Style recognition fixes (#1416)

lib/src/models/documents/document.dart

@@ -156,19 +156,28 @@ class Document {
   /// included in the result.
   Style collectStyle(int index, int len) {
     final res = queryChild(index);
-    // -1 because the cursor is at the part of the line that is not visible
-    // Bug: When the caret is in the middle of the paragraph
-    // and at the end of the format string, it will display the wrong state
-    // of the format button
-    final isLinkStyle =
-        res.node?.style.attributes[Attribute.link.key]?.value == true;
-    // In this case, we have an exception, this is a link.
-    // When node is a link we will not -1
-    return (res.node as Line).collectStyle(
-        len == 0 && res.node != null && !isLinkStyle
-            ? res.offset - 1
-            : res.offset,
-        len);
+    Style rangeStyle;
+    if (len > 0) {
+      return (res.node as Line).collectStyle(res.offset, len);
+    }
+    if (res.offset == 0) {
+      rangeStyle = (res.node as Line).collectStyle(res.offset, len);
+      return rangeStyle.removeAll({
+        for (final attr in rangeStyle.values)
+          if (attr.isInline) attr
+      });
+    }
+    rangeStyle = (res.node as Line).collectStyle(res.offset - 1, len);
+    final linkAttribute = rangeStyle.attributes[Attribute.link.key];
+    if ((linkAttribute != null) &&
+        (linkAttribute.value !=
+            (res.node as Line)
+                .collectStyle(res.offset, len)
+                .attributes[Attribute.link.key]
+                ?.value)) {
+      return rangeStyle.removeAll({linkAttribute});
+    }
+    return rangeStyle;
   }
 
   /// Returns all styles and Embed for each node within selection

lib/src/models/documents/nodes/line.dart

@@ -352,18 +352,13 @@ class Line extends Container<Leaf?> {
     final excluded = <Attribute>{};
 
     void _handle(Style style) {
-      if (result.isEmpty) {
-        excluded.addAll(style.values);
-      } else {
-        for (final attr in result.values) {
-          if (!style.containsKey(attr.key)) {
-            excluded.add(attr);
-          }
+      for (final attr in result.values) {
+        if (!style.containsKey(attr.key) ||
+            (style.attributes[attr.key] != attr.value)) {
+          excluded.add(attr);
         }
       }
-      final remaining = style.removeAll(excluded);
       result = result.removeAll(excluded);
-      result = result.mergeAll(remaining);
     }
 
     final data = queryChild(offset, true);