{-# OPTIONS_GHC -fwarn-incomplete-patterns #-}
module Database.Beam.Query
    ( -- * Query type
      module Database.Beam.Query.Types

    -- ** Query expression contexts
    -- | A context is a type-level value that signifies where an expression can
    --   be used. For example, 'QExpr' corresponds to 'QGenExpr's that result in
    --   values. In reality, 'QExpr' is really 'QGenExpr' parameterized over the
    --   'QValueContext'. Similarly, 'QAgg' represents expressions that contain
    --   aggregates, but it is just 'QGenExpr' parameterized over
    --   'QAggregateContext'
    , QAggregateContext, QGroupingContext, QValueContext
    , QWindowingContext, QWindowFrameContext

    , QueryableSqlSyntax

    , QGenExprTable, QExprTable

    , module Database.Beam.Query.Combinators
    , module Database.Beam.Query.Extensions

    , module Database.Beam.Query.Relationships

    -- * Operators
    , module Database.Beam.Query.Operator

    -- ** ANSI SQL Booleans
    , Beam.SqlBool
    , isTrue_, isNotTrue_
    , isFalse_, isNotFalse_
    , isUnknown_, isNotUnknown_
    , unknownAs_, sqlBool_

    -- ** Unquantified comparison operators
    , HasSqlEqualityCheck(..), HasSqlQuantifiedEqualityCheck(..)
    , SqlEq(..), SqlOrd(..)

    -- ** Quantified Comparison Operators #quantified-comparison-operator#
    , SqlEqQuantified(..), SqlOrdQuantified(..)
    , QQuantified
    , anyOf_, allOf_, anyIn_, allIn_
    , between_
    , in_

    , module Database.Beam.Query.Aggregate

    , module Database.Beam.Query.CustomSQL

    -- * SQL Command construction and execution
    -- ** @SELECT@
    , SqlSelect(..)
    , select, lookup_
    , runSelectReturningList
    , runSelectReturningOne
    , dumpSqlSelect

    -- ** @INSERT@
    , SqlInsert(..)
    , insert, insertOnly
    , runInsert

    , SqlInsertValues(..)
    , insertExpressions
    , insertValues
    , insertFrom
    , insertData

    -- ** @UPDATE@
    , SqlUpdate(..)
    , update, save
    , runUpdate

    -- ** @DELETE@
    , SqlDelete(..)
    , delete
    , runDelete ) where

import Prelude hiding (lookup)

import Database.Beam.Query.Aggregate
import Database.Beam.Query.Combinators
import Database.Beam.Query.CustomSQL
import Database.Beam.Query.Extensions
import Database.Beam.Query.Internal
import Database.Beam.Query.Operator hiding (SqlBool)
import qualified Database.Beam.Query.Operator as Beam
import Database.Beam.Query.Ord
import Database.Beam.Query.Relationships
import Database.Beam.Query.Types (QGenExpr) -- hide QGenExpr constructor
import Database.Beam.Query.Types hiding (QGenExpr)

import Database.Beam.Backend.Types
import Database.Beam.Backend.SQL
import Database.Beam.Backend.SQL.Builder
import Database.Beam.Schema.Tables

import Control.Monad.Identity
import Control.Monad.Writer

import Data.Text (Text)
import Data.Proxy

-- * Query

data QueryInaccessible

-- | A version of the table where each field is a 'QGenExpr'
type QGenExprTable ctxt syntax s tbl = tbl (QGenExpr ctxt syntax s)

type QExprTable syntax s tbl = QGenExprTable QValueContext syntax s tbl

-- * SELECT

-- | Represents a select statement over the syntax 'select' that will return
--   rows of type 'a'.
newtype SqlSelect select a
    = SqlSelect select

type QueryableSqlSyntax cmd =
  ( IsSql92Syntax cmd
  , Sql92SanityCheck cmd
  , HasQBuilder (Sql92SelectSyntax cmd) )

-- | Build a 'SqlSelect' for the given 'Q'.
select :: forall syntax db res.
          ( ProjectibleInSelectSyntax syntax res
          , IsSql92SelectSyntax syntax
          , HasQBuilder syntax ) =>
          Q syntax db QueryInaccessible res -> SqlSelect syntax (QExprToIdentity res)
select q =
  SqlSelect (buildSqlQuery "t" q)

