descpage: Implement gnuplot script update

Replace the current wiki script with local variant

Issue #1 (https://git.golderweb.de/wiki/jogobot-euroexchange/issues/1)

euroexchange/descpage.py

@@ -49,6 +49,9 @@ class DescPageBot(pywikibot.bot.Bot):
         # Parse filepage
         self.parse_page()
 
+        # Update gnuplot script
+        self.update_gnuplot_script()
+
         # Update wiki page
         self.update_page()
 
@@ -90,6 +93,19 @@ class DescPageBot(pywikibot.bot.Bot):
         """
         self.current_page.wikicode = mwparser.parse(self.current_page.text)
 
+    def update_gnuplot_script(self):
+        """
+        Update the gnuplot script embedded in page
+        """
+
+        # Get source tag with gnuplot script
+        gnuplot_script = next(
+            self.current_page.wikicode.ifilter_tags(
+                matches="<source lang=\"gnuplot\">" ) )
+
+        # Replace script
+        gnuplot_script.contents = "\n" + self.prepare_gnuplot_script() + "\n"
+
     def update_page(self):
         """
         Put updated content to wiki