-- -*- mode: haskell; -*-
{-
Copyright (C) 2006 John Goerzen <jgoerzen@complete.org>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
-}

module Database.HDBC.PostgreSQL.PTypeConv where
import Database.HDBC.ColTypes
import Data.Word
import Data.Int

#include "pgtypes.h"
#include <libpq-fe.h>


colDescForPGAttr :: #{type Oid} -> Int -> String -> Bool -> SqlColDesc
colDescForPGAttr atttypeid attlen formattedtype attnotnull =
    let
        coltype = oidToColType atttypeid

        size = if attlen == -1 then maybeExtractFirstParenthesizedNumber formattedtype
               else Just attlen

        decDigs = if coltype == SqlNumericT then maybeExtractSecondParenthesizedNumber formattedtype
                  else Nothing
    in
      SqlColDesc { colType = coltype,
                   colSize = size,
                   colOctetLength = Nothing, -- not available in postgres
                   colDecDigits = decDigs,
                   colNullable = Just attnotnull }
    where
      maybeExtractFirstParenthesizedNumber s = case extractParenthesizedInts s of n:_ -> Just n; _ -> Nothing

      maybeExtractSecondParenthesizedNumber s = case extractParenthesizedInts s of n1:n2:_ -> Just n2; _ -> Nothing

      extractParenthesizedInts :: String -> [Int]
      extractParenthesizedInts s =
          case takeWhile (/=')') $ dropWhile (/='(') s of
            '(':textBetweenParens ->
                case map fst $ reads $ "[" ++ textBetweenParens ++ "]" of
                  l:_ -> l
                  [] -> []
            _ -> []



oidToColDef :: #{type Oid} -> SqlColDesc
oidToColDef oid =
    SqlColDesc {colType = (oidToColType oid),
                colSize = Nothing,
                colOctetLength = Nothing,
                colDecDigits = Nothing,
                colNullable = Nothing}

oidToColType :: #{type Oid} -> SqlTypeId
oidToColType oid =
    case oid of
      #{const PG_TYPE_CHAR} -> SqlCharT
      #{const PG_TYPE_CHAR2} -> SqlCharT
      #{const PG_TYPE_CHAR4} -> SqlCharT
      #{const PG_TYPE_CHAR8} -> SqlCharT
      #{const PG_TYPE_NAME} -> SqlVarCharT
      #{const PG_TYPE_BPCHAR} -> SqlCharT
      #{const PG_TYPE_VARCHAR} -> SqlVarCharT
      #{const PG_TYPE_TEXT} -> SqlVarCharT
      #{const PG_TYPE_BYTEA} -> SqlVarBinaryT
      #{const PG_TYPE_INT2} -> SqlSmallIntT
      #{const PG_TYPE_OID} -> SqlIntegerT
      #{const PG_TYPE_XID} -> SqlIntegerT
      #{const PG_TYPE_INT4} -> SqlBigIntT
      #{const PG_TYPE_INT8} -> SqlBigIntT
      #{const PG_TYPE_NUMERIC} -> SqlNumericT
      #{const PG_TYPE_FLOAT4} -> SqlRealT
      #{const PG_TYPE_FLOAT8} -> SqlFloatT
      #{const PG_TYPE_DATE} -> SqlDateT
      #{const PG_TYPE_ABSTIME} -> SqlTimestampT
      #{const PG_TYPE_DATETIME} -> SqlTimestampT
      #{const PG_TYPE_TIMESTAMP_NO_TMZONE} -> SqlTimestampT
      #{const PG_TYPE_TIMESTAMP} -> SqlTimestampT
      #{const PG_TYPE_TIME} -> SqlTimeT
      #{const PG_TYPE_TIME_WITH_TMZONE} -> SqlTimeT
      #{const PG_TYPE_TINTERVAL} -> SqlIntervalT SqlIntervalMonthT -- SqlIntervalMonthT chosen arbitrarily in these two. PG allows any parts
      #{const PG_TYPE_RELTIME}   -> SqlIntervalT SqlIntervalMonthT -- of an interval (microsecond to millennium) to be specified together.
      #{const PG_TYPE_BOOL} -> SqlBitT
      x -> SqlUnknownT (show x)