contrib bots: Edit code for uniformity.

Add one function (get_bot_botname_response()) that generates response
from the given input and replies back to the handle_message with the final
content of response to be sent. Also add code to bots(except followup) to
reply to private messages along with stream messages.

contrib_bots/bots/define/define.py

@@ -0,0 +1,78 @@
+# See readme.md for instructions on running this code.
+import logging
+import json
+import requests
+import html2text
+
+class DefineHandler(object):
+    '''
+    This plugin define a word that the user inputs. It
+    looks for messages starting with '@mention-bot'.
+    '''
+
+    DEFINITION_API_URL = 'https://owlbot.info/api/v1/dictionary/{}?format=json'
+    REQUEST_ERROR_MESSAGE = 'Definition not available.'
+    EMPTY_WORD_REQUEST_ERROR_MESSAGE = 'Please enter a word to define.'
+    PHRASE_ERROR_MESSAGE = 'Definitions for phrases are not available.'
+
+    def usage(self):
+        return '''
+            This plugin will allow users to define a word. Users should preface
+            messages with @mention-bot.
+            '''
+
+    def handle_message(self, message, client, state_handler):
+        original_content = message['content'].strip()
+        bot_response = self.get_bot_define_response(original_content)
+
+        if message['type'] == 'private':
+            client.send_message(dict(
+                type='private',
+                to=message['sender_email'],
+                content=bot_response,
+            ))
+        else:
+            client.send_message(dict(
+                type='stream',
+                to=message['display_recipient'],
+                subject=message['subject'],
+                content=bot_response,
+            ))
+
+    def get_bot_define_response(self, original_content):
+        split_content = original_content.split(' ')
+        # If there are more than one word (a phrase)
+        if len(split_content) > 1:
+            return DefineHandler.PHRASE_ERROR_MESSAGE
+
+        to_define = split_content[0].strip()
+        to_define_lower = to_define.lower()
+
+        # No word was entered.
+        if not to_define_lower:
+            return self.EMPTY_WORD_REQUEST_ERROR_MESSAGE
+        else:
+            response = '**{}**:\n'.format(to_define)
+
+            try:
+                # Use OwlBot API to fetch definition.
+                api_result = requests.get(self.DEFINITION_API_URL.format(to_define_lower))
+                # Convert API result from string to JSON format.
+                definitions = api_result.json()
+
+                # Could not fetch definitions for the given word.
+                if not definitions:
+                    response += self.REQUEST_ERROR_MESSAGE
+                else: # Definitions available.
+                    # Show definitions line by line.
+                    for d in definitions:
+                        example = d['example'] if d['example'] else '*No example available.*'
+                        response += '\n' + '* (**{}**) {}\n  {}'.format(d['type'], d['defenition'], html2text.html2text(example))
+
+            except Exception as e:
+                response += self.REQUEST_ERROR_MESSAGE
+                logging.exception(e)
+
+            return response
+
+handler_class = DefineHandler