{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE PatternSynonyms #-}

module Ringo.Validator (validateConfig) where

import qualified Data.Map as Map
import qualified Data.Text as Text

import Prelude.Compat
import Control.Monad.Reader (Reader, ask, runReader)
import Data.Function        (on)
import Data.Maybe           (isJust, fromJust)
import Data.List            (nub, group, groupBy, sort)

import Ringo.Extractor.Internal
import Ringo.Types.Internal
import Ringo.Utils

checkTableForCol :: Table -> ColumnName -> [ValidationError]
checkTableForCol tab colName =
  [ MissingColumn (tableName tab) colName |
      not . any ((colName ==) . columnName) . tableColumns $ tab ]

validateTable :: Table -> Reader Config [ValidationError]
validateTable table = do
  Config tables _ _ _ <- ask
  return . concatMap (checkConstraint tables) . tableConstraints $ table
  where
    checkConstraint _ (PrimaryKey colName)    = checkTableForCol table colName
    checkConstraint _ (UniqueKey columnNames) = checkTableForColRefs table columnNames
    checkConstraint tables (ForeignKey oTableName columnNames) =
      case findTable oTableName tables of
        Just oTable -> checkTableForColRefs table (map fst columnNames)
                         ++ checkTableForColRefs oTable (map snd columnNames)
        Nothing     -> [ MissingTable oTableName ]

    checkTableForColRefs tab = concatMap (checkTableForCol tab)

validateFact :: Fact -> Reader Config [ValidationError]
validateFact Fact {..} = do
  Config tables _ _ typeDefaults <- ask
  let defaults = Map.keys typeDefaults
  case findTable factTableName tables of
    Nothing    -> return [ MissingTable factTableName ]
    Just table -> do
      tableVs           <- validateTable table
      parentVs          <- concat <$> mapM checkFactParents factParentNames
      let colVs         = concatMap (checkColumn tables table) factColumns
          timeVs        = [ MissingTimeColumn factTableName
                            | null ([ cName | FactColumn cName DimTime <- factColumns ] :: [ColumnName]) ]
          notNullVs     = [ MissingNotNullConstraint factTableName cName
                            | FactColumn cName DimTime <- factColumns
                            , let col                  = findColumn cName (tableColumns table)
                            , isJust col
                            , columnNullable (fromJust col) == Null ]
          typeDefaultVs =
            [ MissingTypeDefault cType
              | cName   <- [ c | FactColumn c DimVal {..} <- factColumns ]
                        ++ [ c | FactColumn c NoDimId     <- factColumns ]
                        ++ [ c | FactColumn c TenantId    <- factColumns ]
                        ++ [ c | FactColumn c DimId {..}  <- factColumns ]
              , let col = findColumn cName (tableColumns table)
              , isJust col
              , let cType = columnType $ fromJust col
              , not . any (`Text.isPrefixOf` cType) $ defaults ]

      return $ tableVs ++ parentVs ++ colVs ++ timeVs ++ notNullVs ++ typeDefaultVs
  where
    checkFactParents fName = do
      Config _ facts _ _ <- ask
      case findFact fName facts of
        Nothing    -> return [ MissingFact fName ]
        Just pFact -> validateFact pFact

    checkColumn tables table factCol =
      maybe [] (checkTableForCol table) (factSourceColumnName factCol)
        ++ checkColumnTable tables factCol

    checkColumnTable :: [Table] -> FactColumn -> [ValidationError]
    checkColumnTable tables FactColumn {..} = case factColType of
      DimId {factColTargetTable = tName} -> maybe [ MissingTable tName ] (const []) $ findTable tName tables
      _                                  -> []

validateConfig :: [Table] -> [Fact] -> Settings -> TypeDefaults -> Either [ValidationError] Config
validateConfig tables facts settings@Settings {..} typeDefaults = let
    config = Config tables facts settings typeDefaults
  in flip runReader config $ do
       tableVs <- concat <$> mapM validateTable tables
       factVs  <- concat <$> mapM validateFact facts
       let dupTableVs = [ DuplicateTable table | table <- findDups . map tableName $ tables ]
           dupFactVs  = [ DuplicateFact fact   | fact  <- findDups . map factName $ facts ]
           dupColVs   = [ DuplicateColumn tableName col
                          | Table{..} <- tables
                          , col       <- findDups . map columnName $ tableColumns ]
           dupDimVs   = facts
                        >>- concatMap (dimColumnMappings settingDimPrefix)
                        >>> sort
                        >>> groupBy ((==) `on` fst)
                        >>> filter (map snd >>> nub >>> length >>> (/= 1))
                        >>> map (head >>> fst >>> DuplicateDimension)
           errors     = nub $ tableVs ++ factVs ++ dupTableVs ++ dupFactVs ++ dupColVs ++ dupDimVs
       return $ if null errors
         then Right config
         else Left errors
  where
    findDups =
      sort >>> group >>> map (head &&& length) >>> filter (snd >>> (> 1)) >>> map fst