{-# LANGUAGE BlockArguments #-}

module ThreadingTest (tests) where

import Control.Concurrent (forkFinally, newEmptyMVar, putMVar, takeMVar)
import Data.Int (Int64)
import Database.DuckDB.FFI
import Foreign.C.String (CString, withCString)
import Foreign.C.Types (CBool (..))
import Foreign.Marshal.Alloc (alloca)
import Foreign.Ptr (nullPtr)
import Foreign.Storable (peek)
import Test.Tasty (TestTree, testGroup)
import Test.Tasty.HUnit (assertBool, assertFailure, testCase, (@?=))
import Utils (withConnection, withDatabase)

tests :: TestTree
tests =
    testGroup
        "Threading Information"
        [ executeTasksCompletesPendingQuery
        , taskStateControlsExecutionLifecycle
        ]

executeTasksCompletesPendingQuery :: TestTree
executeTasksCompletesPendingQuery =
    testCase "execute_tasks drives pending query to completion" $
        withDatabase \db ->
            withConnection db \conn -> do
                setupAggTable conn

                withCString "SELECT SUM(val) FROM threading_numbers;" \querySql ->
                    alloca \stmtPtr -> do
                        stPrepare <- c_duckdb_prepare conn querySql stmtPtr
                        stPrepare @?= DuckDBSuccess
                        stmt <- peek stmtPtr
                        assertBool "prepared statement should not be null" (stmt /= nullPtr)

                        alloca \pendingPtr -> do
                            stPending <- c_duckdb_pending_prepared stmt pendingPtr
                            stPending @?= DuckDBSuccess
                            pending <- peek pendingPtr
                            assertBool "pending result should not be null" (pending /= nullPtr)

                            finishedBefore <- c_duckdb_execution_is_finished conn
                            finishedBefore @?= CBool 0

                            driveTasks db conn

                            finishedAfter <- c_duckdb_execution_is_finished conn
                            finishedAfter @?= CBool 1

                            alloca \resPtr -> do
                                stExec <- c_duckdb_execute_pending pending resPtr
                                stExec @?= DuckDBSuccess
                                sumVal <- c_duckdb_value_int64 resPtr 0 0
                                (sumVal :: Int64) @?= 15
                                c_duckdb_destroy_result resPtr

                            c_duckdb_destroy_pending pendingPtr

                        c_duckdb_destroy_prepare stmtPtr

taskStateControlsExecutionLifecycle :: TestTree
taskStateControlsExecutionLifecycle =
    testCase "task state executes batches and finishes on request" $
        withDatabase \db ->
            withConnection db \conn -> do
                setupAggTable conn

                taskState <- c_duckdb_create_task_state db
                assertBool "task state should not be null" (taskState /= nullPtr)

                doneVar <- newEmptyMVar
                _ <- forkFinally (c_duckdb_execute_tasks_state taskState) (const (putMVar doneVar ()))

                executed <- c_duckdb_execute_n_tasks_state taskState 0
                assertBool "execute_n_tasks_state should not report negative work" (executed >= 0)

                isFinishedBefore <- c_duckdb_task_state_is_finished taskState
                isFinishedBefore @?= CBool 0

                c_duckdb_finish_execution taskState

                isFinishedAfter <- c_duckdb_task_state_is_finished taskState
                isFinishedAfter @?= CBool 1

                takeMVar doneVar
                c_duckdb_destroy_task_state taskState

setupAggTable :: DuckDBConnection -> IO ()
setupAggTable conn = do
    withCString "CREATE TABLE threading_numbers(val INTEGER);" $ \createSql ->
        execStatement conn createSql
    withCString "INSERT INTO threading_numbers VALUES (1), (2), (3), (4), (5);" $ \insertSql ->
        execStatement conn insertSql

driveTasks :: DuckDBDatabase -> DuckDBConnection -> IO ()
driveTasks db conn = go 0
  where
    go :: Int -> IO ()
    go attempts
        | attempts > 10 = assertFailure "execute_tasks did not finish query within expected iterations"
        | otherwise = do
            c_duckdb_execute_tasks db 1000
            finished <- c_duckdb_execution_is_finished conn
            if finished == CBool 1
                then pure ()
                else go (attempts + 1)

execStatement :: DuckDBConnection -> CString -> IO ()
execStatement conn sql =
    alloca \resPtr -> do
        st <- c_duckdb_query conn sql resPtr
        st @?= DuckDBSuccess
        c_duckdb_destroy_result resPtr