webhook: integrate bot instance with Bottle

[HumorBaby]

This PR makes use of WSGI middleware and a Bottle plugin to ensure that the bot instance is accessible wherever the Bottle app is visible (bottle is import'd).

There are two main goals of this PR:

1. Obviate the need for unsightly globals. See:
   

   sopel-github/sopel_modules/github/webhook.py

   Lines 32 to 33 in 853a6c5

   	# Because I'm a horrible person
   	sopel_instance = None

   • The plugin allows @route decorated callbacks to accept an optional bot parameter that corresponds to the actual bot instance, making the webhook callbacks more like normal Sopel callables. For example:

     diff --git a/sopel_modules/github/webhook.py b/sopel_modules/github/webhook.py
     index 9f4bfd6..8c5a88a 100644
     --- a/sopel_modules/github/webhook.py
     +++ b/sopel_modules/github/webhook.py
     @@ -108,8 +108,8 @@ def get_targets(repo):  
     
     
     @bottle.get("/webhook")
     -def show_hook_info():
     -    return 'Listening for webhook connections!'
     +def show_hook_info(bot):
     +    return 'Hi, I\'m {}! You caught me listening for webhook connections!'.format(bot.config.core.nick)

     Omitting the bot parameter if it is not needed would be perfectly acceptable. Thanks to Bottle plugins, no extra work is necessary to decorate webhook callbacks.

2. Expose the bot instance through bottle

   • The middleware puts the bot in the server environment, making it easily accessible in many contexts. For example:

     diff --git a/sopel_modules/github/formatting.py b/sopel_modules/github/formatting.py
     index 7d5bf10..8db0396 100644                                                       
     --- a/sopel_modules/github/formatting.py                                            
     +++ b/sopel_modules/github/formatting.py                                            
     @@ -17,12 +17,15 @@ Copyright 2015 Max Gurela                                       
     from __future__ import unicode_literals                                            
                                                                                         
     import re                                                                          
     +import bottle                                                                      
     import requests                                                                    
                                                                                         
     from sopel.formatting import color                                                 
                                                                                         
     current_row = None                                                                 
     current_payload = None                                                             
     +the_bot = None                                                                     
                                                                                         
                                                                                         
     def fmt_url(s, row=None):                                                          
     @@ -372,9 +375,10 @@ def shorten_url(url):                                          
                                                                                         
                                                                                         
     def get_formatted_response(payload, row):                                          
     -    global current_row, current_payload                                            
     +    global current_row, current_payload, the_bot                                   
         current_payload = payload                                                      
         current_row = row                                                              
     +    the_bot = bottle.request.environ.get('bot')                                    
                                                                                         
         messages = []                                                                  
         if payload['event'] == 'push':                                                 
     

   Then, each subsequent call has access to the the_bot global variable. Other options include getting the bot instance from bottle.request.environ... in each function as needed, and making the_bot a local variable and passing it to functions as needed.

Hopefully, this can serve as a starting point for #19 since it now exposes the bot instance (so bot.config or the DB can be accessed for settings) in formatting.py, which in my understanding is the current limitation.

Coming soon

1. A PR based on this one to completely remove the use of globals in webhook.py and instead use the bot instance provided by @bottle.route. Ended up adding it to this PR.
2. Maybe imports can be fixed too one day... 😁

[dgw]

@HumorBaby Switching to use the in operator (#33) created a merge conflict. No rush, but needs sorting when you have a free moment.

[HumorBaby]

@HumorBaby Switching to use the in operator (#33) created a merge conflict. No rush, but needs sorting when you have a free moment.

Done.

[HumorBaby]

👍

[dgw]

More merge conflicts, oh boy! 🙁

[dgw]

I was looking at release notes because #141 came up again on IRC. bottle 0.13 turned Bottle instances into context managers. Does that make any of this patch easier?

Asking since it needs a rebase anyway 😅