{-# OPTIONS -Wall #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE CPP #-}
-- | A DB2 backend for @persistent@.
module Database.Persist.MigrateDB2
    ( getMigrationStrategy
    ) where

import Control.Arrow
import Control.Monad.IO.Class (MonadIO (..))
import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Except (runExceptT)
import Control.Monad.Trans.Resource (runResourceT)
import Data.ByteString (ByteString)
import Data.Either (partitionEithers)
import Data.Function (on)
import Data.List (find, intercalate, sort, groupBy)
import Data.Text (Text, pack)

import Data.Conduit (connect, (.|))
import qualified Data.Conduit.List as CL
import qualified Data.Text as T
import qualified Data.Text.Encoding as T

import Database.Persist.Sql
import Database.Persist.ODBCTypes
import Data.Acquire (with)

#if DEBUG
import Debug.Trace
tracex :: String -> a -> a
tracex = trace
#else
tracex :: String -> a -> a
tracex _ b = b
#endif

getMigrationStrategy :: DBType -> MigrationStrategy
getMigrationStrategy dbtype@DB2 {} =
     MigrationStrategy
                          { dbmsLimitOffset=decorateSQLWithLimitOffset "LIMIT 99999999"
                           ,dbmsMigrate=migrate'
                           ,dbmsInsertSql=insertSql'
                           ,dbmsEscape=T.pack . escapeDBName
                           ,dbmsType=dbtype
                          }
getMigrationStrategy dbtype = error $ "DB2: calling with invalid dbtype " ++ show dbtype

-- | Create the migration plan for the given 'PersistEntity'
-- @val@.
migrate' :: [EntityDef]
         -> (Text -> IO Statement)
         -> EntityDef
         -> IO (Either [Text] [(Bool, Text)])
migrate' allDefs getter val = do
    let name = entityDB val
    (idClmn, old) <- getColumns getter val
    let (newcols, udefs, fdefs) = mkColumns allDefs val
    liftIO $ putStrLn $ "\n\nold="++show old
    liftIO $ putStrLn $ "\n\nfdefs="++show fdefs

    let udspair = map udToPair udefs
    case (idClmn, old, partitionEithers old) of
      -- Nothing found, create everything
      ([], [], _) -> do
        let idtxt = case entityPrimary val of
                Just pdef -> tracex ("found it!!! val=" ++ show val) $
                              concat [" CONSTRAINT ", escapeDBName (pkeyName (entityDB val)), " PRIMARY KEY (", intercalate "," $ map (escapeDBName . fieldDB) $ compositeFields pdef, ")"]
                Nothing   -> tracex ("not found val=" ++ show val) $
                              concat [escapeDBName $ fieldDB $ entityId val
                            , " SMALLINT NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1) PRIMARY KEY "]
        let addTable = AddTable $ concat
                -- Lower case e: see Database.Persist.Sql.Migration
                [ "CREATe TABLE "
                , escapeDBName name
                , "("
                , idtxt
                , if null newcols then [] else ","
                , intercalate "," $ map showColumn newcols
                , ")"
                ]
        let uniques = flip concatMap udspair $ \(uname, ucols) ->
                      [ AlterTable name $
                        AddUniqueConstraint uname $
                        map (findTypeOfColumn allDefs name) ucols ]
        let foreigns = tracex ("in migrate' newcols=" ++ show newcols) $ do
              Column { cName=cname, cReference=Just (refTblName, a) } <- newcols
              tracex ("\n\n111foreigns cname="++show cname++" name="++show name++" refTblName="++show refTblName++" a="++show a) $
               return $ AlterColumn name (refTblName, addReference allDefs (refName name cname) refTblName cname)

        let foreignsAlt = map (\fdef -> let (childfields, parentfields) = unzip (map (\((_,b),(_,d)) -> (b,d)) (foreignFields fdef))
                                        in AlterColumn name (foreignRefTableDBName fdef, AddReference (foreignRefTableDBName fdef) (foreignConstraintNameDBName fdef) childfields parentfields)) fdefs

