{-# LINE 1 "src/Data/QRCode.hsc" #-}
{-# LANGUAGE CPP, ForeignFunctionInterface #-}
{-# LINE 2 "src/Data/QRCode.hsc" #-}

-- | Haskell bindings for libqrencode. <http://fukuchi.org/works/qrencode/index.en.html>
--
--   Libqrencode is a C library for encoding data in a QR Code symbol, a kind of 2D symbology 
--   that can be scanned by handy terminals such as a mobile phone with CCD. The capacity of 
--   QR Code is up to 7000 digits or 4000 characters, and is highly robust.

module Data.QRCode (encodeByteString, 
                    encodeString,
                    getQRCodeVersion,
                    getQRCodeWidth,
                    getQRCodeString,
                    toMatrix,
                    QREncodeLevel (..), 
                    QREncodeMode (..)) where

import Control.Monad
import Data.ByteString (ByteString, unpack, useAsCString, packCString)
import qualified Data.ByteString as BS
import Data.Maybe
import Foreign
import Foreign.C.String
import Foreign.C.Types
import Foreign.Storable


{-# LINE 28 "src/Data/QRCode.hsc" #-}

data QREncodeLevel = QR_ECLEVEL_L 
                   | QR_ECLEVEL_M 
                   | QR_ECLEVEL_Q 
                   | QR_ECLEVEL_H

data QREncodeMode  = QR_MODE_NUM        -- ^ Numeric mode
                   | QR_MODE_AN         -- ^ Alphabet-numeric mode
                   | QR_MODE_EIGHT      -- ^ 8-bit data mode
                   | QR_MODE_KANJI      -- ^ Kanji (shift-jis) mode

convertQREncodeLevel :: QREncodeLevel -> CInt
convertQREncodeLevel QR_ECLEVEL_L = 0
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convertQREncodeLevel QR_ECLEVEL_M = 1
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convertQREncodeLevel QR_ECLEVEL_Q = 2
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convertQREncodeLevel QR_ECLEVEL_H = 3
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convertQREncodeMode :: QREncodeMode -> CInt
convertQREncodeMode QR_MODE_NUM       = 0
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convertQREncodeMode QR_MODE_AN        = 1
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convertQREncodeMode QR_MODE_EIGHT     = 2
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convertQREncodeMode QR_MODE_KANJI     = 3
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data QRcode = QRcode { 
      getQRCodeVersion :: Int,
      getQRCodeWidth   :: Int,
      getQRCodeString  :: ByteString
    } deriving (Show, Read)

data QRcodeStruct = QRcodeStruct {
      c_version :: CInt,
      c_width   :: CInt,
      c_data    :: CString
    } deriving (Show)


{-# LINE 64 "src/Data/QRCode.hsc" #-}

instance Storable QRcodeStruct where

    alignment _ = 4
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    sizeOf _ = (12)
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    peek ptr = do
      version <- (\hsc_ptr -> peekByteOff hsc_ptr 0) ptr
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      width   <- (\hsc_ptr -> peekByteOff hsc_ptr 4) ptr
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      data'   <- (\hsc_ptr -> peekByteOff hsc_ptr 8) ptr
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      return $ QRcodeStruct version width data'

    poke ptr (QRcodeStruct version width data') = do
      (\hsc_ptr -> pokeByteOff hsc_ptr 0) ptr version
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      (\hsc_ptr -> pokeByteOff hsc_ptr 4) ptr width
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      (\hsc_ptr -> pokeByteOff hsc_ptr 8) ptr data'
{-# LINE 81 "src/Data/QRCode.hsc" #-}


foreign import ccall unsafe "QRcode_encodeString" 
    c_encodeString :: CString -- string
                   -> CInt    -- version
                   -> CInt    -- level
                   -> CInt    -- hint
                   -> CInt    -- casesensitive
                   -> IO (Ptr QRcodeStruct)

-- | create a QR code from a ByteString
encodeByteString :: ByteString    -- ^ String to encode
                 -> Maybe Int     -- ^ Version (auto if Nothing)
                 -> QREncodeLevel -- ^ Encode Level
                 -> QREncodeMode  -- ^ Encode Mode
                 -> Bool          -- ^ Case-sensative
                 -> IO QRcode     
encodeByteString str version level mode casesensitive = do
    when (BS.null str) $ error "empty bytestring provided" 
    useAsCString str $ \s-> encoder s version level mode casesensitive

-- | create a QR code from a String
encodeString :: String        -- ^ String to encode
             -> Maybe Int     -- ^ Version (auto if Nothing)
             -> QREncodeLevel -- ^ Encode Level
             -> QREncodeMode  -- ^ Encode Mode
             -> Bool          -- ^ Case-sensative
             -> IO QRcode
encodeString str version  level mode casesensitive = do
    when (null str) $ error "empty string provided" 
    newCAString str >>= \s-> encoder s version level mode casesensitive
    
encoder :: CString -> Maybe Int -> QREncodeLevel -> QREncodeMode -> Bool -> IO QRcode
encoder cstr ver level mode casesensitive = do
  let l = convertQREncodeLevel level
  let m = convertQREncodeMode mode
  c_qr <- join $ fmap peek $ c_encodeString cstr (fromIntegral $ fromMaybe 0 ver) l m (b2i casesensitive) 
  let version = fromIntegral (c_version c_qr)                           
  let width   = fromIntegral (c_width   c_qr)                           
  str <- packCString (c_data c_qr) 
  return (QRcode version width str)                                     
  where
    b2i True  = 1                                   
    b2i False = 0                                   

-- | Convert a QRcode to a matrix of ones and zeros (1 = On, 0 = Off)
toMatrix :: QRcode -> [[Word8]]
toMatrix (QRcode _ width str) = 
    regroup . map tobin . unpack $ str
    where
      tobin c = c .&. 1                               
      regroup [] = []                               
      regroup x = take width x : regroup (drop width x)