{-# LANGUAGE TupleSections #-}
module Opaleye.Internal.Aggregate where

import           Control.Applicative (liftA2)
import           Data.Foldable (toList)
import           Data.Traversable (for)

import qualified Data.Profunctor as P
import qualified Data.Profunctor.Product as PP

import qualified Opaleye.Field as F
import qualified Opaleye.Internal.Column as C
import qualified Opaleye.Internal.Order as O
import qualified Opaleye.Internal.PackMap as PM
import qualified Opaleye.Internal.PrimQuery as PQ
import qualified Opaleye.Internal.Tag as T
import qualified Opaleye.Internal.Unpackspec as U
import qualified Opaleye.SqlTypes as T

import qualified Opaleye.Internal.HaskellDB.PrimQuery as HPQ

{-|
An 'Aggregator' takes a collection of rows of type @a@, groups
them, and transforms each group into a single row of type @b@. This
corresponds to aggregators using @GROUP BY@ in SQL.

You should combine basic 'Aggregator's into 'Aggregator's on compound
types by using the operations in "Data.Profunctor.Product".

An 'Aggregator' corresponds closely to a 'Control.Foldl.Fold' from the
@foldl@ package.  Whereas an 'Aggregator' @a@ @b@ takes each group of
type @a@ to a single row of type @b@, a 'Control.Foldl.Fold' @a@ @b@
takes a list of @a@ and returns a single value of type @b@.
-}
newtype Aggregator a b =
  Aggregator (PM.PackMap HPQ.Aggregate HPQ.PrimExpr a b)

makeAggr' :: Maybe HPQ.AggrOp -> Aggregator (C.Field_ n a) (C.Field_ n' b)
makeAggr' :: forall (n :: Nullability) a (n' :: Nullability) b.
Maybe AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr' Maybe AggrOp
mAggrOp = forall (p :: * -> * -> *) a b c d.
Profunctor p =>
(a -> b) -> (c -> d) -> p b c -> p a d
P.dimap forall (n :: Nullability) a. Field_ n a -> PrimExpr
C.unColumn forall (n :: Nullability) sqlType. PrimExpr -> Field_ n sqlType
C.Column forall a b. (a -> b) -> a -> b
$ forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall a b s t.
(forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t)
-> PackMap a b s t
PM.PackMap
  (\Aggregate -> f PrimExpr
f PrimExpr
e -> Aggregate -> f PrimExpr
f (forall {a}. a -> Aggregate' a
aggr PrimExpr
e)))
  where
    aggr :: a -> Aggregate' a
aggr = case Maybe AggrOp
mAggrOp of
      Maybe AggrOp
Nothing -> forall {a}. a -> Aggregate' a
HPQ.GroupBy
      Just AggrOp
op -> \a
e -> forall a. Aggr' a -> Aggregate' a
HPQ.Aggregate (forall a.
AggrOp
-> [a]
-> [OrderExpr' a]
-> AggrDistinct
-> [OrderExpr' a]
-> Maybe PrimExpr
-> Aggr' a
HPQ.Aggr AggrOp
op [a
e] [] AggrDistinct
HPQ.AggrAll [] forall a. Maybe a
Nothing)

makeAggr :: HPQ.AggrOp -> Aggregator (C.Field_ n a) (C.Field_ n' b)
makeAggr :: forall (n :: Nullability) a (n' :: Nullability) b.
AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr = forall (n :: Nullability) a (n' :: Nullability) b.
Maybe AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr' forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. a -> Maybe a
Just

makeAggrExplicit :: U.Unpackspec a a' -> HPQ.AggrOp -> Aggregator a (C.Field_ n b)
makeAggrExplicit :: forall a a' (n :: Nullability) b.
Unpackspec a a' -> AggrOp -> Aggregator a (Field_ n b)
makeAggrExplicit Unpackspec a a'
unpackspec AggrOp
op =
  forall (n :: Nullability) sqlType. PrimExpr -> Field_ n sqlType
C.Column forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall a b s t.
(forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t)
-> PackMap a b s t
PM.PackMap (\Aggregate -> f PrimExpr
f a
e -> Aggregate -> f PrimExpr
f (a -> Aggregate
aggr a
e)))
  where
    aggr :: a -> Aggregate
aggr a
a = forall a. Aggr' a -> Aggregate' a
HPQ.Aggregate (forall a.
AggrOp
-> [a]
-> [OrderExpr' a]
-> AggrDistinct
-> [OrderExpr' a]
-> Maybe PrimExpr
-> Aggr' a
HPQ.Aggr AggrOp
op [PrimExpr]
exprs [] AggrDistinct
HPQ.AggrAll [] forall a. Maybe a
Nothing)
      where
        exprs :: [PrimExpr]
exprs = forall s t. Unpackspec s t -> s -> [PrimExpr]
U.collectPEs Unpackspec a a'
unpackspec a
a