        return $ Right $ map showAlterDb $ addTable : uniques ++ foreigns ++ foreignsAlt
      -- No errors and something found, migrate
      (_, _, ([], old')) -> do
        let excludeForeignKeys (xs,ys) = (map (\c -> case cReference c of
                                                    Just (_,fk) -> case find (\f -> fk == foreignConstraintNameDBName f) fdefs of
                                                                     Just _ -> tracex ("\n\n\nremoving cos a composite fk="++show fk) $
                                                                                c { cReference = Nothing }
                                                                     Nothing -> c
                                                    Nothing -> c) xs,ys)
            (acs, ats) = getAlters allDefs name (newcols, udspair) $ excludeForeignKeys $ partitionEithers old'
            acs' = map (AlterColumn name) acs
            ats' = map (AlterTable  name) ats
        return $ Right $ map showAlterDb $ acs' ++ ats'
      -- Errors
      (_, _, (errs, _)) -> return $ Left errs

pkeyName :: DBName -> DBName
pkeyName (DBName table) =
    DBName $ T.concat [table, "_pkey"]

-- | Find out the type of a column.
findTypeOfColumn :: [EntityDef] -> DBName -> DBName -> (DBName, FieldType)
findTypeOfColumn allDefs name col =
    maybe (error $ "Could not find type of column " ++
                   show col ++ " on table " ++ show name ++
                   " (allDefs = " ++ show allDefs ++ ")")
          ((,) col) $ do
            entDef   <- find ((== name) . entityDB) allDefs
            fieldDef <- find ((== col)  . fieldDB) (entityFields entDef)
            return (fieldType fieldDef)


-- | Helper for 'AddRefence' that finds out the 'entityId'.
addReference :: [EntityDef] -> DBName -> DBName -> DBName -> AlterColumn
addReference allDefs fkeyname reftable cname = tracex ("\n\naddreference cname="++show cname++" fkeyname="++show fkeyname++" reftable="++show reftable++" id_="++show id_) $
                                  AddReference reftable fkeyname [cname] [id_]
    where
      id_ = maybe (error $ "Could not find ID of entity " ++ show reftable
                         ++ " (allDefs = " ++ show allDefs ++ ")")
                  id $ do
                    entDef <- find ((== reftable) . entityDB) allDefs
                    return (fieldDB (entityId entDef))

data AlterColumn = Change Column
                 | IsNull
                 | NotNull
                 | Add' Column
                 | Drop
                 | Default String
                 | NoDefault
                 | Update' String
                 | AddReference DBName DBName [DBName] [DBName]
                 | DropReference DBName

type AlterColumn' = (DBName, AlterColumn)

data AlterTable = AddUniqueConstraint DBName [(DBName, FieldType)]
                | DropUniqueConstraint DBName

data AlterDB = AddTable String
             | AlterColumn DBName AlterColumn'
             | AlterTable DBName AlterTable


udToPair :: UniqueDef -> (DBName, [DBName])
udToPair ud = (uniqueDBName ud, map snd $ uniqueFields ud)

----------------------------------------------------------------------


-- | Returns all of the 'Column'@s@ in the given table currently
-- in the database.
getColumns :: (Text -> IO Statement)
           -> EntityDef
           -> IO ( [Either Text (Either Column (DBName, [DBName]))] -- ID column
                 , [Either Text (Either Column (DBName, [DBName]))] -- everything else
                 )
getColumns getter def = do
    -- Find out ID column.
    stmtIdClmn <- getter $ T.concat
                          ["SELECT "
                          ,"colname column_name "
                          ,",nulls is_nullable "
                          ,",typename "
                          ,",default column_default "
                          ,",length "
                          ,",scale "
                          ,"FROM syscat.columns "
                          ,"WHERE tabschema=current_schema "
                          ,"AND tabname=? "
                          ,"AND colname <> ?"]

    inter1 <- with (stmtQuery stmtIdClmn vals) (`connect` CL.consume)
    ids <- runResourceT $ CL.sourceList inter1 `connect` helperClmns -- avoid nested queries

    -- Find out all columns.
    stmtClmns <- getter $ T.concat
                          ["SELECT "
                          ,"colname column_name "
                          ,",nulls is_nullable "
                          ,",typename "
                          ,",default column_default "
                          ,",length "
                          ,",scale "
                          ,"FROM syscat.columns "
                          ,"WHERE tabschema=current_schema "
                          ,"AND tabname=? "
                          ,"AND colname <> ?"]
    inter2 <- with (stmtQuery stmtClmns vals) (`connect` CL.consume)
    cs <- runResourceT $ CL.sourceList inter2 `connect` helperClmns -- avoid nested queries

