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

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

-- | MySQL helpers.
module Harness.Backend.Mysql
  ( livenessCheck,
    run_,
    defaultSourceMetadata,
    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)
import Data.Text qualified as T
import Data.Text.Extended (commaSeparated)
import Database.MySQL.Simple as Mysql
import Harness.Constants as Constants
import Harness.Exceptions
import Harness.GraphqlEngine qualified as GraphqlEngine
import Harness.Quoter.Yaml (yaml)
import Harness.State (State)
import Harness.Test.Context (BackendType (MySQL), defaultBackendTypeString, defaultSource)
import Harness.Test.Schema qualified as Schema
import System.Process.Typed
import Prelude

-- | Check that the MySQL service is live and ready to accept connections.
livenessCheck :: HasCallStack => IO ()
livenessCheck = loop Constants.mysqlLivenessCheckAttempts
  where
    loop 0 = error ("Liveness check failed for MySQL.")
    loop attempts =
      catch
        ( bracket
            (Mysql.connect Constants.mysqlConnectInfo)
            Mysql.close
            (const (pure ()))
        )
        ( \(_failure :: ExitCodeException) -> do
            threadDelay
              Constants.mysqlLivenessCheckIntervalMicroseconds
            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
        (Mysql.connect Constants.mysqlConnectInfo)
        Mysql.close
        (\conn -> void (Mysql.execute_ conn (fromString query')))
    )
    ( \(e :: SomeException) ->
        error
          ( unlines
              [ "MySQL query error:",
                show e,
                "SQL was:",
                query'
              ]
          )
    )

-- | Metadata source information for the default Mysql instance.
defaultSourceMetadata :: Value
defaultSourceMetadata =
  let source = defaultSource MySQL
      backendType = defaultBackendTypeString MySQL
   in [yaml|
name: *source
kind: *backendType
tables: []
configuration:
  database: *mysqlDb
  user: *mysqlUser
  password: *mysqlPassword
  host: *mysqlHost
  port: *mysqlPort
  pool_settings: {}
  |]

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

scalarType :: HasCallStack => Schema.ScalarType -> Text
scalarType = \case
  Schema.TInt -> "INT UNSIGNED"
  Schema.TStr -> "TEXT"
  Schema.TUTCTime -> "DATETIME"
  Schema.TBool -> "BIT"
  t -> error $ "Unexpected scalar type used for MySQL: " <> show t

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

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

mkReference :: Schema.Reference -> Text
mkReference Schema.Reference {referenceLocalColumn, referenceTargetTable, referenceTargetColumn} =
  T.unwords
    [ "FOREIGN KEY",
      "(",
      referenceLocalColumn,
      ")",
      "REFERENCES",
      referenceTargetTable,
      "(",
      referenceTargetColumn,
      ")",
      "ON DELETE CASCADE",
      "ON UPDATE CASCADE"
    ]

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

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

-- | Serialize Table into an SQL DROP statement and execute it
dropTable :: 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.mysqlDb <> "." <> tableName,
          ";"
        ]

-- | Post an http request to start tracking the table
trackTable :: State -> Schema.Table -> IO ()
trackTable state table =
  Schema.trackTable MySQL (defaultSource MySQL) table state

-- | Post an http request to stop tracking the table
untrackTable :: State -> Schema.Table -> IO ()
untrackTable state table =
  Schema.untrackTable MySQL (defaultSource MySQL) table state

-- | Setup the schema in the most expected way.
-- NOTE: Certain test modules may warrant having their own local version.
setup :: [Schema.Table] -> (State, ()) -> IO ()
setup tables (state, _) = do
  -- Clear and reconfigure the metadata
  GraphqlEngine.setSource state defaultSourceMetadata
  -- Setup and track tables
  for_ tables $ \table -> do
    createTable table
    insertTable table
    trackTable state table
  -- Setup relationships
  for_ tables $ \table -> do
    Schema.trackObjectRelationships MySQL table state
    Schema.trackArrayRelationships MySQL table state

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