Plugin(matchPlugin): Get our functions to actually work with `Bot`

Previously we added the `Bot` monad to our signature, but we didn't have
a way to filter and match plugins wrapped in the `Bot` monad. This is
what we're doing here. It's the same work as before, but we need to
account for a wrapped `Plugin` type.

There's a lot of extra cruft code here from when I was trying things out
to get it working. The short story is that I do some binding and
sequencing dances to extract `Plugin`s so that we can actually match
against them.

I've seen recommendations against `fail`, which is why I tried to use
`mzero`, but it just seemed to be too complicated so went with `fail`,
which seems to make sense in context.

2 files changed, 45 insertions, 3 deletions

diff --git a/src/Bot.hs b/src/Bot.hs
index fe1b0a1..8b78497 100644
--- a/src/Bot.hs
+++ b/src/Bot.hs
@@ -17,3 +17,5 @@ newtype Bot a = Bot
     { runBot :: ReaderT Options IO a
     -- } deriving (Monad, Functor, Applicative, BotConfig, MonadIO)
     } deriving (Monad, Functor, Applicative, MonadReader Options, MonadIO)
+
+-- instance MonadPlus Bot
diff --git a/src/Plugin.hs b/src/Plugin.hs
index a79e815..04a8054 100644
--- a/src/Plugin.hs
+++ b/src/Plugin.hs
@@ -4,6 +4,7 @@ module Plugin
     , plugins
     ) where
 
+import Control.Monad (mzero)
 import qualified Data.Text as T
 
 import Text.Regex.TDFA
@@ -16,15 +17,54 @@ import Plugin.Help (help)
 
 -- | Get the first plugin that matches the given message text.
 matchPlugin :: M.Message -> Maybe (Bot Plugin)
-matchPlugin message = firstPlugin $ matchPlugins message plugins
+matchPlugin message = do
+    -- plugins' <- return $ sequence plugins
+    -- firstPlugin $ matchPlugins message plugins'
+    return $ firstPlugin $ matchBotPlugins message
   where
-    firstPlugin []     = Nothing
-    firstPlugin (p:ps) = Just p
+    firstPlugin :: Bot [Plugin] -> Bot Plugin
+    -- firstPlugin []     = Nothing
+    -- firstPlugin (p:ps) = Just p
+    firstPlugin plugins = do
+        plugins' <- plugins
+        case plugins' of
+            -- []     -> mzero
+            []     -> fail "Empty plugin list"
+            (p:ps) -> return p
+
+    -- matchBotPlugins :: M.Message -> [Bot Plugin]
+    -- matchBotPlugins message = do
+    --     -- plugins' <- sequence plugins
+    --     -- return $ matchPlugins message plugins'
+    --     return $ matchPlugins message plugins
+    matchBotPlugins :: M.Message -> Bot [Plugin]
+    matchBotPlugins message = do
+        plugins' <- sequence plugins
+        return $ matchPlugins message plugins'
 
 -- | Filter the list of plugins to those that match the given message.
 matchPlugins :: M.Message -> [Plugin] -> [Plugin]
 matchPlugins message plugins =
     [p | p <- plugins, M.textStr message =~ matchRegex p]
+  -- where
+  --   matches :: M.Message -> Bot Plugin -> Bool
+  --   matches message pluginM = do
+  --       p <- pluginM
+  --       M.textStr message =~ matchRegex p
+-- ---
+-- matchPlugins :: M.Message -> [Bot Plugin] -> [Bot Plugin]
+-- matchPlugins message plugins =
+--     [p | p <- plugins, matches message p]
+--   where
+--     matches :: M.Message -> Bot Plugin -> Bool
+--     matches message pluginM = do
+--         p <- pluginM
+--         M.textStr message =~ matchRegex p
+-- ---
+-- matchPlugins :: M.Message -> [Bot Plugin] -> [Bot Plugin]
+-- matchPlugins message plugins = do
+--     _ <- return $ sequence plugins
+--     [return p | p <- plugins', M.textStr message =~ matchRegex p]
 
 -- | Run the action belonging to the plugin, stored in its `perform` field.
 performPlugin :: Plugin -> PluginAction