Connect plugins to the database

The GitHub Commit plugin needs access to the database in order to work
properly. Include 'sqlite-simple' to give us access to the database and
have it transform rows into Haskell objects.

This change has the unfortunate effect of forcing us to make
`PluginAction` an IO type. This means we'll need to make all our plugin
action functions use IO, even the pure ones. `PluginAction` now takes a
database connection as a second argument, and returns an `IO String`.

I don't like the fact that the database argument is effectively
hard-coded. Thus the TODO note to try to make a type class to replace it
so we can pass a null database connection when it isn't needed.
Eventually, if more things like this need to be passed into the
function, we might consider making a new struct type for the purpose.

In order to be able to use the `query_` function, which takes a
String-like `Query`, we have to declare `OverloadedStrings`. Now in
`gitHubCommitAction` we take the database connection as an argument,
select a row (for now it's always the first one to test this out), and
send back a GitHub commit URL (if a record matched, otherwise return an
empty string). Eventually we'll want to make this more real by selecting
the row corresponding to the channel in `message`. Also, instead of
returning an empty string, we should be returning an `Either`, so the
error state is clear.

Update the `ChannelRepoUrl` data constructor to use record syntax so we
can name its fields.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/Lib.hs b/src/Lib.hs
index 63fd3b8..b98c18d 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -2,6 +2,8 @@ module Lib
     ( someFunc
     ) where
 
+import Database.SQLite.Simple
+
 import Message
 import Plugin
 
@@ -13,4 +15,7 @@ someFunc = do
             , nick    = "anon"
             }
         Just plugin = matchPlugin message
-    putStrLn $ performPlugin plugin message
+    dbConn <- open "db/sorbot_development.sqlite3"
+    response <- performPlugin plugin message dbConn
+    putStrLn response
+    close dbConn