{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE ViewPatterns #-}

{-# OPTIONS -Wno-redundant-constraints #-}

-- | SQLServer helpers.
module Harness.Backend.Sqlserver
  ( livenessCheck,
    run_,
    defaultSourceMetadata,
    defaultSourceConfiguration,
    createTable,
    insertTable,
    trackTable,
    dropTable,
    untrackTable,
    setup,
    teardown,
  )
where

import Control.Concurrent
import Control.Monad.Reader
import Data.Aeson (Value)
import Data.Bool (bool)
import Data.Foldable (for_)
import Data.String
import Data.Text (Text, pack, replace)
import Data.Text qualified as T (pack, unpack, unwords)
import Data.Text.Extended (commaSeparated)
import Data.Time (defaultTimeLocale, formatTime)
import Database.ODBC.SQLServer qualified as Sqlserver
import Harness.Constants qualified as Constants
import Harness.Exceptions
import Harness.GraphqlEngine qualified as GraphqlEngine
import Harness.Quoter.Yaml (yaml)
import Harness.Test.Context (BackendType (SQLServer), defaultBackendTypeString, defaultSource)
import Harness.Test.Schema (BackendScalarType (..), BackendScalarValue (..), ScalarValue (..))
import Harness.Test.Schema qualified as Schema
import Harness.TestEnvironment (TestEnvironment)
import Hasura.Prelude (tshow)
import System.Process.Typed
import Prelude

-- | Check that the SQLServer service is live and ready to accept connections.
livenessCheck :: HasCallStack => IO ()
livenessCheck = loop Constants.sqlserverLivenessCheckAttempts
  where
    loop 0 = error ("Liveness check failed for SQLServer.")
    loop attempts =
      catch
        ( bracket
            (Sqlserver.connect Constants.sqlserverConnectInfo)
            Sqlserver.close
            (const (pure ()))
        )
        ( \(_failure :: ExitCodeException) -> do
            threadDelay
              Constants.sqlserverLivenessCheckIntervalMicroseconds
            loop (attempts - 1)
        )

-- | Run a plain SQL string against the server, ignore the
-- result. Just checks for errors.
run_ :: HasCallStack => String -> IO ()
run_ query' =
  catch
    ( bracket
        (Sqlserver.connect Constants.sqlserverConnectInfo)
        Sqlserver.close
        (\conn -> void (Sqlserver.exec conn (fromString query')))
    )
    ( \(e :: SomeException) ->
        error
          ( unlines
              [ "SQLServer query error:",
                show e,
                "SQL was:",
                query'
              ]
          )
    )

-- | Metadata source information for the default MSSQL instance.
defaultSourceMetadata :: Value
defaultSourceMetadata =
  let source = defaultSource SQLServer
      backendType = defaultBackendTypeString SQLServer
   in [yaml|
name: *source
kind: *backendType
tables: []
configuration: *defaultSourceConfiguration
  |]

defaultSourceConfiguration :: Value
defaultSourceConfiguration =
  [yaml|
connection_info:
  database_url: *sqlserverConnectInfo
  pool_settings: {}
|]
  where
    sqlserverConnectInfo = Constants.sqlserverConnectInfo

-- | Serialize Table into a T-SQL statement, as needed, and execute it on the Sqlserver backend
createTable :: Schema.Table -> IO ()
createTable Schema.Table {tableName, tableColumns, tablePrimaryKey = pk, tableReferences} = do
  run_ $
    T.unpack $
      T.unwords
        [ "CREATE TABLE",
          T.pack Constants.sqlserverDb <> "." <> tableName,
          "(",
          commaSeparated $
            (mkColumn <$> tableColumns)
              <> (bool [mkPrimaryKey pk] [] (null pk))
              <> (mkReference <$> tableReferences),
          ");"
        ]

scalarType :: HasCallStack => Schema.ScalarType -> Text
scalarType = \case
  Schema.TInt -> "INT"
  Schema.TStr -> "NVARCHAR(127)"
  Schema.TUTCTime -> "DATETIME"
  Schema.TBool -> "BOOLEAN"
  Schema.TCustomType txt -> Schema.getBackendScalarType txt bstMssql

mkColumn :: Schema.Column -> Text
mkColumn Schema.Column {columnName, columnType, columnNullable, columnDefault} =
  T.unwords
    [ wrapIdentifier columnName,
      scalarType columnType,
      bool "NOT NULL" "DEFAULT NULL" columnNullable,
      maybe "" ("DEFAULT " <>) columnDefault
    ]

mkPrimaryKey :: [Text] -> Text
mkPrimaryKey key =
  T.unwords
    [ "PRIMARY KEY",
      "(",
      commaSeparated $ map wrapIdentifier key,
      ")"
    ]

