Added a preliminary Dark Sky weather plugin

It has the same functionality as my old shell script, but now it's
written in Python.  The code is far from the most elegant it could be,
but it's a decent example of how the new plugin API can be used for
something practical.

kayleevc/plugins/darksky.py

@@ -0,0 +1,139 @@
+# This is part of Kaylee
+# -- this code is licensed GPLv3
+# Copyright 2015-2016 Clayton G. Hobbs
+# Portions Copyright 2013 Jezra
+
+"""Dark Sky weather plugin for Kaylee
+
+This plugin provides weather information `powered by Dark Sky
+<https://darksky.net/poweredby/>`__.  The user must provide a key for
+the Dark Sky API, as well as decimal latitude and longitude::
+
+    ".darksky": {
+        "api_key": "USER_API_KEY",
+        "latitude": USER_LATITUDE,
+        "longitude": USER_LONGITUDE
+    }
+"""
+
+import json
+import os
+import time
+
+import requests
+
+from .pluginbase import PluginBase
+
+
+class Plugin(PluginBase):
+    """Main class for the Dark Sky weather plugin"""
+
+    def __init__(self, config, name):
+        """Initialize the Dark Sky weather plugin"""
+        super().__init__(config, name)
+
+        self._cache_filename = os.path.join(config.cache_dir, 'darksky.json')
+        self._weather_url = 'https://api.darksky.net/forecast/{}/{},{}'.format(
+            self.options['api_key'],
+            self.options['latitude'],
+            self.options['longitude']
+        )
+        self._cache_max_age = 1800
+
+        self.commands = {
+            'whats the temperature': self._temperature,
+            'whats todays low': self._todays_low,
+            'whats todays high': self._todays_high,
+            'whats tomorrows high': self._tomorrows_high,
+            'whats the humidity': self._relative_humidity,
+            'whats the weather': self._current_conditions,
+            'whens sunset': self._sunset_time,
+            'hoos your weather provider': self._provider_credits
+        }
+
+        self.corpus_strings.update(self.commands)
+
+    def _temperature(self):
+        return '{:.1f} degrees Fahrenheit'.format(
+            self.cache['currently']['temperature'])
+
+    def _todays_low(self):
+        return '{:.1f} degrees Fahrenheit'.format(
+            self.cache['daily']['data'][0]['temperatureMin'])
+
+    def _todays_high(self):
+        return '{:.1f} degrees Fahrenheit'.format(
+            self.cache['daily']['data'][0]['temperatureMax'])
+
+    def _tomorrows_high(self):
+        return '{:.1f} degrees Fahrenheit'.format(
+            self.cache['daily']['data'][1]['temperatureMax'])
+
+    def _relative_humidity(self):
+        return '{:.0f} percent'.format(
+            100 * self.cache['currently']['humidity'])
+
+    def _current_conditions(self):
+        return '{}, {}, relative humidity {}'.format(
+            self.cache['currently']['summary'],
+            self._temperature(),
+            self._relative_humidity())
+
+    def _sunset_time(self):
+        # Get the time in a more useful structure
+        t = time.localtime(self.cache['daily']['data'][0]['sunsetTime'])
+
+        # Format each part of the time to be pronounced nicely
+        hour = time.strftime('%I', t)
+        if hour[0] == '0':
+            hour = hour[1]
+
+        minute = time.strftime('%M', t)
+        if minute[0] == '0':
+            if minute[1] == '0':
+                minute = "o'clock"
+            else:
+                minute = 'O' + minute[1]
+
+        ante_post = time.strftime('%p', t)
+        if ante_post[0] == 'A':
+            ante_post = 'AE ' + ante_post[1]
+
+        # Put the parts together
+        return '{} {} {}'.format(hour, minute, ante_post)
+
+    def _provider_credits(self):
+        return 'Powered by Dark Sky, https://darksky.net/poweredby/.'
+
+    def _update_cache_if_stale(self):
+        try:
+            st = os.stat(self._cache_filename)
+        except FileNotFoundError:
+            # If there's no cache file, we need to get one
+            self._update_cache()
+        else:
+            if time.time() - st.st_mtime > self._cache_max_age:
+                self._update_cache()
+
+    def _update_cache(self):
+        r = requests.get(self._weather_url, stream=True)
+        if r.status_code == 200:
+            with open(self._cache_filename, 'wb') as f:
+                for chunk in r:
+                    f.write(chunk)
+
+    def _read_cache(self):
+        with open(self._cache_filename, 'r') as f:
+            return json.load(f)
+
+    def recognizer_finished(self, recognizer, text):
+        """Speak reasonably up-to-date weather information"""
+        # Is there a matching command?
+        if text in self.corpus_strings:
+            self.emit('processed', text)
+            self._update_cache_if_stale()
+            self.cache = self._read_cache()
+            self.emit('tts', self.commands[text]())
+            return True
+        else:
+            return False