-- | Convenience function to generate a 'SqlSelect' that looks up a table row
--   given a primary key.
lookup_ :: ( HasQBuilder syntax
           , Sql92SelectSanityCheck syntax

           , SqlValableTable (PrimaryKey table) (Sql92SelectExpressionSyntax syntax)
           , HasSqlValueSyntax (Sql92ExpressionValueSyntax (Sql92SelectExpressionSyntax syntax)) Bool

           , HasTableEquality (Sql92SelectExpressionSyntax syntax) (PrimaryKey table)

           , Beamable table, Table table

           , Database be db )
        => DatabaseEntity be db (TableEntity table)
        -> PrimaryKey table Identity
        -> SqlSelect syntax (table Identity)
lookup_ tbl tblKey =
  select $
  filter_ (\t -> pk t ==. val_ tblKey) $
  all_ tbl

-- | Run a 'SqlSelect' in a 'MonadBeam' and get the results as a list
runSelectReturningList ::
  (IsSql92Syntax cmd, MonadBeam cmd be hdl m, FromBackendRow be a) =>
  SqlSelect (Sql92SelectSyntax cmd) a -> m [ a ]
runSelectReturningList (SqlSelect s) =
  runReturningList (selectCmd s)

-- | Run a 'SqlSelect' in a 'MonadBeam' and get the unique result, if there is
--   one. Both no results as well as more than one result cause this to return
--   'Nothing'.
runSelectReturningOne ::
  (IsSql92Syntax cmd, MonadBeam cmd be hdl m, FromBackendRow be a) =>
  SqlSelect (Sql92SelectSyntax cmd) a -> m (Maybe a)
runSelectReturningOne (SqlSelect s) =
  runReturningOne (selectCmd s)

-- | Use a special debug syntax to print out an ANSI Standard @SELECT@ statement
--   that may be generated for a given 'Q'.
dumpSqlSelect :: ProjectibleInSelectSyntax SqlSyntaxBuilder res =>
                 Q SqlSyntaxBuilder db QueryInaccessible res -> IO ()
dumpSqlSelect q =
    let SqlSelect s = select q
    in putStrLn (renderSql s)

-- * INSERT

-- | Represents a SQL @INSERT@ command that has not yet been run
data SqlInsert syntax
  = SqlInsert syntax
  | SqlInsertNoRows

-- | Generate a 'SqlInsert' over only certain fields of a table
insertOnly :: ( IsSql92InsertSyntax syntax, Projectible Text (QExprToField r) )
           => DatabaseEntity be db (TableEntity table)
              -- ^ Table to insert into
           -> (table (QField s) -> QExprToField r)
           -> SqlInsertValues (Sql92InsertValuesSyntax syntax) r
              -- ^ Values to insert. See 'insertValues', 'insertExpressions', 'insertData', and 'insertFrom' for possibilities.
           -> SqlInsert syntax
insertOnly _ _ SqlInsertValuesEmpty = SqlInsertNoRows
insertOnly (DatabaseEntity (DatabaseTable tblNm tblSettings)) mkProj (SqlInsertValues vs) =
    SqlInsert (insertStmt tblNm proj vs)
  where
    tblFields = changeBeamRep (\(Columnar' (TableField name)) -> Columnar' (QField False tblNm name)) tblSettings
    proj = execWriter (project' (Proxy @AnyType) (\_ f -> tell [f ""] >> pure f)
                                (mkProj tblFields))

-- | Generate a 'SqlInsert' given a table and a source of values.
insert :: ( IsSql92InsertSyntax syntax, Projectible Text (table (QField s)) )
       => DatabaseEntity be db (TableEntity table)
          -- ^ Table to insert into
       -> SqlInsertValues (Sql92InsertValuesSyntax syntax) (table (QExpr (Sql92InsertExpressionSyntax syntax) s))
          -- ^ Values to insert. See 'insertValues', 'insertExpressions', and 'insertFrom' for possibilities.
       -> SqlInsert syntax
insert tbl values = insertOnly tbl id values

-- | Run a 'SqlInsert' in a 'MonadBeam'
runInsert :: (IsSql92Syntax cmd, MonadBeam cmd be hdl m)
          => SqlInsert (Sql92InsertSyntax cmd) -> m ()
runInsert SqlInsertNoRows = pure ()
runInsert (SqlInsert i) = runNoReturn (insertCmd i)

