module CircuitParser (parseCircuit, showCircuit) where

import Text.ParserCombinators.ReadP
import Data.List

import CircuitBase

-- instance Show Circuit where
-- 	show = showCircuit

showCircuit (Circuit op inpins) = (formatPin ip) ++ ":" ++ (joinWith "," (nodes inpins outpins)) ++ ":" ++ (formatPin op) where
	nodes :: [Int] -> [Int] -> [String]
	nodes [] [] = []
	nodes (a:b:i) (c:d:o) = ((formatPin a) ++ (formatPin b) ++ "0#" ++ (formatPin c) ++ (formatPin d)):nodes i o
	joinWith sep [] = []
	joinWith sep (x:xs) = (x ++) $ concat $ map (sep ++) xs
	-- build reverse pin mapping
	(ip:outpins) = map snd $ sort $ zip (op:inpins) [-1..]
	formatPin p = if (-1 == p) then "X" else (show (p `div` 2)) ++ (if even p then "L" else "R")

-- Circuit Syntax:
-- <inPin>:[<gates>]:<outPin>
-- each Pin is either "X" (circuit IN or OUT)
--   or <gate-number> + ("L" | "R")
-- gates are numbered from 0
-- one gate is <inPinLeft><inPinRight>0#<outPinLeft><outPinRight>
--   obviously you specify the connector of the other side
--   (0 is probably the gate "function")
-- this contains redundancy ofc, it would be enough to specify only the in pins of the gates and the circuit OUT
--   (internal representation)

readPlace :: ReadP Int
readPlace = (char 'L' >> return 0) <++ (char 'R' >> return 1)

readInt :: ReadP Int
readInt = readS_to_P reads

readPin :: ReadP Int
readPin = (char 'X' >> return (-1)) <++ do
	i <- readInt
	p <- readPlace
	return $ (2*i) + p

readNode :: ReadP [Int]
readNode = do
	a <- readPin
	b <- readPin
	char '0'
	char '#'
	readPin
	readPin
	return [a,b]

readNodes1 :: ReadP [Int]
readNodes1 = (do
	char ','
	x <- readNode
	xl <- readNodes1
	return $ x ++ xl
	) <++ (return [])

readNodes :: ReadP [Int]
readNodes = (do
	x <- readNode
	xl <- readNodes1
	return $ x ++ xl
	) <++ (return [])


readCircuit :: ReadP Circuit
readCircuit = do
	readPin
	char ':'
	nodes <- readNodes
	char ':'
	outPin <- readPin
	return $ Circuit outPin nodes

doparse p s = fst $ head $ readP_to_S p s                                                                                                                                                                                                       
parseCircuit s = doparse readCircuit s