Improve font characteristics parsing at FontSelector level

Parse font characteristics of specific font-family rather than
falsely reuse the characteristics of the previously parse family

DEVSIX-5587

Author: dmitry.radchuk

layout/src/main/java/com/itextpdf/layout/font/FontSelector.java

@@ -130,31 +130,31 @@ public int compare(FontInfo o1, FontInfo o2) {
             // It's important to mention that at the FontProvider level we add the default font-family
             // which is to be processed if for all provided font-families the score is 0.
             for (int i = 0; i < fontFamilies.size() && res == 0; i++) {
-                FontCharacteristics fc = fontStyles.get(i);
+                final FontCharacteristics fc = fontStyles.get(i);
                 String fontFamily = fontFamilies.get(i);
-
-                if ("monospace".equalsIgnoreCase(fontFamily)) {
-                    fc.setMonospaceFlag(true);
-                }
                 boolean isLastFontFamilyToBeProcessed = i == fontFamilies.size() - 1;
                 res = characteristicsSimilarity(fontFamily, fc, o2, isLastFontFamilyToBeProcessed) - characteristicsSimilarity(fontFamily, fc, o1, isLastFontFamilyToBeProcessed);
             }
             return res;
         }
 
-        private static FontCharacteristics parseFontStyle(String fontFamily, FontCharacteristics fc) {
-            if (fc == null) {
-                fc = new FontCharacteristics();
+        private static FontCharacteristics parseFontStyle(String fontFamily, FontCharacteristics defaultFc) {
+            if (defaultFc == null) {
+                defaultFc = new FontCharacteristics();
             }
-            if (fc.isUndefined()) {
+            final FontCharacteristics parsedFc = new FontCharacteristics(defaultFc);
+            if (parsedFc.isUndefined()) {
+                if ("monospace".equalsIgnoreCase(fontFamily)) {
+                    parsedFc.setMonospaceFlag(true);
+                }
                 if (fontFamily.contains("bold")) {
-                    fc.setBoldFlag(true);
+                    parsedFc.setBoldFlag(true);
                 }
                 if (fontFamily.contains("italic") || fontFamily.contains("oblique")) {
-                    fc.setItalicFlag(true);
+                    parsedFc.setItalicFlag(true);
                 }
             }
-            return fc;
+            return parsedFc;
         }
 
         /**

layout/src/test/java/com/itextpdf/layout/FontSelectorTest.java

@@ -1063,6 +1063,37 @@ public void openSansOutOfNotBoldFontWeightTest() {
                 new FontSelector(set.getFonts(), fontFamilies, fc).bestMatch().getDescriptor().getFontName());
     }
 
+    @Test
+    public void fontCharacteristicIsUnmodifiedTest() {
+        FontSet set = getOpenSansFontSet();
+
+        List<String> fontFamilies = new ArrayList<>();
+        fontFamilies.add("OpenSans italic");
+        fontFamilies.add("OpenSans bold");
+
+        FontCharacteristics fc = new FontCharacteristics();
+        FontCharacteristics expectedFc = new FontCharacteristics(fc);
+
+        // previously font characteristics might have been updated while sorting fonts
+        new FontSelector(set.getFonts(), fontFamilies, fc);
+
+        Assert.assertEquals(expectedFc, fc);
+    }
+
+    @Test
+    public void fontCharacteristicsNullTest() {
+        FontSet set = getOpenSansFontSet();
+
+        List<String> fontFamilies = new ArrayList<>();
+        fontFamilies.add("test");
+
+        FontCharacteristics fc = null;
+        FontSelector fontSelector = new FontSelector(set.getFonts(), fontFamilies, fc);
+
+        // We expect default font characteristics to be used, e.g. as a result regular font must be the best
+        Assert.assertEquals("OpenSans-Regular", fontSelector.bestMatch().getDescriptor().getFontName());
+    }
+
     private void checkSelector(Collection<FontInfo> fontInfoCollection, String fontFamily,
                                String expectedNormal, String expectedBold, String expectedItalic, String expectedBoldItalic) {
         List<String> fontFamilies = new ArrayList<>();