    -- Find out the constraints.
    stmtCntrs <- getter $ T.concat ["SELECT "
                          ,"a.constname constraint_name "
                          ,",a.colname column_name "
                          ,"FROM SYSCAT.KEYCOLUSE A, SYSCAT.TABCONST B "
                          ,"WHERE A.CONSTNAME=B.CONSTNAME "
                          ,"AND a.tabschema=current_schema "
                          ,"AND b.tabschema=a.tabschema "
                          ,"AND a.tabname=? "
                          ,"AND a.colname <> ? "
                          ,"AND b.type not in ('F','P') "
                          ,"UNION "
                          ,"SELECT "
                          ,"constname constraint_name "
                          ,",trim(pk_colnames) column_name "
                          ,"FROM syscat.references "
                          ,"WHERE tabschema=current_schema "
                          ,"AND tabname=? "
                          ,"AND trim(pk_colnames) <> ? "
                          ,"ORDER BY constraint_name, column_name"]

    us <- with (stmtQuery stmtCntrs (vals++vals)) (`connect` helperCntrs)
    liftIO $ putStrLn $ "\n\ngetColumns cs="++show cs++"\n\nus="++show us
    -- Return both
    return (ids, cs ++ us)
  where
    vals = [ PersistText $ unDBName $ entityDB def
           , PersistText $ unDBName $ fieldDB $ entityId def ]

    helperClmns = CL.mapM getIt .| CL.consume
        where
          getIt = fmap (either Left (Right . Left)) .
                  liftIO .
                  getColumn getter (entityDB def)

    helperCntrs = do
      let check [ PersistByteString cntrName
                , PersistByteString clmnName] = return ( T.decodeUtf8 cntrName
                                                       , T.decodeUtf8 clmnName )
          check other = fail $ "helperCntrs: unexpected " ++ show other
      rows <- mapM check =<< CL.consume
      return $ map (Right . Right . (DBName . fst . head &&& map (DBName . snd)))
             $ groupBy ((==) `on` fst) rows


-- | Get the information about a column in a table.
getColumn :: (Text -> IO Statement)
          -> DBName
          -> [PersistValue]
          -> IO (Either Text Column)
getColumn getter tname [ PersistByteString cname
                                   , PersistByteString null_
                                   , PersistByteString type'
                                   , default'
                                   , npre
                                   , nscl] =
    fmap (either (Left . pack) Right) $
    runExceptT $ do
      -- Default value
      default_ <- case default' of
                    PersistNull   -> return Nothing
                    PersistText t -> return (Just t)
                    PersistByteString bs ->
                      case T.decodeUtf8' bs of
                        Left exc -> fail $ "Invalid default column: " ++
                                           show default' ++ " (error: " ++
                                           show exc ++ ")"
                        Right t  -> return (Just t)
                    _ -> fail $ "Invalid default column: " ++ show default'

      -- Column type
      type_ <- parseType type' npre nscl

      -- Foreign key (if any)
      stmt <- lift $ getter $ T.concat ["SELECT "
                       ,"tabname REFERENCED_TABLE_NAME, "
                       ,"constname, 1 "
                       ,"FROM syscat.references "
                       ,"WHERE tabschema=current_schema "
                       ,"AND tabname=? "
                       ,"AND trim(fk_colnames)=? "
                       ,"order by constname, fk_colnames "
                       ]
      let vars = [ PersistText $ unDBName tname
                 , PersistByteString cname
                 ]
      cntrs <- liftIO $ with (stmtQuery stmt vars) (`connect` CL.consume)
      ref <- case cntrs of
               [] -> return Nothing
               [[PersistByteString tab, PersistByteString ref, PersistInt64 pos]] ->
                   tracex ("\n\n\nGBREF "++show (tab,ref,pos)++"\n\n") $
                    return $ Just (DBName $ T.decodeUtf8 tab, DBName $ T.decodeUtf8 ref)
               a1 -> fail $ "DB2.getColumn/getRef: never here error[" ++ show a1 ++ "]"

      -- Okay!
      return Column
        { cName = DBName $ T.decodeUtf8 cname
        , cNull = null_ == "Y"
        , cSqlType = type_
        , cDefault = default_
        , cDefaultConstraintName = Nothing
        , cMaxLen = Nothing -- FIXME: maxLen
        , cReference = ref
        }

getColumn _ _ x =
    return $ Left $ pack $ "Invalid result from INFORMATION_SCHEMA: " ++ show x


