *testing.T) {
 	// So both rel="icon" links are found first, then the rel="shortcut icon" link
 	expected := []string{
 		"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNkYPhfDwAChAGAhGAQ+QAAAABJRU5ErkJggg==",
-		"/regular-icon.ico",
+		"https://example.org/regular-icon.ico",
 		"data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg'></svg>",
 	}
 
@@ -277,17 +277,17 @@ func TestFindIconURLsFromHTMLDocument_RelativeAndAbsoluteURLs(t *testing.T) {
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org/folder/", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	expected := []string{
-		"/absolute-path.ico",
-		"relative-path.ico",
-		"../parent-dir.ico",
+		"https://example.org/absolute-path.ico",
+		"https://example.org/folder/relative-path.ico",
+		"https://example.org/parent-dir.ico",
 		"https://example.com/external.ico",
-		"//cdn.example.com/protocol-relative.ico",
+		"https://cdn.example.com/protocol-relative.ico",
 	}
 
 	if len(iconURLs) != len(expected) {
@@ -311,7 +311,7 @@ func TestFindIconURLsFromHTMLDocument_InvalidHTML(t *testing.T) {
 </head>
 </html>`
 
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(html), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org", strings.NewReader(html), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -324,7 +324,7 @@ func TestFindIconURLsFromHTMLDocument_InvalidHTML(t *testing.T) {
 	// Should at least find the valid ones
 	foundValidIcon := false
 	for _, url := range iconURLs {
-		if url == "/valid-before-error.ico" || url == "/valid-after-error.ico" {
+		if url == "https://example.org/valid-before-error.ico" || url == "https://example.org/valid-after-error.ico" {
 			foundValidIcon = true
 			break
 		}
@@ -336,7 +336,7 @@ func TestFindIconURLsFromHTMLDocument_InvalidHTML(t *testing.T) {
 }
 
 func TestFindIconURLsFromHTMLDocument_EmptyDocument(t *testing.T) {
-	iconURLs, err := findIconURLsFromHTMLDocument(strings.NewReader(""), "text/html")
+	iconURLs, err := findIconURLsFromHTMLDocument("https://example.org", strings.NewReader(""), "text/html")
 	if err != nil {
 		t.Fatal(err)
 	}

internal/urllib/url.go

@@ -18,7 +18,7 @@ func IsAbsoluteURL(link string) bool {
 	return u.IsAbs()
 }
 
-// GetAbsoluteURL return the absolute form of `input` is possible, as well as its parser form.
+// GetAbsoluteURL returns the absolute form of `input` if possible, as well as its parsed form.
 func GetAbsoluteURL(input string) (string, *url.URL, error) {
 	if strings.HasPrefix(input, "//") {
 		return "https:" + input, nil, nil