[books] Fix resume reading link and page calc

vrobbler/apps/scrobbles/models.py

@@ -593,6 +593,17 @@ class Scrobble(TimeStampedModel):
                 self.stop_timestamp - self.timestamp
             ).seconds
 
+        if (
+            self.log
+            and isinstance(self.log, dict)
+            and self.log.get("page_start") is not None
+            and self.log.get("page_end") is not None
+            and "pages_read" not in self.log
+        ):
+            self.log["pages_read"] = (
+                self.log["page_end"] - self.log["page_start"] + 1
+            )
+
         return super(Scrobble, self).save(*args, **kwargs)
 
     def get_absolute_url(self):
@@ -1452,38 +1463,38 @@ class Scrobble(TimeStampedModel):
         return False
 
     def calculate_reading_stats(self, commit=True):
-        # --- Sort safely by numeric page_number ---
-        def safe_page_number(entry):
-            try:
-                return int(getattr("page_number", entry), 0)
-            except (ValueError, TypeError):
-                return float("inf")  # push invalid entries to the end
-
         page_data = self.log.get("page_data")
 
-        if not page_data:
-            logger.warning("No page data found to calculate")
-            return
+        if page_data:
+            # --- Sort safely by numeric page_number ---
+            def safe_page_number(entry):
+                try:
+                    return int(getattr("page_number", entry), 0)
+                except (ValueError, TypeError):
+                    return float("inf")
 
-        if isinstance(page_data, dict):
-            logger.warning("Page data is dict, migrate koreader data")
-            return
+            if isinstance(page_data, dict):
+                logger.warning("Page data is dict, migrate koreader data")
+                return
 
-        page_data.sort(key=safe_page_number)
+            page_data.sort(key=safe_page_number)
 
-        # --- Extract valid numeric page numbers ---
-        valid_pages = []
-        for page in page_data:
-            try:
-                valid_pages.append(int(page["page_number"]))
-            except (ValueError, TypeError):
-                continue
+            valid_pages = []
+            for page in page_data:
+                try:
+                    valid_pages.append(int(page["page_number"]))
+                except (ValueError, TypeError):
+                    continue
 
-        # --- Compute stats ---
-        if valid_pages:
-            self.log["page_start"] = min(valid_pages)
-            self.log["page_end"] = max(valid_pages)
-            self.log["pages_read"] = len(set(valid_pages))
+            if valid_pages:
+                self.log["page_start"] = min(valid_pages)
+                self.log["page_end"] = max(valid_pages)
+                self.log["pages_read"] = len(set(valid_pages))
+        else:
+            page_start = self.log.get("page_start")
+            page_end = self.log.get("page_end")
+            if page_start is not None and page_end is not None:
+                self.log["pages_read"] = page_end - page_start + 1
 
-            if commit:
-                self.save(update_fields=["log"])
+        if commit and "pages_read" in self.log:
+            self.save(update_fields=["log"])