From 8e3121447d7a72ab5467276983f8618074a04bcf Mon Sep 17 00:00:00 2001
From: Joseph Milazzo <joseph.v.milazzo@gmail.com>
Date: Tue, 19 Oct 2021 06:12:49 -0700
Subject: [PATCH] More EPUB Scoping Fixes (#691)

* Added better handling around when importing css files that are empty. Moved comment removal on css files to before some css whitespace cleanup to get better matches.

* Some enhancements on the checks to see if we need the bottom action bar on reader. Now we don't query DOM and have something that works more reliably.
---
 API/Controllers/BookController.cs             |  5 ++++-
 API/Services/BookService.cs                   | 22 ++++++++++++++++---
 .../book-reader/book-reader.component.ts      | 10 +--------
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/API/Controllers/BookController.cs b/API/Controllers/BookController.cs
index 448d45c02..cf5e66e22 100644
--- a/API/Controllers/BookController.cs
+++ b/API/Controllers/BookController.cs
@@ -259,7 +259,10 @@ namespace API.Controllers
                             }
 
                             var styleContent = await _bookService.ScopeStyles(await book.Content.Css[key].ReadContentAsync(), apiBase, book.Content.Css[key].FileName, book);
-                            body.PrependChild(HtmlNode.CreateNode($"<style>{styleContent}</style>"));
+                            if (styleContent != null)
+                            {
+                                body.PrependChild(HtmlNode.CreateNode($"<style>{styleContent}</style>"));
+                            }
                         }
                     }
 
diff --git a/API/Services/BookService.cs b/API/Services/BookService.cs
index 4449b6834..71f633e4c 100644
--- a/API/Services/BookService.cs
+++ b/API/Services/BookService.cs
@@ -154,6 +154,8 @@ namespace API.Services
             var styleContent = RemoveWhiteSpaceFromStylesheets(stylesheetHtml);
             styleContent = styleContent.Replace("body", ".reading-section");
 
+            if (string.IsNullOrEmpty(styleContent)) return string.Empty;
+
             var stylesheet = await _cssParser.ParseAsync(styleContent);
             foreach (var styleRule in stylesheet.StyleRules)
             {
@@ -508,15 +510,29 @@ namespace API.Services
 
         private static string RemoveWhiteSpaceFromStylesheets(string body)
         {
+            if (string.IsNullOrEmpty(body))
+            {
+                return string.Empty;
+            }
+
+            // Remove comments from CSS
+            body = Regex.Replace(body, @"/\*[\d\D]*?\*/", string.Empty);
+
             body = Regex.Replace(body, @"[a-zA-Z]+#", "#");
             body = Regex.Replace(body, @"[\n\r]+\s*", string.Empty);
             body = Regex.Replace(body, @"\s+", " ");
             body = Regex.Replace(body, @"\s?([:,;{}])\s?", "$1");
-            body = body.Replace(";}", "}");
+            try
+            {
+                body = body.Replace(";}", "}");
+            }
+            catch (Exception)
+            {
+                /* Swallow exception. Some css doesn't have style rules ending in ; */
+            }
+
             body = Regex.Replace(body, @"([\s:]0)(px|pt|%|em)", "$1");
 
-            // Remove comments from CSS
-            body = Regex.Replace(body, @"/\*[\d\D]*?\*/", string.Empty);
 
             return body;
         }
diff --git a/UI/Web/src/app/book-reader/book-reader/book-reader.component.ts b/UI/Web/src/app/book-reader/book-reader/book-reader.component.ts
index 0eee0bfb0..514ea6a01 100644
--- a/UI/Web/src/app/book-reader/book-reader/book-reader.component.ts
+++ b/UI/Web/src/app/book-reader/book-reader/book-reader.component.ts
@@ -717,15 +717,7 @@ export class BookReaderComponent implements OnInit, AfterViewInit, OnDestroy {
 
   setupPage(part?: string | undefined, scrollTop?: number | undefined) {
     this.isLoading = false;
-    this.scrollbarNeeded = this.readingSectionElemRef.nativeElement.scrollHeight > this.readingSectionElemRef.nativeElement.clientHeight;
-
-    const itemsOnScreen = Array.from(this.readingHtml.nativeElement.querySelectorAll('*')).filter(elem => (elem as HTMLElement).nodeName != 'STYLE');
-    const itemsWithAbsolutePositioning = itemsOnScreen.filter(elem => (elem as HTMLElement).style.getPropertyValue('position') === 'absolute').length;
-
-    if (itemsWithAbsolutePositioning >= itemsOnScreen.length) {
-      // Supress bottom actionbar. This is because of how the html is structured, with abs positioning, it will render inside images, etc. 
-      this.scrollbarNeeded = false;
-    }
+    this.scrollbarNeeded = this.readingHtml.nativeElement.clientHeight > this.readingSectionElemRef.nativeElement.clientHeight;
 
     // Find all the part ids and their top offset
     this.setupPageAnchors();