module Main where

import Prelude
import qualified Hasql.Connection as A
import qualified Hasql.Session as B
import qualified Hasql.Statement as C
import qualified Hasql.Decoders as D
import qualified Hasql.Encoders as E
import qualified Data.Vector as F


main =
  do
    Right connection <- acquireConnection
    traceEventIO "START Session"
    Right result <- B.run sessionWithManySmallResults connection
    traceEventIO "STOP Session"
    return ()
  where
    acquireConnection =
      A.acquire settings
      where
        settings =
          A.settings host port user password database
          where
            host = "localhost"
            port = 5432
            user = "postgres"
            password = ""
            database = "postgres"


-- * Sessions
-------------------------

sessionWithManySmallParameters :: Vector (Int64, Int64) -> B.Session ()
sessionWithManySmallParameters =
  error "TODO: sessionWithManySmallParameters"

sessionWithSingleLargeResultInVector :: B.Session (Vector (Int64, Int64))
sessionWithSingleLargeResultInVector =
  B.statement () statementWithManyRowsInVector

sessionWithSingleLargeResultInList :: B.Session [(Int64, Int64)]
sessionWithSingleLargeResultInList =
  B.statement () statementWithManyRowsInList

sessionWithManySmallResults :: B.Session (Vector (Int64, Int64))
sessionWithManySmallResults =
  F.replicateM 1000 (B.statement () statementWithSingleRow)


-- * Statements
-------------------------

statementWithManyParameters :: C.Statement (Vector (Int64, Int64)) ()
statementWithManyParameters =
  error "TODO: statementWithManyParameters"

statementWithSingleRow :: C.Statement () (Int64, Int64)
statementWithSingleRow =
  C.Statement template encoder decoder True
  where
    template =
      "SELECT 1, 2"
    encoder =
      conquer
    decoder =
      D.singleRow row
      where
        row =
          tuple <$> (D.column . D.nonNullable) D.int8 <*> (D.column . D.nonNullable) D.int8
          where
            tuple !a !b =
              (a, b)

statementWithManyRows :: (D.Row (Int64, Int64) -> D.Result result) -> C.Statement () result
statementWithManyRows decoder =
  C.Statement template encoder (decoder rowDecoder) True
  where
    template =
      "SELECT generate_series(0,1000) as a, generate_series(1000,2000) as b"
    encoder =
      conquer
    rowDecoder =
      tuple <$> (D.column . D.nonNullable) D.int8 <*> (D.column . D.nonNullable) D.int8
      where
        tuple !a !b =
          (a, b)

statementWithManyRowsInVector :: C.Statement () (Vector (Int64, Int64))
statementWithManyRowsInVector =
  statementWithManyRows D.rowVector

statementWithManyRowsInList :: C.Statement () [(Int64, Int64)]
statementWithManyRowsInList =
  statementWithManyRows D.rowList