-- | Parse the type of column as returned by MySQL's
-- @INFORMATION_SCHEMA@ tables.
parseType :: Monad m => ByteString -> PersistValue -> PersistValue -> m SqlType
parseType "SMALLINT"    _ _ = return SqlInt32
parseType "BIGINT"      _ _ = return SqlInt64
parseType "VARCHAR"     _ _ = return SqlString
parseType "DATE"        _ _ = return SqlDay
parseType "CHARACTER"   _ _ = return SqlBool
parseType "TIMESTAMP"   _ _ = return SqlDayTime
--parseType "TIMESTAMP WITH TIMEZONE" _ _ = return SqlDayTimeZoned
parseType "FLOAT"       _ _ = return SqlReal
parseType "DOUBLE"      _ _ = return SqlReal
parseType "DECIMAL"     _ _ = return SqlReal
parseType "BLOB"        _ _ = return SqlBlob
parseType "TIME"        _ _ = return SqlTime
parseType "NUMERIC"     npre nscl = return $ getNumeric npre nscl
parseType a             _ _ = error $ "what is this type a="++ show a -- Right $ SqlOther a

getNumeric :: PersistValue -> PersistValue -> SqlType
getNumeric (PersistInt64 a) (PersistInt64 b) = SqlNumeric (fromIntegral a) (fromIntegral b)
getNumeric a b = error $ "Can not get numeric field precision, got: " ++ show a ++ " and " ++ show b ++ " as precision and scale"


----------------------------------------------------------------------


-- | @getAlters allDefs tblName new old@ finds out what needs to
-- be changed from @old@ to become @new@.
getAlters :: [EntityDef]
          -> DBName
          -> ([Column], [(DBName, [DBName])])
          -> ([Column], [(DBName, [DBName])])
          -> ([AlterColumn'], [AlterTable])
getAlters allDefs tblName (c1, u1) (c2, u2) =
    (getAltersC c1 c2, getAltersU u1 u2)
  where
    getAltersC [] old = concatMap dropColumn old
    getAltersC (new:news) old =
        let (alters, old') = findAlters tblName allDefs new old
         in alters ++ getAltersC news old'

    dropColumn col =
      map ((,) (cName col)) $
        [DropReference n | Just (_, n) <- [cReference col]] ++
        [Drop]

    getAltersU [] old = map (DropUniqueConstraint . fst) old
    getAltersU ((name, cols):news) old =
        case lookup name old of
            Nothing ->
                AddUniqueConstraint name (map findType cols) : getAltersU news old
            Just ocols ->
                let old' = filter (\(x, _) -> x /= name) old
                 in if sort cols == ocols
                        then getAltersU news old'
                        else  DropUniqueConstraint name
                            : AddUniqueConstraint name (map findType cols)
                            : getAltersU news old'
        where
          findType = findTypeOfColumn allDefs tblName


-- | @findAlters newColumn oldColumns@ finds out what needs to be
-- changed in the columns @oldColumns@ for @newColumn@ to be
-- supported.
findAlters :: DBName -> [EntityDef] -> Column -> [Column] -> ([AlterColumn'], [Column])
findAlters tblName allDefs col@(Column name isNull type_ def _defConstraintName _maxLen ref) cols =
    tracex ("\n\n\nfindAlters tablename="++show tblName++ " name="++ show name++" col="++show col++"\ncols="++show cols++"\n\n\n") $
      case filter ((name ==) . cName) cols of
        [] -> case ref of
               Nothing -> ([(name, Add' col)], [])
               Just (tname, b) -> let cnstr = tracex ("\n\ncols="++show cols++"\n\n2222findalters new foreignkey col["++showColumn col++"] name["++show name++"] tname["++show tname++"] b["++show b ++ "]") $
                                              [addReference allDefs (refName tblName name) tname name]
                                  in (map ((,) name) (Add' col : cnstr), cols)
        Column _ isNull' type_' def' _defConstraintName' _maxLen' ref':_ ->
            let -- Foreign key
                refDrop = case (ref == ref', ref') of
                            (False, Just (_, cname)) -> tracex ("\n\n44444findalters dropping foreignkey cname[" ++ show cname ++ "] ref[" ++ show ref ++"]") $
                                                        [(name, DropReference cname)]
                            _ -> []
                refAdd  = case (ref == ref', ref) of
                            (False, Just (tname, cname)) -> tracex ("\n\n33333 findalters foreignkey has changed cname["++show cname++"] name["++show name++"] tname["++show tname++"] ref["++show ref++"] ref'["++show ref' ++ "]") $
                                                             [(tname, addReference allDefs (refName tblName name) tname name)]
                            _ -> []
                -- Type and nullability
                modType | tpcheck type_ type_' && isNull == isNull' = []
                        | otherwise = [(name, Change col)]
                -- Default value
                modDef | cmpdef def def' = []
                       | otherwise   = --tracex ("findAlters col=" ++ show col ++ " def=" ++ show def ++ " def'=" ++ show def') $
                                       case def of
                                         Nothing -> [(name, NoDefault)]
                                         Just s -> [(name, Default $ T.unpack s)]
            in ( refDrop ++ modType ++ modDef ++ refAdd
               , filter ((name /=) . cName) cols )