-- | Represents a source of values that can be inserted into a table shaped like
--   'tbl'.
data SqlInsertValues insertValues proj --(tbl :: (* -> *) -> *)
    = SqlInsertValues insertValues
    | SqlInsertValuesEmpty

-- | Build a 'SqlInsertValues' from series of expressions in tables
insertExpressions ::
    forall syntax table s.
    ( Beamable table
    , IsSql92InsertValuesSyntax syntax ) =>
    (forall s'. [ table (QExpr (Sql92InsertValuesExpressionSyntax syntax) s') ]) ->
    SqlInsertValues syntax (table (QExpr (Sql92InsertValuesExpressionSyntax syntax) s))
insertExpressions tbls =
  case sqlExprs of
    [] -> SqlInsertValuesEmpty
    _  -> SqlInsertValues (insertSqlExpressions sqlExprs)
    where
      sqlExprs = map mkSqlExprs tbls

      mkSqlExprs :: forall s'. table (QExpr (Sql92InsertValuesExpressionSyntax syntax) s') -> [Sql92InsertValuesExpressionSyntax syntax]
      mkSqlExprs = allBeamValues (\(Columnar' (QExpr x)) -> x "t")

-- | Build a 'SqlInsertValues' from concrete table values
insertValues ::
    forall table syntax s.
    ( Beamable table
    , IsSql92InsertValuesSyntax syntax
    , FieldsFulfillConstraint (HasSqlValueSyntax (Sql92ExpressionValueSyntax (Sql92InsertValuesExpressionSyntax syntax))) table) =>
    [ table Identity ] -> SqlInsertValues syntax (table (QExpr (Sql92InsertValuesExpressionSyntax syntax) s))
insertValues x = insertExpressions (map val_ x :: forall s'. [table (QExpr (Sql92InsertValuesExpressionSyntax syntax) s') ])

-- | Build a 'SqlInsertValues' from arbitrarily shaped data containing expressions
insertData :: forall syntax r
            . ( Projectible (Sql92InsertValuesExpressionSyntax syntax) r
              , IsSql92InsertValuesSyntax syntax )
           => [ r ] -> SqlInsertValues syntax r
insertData rows =
  case rows of
    [] -> SqlInsertValuesEmpty
    _  -> SqlInsertValues (insertSqlExpressions (map mkSqlExprs rows))
  where
    mkSqlExprs :: r -> [Sql92InsertValuesExpressionSyntax syntax]
    mkSqlExprs r = execWriter (project' (Proxy @AnyType) (\_ s -> tell [ s "t" ] >> pure s) r)

-- | Build a 'SqlInsertValues' from a 'SqlSelect' that returns the same table
insertFrom
    :: ( IsSql92InsertValuesSyntax syntax
       , HasQBuilder (Sql92InsertValuesSelectSyntax syntax)
       , Projectible (Sql92SelectExpressionSyntax (Sql92InsertValuesSelectSyntax syntax)) r )
    => Q (Sql92InsertValuesSelectSyntax syntax) db QueryInaccessible r
    -> SqlInsertValues syntax r
insertFrom s = SqlInsertValues (insertFromSql (buildSqlQuery "t" s))

-- * UPDATE

-- | Represents a SQL @UPDATE@ statement for the given @table@.
data SqlUpdate syntax (table :: (* -> *) -> *)
  = SqlUpdate syntax
  | SqlIdentityUpdate -- An update with no assignments

-- | Build a 'SqlUpdate' given a table, a list of assignments, and a way to
--   build a @WHERE@ clause.
--
--   See the '(<-.)' operator for ways to build assignments. The argument to the
--   second argument is a the table parameterized over 'QField', which
--   represents the left hand side of assignments. Sometimes, you'd like to also
--   get the current value of a particular column. You can use the 'current_'
--   function to convert a 'QField' to a 'QExpr'.
update :: ( Beamable table
          , IsSql92UpdateSyntax syntax) =>
          DatabaseEntity be db (TableEntity table)
          -- ^ The table to insert into
       -> (forall s. table (QField s) -> [ QAssignment (Sql92UpdateFieldNameSyntax syntax) (Sql92UpdateExpressionSyntax syntax) s ])
          -- ^ A sequence of assignments to make.
       -> (forall s. table (QExpr (Sql92UpdateExpressionSyntax syntax) s) -> QExpr (Sql92UpdateExpressionSyntax syntax) s Bool)
          -- ^ Build a @WHERE@ clause given a table containing expressions
       -> SqlUpdate syntax table
update (DatabaseEntity (DatabaseTable tblNm tblSettings)) mkAssignments mkWhere =
  case assignments of
    [] -> SqlIdentityUpdate
    _  -> SqlUpdate (updateStmt tblNm assignments (Just (where_ "t")))
  where
    assignments = concatMap (\(QAssignment as) -> as) (mkAssignments tblFields)
    QExpr where_ = mkWhere tblFieldExprs

