BUG: fixed file date for F10.7 'daily' data

Fixed the file date for F10.7 'daily' data, which can be obtained from the file as done in other files.  Simplified the code by creating a function to do this and inform users of any changes in a way that still allows the files to be processed.

pysatSpaceWeather/instruments/methods/swpc.py

@@ -77,18 +77,24 @@ def daily_dsd_download(name, today, data_path, mock_download_dir=None):
                       general.get_instrument_data_path(
                           'sw_{:s}'.format(data_name), tag='daily')
                       for data_name in ['f107', 'flare', 'ssn', 'sbfield']}
+
+        # Try and obtain the file date; otherwise assume it was issued today
+        fdate = find_issue_date(raw_txt)
+        if fdate is None:
+            fdate = today
+
         outfiles = {
             data_name: os.path.join(file_paths[data_name], '_'.join([
                 data_name, 'daily', '{:s}.txt'.format(
-                    today.strftime('%Y-%m-%d'))]))
+                    fdate.strftime('%Y-%m-%d'))]))
             for data_name in file_paths.keys()}
 
         # Check that the directories exist
         for data_path in file_paths.values():
             pysat.utils.files.check_and_make_path(data_path)
 
         # Save the output
-        rewrite_daily_solar_data_file(today.year, outfiles, raw_txt)
+        rewrite_daily_solar_data_file(fdate.year, outfiles, raw_txt)
 
     return
 
@@ -442,8 +448,7 @@ def solar_geomag_predictions_download(name, date_array, data_path,
                                    "filename."]))
     else:
         # Parse text to get the date the prediction was generated
-        date_str = raw_txt.split(':Issued: ')[-1].split(' UTC')[0]
-        dl_date = dt.datetime.strptime(date_str, '%Y %b %d %H%M')
+        dl_date = find_issue_date(raw_txt, '%Y %b %d %H%M UTC')
 
         # Parse the data to get the prediction dates
         date_strs = raw_txt.split(':Prediction_dates:')[-1].split('\n')[0]
@@ -616,8 +621,7 @@ def geomag_forecast_download(name, date_array, data_path,
                                    "been saved to an unexpected filename."]))
     else:
         # Parse text to get the date the prediction was generated
-        date_str = raw_txt.split(':Issued: ')[-1].split(' UTC')[0]
-        dl_date = dt.datetime.strptime(date_str, '%Y %b %d %H%M')
+        dl_date = find_issue_date(raw_txt, '%Y %b %d %H%M UTC')
 
         # Separate out the data by chunks
         ap_raw = raw_txt.split('NOAA Ap Index Forecast')[-1]
@@ -745,8 +749,7 @@ def kp_ap_recent_download(name, date_array, data_path, mock_download_dir=None):
                                    "filename."]))
     else:
         # Parse text to get the date the prediction was generated
-        date_str = raw_txt.split(':Issued: ')[-1].split('\n')[0]
-        dl_date = dt.datetime.strptime(date_str, '%H%M UT %d %b %Y')
+        dl_date = find_issue_date(raw_txt)
 
         # Data is the forecast value for the next three days
         raw_data = raw_txt.split('#  Date ')[-1]
@@ -858,8 +861,7 @@ def recent_ap_f107_download(name, date_array, data_path,
                                    " saved to an unexpected filename."]))
     else:
         # Parse text to get the date the prediction was generated
-        date_str = raw_txt.split(':Issued: ')[-1].split(' UTC')[0]
-        dl_date = dt.datetime.strptime(date_str, '%Y %b %d %H%M')
+        dl_date = find_issue_date(raw_txt, '%Y %b %d %H%M UTC')
 
         # Get to the forecast data
         raw_data = raw_txt.split('45-DAY AP FORECAST')[-1]
@@ -880,6 +882,10 @@ def recent_ap_f107_download(name, date_array, data_path,
         data = {'ap': pds.DataFrame(ap, index=ap_times, columns=['daily_Ap']),
                 'f107': pds.DataFrame(f107, index=f107_times, columns=['f107'])}
 
+        # Ensure there is a download date
+        if dl_date is None:
+            dl_date = ap_times[0]
+
         # Write out the data files
         for data_name in data.keys():
             file_name = '{:s}_45day_{:s}.txt'.format(
@@ -963,3 +969,43 @@ def list_files(name, tag, inst_id, data_path, format_str=None):
         files.loc[files.index[-1] + pds_offset] = files.values[-1]
 
     return files
+
+
+def find_issue_date(file_txt, date_fmt="%H%M UT %d %b %Y"):
+    """Find the issue date for a SWPC file.
+
+    Parameters
+    ----------
+    file_txt : str
+        String containing all text in a file.
+    date_fmt : str
+        Expected date format (default='%H%M UT %d %b %Y')
+
+    Returns
+    -------
+    dl_date : dt.datetime or NoneType
+        Datetime object with time that the file was issued or None if an
+        error is encountered
+
+    Note
+    ----
+    Assumes the file has a line formatted as: ':Issued: <date_fmt>\n'
+
+    """
+    dl_date = None
+
+    # Parse text to get the date the prediction was generated
+    if file_txt.find(':Issued:') >= 0:
+        date_str = file_txt.split(':Issued: ')[-1].split('\n')[0]
+
+        try:
+            dl_date = dt.datetime.strptime(date_str, date_fmt)
+        except Exception as err:
+            pysat.logger.critical(''.join(['Unexpected issued date format ',
+                                           repr(date_str), ' did not match ',
+                                           date_fmt, '; failed with error: ',
+                                           repr(err)]))
+    else:
+        pysat.logger.critical('Unable to find issue line in file')
+
+    return dl_date