1 files changed, 106 insertions, 0 deletions
diff --git a/src/exe/Main.lhs b/src/exe/Main.lhs
new file mode 100644
index 0000000..2f67ffd
--- /dev/null
+++ b/src/exe/Main.lhs
@@ -0,0 +1,106 @@
+User interface
+++++++++++++++
+
+.. class:: nodoc
+
+> module Main (main) where
+> import System.Environment (getArgs)
+> import Data.List (intercalate)
+>
+> import Codec.Pesto.Parse (parse, Instruction (Ingredient), Quantity (..))
+> import Codec.Pesto.Graph (extract, toGraph, firstNodeId, resolveReferences)
+> import Codec.Pesto.Lint (lint, extractMetadata, Metadata(..), LintResult (LintResult))
+> import Codec.Pesto.Serialize (serialize)
+
+The user-interface has different modes of operation. All of them read a single
+recipe from the standard input.
+
+> main = do
+> 	(op:_) <- getArgs
+> 	s <- getContents
+>	either malformedRecipe (run op) (parse s)
+
+> run "dot" = runDot
+> run "metadata" = runMeta
+> run "ingredients" = runIngredients
+> run _ = const (putStrLn "unknown operation")
+
+> malformedRecipe = print
+
+> streamToGraph stream = (nodes, edges)
+> 	where
+> 		doc = (head . extract . snd . unzip) stream
+> 		nodes = zip [firstNodeId..] doc
+> 		edges = toGraph nodes ++ resolveReferences nodes
+
+dot
+^^^
+
+Since each recipe is just a directed graph (digraph), GraphViz’ dot language
+can represent recipes as well. Example:
+
+.. code:: bash
+
+	cabal run --verbose=0 pesto dot < spaghetti.pesto | dot -Tpng > spaghetti.png
+
+> runDot stream = putStrLn $ toDot dotNodes dotEdges
+> 	where
+> 		(nodes, edges) = streamToGraph stream
+> 		maxId = (maximum $ map fst nodes) + 1
+> 		(lintNodes, lintEdges) = unzip $ map (uncurry lintToNodesEdges)
+> 				$ zip [maxId..] (lint nodes edges)
+> 		dotNodes = concat [
+>				  [("node", [("fontname", "Roboto Semi-Light")])]
+> 				, map (\(a, label) -> (show a, [("label", serialize label)])) nodes
+> 				, lintNodes
+>				]
+> 		dotEdges = concat [
+> 				  map (both show) edges
+> 				, concat lintEdges
+> 				]
+
+> lintToNodesEdges nodeid (LintResult t nodes) = let
+> 	n = (show nodeid, [("label", show t), ("color", "red")])
+> 	e = map (\i -> both show (nodeid, i)) nodes
+> 	in (n, e)
+
+> both f (a, b) = (f a, f b)
+
+> toDot nodes edges = "digraph a {"
+> 		<> mconcat (map nodeToDot nodes)
+> 		<> mconcat (map edgeToDot edges)
+> 		<> "}"
+> 	where
+> 		edgeToDot (a, b) = a <> " -> " <> b <> ";"
+>		nodeToDot (a, b) = a <> " [" <> mconcat (mapToDot b) <> "];"
+
+> mapToDot = map kvToDot
+> kvToDot (k, v) = k <> "=\"" <> quoteString v <> "\""
+> quoteString s = mconcat $ map quoteChar s
+> quoteChar '\n' = "\\n"
+> quoteChar '"' = "\\\""
+> quoteChar x = [x]
+
+metadata
+^^^^^^^^
+
+Print metadata as key-value pairs, separated by ``=``.
+
+> runMeta stream = maybe (return ()) (mapM_ printMeta) $ uncurry extractMetadata $ streamToGraph stream
+
+ingredients
+^^^^^^^^^^^
+
+Extract ingredients and print them in CSV format. This does not take
+alternatives into account yet.
+
+> runIngredients stream = mapM_ (putStrLn . csvQty) $ reverse $ foldl getIngredient [] stream
+> 	where
+> 		getIngredient xs (_, Ingredient q) = q:xs
+> 		getIngredient xs _ = xs
+
+> printMeta (_, (key, MetaStr value)) = putStrLn $ key ++ "=" ++ value
+> printMeta (_, (key, MetaQty q)) = putStrLn $ key ++ "=" ++ csvQty q
+
+> csvQty (Quantity a b c) = intercalate "," [serialize a, b, c]
+