module CreateTypes where
	import Language.Haskell.TH
	import Language.Haskell.TH.Syntax
	import StringUtil
	import System.IO (putStr, getLine)
	import Data.List
	import Data.Maybe
	import GenDataTypes
	import GetTypes

	{-
	 - generatedType:
	 -
	 - At compile time takes the name of the data file which the types are being generated from.  After compilation
	 - generatedType will just be a list of doubles of type representations, e.g.:
	 -
	 - [("String", []), ("Int", []), ("T0", ["Male", "Female"])]
	 -}

	generatedType = $(
		let
			types = putStr "Enter file name: " >> getLine >>= readFile
				>>= \fc ->
					return (getTypes fc) -- The types are generated, the type IO [(String, [String])] is the result of the monadic operations.
		in
			lift =<< runIO types) -- Run the IO operation in the Q monad, and then lift that to an expression which is then spliced.

	{-
	 - createTypes:
	 -
	 - Generates the declarations for the new types and type synonym based on the contents of the type representation
	 - list bound to generatedType by the splice.
	 -}

	createTypes = 
		let
			dtList = filter ((/=) [] . snd) generatedType -- Gets all of the representation list elements which need a new type declaration.
			newDataType x = makeType (fst x) (snd x) -- Takes a double and calls the makeType function on the first and second elements.
			newDataTypes = map newDataType dtList -- Make a list of declarations from the new type representations.
			newTypeSyn = makeTypeSyn "MainType" (map fst generatedType) -- Generates the new type synonym declaration from the type representation list.
		in
			sequenceQ (newDataTypes++[newTypeSyn]) -- Converts from [Q Dec] to Q [Dec] so the declarations can be spliced.