{-# LANGUAGE OverloadedStrings #-}

-- Copyright (C) 2009-2011 John Millikin <jmillikin@gmail.com>
-- 
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, either version 3 of the License, or
-- any later version.
-- 
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-- GNU General Public License for more details.
-- 
-- You should have received a copy of the GNU General Public License
-- along with this program.  If not, see <http://www.gnu.org/licenses/>.

module Main (main) where

import           Control.Concurrent (threadDelay)
import           Control.Monad
import           Data.List (intercalate)
import           Data.Maybe
import           Data.Int
import           Data.Word
import           Data.Text (Text)
import qualified Data.Text
import           System.Environment
import           System.Exit
import           System.IO
import           System.Console.GetOpt

import           DBus
import           DBus.Socket

data Bus = Session | System
	deriving (Show)

data Option = BusOption Bus | AddressOption String
	deriving (Show)

optionInfo :: [OptDescr Option]
optionInfo = [
	  Option [] ["session"] (NoArg (BusOption Session))
	         "Monitor the session message bus. (default)"
	, Option [] ["system"] (NoArg (BusOption System))
	         "Monitor the system message bus."
	, Option [] ["address"] (ReqArg AddressOption "ADDRESS")
	         "Connect to a particular bus address."
	]

usage :: String -> String
usage name = "Usage: " ++ name ++ " [OPTION...]"

findSocket :: [Option] -> IO Socket
findSocket opts = getAddress opts >>= open where
	session = do
		got <- getSessionAddress
		case got of
			Just addr -> return addr
			Nothing -> error "DBUS_SESSION_BUS_ADDRESS is not a valid address"
	
	system = do
		got <- getSystemAddress
		case got of
			Just addr -> return addr
			Nothing -> error "DBUS_SYSTEM_BUS_ADDRESS is not a valid address"
	
	getAddress [] = session
	getAddress ((BusOption Session):_) = session
	getAddress ((BusOption System):_) = system
	getAddress ((AddressOption addr):_) = case parseAddress addr of
		Nothing -> error (show addr ++ " is not a valid address")
		Just parsed -> return parsed

addMatch :: Socket -> String -> IO ()
addMatch sock match = send sock (methodCall "/org/freedesktop/DBus" "org.freedesktop.DBus" "AddMatch")
	{ methodCallDestination = Just "org.freedesktop.DBus"
	, methodCallBody = [toVariant match]
	} (\_ -> return ())

defaultFilters :: [String]
defaultFilters =
	[ "type='signal'"
	, "type='method_call'"
	, "type='method_return'"
	, "type='error'"
	]

main :: IO ()
main = do
	args <- getArgs
	let (options, userFilters, errors) = getOpt Permute optionInfo args
	unless (null errors) $ do
		name <- getProgName
		hPutStrLn stderr (concat errors)
		hPutStrLn stderr (usageInfo (usage name) optionInfo)
		exitFailure
	
	sock <- findSocket options
	
	send sock (methodCall "/org/freedesktop/DBus" "org.freedesktop.DBus" "Hello")
		{ methodCallDestination = Just "org.freedesktop.DBus"
		} (\_ -> return ())
	
	mapM_ (addMatch sock) (if null userFilters then defaultFilters else userFilters)
	
	forever $ do
		received <- receive sock
		putStrLn (formatMessage received ++ "\n")

-- Message formatting is verbose and mostly uninteresting, except as an
-- excersise in string manipulation.

formatMessage :: ReceivedMessage -> String

-- Method call
formatMessage (ReceivedMethodCall serial msg) = concat
	[ "method call"
	, " sender="
	, maybe "(null)" formatBusName (methodCallSender msg)
	, " -> dest="
	, maybe "(null)" formatBusName (methodCallDestination msg)
	, " serial="
	, show (serialValue serial)
	, " path="
	, formatObjectPath (methodCallPath msg)
	, "; interface="
	, maybe "(null)" formatInterfaceName (methodCallInterface msg)
	, "; member="
	, formatMemberName (methodCallMember msg)
	, formatBody (methodCallBody msg)
	]

-- Method return
formatMessage (ReceivedMethodReturn _ msg) = concat
	[ "method return"
	, " sender="
	, maybe "(null)" formatBusName (methodReturnSender msg)
	, " -> dest="
	, maybe "(null)" formatBusName (methodReturnDestination msg)
	, " reply_serial="
	, show (serialValue (methodReturnSerial msg))
	, formatBody (methodReturnBody msg)
	]

