--- The Map module defines getAddressLocations and getAddresses

import List
import Maybe
import System
import URL
import XML 


--- 
main = "done."

--import GetOpt
--import Map

--main2 :: IO
--main2
--  = let (flags, addresses, errors) = getOpt Permute options (unsafePerformIO $ --getArgs)
--      in if length errors > 0
--           then error $ "Error: Invalid command line. " ++ usage
--           else if elem Help flags
--                  then usage
--                  else unsafePerformIO $ getAddressesLocationsWikiCode addresses
---
--data Flag = Help
--
--options = [Option "h" ["help"] (NoArg Help) "Displays this help message."]
--
--usage = usageInfo "Usage: map [OPTION...] address ..." options


--- Represents locations.
data Location = Location 
                  String -- longitude
                  String -- latitude
                  String -- label

--- Accepts a location and returns its longitude.
getLocationLongitude :: Location -> String
getLocationLongitude (Location lon _ _) = lon 

--- Accepts a location and returns its latitude.
getLocationLatitude :: Location -> String
getLocationLatitude (Location _ lat _) = lat 

--- Accepts a location and returns its label.
getLocationLabel :: Location -> String
getLocationLabel (Location _ _ label) = label

--- Accepts a list of addresses and returns a
--- WikiCode command that displays a map plotting
--- the addresses.
getAddressesLocationsWikiCode :: [String] -> IO String
getAddressesLocationsWikiCode addresses
  = getAddressesLocations addresses >>= return . locationsToWikiCode

--- Accepts a list of addresses and returns the
--- first location returned by Open Street Map for
--- each address.
getAddressesLocations :: [String] -> IO [Location]
getAddressesLocations addresses = mapIO getAddressLocation addresses >>= return . catMaybes

--- Accepts an address and returns the first
--- location returned by Open Street Map.
getAddressLocation :: String -> IO (Maybe Location)
getAddressLocation address
  = do locations <- getAddressLocations address 
       return $ if length locations == 0
                  then Nothing
                  else Just $ head locations

--- Accepts an address and returns the location of
--- the address according to Open Street Map.
getAddressLocations :: String -> IO [Location]
getAddressLocations address
  = getContentsOfUrl ("http://nominatim.openstreetmap.org/search?format=xml&q=" ++ address) >>= return . parseXmlString >>= return . concatMap parseSearchResults

--- Accepts a location and returns a WikiCode
--- string that represents the location as a map
--- point.
locationToWikiCode :: Location -> String
locationToWikiCode location
  = getLocationLatitude location ++ "," ++ getLocationLongitude location ++ "~" ++ getLocationLabel location 

--- Accepts a list of locations and returns a
--- WikiCode command that maps the locations.
locationsToWikiCode :: [Location] -> String
locationsToWikiCode locations
  = "{{#isplay_map: " ++ (intercalate ";" $ map locationToWikiCode locations) ++ "}}"

--- Accepts an XML Element that represents a Search
--- Results element and returns the set of
--- locations in the search results.
parseSearchResults :: XmlExp -> [Location]
parseSearchResults = map parsePlace . elemsOf

--- Accepts an XML Place element and returns the
--- location represented by the element.
parsePlace :: XmlExp -> Location
parsePlace element
  = let message = "[parsePlace] Error: An error occured while trying to parse a place element."
    in case element of
         XText _                    -> error message 
         XElem tagName attributes _ -> Location 
                                         (fromMaybe (error $ message ++ " The 'lat' attribute is missing.") $ lookup "lat" attributes)
                                         (fromMaybe (error $ message ++ " The 'lon' attribute is missing.") $ lookup "lon" attributes)
                                         (fromMaybe (error $ message ++ " The 'display_name' attribute is missing.") $ lookup "display_name" attributes)