{-# OPTIONS -fglasgow-exts #-}

-- Low-level interface/wrappers to FastCGI C client library:
-- (<http://www.fastcgi.com/#TheDevKit>).
-- This code is based on "Network.FastCGI", and some of it
-- is almost identical, but the overall design is new\/simplified.

-- Note the rule: the names of all datatypes that are passed to/from
-- C functions should start with the letter C: CInt, CDouble, CString.
-- Writing fromIntegral is not a chore but necessity, to keep the
-- ocde portable. GHC optimizes fromIntegral to NOP if Int is the 
-- same as CInt.


module Network.FastCGI where

import Foreign
import Foreign.C
import Foreign.Storable
import Foreign.Marshal
import System.Posix                     ( Fd )

#include <fcgiapp.h>
-- An environment is an array of strings:
type Environ = Ptr CString

data FCGX_Request
data FCGX_Stream

foreign import ccall unsafe "fcgiapp.h FCGX_Init" cFCGX_Init
  :: IO CInt

foreign import ccall unsafe "fcgiapp.h FCGX_OpenSocket" cFCGX_OpenSocket
  :: CString -> CInt -> IO Fd

foreign import ccall unsafe "fcgiapp.h FCGX_InitRequest" cFCGX_InitRequest
  :: Ptr FCGX_Request -> Fd -> CInt -> IO CInt

foreign import ccall unsafe "fcgiapp.h FCGX_Accept_r" cFCGX_Accept_r
  :: Ptr FCGX_Request -> IO CInt

foreign import ccall unsafe "fcgiapp.h FCGX_Finish_r" cFCGX_Finish_r
  :: Ptr FCGX_Request -> IO ()

foreign import ccall unsafe "fcgiapp.h FCGX_IsCGI" cFCGX_IsCGI
  :: IO Bool

foreign import ccall unsafe "fcgiapp.h FCGX_GetStr" cFCGX_GetStr
  :: CString -> CInt -> Ptr FCGX_Stream -> IO CInt

foreign import ccall unsafe "fcgiapp.h FCGX_PutStr" cFCGX_PutStr
  :: CString -> CInt -> Ptr FCGX_Stream -> IO CInt

foreign import ccall unsafe "fcgiapp.h FCGX_FFlush" cFCGX_FFlush
  :: Ptr FCGX_Stream -> IO CInt

foreign import ccall unsafe "fcgiapp.h FCGX_SetExitStatus" cFCGX_SetExitStatus
  :: CInt -> Ptr FCGX_Stream -> IO ()

-- | Accessors to get the various streams out of the request object.
requestIn, requestOut, requestErr :: Ptr FCGX_Request -> IO (Ptr FCGX_Stream)
requestIn       = #{peek FCGX_Request, in}
requestOut      = #{peek FCGX_Request, out}
requestErr      = #{peek FCGX_Request, err}

-- | Get the environment out of the request object.
requestEnv     :: Ptr FCGX_Request -> IO Environ
requestEnv      = #{peek FCGX_Request, envp}

-- Allocate the request object
requestSize = #{size FCGX_Request}