    tblFields = changeBeamRep (\(Columnar' (TableField name)) -> Columnar' (QField False tblNm name)) tblSettings
    tblFieldExprs = changeBeamRep (\(Columnar' (QField _ _ nm)) -> Columnar' (QExpr (pure (fieldE (unqualifiedField nm))))) tblFields

-- | Generate a 'SqlUpdate' that will update the given table with the given value.
--
--   The SQL @UPDATE@ that is generated will set every non-primary key field for
--   the row where each primary key field is exactly what is given.
--
--   Note: This is a pure SQL @UPDATE@ command. This does not upsert or merge values.
save :: forall table syntax be db.
        ( Table table
        , IsSql92UpdateSyntax syntax

        , SqlValableTable (PrimaryKey table) (Sql92UpdateExpressionSyntax syntax)
        , SqlValableTable table (Sql92UpdateExpressionSyntax syntax)

        , HasTableEquality (Sql92UpdateExpressionSyntax syntax) (PrimaryKey table)

        , HasSqlValueSyntax (Sql92ExpressionValueSyntax (Sql92UpdateExpressionSyntax syntax)) Bool
        )
     => DatabaseEntity be db (TableEntity table)
        -- ^ Table to update
     -> table Identity
        -- ^ Value to set to
     -> SqlUpdate syntax table
save tbl@(DatabaseEntity (DatabaseTable _ tblSettings)) v =
  update tbl (\(tblField :: table (QField s)) ->
                execWriter $
                zipBeamFieldsM
                  (\(Columnar' field) c@(Columnar' value) ->
                     do when (qFieldName field `notElem` primaryKeyFieldNames) $
                          tell [ field <-. value ]
                        pure c)
                  tblField (val_ v :: table (QExpr (Sql92UpdateExpressionSyntax syntax) s)))
             (\tblE -> primaryKey tblE ==. val_ (primaryKey v))

  where
    primaryKeyFieldNames =
      allBeamValues (\(Columnar' (TableField fieldNm)) -> fieldNm) (primaryKey tblSettings)

-- | Run a 'SqlUpdate' in a 'MonadBeam'.
runUpdate :: (IsSql92Syntax cmd, MonadBeam cmd be hdl m)
          => SqlUpdate (Sql92UpdateSyntax cmd) tbl -> m ()
runUpdate (SqlUpdate u) = runNoReturn (updateCmd u)
runUpdate SqlIdentityUpdate = pure ()

-- * DELETE

-- | Represents a SQL @DELETE@ statement for the given @table@
newtype SqlDelete syntax (table :: (* -> *) -> *) = SqlDelete syntax

-- | Build a 'SqlDelete' from a table and a way to build a @WHERE@ clause
delete :: IsSql92DeleteSyntax delete
       => DatabaseEntity be db (TableEntity table)
          -- ^ Table to delete from
       -> (forall s. table (QExpr (Sql92DeleteExpressionSyntax delete) s) -> QExpr (Sql92DeleteExpressionSyntax delete) s Bool)
          -- ^ Build a @WHERE@ clause given a table containing expressions
       -> SqlDelete delete table
delete (DatabaseEntity (DatabaseTable tblNm tblSettings)) mkWhere =
  SqlDelete (deleteStmt tblNm (Just (where_ "t")))
  where
    QExpr where_ = mkWhere (changeBeamRep (\(Columnar' (TableField name)) -> Columnar' (QExpr (pure (fieldE (unqualifiedField name))))) tblSettings)

-- | Run a 'SqlDelete' in a 'MonadBeam'
runDelete :: (IsSql92Syntax cmd, MonadBeam cmd be hdl m)
          => SqlDelete (Sql92DeleteSyntax cmd) table -> m ()
runDelete (SqlDelete d) = runNoReturn (deleteCmd d)