-- | Order the values within each aggregation in `Aggregator` using
-- the given ordering. This is only relevant for aggregations that
-- depend on the order they get their elements, like
-- `Opaleye.Aggregate.arrayAgg` and `Opaleye.Aggregate.stringAgg`.
--
-- You can either apply it to an aggregation of multiple columns, in
-- which case it will apply to all aggregation functions in there
--
-- Example:
--
-- > x :: Aggregator (Column a, Column b) (Column (PGArray a), Column (PGArray b))
-- > x = orderAggregate (asc snd) $ p2 (arrayAgg, arrayAgg)
--
-- This will generate:
--
-- @
-- SELECT array_agg(a ORDER BY b ASC), array_agg(b ORDER BY b ASC)
-- FROM (SELECT a, b FROM ...)
-- @
--
-- Or you can apply it to a single column, and then compose the aggregations
-- afterwards.
--
-- Example:
--
-- > x :: Aggregator (Column a, Column b) (Column (PGArray a), Column (PGArray a))
-- > x = (,) <$> orderAggregate (asc snd) (lmap fst arrayAgg)
-- >         <*> orderAggregate (desc snd) (lmap fst arrayAgg)
--
-- This will generate:
--
-- @
-- SELECT array_agg(a ORDER BY b ASC), array_agg(a ORDER BY b DESC)
-- FROM (SELECT a, b FROM ...)
-- @

orderAggregate :: O.Order a -> Aggregator a b -> Aggregator a b
orderAggregate :: forall a b. Order a -> Aggregator a b -> Aggregator a b
orderAggregate Order a
o (Aggregator (PM.PackMap forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f b
pm)) = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall a b s t.
(forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t)
-> PackMap a b s t
PM.PackMap
  (\Aggregate -> f PrimExpr
f a
c -> forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f b
pm (Aggregate -> f PrimExpr
f forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall {a}. [OrderExpr' a] -> Aggregate' a -> Aggregate' a
setOrder (forall a. a -> Order a -> [OrderExpr]
O.orderExprs a
c Order a
o)) a
c))
  where
    setOrder :: [OrderExpr' a] -> Aggregate' a -> Aggregate' a
setOrder [OrderExpr' a]
_ (HPQ.GroupBy a
e) = forall {a}. a -> Aggregate' a
HPQ.GroupBy a
e
    setOrder [OrderExpr' a]
order (HPQ.Aggregate Aggr' a
aggr) =
      forall a. Aggr' a -> Aggregate' a
HPQ.Aggregate Aggr' a
aggr
        { aggrOrder :: [OrderExpr' a]
HPQ.aggrOrder = [OrderExpr' a]
order
        }

runAggregator
  :: Applicative f
  => Aggregator a b
  -> (HPQ.Aggregate -> f HPQ.PrimExpr)
  -> a -> f b
runAggregator :: forall (f :: * -> *) a b.
Applicative f =>
Aggregator a b -> (Aggregate -> f PrimExpr) -> a -> f b
runAggregator (Aggregator PackMap Aggregate PrimExpr a b
a) = forall (f :: * -> *) a b s t.
Applicative f =>
PackMap a b s t -> (a -> f b) -> s -> f t
PM.traversePM PackMap Aggregate PrimExpr a b
a

-- For rel8.
--
-- Like https://www.stackage.org/haddock/lts-19.10/base-4.15.1.0/Control-Arrow.html#t:ArrowApply
aggregatorApply :: Aggregator (Aggregator a b, a) b
aggregatorApply :: forall a b. Aggregator (Aggregator a b, a) b
aggregatorApply = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator forall a b. (a -> b) -> a -> b
$ forall a b s t.
(forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t)
-> PackMap a b s t
PM.PackMap forall a b. (a -> b) -> a -> b
$ \Aggregate -> f PrimExpr
f (Aggregator a b
agg, a
a) ->
  case Aggregator a b
agg of
    Aggregator (PM.PackMap forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f b
inner) -> forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f b
inner Aggregate -> f PrimExpr
f a
a