-- Method error
formatMessage (ReceivedMethodError _ msg) = concat
	[ "error"
	, " sender="
	, maybe "(null)" formatBusName (methodErrorSender msg)
	, " -> dest="
	, maybe "(null)" formatBusName (methodErrorDestination msg)
	, " error_name="
	, formatErrorName (methodErrorName msg)
	, " reply_serial="
	, show (serialValue (methodErrorSerial msg))
	, formatBody (methodErrorBody msg)
	]

-- Signal
formatMessage (ReceivedSignal serial msg) = concat
	[ "signal"
	, " sender="
	, maybe "(null)" formatBusName (signalSender msg)
	, " -> dest="
	, maybe "(null)" formatBusName (signalDestination msg)
	, " serial="
	, show (serialValue serial)
	, " path="
	, formatObjectPath (signalPath msg)
	, "; interface="
	, formatInterfaceName (signalInterface msg)
	, "; member="
	, formatMemberName (signalMember msg)
	, formatBody (signalBody msg)
	]

formatMessage msg = concat
	[ "unknown"
	, " sender="
	, maybe "(null)" formatBusName (receivedMessageSender msg)
	, " serial="
	, show (serialValue (receivedMessageSerial msg))
	, formatBody (receivedMessageBody msg)
	]

formatBody :: [Variant] -> String
formatBody body = formatted where
	tree = Children (map formatVariant body)
	formatted = intercalate "\n" ("" : collapseTree 0 tree)

-- A string tree allows easy indentation of nested structures
data StringTree = Line String | MultiLine [StringTree] | Children [StringTree]
	deriving (Show)

collapseTree :: Int -> StringTree -> [String]
collapseTree d (Line x)       = [replicate (d*3) ' ' ++ x]
collapseTree d (MultiLine xs) = concatMap (collapseTree d) xs
collapseTree d (Children xs)  = concatMap (collapseTree (d + 1)) xs

-- Formatting for various kinds of variants, keyed to their signature type.
formatVariant :: Variant -> StringTree
formatVariant x = case variantType x of
	
	TypeBoolean -> Line $ let
		Just x' = fromVariant x
		in "boolean " ++ if x' then "true" else "false"
	
	TypeWord8 -> Line $ let
		Just x' = fromVariant x
		in "byte " ++ show (x' :: Word8)
	
	TypeWord16 -> Line $ let
		Just x' = fromVariant x
		in "uint16 " ++ show (x' :: Word16)
	
	TypeWord32 -> Line $ let
		Just x' = fromVariant x
		in "uint32 " ++ show (x' :: Word32)
	
	TypeWord64 -> Line $ let
		Just x' = fromVariant x
		in "uint64 " ++ show (x' :: Word64)
	
	TypeInt16 -> Line $ let
		Just x' = fromVariant x
		in "int16 " ++ show (x' :: Int16)
	
	TypeInt32 -> Line $ let
		Just x' = fromVariant x
		in "int32 " ++ show (x' :: Int32)
	
	TypeInt64 -> Line $ let
		Just x' = fromVariant x
		in "int64 " ++ show (x' :: Int64)
	
	TypeDouble -> Line $ let
		Just x' = fromVariant x
		in "double " ++ show (x' :: Double)
	
	TypeString -> Line $ let
		Just x' = fromVariant x
		in "string " ++ show (x' :: String)
	
	TypeObjectPath -> Line $ let
		Just x' = fromVariant x
		in "object path " ++ show (formatObjectPath x')
	
	TypeSignature -> Line $ let
		Just x' = fromVariant x
		in "signature " ++ show (formatSignature x')
	
	TypeArray _ -> MultiLine $ let
		Just x' = fromVariant x
		items = arrayItems x'
		lines' = [ Line "array ["
		         , Children (map formatVariant items)
		         , Line "]"
		         ]
		in lines'
	
	TypeDictionary _ _ -> MultiLine $ let
		Just x' = fromVariant x
		items = dictionaryItems x'
		lines' = [ Line "dictionary {"
		         , Children (map formatItem items)
		         , Line "}"
		         ]
		formatItem (k, v) = MultiLine (firstLine : vTail) where
			Line k' = formatVariant k
			v' = collapseTree 0 (formatVariant v)
			vHead = head v'
			vTail = map Line (tail v')
			firstLine = Line (k' ++ " -> " ++ vHead)
		in lines'
	
	TypeStructure _ -> MultiLine $ let
		Just x' = fromVariant x
		items = structureItems x'
		lines' = [ Line "struct ("
		         , Children (map formatVariant items)
		         , Line ")"
		         ]
		in lines'
	
	TypeVariant -> let
		Just x' = fromVariant x
		in MultiLine [Line "variant", Children [formatVariant x']]