Use rain since last upload to Met Office

This is a slightly strange bit of the Met Office API - they want rain
since last upload, not in the last hour.

Signed-off-by: Jim Easterbrook <jim@jim-easterbrook.me.uk>

src/pywws/__init__.py

@@ -1,3 +1,3 @@
 __version__ = '18.5.0'
-_release = '1529'
-_commit = 'e5e311b'
+_release = '1530'
+_commit = 'f3856a1'

src/pywws/service/metoffice.py

@@ -56,6 +56,7 @@
 import requests
 
 import pywws
+from pywws.conversions import rain_inch
 import pywws.service
 
 __docformat__ = "restructuredtext en"
@@ -65,7 +66,7 @@
 
 class ToService(pywws.service.BaseToService):
     catchup = 7
-    fixed_data = {'softwaretype': 'pywws v' + pywws.__version__}
+    fixed_data = {'softwaretype': 'pywws-' + pywws.__version__}
     interval = timedelta(seconds=300)
     logger = logger
     service_name = service_name
@@ -79,12 +80,16 @@ class ToService(pywws.service.BaseToService):
 #temp_out     "'tempf'       : '%.1f'," "" "temp_f(x)"#
 #rel_pressure "'baromin'     : '%.4f'," "" "pressure_inhg(x)"#
 #calc "temp_f(dew_point(data['temp_out'], data['hum_out']))" "'dewptf': '%.1f',"#
-#calc "rain_inch(rain_hour(data))" "'rainin': '%g',"#
-#daily#
-#rain         "'dailyrainin' : '%g'," "" "rain_inch(x)"#
 """
 
     def __init__(self, context):
+        # initialise rain history
+        last_update = context.status.get_datetime('last update', service_name)
+        if last_update:
+            last_update = context.calib_data.nearest(last_update)
+            self.last_rain = context.calib_data[last_update]['rain']
+        else:
+            self.last_rain = None
         # get configurable "fixed data"
         self.fixed_data.update({
             'siteid'               : context.params.get(
@@ -100,6 +105,23 @@ def session(self):
         with requests.Session() as session:
             yield session
 
+    def prepare_data(self, data):
+        prepared_data = super(ToService, self).prepare_data(data)
+        # compute rain since last upload
+        if self.last_rain is not None:
+            rain = data['rain'] - self.last_rain
+            if rain >= -0.001:
+                prepared_data['rainin'] = '{:.4f}'.format(rain_inch(rain))
+        self.last_rain = data['rain']
+        # compute rain since day start
+        day_start = self.context.daily_data.nearest(data['idx'])
+        day_start = self.context.daily_data[day_start]['start']
+        day_start = self.context.calib_data.after(day_start)
+        rain = data['rain'] - self.context.calib_data[day_start]['rain']
+        if rain >= -0.001:
+            prepared_data['dailyrainin'] = '{:.4f}'.format(rain_inch(rain))
+        return prepared_data
+
     def valid_data(self, data):
         return any([data[x] is not None for x in (
             'wind_dir', 'wind_ave', 'wind_gust', 'hum_out', 'temp_out',