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|
-- | Module containing a small, simple http file server for testing and preview
-- purposes.
module Network.Hakyll.SimpleServer
( simpleServer
) where
import Prelude hiding (log)
import Network
import Control.Monad (forever)
import Control.Monad.Reader (ReaderT, runReaderT, ask, liftIO)
import System.IO
import System.Directory (doesFileExist, doesDirectoryExist)
import Control.Concurrent (forkIO)
import Control.Concurrent.Chan (Chan, newChan, readChan, writeChan)
import System.FilePath (takeExtension)
import qualified Data.Map as M
import Data.List (intercalate)
import Text.Hakyll.Util
import Text.Hakyll.Regex
-- | Function to log from a chan.
log :: Chan String -> IO ()
log logChan = forever (readChan logChan >>= hPutStrLn stderr)
-- | General server configuration.
data ServerConfig = ServerConfig { documentRoot :: FilePath
, portNumber :: PortNumber
, logChannel :: Chan String
}
-- | Custom monad stack.
type Server = ReaderT ServerConfig IO
-- | Simple representation of a HTTP request.
data Request = Request { requestMethod :: String
, requestURI :: String
, requestVersion :: String
} deriving (Ord, Eq)
instance Show Request where
show request = requestMethod request ++ " "
++ requestURI request ++ " "
++ requestVersion request
-- | Read a HTTP request from a 'Handle'. For now, this will ignore the request
-- headers and body.
readRequest :: Handle -> Server Request
readRequest handle = do
requestLine <- liftIO $ hGetLine handle
let [method, uri, version] = map trim $ splitRegex " " requestLine
return $ Request { requestMethod = method
, requestURI = uri
, requestVersion = version
}
-- | Simple representation of the HTTP response we send back.
data Response = Response { responseVersion :: String
, responseStatusCode :: Int
, responsePhrase :: String
, responseHeaders :: M.Map String String
, responseBody :: String
} deriving (Ord, Eq)
instance Show Response where
show response = responseVersion response ++ " "
++ (show $ responseStatusCode response) ++ " "
++ responsePhrase response
-- | A default response.
defaultResponse :: Response
defaultResponse = Response { responseVersion = "HTTP/1.1"
, responseStatusCode = 0
, responsePhrase = ""
, responseHeaders = M.empty
, responseBody = ""
}
-- | Create a response for a given HTTP request.
createResponse :: Request -> Server Response
createResponse request
| requestMethod request == "GET" = createGetResponse request
| otherwise = return $ createErrorResponse 501 "Not Implemented"
-- | Create a simple error response.
createErrorResponse :: Int -- ^ Error code.
-> String -- ^ Error phrase.
-> Response -- ^ Result.
createErrorResponse statusCode phrase = defaultResponse
{ responseStatusCode = statusCode
, responsePhrase = phrase
, responseHeaders = M.singleton "Content-Type" "text/html"
, responseBody =
"<html> <head> <title>" ++ show statusCode ++ "</title> </head>"
++ "<body> <h1>" ++ show statusCode ++ "</h1>\n"
++ "<p>" ++ phrase ++ "</p> </body> </html>"
}
-- | Create a simple get response.
createGetResponse :: Request -> Server Response
createGetResponse request = do
-- Construct the complete fileName of the requested resource.
config <- ask
let uri = requestURI request
log' = writeChan (logChannel config)
isDirectory <- liftIO $ doesDirectoryExist $ documentRoot config ++ uri
let fileName =
(documentRoot config) ++ if isDirectory then uri ++ "/index.html"
else uri
create200 = do
h <- openFile fileName ReadMode
contentLength <- hFileSize h
hClose h
body <- readFile fileName
let headers =
[ ("Content-Length", show $ contentLength)
] ++ getMIMEHeader fileName
return $ defaultResponse
{ responseStatusCode = 200
, responsePhrase = "OK"
, responseHeaders = (responseHeaders defaultResponse)
`M.union` M.fromList headers
, responseBody = body
}
-- Called when an error occurs during the creation of a 200 response.
create500 e = do
log' $ "Internal Error: " ++ show e
return $ createErrorResponse 500 "Internal Server Error"
-- Send back the page if found.
exists <- liftIO $ doesFileExist fileName
if exists
then do response <- liftIO $ catch create200 create500
return response
else do liftIO $ log' $ "Not Found: " ++ fileName
return $ createErrorResponse 404 "Not Found"
-- | Get the mime header for a certain filename. This is based on the extension
-- of the given 'FilePath'.
getMIMEHeader :: FilePath -> [(String, String)]
getMIMEHeader fileName =
case result of (Just x) -> [("Content-Type", x)]
Nothing -> []
where
result = lookup (takeExtension fileName) [ (".css", "text/css")
, (".gif", "image/gif")
, (".htm", "text/html")
, (".html", "text/html")
, (".jpeg", "image/jpeg")
, (".jpg", "image/jpeg")
, (".js", "text/javascript")
, (".png", "image/png")
, (".txt", "text/plain")
, (".xml", "text/xml")
]
-- | Respond to an incoming request.
respond :: Handle -> Server ()
respond handle = do
-- Read the request and create a response.
request <- readRequest handle
response <- createResponse request
-- Generate some output.
config <- ask
liftIO $ writeChan (logChannel config)
$ show request ++ " => " ++ show response
-- Send the response back to the handle.
liftIO $ putResponse response
where
putResponse response = do hPutStr handle $ intercalate " "
[ responseVersion response
, show $ responseStatusCode response
, responsePhrase response
]
hPutStr handle "\r\n"
mapM_ putHeader
(M.toList $ responseHeaders response)
hPutStr handle "\r\n"
hPutStr handle $ responseBody response
hPutStr handle "\r\n"
hClose handle
putHeader (key, value) =
hPutStr handle $ key ++ ": " ++ value ++ "\r\n"
-- | Start a simple http server on the given 'PortNumber', serving the given
-- directory.
simpleServer :: PortNumber -> FilePath -> IO ()
simpleServer port root = do
-- Channel to send logs to
logChan <- newChan
let config = ServerConfig { documentRoot = root
, portNumber = port
, logChannel = logChan
}
-- When a client connects, respond in a separate thread.
listen socket = do (handle, _, _) <- accept socket
forkIO (runReaderT (respond handle) config)
-- Handle logging in a separate thread
_ <- forkIO (log logChan)
writeChan logChan $ "Starting hakyll server on port " ++ show port ++ "..."
socket <- listenOn (PortNumber port)
forever (listen socket)
|