cmpdef :: Maybe Text -> Maybe Text -> Bool
cmpdef Nothing Nothing = True
cmpdef (Just def) (Just def') | def==def' = True
                              | otherwise =
        let (a,_)=T.breakOnEnd ":" def'
        in case T.stripSuffix "::" a of
              Just xs -> def==xs
              Nothing -> False
cmpdef _ _ = False

tpcheck :: SqlType -> SqlType -> Bool
tpcheck (SqlNumeric _ _) SqlReal = True -- else will try to migrate rational columns
tpcheck SqlReal (SqlNumeric _ _) = True
tpcheck a b = a==b
----------------------------------------------------------------------


-- | Prints the part of a @CREATE TABLE@ statement about a given
-- column.
showColumn :: Column -> String
showColumn (Column n nu t def _defConstraintName maxLen _ref) = concat
    [ escapeDBName n
    , " "
    , showSqlType t maxLen
    , " "
    , if nu then "NULL" else "NOT NULL"
    , case def of
        Nothing -> ""
        Just s -> " DEFAULT " ++ T.unpack s
    ]

-- | Renders an 'SqlType' in DB2's format.
showSqlType :: SqlType
            -> Maybe Integer -- ^ @maxlen@
            -> String
showSqlType SqlString Nothing = "VARCHAR(1000)"
showSqlType SqlString (Just len) = "VARCHAR(" ++ show len ++ ")"
showSqlType SqlInt32 _ = "SMALLINT"
showSqlType SqlInt64 _ = "BIGINT"
showSqlType SqlReal _ = "DOUBLE PRECISION"
showSqlType (SqlNumeric _s prec) _ = "NUMERIC(" ++ show prec ++ ")"
showSqlType SqlDay _ = "DATE"
showSqlType SqlTime _ = "TIME"
showSqlType SqlDayTime _ = "TIMESTAMP"
--showSqlType SqlDayTimeZoned _ = "TIMESTAMP WITH TIME ZONE"
showSqlType SqlBlob _ = "BLOB"
showSqlType SqlBool Nothing = "CHARACTER"
showSqlType SqlBool (Just 1) = "CHARACTER"
showSqlType SqlBool (Just n) = "CHARACTER(" ++ show n ++ ")"
showSqlType (SqlOther t) _ = T.unpack t

-- | Render an action that must be done on the database.
showAlterDb :: AlterDB -> (Bool, Text)
showAlterDb (AddTable s) = (False, pack s)
showAlterDb (AlterColumn t (c, ac)) =
    (isUnsafe ac, pack $ showAlter t (c, ac))
  where
    isUnsafe Drop = True
    isUnsafe _    = False
showAlterDb (AlterTable t at) = (False, pack $ showAlterTable t at)


-- | Render an action that must be done on a table.
showAlterTable :: DBName -> AlterTable -> String
showAlterTable table (AddUniqueConstraint cname cols) = concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " ADD CONSTRAINT "
    , escapeDBName cname
    , " UNIQUE("
    , intercalate "," $ map (escapeDBName . fst) cols
    , ")"
    ]
    --where
    --  escapeDBName' (name, FTTypeCon _ "Text"      ) = escapeDBName name ++ "(200)"
    --  escapeDBName' (name, FTTypeCon _ "String"    ) = escapeDBName name ++ "(200)"
    --  escapeDBName' (name, FTTypeCon _ "ByteString") = escapeDBName name ++ "(200)"
    --  escapeDBName' (name, _                       ) = escapeDBName name
showAlterTable table (DropUniqueConstraint cname) = concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " DROP CONSTRAINT "
    , escapeDBName cname
    ]


