From 89989b66f4f054d0d22bc4792c8b9737743bf56f Mon Sep 17 00:00:00 2001
From: shirshasa <katerinagorbac@gmail.com>
Date: Tue, 21 Jul 2020 15:43:41 +0300
Subject: [PATCH] fix error on book without right TOC

---
 src/book.py | 43 ++++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/src/book.py b/src/book.py
index ccc7b55..0707cc3 100644
--- a/src/book.py
+++ b/src/book.py
@@ -594,7 +594,6 @@ class Book:
 
             footnotes.append(content)
 
-
         self.footnotes = footnotes
 
     def _process_images(self):
@@ -705,28 +704,29 @@ class Book:
         headers_info = []
         header_tags = self.body_tag.find_all(re.compile("^h[1-9]$"))
         headers_outline = [int(re.sub(r"^h", "", tag.name)) for tag in header_tags]
-        top_level_outline = min(headers_outline)
-        top_level_headers = [tag for tag in header_tags
-                             if int(re.sub(r"^h", "", tag.name)) == top_level_outline]
+        if headers_outline:
+            top_level_outline = min(headers_outline)
+            top_level_headers = [tag for tag in header_tags
+                                 if int(re.sub(r"^h", "", tag.name)) == top_level_outline]
 
-        for tag in top_level_headers:
-            if tag.parent.name == "li":
-                tag.parent.unwrap()
-                while tag.parent.name == "ol":
+            for tag in top_level_headers:
+                if tag.parent.name == "li":
                     tag.parent.unwrap()
+                    while tag.parent.name == "ol":
+                        tag.parent.unwrap()
 
-            title = tag.text
-            title = re.sub(r'\s+', ' ', title).strip()
-            number = re.match(r'^(?:\.?\d+\.? ?)+', title)
-            is_numbered = number is not None
+                title = tag.text
+                title = re.sub(r'\s+', ' ', title).strip()
+                number = re.match(r'^(?:\.?\d+\.? ?)+', title)
+                is_numbered = number is not None
 
-            cleaned_title = self.clean_header_title(tag.text)
-            is_introduction = cleaned_title.lower() == 'introduction'
+                cleaned_title = self.clean_header_title(tag.text)
+                is_introduction = cleaned_title.lower() == 'introduction'
 
-            headers_info.append({
-                'title': cleaned_title,
-                'is_numbered': is_numbered,
-                'is_introduction': is_introduction})
+                headers_info.append({
+                    'title': cleaned_title,
+                    'is_numbered': is_numbered,
+                    'is_introduction': is_introduction})
 
         return headers_info
 
@@ -973,10 +973,11 @@ class Book:
 
         # Add is_introduction field to json structure
         # after deleting content before toc, some chapters can be deleted
-        same_first_titles = self.top_level_headers[0]['title'] == json_strc[0]['title']
-        is_first_header_introduction = not self.top_level_headers[0]['should_be_numbered']
+        if self.top_level_headers:
+            same_first_titles = self.top_level_headers[0]['title'] == json_strc[0]['title']
+            is_first_header_introduction = not self.top_level_headers[0]['should_be_numbered']
 
-        json_strc[0]['is_introduction'] = is_first_header_introduction and same_first_titles
+            json_strc[0]['is_introduction'] = is_first_header_introduction and same_first_titles
 
         self.content_dict = {
             "content": json_strc,