-- In Postgres (and, I believe, standard SQL) "aggregate functions are
-- not allowed in FROM clause of their own query level".  There
-- doesn't seem to be any fundamental reason for this, but we are
-- stuck with it.  That means that in a lateral subquery containing an
-- aggregation over a field C from a previous subquery we have to
-- create a new field name for C before we are allowed to aggregate it!
-- For more information see
--
--     https://www.postgresql.org/message-id/20200513110251.GC24083%40cloudinit-builder
--
--     https://github.com/tomjaguarpaw/haskell-opaleye/pull/460#issuecomment-626716160
--
-- Instead of detecting when we are aggregating over a field from a
-- previous query we just create new names for all field before we
-- aggregate.  On the other hand, referring to a field from a previous
-- query in an ORDER BY expression is totally fine!
aggregateU :: Aggregator a b
           -> (a, PQ.PrimQuery, T.Tag) -> (b, PQ.PrimQuery)
aggregateU :: forall a b. Aggregator a b -> (a, PrimQuery, Tag) -> (b, PrimQuery)
aggregateU Aggregator a b
agg (a
c0, PrimQuery
primQ, Tag
t0) = (b
c1, PrimQuery
primQ')
  where (b
c1, [((Symbol, Aggregate' Symbol), Bindings PrimExpr)]
projPEs_inners) =
          forall a r. PM [a] r -> (r, [a])
PM.run (forall (f :: * -> *) a b.
Applicative f =>
Aggregator a b -> (Aggregate -> f PrimExpr) -> a -> f b
runAggregator Aggregator a b
agg (forall (t :: * -> *).
Traversable t =>
Tag
-> t PrimExpr
-> PM [((Symbol, t Symbol), Bindings PrimExpr)] PrimExpr
extractAggregateFields Tag
t0) a
c0)

        projPEs :: [(Symbol, Aggregate' Symbol)]
projPEs = forall a b. (a -> b) -> [a] -> [b]
map forall a b. (a, b) -> a
fst [((Symbol, Aggregate' Symbol), Bindings PrimExpr)]
projPEs_inners
        inners :: Bindings PrimExpr
inners  = forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap forall a b. (a, b) -> b
snd [((Symbol, Aggregate' Symbol), Bindings PrimExpr)]
projPEs_inners

        primQ' :: PrimQuery
primQ' = forall a.
[(Symbol, Aggregate' Symbol)] -> PrimQuery' a -> PrimQuery' a
PQ.Aggregate [(Symbol, Aggregate' Symbol)]
projPEs (forall a. Bool -> Bindings PrimExpr -> PrimQuery' a -> PrimQuery' a
PQ.Rebind Bool
True Bindings PrimExpr
inners PrimQuery
primQ)

extractAggregateFields
  :: Traversable t
  => T.Tag
  -> (t HPQ.PrimExpr)
  -> PM.PM [((HPQ.Symbol,
              t HPQ.Symbol),
              PQ.Bindings HPQ.PrimExpr)]
           HPQ.PrimExpr
extractAggregateFields :: forall (t :: * -> *).
Traversable t =>
Tag
-> t PrimExpr
-> PM [((Symbol, t Symbol), Bindings PrimExpr)] PrimExpr
extractAggregateFields Tag
tag t PrimExpr
agg = do
  String
i <- forall a. PM a String
PM.new

  let souter :: Symbol
souter = String -> Tag -> Symbol
HPQ.Symbol (String
"result" forall a. [a] -> [a] -> [a]
++ String
i) Tag
tag

  t (Symbol, PrimExpr)
bindings <- forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
t a -> (a -> f b) -> f (t b)
for t PrimExpr
agg forall a b. (a -> b) -> a -> b
$ \PrimExpr
pe -> do
    String
j <- forall a. PM a String
PM.new
    let sinner :: Symbol
sinner = String -> Tag -> Symbol
HPQ.Symbol (String
"inner" forall a. [a] -> [a] -> [a]
++ String
j) Tag
tag
    forall (f :: * -> *) a. Applicative f => a -> f a
pure (Symbol
sinner, PrimExpr
pe)