-- | Render an action that must be done on a column.
showAlter :: DBName -> AlterColumn' -> String
showAlter table (oldName, Change (Column _n _nu t _def _defConstraintName _maxLen _ref)) =
    concat
        [ "ALTER TABLE "
        , escapeDBName table
        , " ALTER COLUMN "
        , escapeDBName oldName
        , " SET DATA TYPE "
        , showSqlType t Nothing
        ]
showAlter table (n, IsNull) =
    concat
        [ "ALTER TABLE "
        , escapeDBName table
        , " ALTER COLUMN "
        , escapeDBName n
        , " DROP NOT NULL"
        ]
showAlter table (n, NotNull) =
    concat
        [ "ALTER TABLE "
        , escapeDBName table
        , " ALTER COLUMN "
        , escapeDBName n
        , " SET NOT NULL"
        ]
showAlter table (_, Add' col) =
    concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " ADD COLUMN "
    , showColumn col
    ]
showAlter table (n, Drop) =
    concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " DROP COLUMN "
    , escapeDBName n
    ]
showAlter table (n, Default s) =
    concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " ALTER COLUMN "
    , escapeDBName n
    , " SET DEFAULT "
    , s
    ]
showAlter table (n, NoDefault) =
    concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " ALTER COLUMN "
    , escapeDBName n
    , " DROP DEFAULT"
    ]
showAlter table (n, Update' s) =
    concat
    [ "UPDATE "
    , escapeDBName table
    , " SET "
    , escapeDBName n
    , "="
    , s
    , " WHERE "
    , escapeDBName n
    , " IS NULL"
    ]
showAlter table (_, AddReference reftable fkeyname t2 id2) = concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " ADD CONSTRAINT "
    , escapeDBName fkeyname
    , " FOREIGN KEY("
    , intercalate "," $ map escapeDBName t2
    , ") REFERENCES "
    , escapeDBName reftable
    , "("
    , intercalate "," $ map escapeDBName id2
    , ")"
    ]
showAlter table (_, DropReference cname) = concat
    [ "ALTER TABLE "
    , escapeDBName table
    , " DROP CONSTRAINT "
    , escapeDBName cname
    ]

refName :: DBName -> DBName -> DBName
refName (DBName table) (DBName column) =
    DBName $ T.concat [table, "_", column, "_fkey"]

----------------------------------------------------------------------


-- | Escape a database name to be included on a query.
escapeDBName :: DBName -> String
escapeDBName (DBName s) = '"' : go (T.unpack s)
    where
      go ('"':xs) = '"' : '"' : go xs
      go ( x :xs) =     x     : go xs
      go ""       = "\""
-- | SQL code to be executed when inserting an entity.
insertSql' :: EntityDef -> [PersistValue] -> InsertSqlResult
insertSql' ent vals =
  case entityPrimary ent of
    Just _pdef ->
      ISRManyKeys sql vals
        where sql = pack $ concat
                [ "INSERT INTO "
                , escapeDBName $ entityDB ent
                , "("
                , intercalate "," $ map (escapeDBName . fieldDB) $ entityFields ent
                , ") VALUES("
                , intercalate "," (map (const "?") $ entityFields ent)
                , ")"
                ]
    Nothing ->
      ISRInsertGet doInsert "select IDENTITY_VAL_LOCAL() as last_cod from sysibm.sysdummy1"
      where
        doInsert = pack $ concat
          [ "INSERT INTO "
          , escapeDBName $ entityDB ent
          , "("
          , intercalate "," $ map (escapeDBName . fieldDB) $ entityFields ent
          , ") VALUES("
          , intercalate "," $ zipWith doValue (entityFields ent) vals
          , ")"
          ]
        doValue f@FieldDef { fieldSqlType = SqlBlob } PersistNull = error $ "persistent-odbc db2 currently doesn't support inserting nulls in a blob field f=" ++ show f -- tracex "\n\nin blob with null\n\n" "iif(? is null, convert(varbinary(max), cast ('' as nvarchar(max))), convert(varbinary(max), cast ('' as nvarchar(max))))"
        doValue FieldDef { fieldSqlType = SqlBlob } (PersistByteString _) = "blob(?)" -- tracex "\n\nin blob with a value\n\n" "blob(?)"
        doValue _ _ = "?"