[#108] Skip over emoji blocks

Problem: right now, when find an emoji block in a message, we split the
message in two. This means this message:

```
Hey, let's meet at 10:30 🕐 tomorrow?
```

Will be interpreted as two separate sentences, `["Hey, let's meet at
10:30", "tomorrow?"]`, and "tomorrow" won't be taken into account.

Solution: skip over emoji blocks, and collate adjacent text-like blocks.
This is not parsed as a single sentence `["Hey, let's meet at 10:30
tomorrow?"]`

src/TzBot/Slack/API/MessageBlock.hs

@@ -202,15 +202,24 @@ extractPieces mBlocks = runWriter $ concat <$> mapM goMessageBlock mBlocks
     go :: Maybe Builder -> [Text] -> [WithUnknown BlockElementLevel2] -> Writer [ExtractError] [Text]
     go mbCurPiece prevPieces (e:es) = case unUnknown e of
       Left val -> do
-        let _type = fromMaybe "unknown" (val ^? key "type" . _String)
-        tell [EEUnknownBlockElementLevel2 $ UnknownBlockElementLevel2Error _type val]
-        go Nothing (prependMbCurrentToPrevious mbCurPiece prevPieces) es
+        let blockType = fromMaybe "unknown" (val ^? key "type" . _String)
+        case blockType of
+          "emoji" ->
+            -- skip over emoji blocks
+            go mbCurPiece prevPieces es
+          _ -> do
+            tell [EEUnknownBlockElementLevel2 $ UnknownBlockElementLevel2Error blockType val]
+            -- break the message in two separate `Text` pieces.
+            go Nothing (prependMbCurrentToPrevious mbCurPiece prevPieces) es
       Right (BEL2ElementText elementText) -> do
         let etTextB = fromText elementText.etText
         if (elementText.etStyle >>= styCode) == Just True
-          -- ignore inline code block
-          then go Nothing (prependMbCurrentToPrevious mbCurPiece prevPieces) es
-          else go (Just $ maybe etTextB (<> etTextB) mbCurPiece) prevPieces es
+          then
+            -- ignore inline code block
+            go Nothing (prependMbCurrentToPrevious mbCurPiece prevPieces) es
+          else
+            -- collate this block's text with any adjacent text-like block
+            go (Just $ maybe etTextB (<> etTextB) mbCurPiece) prevPieces es
       Right (BEL2ElementLink elementLink) -> do
         let linkText = fromText elementLink.elText
         go (Just $ maybe linkText (<> linkText) mbCurPiece) prevPieces es

test/Test/TzBot/MessageBlocksSpec.hs

@@ -54,8 +54,7 @@ test_messageBlocksSpec = TestGroup "Message blocks" $
         , "3.1quote block "
         , " 3.2quote block"
         , "4.1plain "
-        , " 4.1strike "
-        , " 4.1bold "
+        , " 4.1strike  4.1bold "
         , "4.2plain "
         , " 4.2strike github  4.2bold "
         , "between the lists\n"
@@ -69,7 +68,7 @@ test_messageBlocksSpec = TestGroup "Message blocks" $
         , "end!"
         ]
       getLevel2Errors (snd res) @?=
-        [ "emoji", "user", "broadcast"
+        [ "user", "broadcast"
         ]
   ]