  let agg' :: t Symbol
agg' = forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap forall a b. (a, b) -> a
fst t (Symbol, PrimExpr)
bindings

  forall a. a -> PM [a] ()
PM.write ((Symbol
souter, t Symbol
agg'), forall (t :: * -> *) a. Foldable t => t a -> [a]
toList t (Symbol, PrimExpr)
bindings)

  forall (f :: * -> *) a. Applicative f => a -> f a
pure (Symbol -> PrimExpr
HPQ.AttrExpr Symbol
souter)

unsafeMax :: Aggregator (C.Field a) (C.Field a)
unsafeMax :: forall a. Aggregator (Field a) (Field a)
unsafeMax = forall (n :: Nullability) a (n' :: Nullability) b.
AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr AggrOp
HPQ.AggrMax

unsafeMin :: Aggregator (C.Field a) (C.Field a)
unsafeMin :: forall a. Aggregator (Field a) (Field a)
unsafeMin = forall (n :: Nullability) a (n' :: Nullability) b.
AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr AggrOp
HPQ.AggrMin

unsafeAvg :: Aggregator (C.Field a) (C.Field a)
unsafeAvg :: forall a. Aggregator (Field a) (Field a)
unsafeAvg = forall (n :: Nullability) a (n' :: Nullability) b.
AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr AggrOp
HPQ.AggrAvg

unsafeSum :: Aggregator (C.Field a) (C.Field a)
unsafeSum :: forall a. Aggregator (Field a) (Field a)
unsafeSum = forall (n :: Nullability) a (n' :: Nullability) b.
AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr AggrOp
HPQ.AggrSum

-- | Aggregate only rows matching the given predicate
filterWhereInternal
  :: (F.FieldNullable T.SqlBool -> b -> mb)
  -> (a -> F.Field T.SqlBool)
  -> Aggregator a b
  -> Aggregator a mb
filterWhereInternal :: forall b mb a.
(FieldNullable SqlBool -> b -> mb)
-> (a -> Field SqlBool) -> Aggregator a b -> Aggregator a mb
filterWhereInternal FieldNullable SqlBool -> b -> mb
maybeField a -> Field SqlBool
predicate Aggregator a b
aggregator =
  case forall (f :: * -> *) a b c.
Applicative f =>
(a -> b -> c) -> f a -> f b -> f c
liftA2 FieldNullable SqlBool -> b -> mb
maybeField forall {a} {n' :: Nullability} {b}. Aggregator a (Field_ n' b)
true Aggregator a b
aggregator of
    Aggregator (PM.PackMap forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f mb
pm) ->
      forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall a b s t.
(forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t)
-> PackMap a b s t
PM.PackMap (\Aggregate -> f PrimExpr
f a
c -> forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f mb
pm (Aggregate -> f PrimExpr
f forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall {a}. a -> Aggregate' a -> Aggregate' a
setFilter a
c) a
c))
  where
    true :: Aggregator a (Field_ n' b)
true = forall (p :: * -> * -> *) a b c.
Profunctor p =>
(a -> b) -> p b c -> p a c
P.lmap (forall a b. a -> b -> a
const (Bool -> Field SqlBool
T.sqlBool Bool
True)) (forall (n :: Nullability) a (n' :: Nullability) b.
AggrOp -> Aggregator (Field_ n a) (Field_ n' b)
makeAggr AggrOp
HPQ.AggrBoolAnd)
    setFilter :: a -> Aggregate' a -> Aggregate' a
setFilter a
_ (HPQ.GroupBy a
e) = forall {a}. a -> Aggregate' a
HPQ.GroupBy a
e
    setFilter a
row (HPQ.Aggregate Aggr' a
aggr) =
      forall a. Aggr' a -> Aggregate' a
HPQ.Aggregate Aggr' a
aggr
        { aggrFilter :: Maybe PrimExpr
HPQ.aggrFilter = Maybe PrimExpr
aggrFilter'
        }
      where
        C.Column PrimExpr
cond' = a -> Field SqlBool
predicate a
row
        aggrFilter' :: Maybe PrimExpr
aggrFilter' = forall a. a -> Maybe a
Just forall a b. (a -> b) -> a -> b
$ case forall a. Aggr' a -> Maybe PrimExpr
HPQ.aggrFilter Aggr' a
aggr of
          Maybe PrimExpr
Nothing -> PrimExpr
cond'
          Just PrimExpr
cond -> BinOp -> PrimExpr -> PrimExpr -> PrimExpr
HPQ.BinExpr BinOp
HPQ.OpAnd PrimExpr
cond PrimExpr
cond'