mkReference :: Schema.Reference -> Text
mkReference Schema.Reference {referenceLocalColumn, referenceTargetTable, referenceTargetColumn} =
  T.unwords
    [ "CONSTRAINT ",
      constraintName,
      "FOREIGN KEY ",
      "(",
      wrapIdentifier referenceLocalColumn,
      ")",
      "REFERENCES",
      T.pack Constants.sqlserverDb <> "." <> referenceTargetTable,
      "(",
      wrapIdentifier referenceTargetColumn,
      ")",
      "ON DELETE CASCADE",
      "ON UPDATE CASCADE"
    ]
  where
    constraintName :: Text
    constraintName =
      "FK_" <> referenceTargetTable <> "_" <> referenceTargetColumn
        <> "_"
        <> referenceLocalColumn

-- | Serialize tableData into a T-SQL insert statement and execute it.
insertTable :: HasCallStack => Schema.Table -> IO ()
insertTable Schema.Table {tableName, tableColumns, tableData}
  | null tableData = pure ()
  | otherwise = do
    run_ $
      T.unpack $
        T.unwords
          [ "INSERT INTO",
            T.pack Constants.sqlserverDb <> "." <> wrapIdentifier tableName,
            "(",
            commaSeparated (wrapIdentifier . Schema.columnName <$> tableColumns),
            ")",
            "VALUES",
            commaSeparated $ mkRow <$> tableData,
            ";"
          ]

-- | MSSQL identifiers which may contain spaces or be case-sensitive needs to be wrapped in @[]@.
--
--   More information can be found in the mssql docs:
--   https://docs.microsoft.com/en-us/sql/relational-databases/databases/database-identifiers
wrapIdentifier :: Text -> Text
wrapIdentifier identifier = "[" <> identifier <> "]"

-- | 'ScalarValue' serializer for Mssql
serialize :: ScalarValue -> Text
serialize = \case
  VInt i -> tshow i
  VStr s -> "'" <> replace "'" "\'" s <> "'"
  VUTCTime t -> pack $ formatTime defaultTimeLocale "'%F %T'" t
  VBool b -> tshow @Int $ if b then 1 else 0
  VNull -> "NULL"
  VCustomValue bsv -> Schema.formatBackendScalarValueType $ Schema.backendScalarValue bsv bsvMssql

mkRow :: [Schema.ScalarValue] -> Text
mkRow row =
  T.unwords
    [ "(",
      commaSeparated $ serialize <$> row,
      ")"
    ]

-- | Serialize Table into a T-SQL DROP statement and execute it
dropTable :: HasCallStack => Schema.Table -> IO ()
dropTable Schema.Table {tableName} = do
  run_ $
    T.unpack $
      T.unwords
        [ "DROP TABLE", -- we don't want @IF EXISTS@ here, because we don't want this to fail silently
          T.pack Constants.sqlserverDb <> "." <> tableName,
          ";"
        ]

-- | Post an http request to start tracking the table
trackTable :: HasCallStack => TestEnvironment -> Schema.Table -> IO ()
trackTable testEnvironment table =
  Schema.trackTable SQLServer (defaultSource SQLServer) table testEnvironment

-- | Post an http request to stop tracking the table
untrackTable :: HasCallStack => TestEnvironment -> Schema.Table -> IO ()
untrackTable testEnvironment table =
  Schema.untrackTable SQLServer (defaultSource SQLServer) table testEnvironment

-- | Setup the schema in the most expected way.
-- NOTE: Certain test modules may warrant having their own local version.
setup :: HasCallStack => [Schema.Table] -> (TestEnvironment, ()) -> IO ()
setup tables (testEnvironment, _) = do
  -- Clear and reconfigure the metadata
  GraphqlEngine.setSource testEnvironment defaultSourceMetadata Nothing
  -- Setup and track tables
  for_ tables $ \table -> do
    createTable table
    insertTable table
    trackTable testEnvironment table
  -- Setup relationships
  for_ tables $ \table -> do
    Schema.trackObjectRelationships SQLServer table testEnvironment
    Schema.trackArrayRelationships SQLServer table testEnvironment

-- | Teardown the schema and tracking in the most expected way.
-- NOTE: Certain test modules may warrant having their own version.
teardown :: HasCallStack => [Schema.Table] -> (TestEnvironment, ()) -> IO ()
teardown tables (testEnvironment, _) = do
  forFinally_ (reverse tables) $ \table ->
    finally
      (Schema.untrackRelationships SQLServer table testEnvironment)
      ( finally
          (untrackTable testEnvironment table)
          (dropTable table)
      )