withinGroup :: O.Order a -> Aggregator a b -> Aggregator a b
withinGroup :: forall a b. Order a -> Aggregator a b -> Aggregator a b
withinGroup Order a
o (Aggregator (PM.PackMap forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f b
pm)) = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall a b s t.
(forall (f :: * -> *). Applicative f => (a -> f b) -> s -> f t)
-> PackMap a b s t
PM.PackMap
  (\Aggregate -> f PrimExpr
f a
c -> forall (f :: * -> *).
Applicative f =>
(Aggregate -> f PrimExpr) -> a -> f b
pm (Aggregate -> f PrimExpr
f forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall {a}. [OrderExpr' a] -> Aggregate' a -> Aggregate' a
setOrder (forall a. a -> Order a -> [OrderExpr]
O.orderExprs a
c Order a
o)) a
c))
  where
    setOrder :: [OrderExpr' a] -> Aggregate' a -> Aggregate' a
setOrder [OrderExpr' a]
_ (HPQ.GroupBy a
e) = forall {a}. a -> Aggregate' a
HPQ.GroupBy a
e
    setOrder [OrderExpr' a]
order (HPQ.Aggregate Aggr' a
aggr) =
      forall a. Aggr' a -> Aggregate' a
HPQ.Aggregate Aggr' a
aggr
        { aggrGroup :: [OrderExpr' a]
HPQ.aggrGroup = [OrderExpr' a]
order
        }

-- { Boilerplate instances

instance Functor (Aggregator a) where
  fmap :: forall a b. (a -> b) -> Aggregator a a -> Aggregator a b
fmap a -> b
f (Aggregator PackMap Aggregate PrimExpr a a
g) = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap a -> b
f PackMap Aggregate PrimExpr a a
g)

instance Applicative (Aggregator a) where
  pure :: forall a. a -> Aggregator a a
pure = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (f :: * -> *) a. Applicative f => a -> f a
pure
  Aggregator PackMap Aggregate PrimExpr a (a -> b)
f <*> :: forall a b.
Aggregator a (a -> b) -> Aggregator a a -> Aggregator a b
<*> Aggregator PackMap Aggregate PrimExpr a a
x = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (PackMap Aggregate PrimExpr a (a -> b)
f forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> PackMap Aggregate PrimExpr a a
x)

instance P.Profunctor Aggregator where
  dimap :: forall a b c d.
(a -> b) -> (c -> d) -> Aggregator b c -> Aggregator a d
dimap a -> b
f c -> d
g (Aggregator PackMap Aggregate PrimExpr b c
q) = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (forall (p :: * -> * -> *) a b c d.
Profunctor p =>
(a -> b) -> (c -> d) -> p b c -> p a d
P.dimap a -> b
f c -> d
g PackMap Aggregate PrimExpr b c
q)

instance PP.ProductProfunctor Aggregator where
  purePP :: forall b a. b -> Aggregator a b
purePP = forall (f :: * -> *) a. Applicative f => a -> f a
pure
  **** :: forall a a b.
Aggregator a (a -> b) -> Aggregator a a -> Aggregator a b
(****) = forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
(<*>)

instance PP.SumProfunctor Aggregator where
  Aggregator PackMap Aggregate PrimExpr a b
x1 +++! :: forall a b a' b'.
Aggregator a b
-> Aggregator a' b' -> Aggregator (Either a a') (Either b b')
+++! Aggregator PackMap Aggregate PrimExpr a' b'
x2 = forall a b. PackMap Aggregate PrimExpr a b -> Aggregator a b
Aggregator (PackMap Aggregate PrimExpr a b
x1 forall (p :: * -> * -> *) a b a' b'.
SumProfunctor p =>
p a b -> p a' b' -> p (Either a a') (Either b b')
PP.+++! PackMap Aggregate PrimExpr a' b'
x2)

-- }