-- allows automatic derivation from Entity type class
{-# LANGUAGE DeriveAnyClass #-}

module PostgresSpec
  ( test,
    spec,
  )
where

import           Database.GP
import           Database.HDBC.PostgreSQL
import           GHC.Generics hiding (Selector)
import           Test.Hspec
import           Control.Exception

-- `test` is here so that this module can be run from GHCi on its own.  It is
-- not needed for automatic spec discovery. 
-- (start up stack repl --test to bring up ghci and have access to all the test functions)
test :: IO ()
test = hspec spec

prepareDB :: IO Conn
prepareDB = do
  con <- connect AutoCommit <$> connectPostgreSQL  "host=localhost dbname=postgres user=postgres password=admin port=5431" 
  let conn = con{implicitCommit=False}
  setupTableFor @Person Postgres conn
  setupTableFor @Book Postgres conn
  _ <- run conn "DROP TABLE IF EXISTS Car;" []
  _ <- run conn "CREATE TABLE Car (carID serial4 PRIMARY KEY, carType varchar);" []
  commit conn
  return conn

-- | A data type with several fields, using record syntax.
data Person = Person
  { personID :: Int,
    name     :: String,
    age      :: Int,
    address  :: String
  }
  deriving (Generic, Show, Eq)

instance Entity Person where
  autoIncrement = False   

data Car = Car
  { carID :: Int,
    carType  :: String
  }
  deriving (Generic, Entity, Show, Eq)

data Book = Book
  { book_id  :: Int,
    title    :: String,
    author   :: String,
    year     :: Int,
    category :: BookCategory
  }
  deriving (Generic, Show, Eq)

data BookCategory = Fiction | Travel | Arts | Science | History | Biography | Other
  deriving (Generic, Read, Show, Eq, Enum)

instance Entity Book where
  idField = "book_id"
  fieldsToColumns = [("book_id", "bookId"), ("title", "bookTitle"), ("author", "bookAuthor"), 
                     ("year", "bookYear"), ("category", "bookCategory")]
  tableName = "BOOK_TBL"
  fromRow _c row = pure $ Book (col 0) (col 1) (col 2) (col 3) (col 4)
    where
      col i = fromSql (row !! i)

  toRow _c b = pure [toSql (book_id b), toSql (title b), toSql (author b), toSql (year b), toSql (category b)]

person :: Person
person = Person 123456 "Alice" 25 "123 Main St"

manyPersons :: [Person]
manyPersons =
  [ Person 1 "Alice" 25 "123 Main St",
    Person 2 "Bob" 30 "456 Elm St",
    Person 3 "Charlie" 35 "789 Pine St",
    Person 4 "Dave" 40 "1011 Oak St",
    Person 5 "Eve" 45 "1213 Maple St",
    Person 6 "Frank" 50 "1415 Walnut St"
  ]

book :: Book
book = Book 1 "The Hobbit" "J.R.R. Tolkien" 1937 Fiction

spec :: Spec
spec = do
  describe "GenericPersistence for PostgreSQL" $ do
    it "retrieves Entities using Generics" $ do
      conn <- prepareDB
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 0
      let bob = Person 1 "Bob" 36 "7 West Street"
          alice = Person 2 "Alice" 25 "7 West Street"
      runRaw conn "INSERT INTO Person (personID, name, age, address) VALUES (1, 'Bob', 36, '7 West Street');"
      runRaw conn "INSERT INTO Person (personID, name, age, address) VALUES (2, 'Alice', 25, '7 West Street');"
      runRaw conn "INSERT INTO Person (personID, name, age, address) VALUES (3, 'Frank', 56, '7 West Street');"
      commit conn
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 3
      head allPersons `shouldBe` bob
      person' <- selectById conn (2 :: Int) :: IO (Maybe Person)
      person' `shouldBe` Just alice
      commit conn
    it "selectById returns Nothing if no Entity was found" $ do
      conn <- prepareDB
      person' <- selectById conn (1 :: Int) :: IO (Maybe Person)
      person' `shouldBe` Nothing
      commit conn
    it "selectById throws a DatabaseError if things go wrong in the DB" $ do 
      conn <- prepareDB
      runRaw conn "DROP TABLE Person;"
      commit conn
      eitherEA <- try (selectById conn (1 :: Int) :: IO (Maybe Person))
      case eitherEA of
        Left (DatabaseError msg) -> msg `shouldContain` "does not exist"
        Left  _ -> expectationFailure "Expected DatabaseError"
        Right _ -> expectationFailure "Expected DatabaseError"  
      rollback conn
    it "retrieves Entities using user implementation" $ do
      conn <- prepareDB
      let hobbit = Book 1 "The Hobbit" "J.R.R. Tolkien" 1937 Fiction
      runRaw conn "INSERT INTO BOOK_TBL (bookId, bookTitle, bookAuthor, bookYear, bookCategory) VALUES (1, 'The Hobbit', 'J.R.R. Tolkien', 1937, 0);"
      runRaw conn "INSERT INTO BOOK_TBL (bookId, bookTitle, bookAuthor, bookYear, bookCategory) VALUES (2, 'The Lord of the Rings', 'J.R.R. Tolkien', 1955, 0);"
      runRaw conn "INSERT INTO BOOK_TBL (bookId, bookTitle, bookAuthor, bookYear, bookCategory) VALUES (3, 'Smith of Wootton Major', 'J.R.R. Tolkien', 1967, 0);"
      commit conn
      allBooks <- select conn allEntries :: IO [Book]
      length allBooks `shouldBe` 3
      head allBooks `shouldBe` hobbit
      book' <- selectById conn (1 :: Int) :: IO (Maybe Book)
      book' `shouldBe` Just hobbit     
      commit conn
    it "select returns Nothing if no Entity was found" $ do
      conn <- prepareDB
      allPersons' <- select @Person conn allEntries
      allPersons' `shouldBe` []
      commit conn
    it "select throws a DatabaseError if things go wrong" $ do 
      conn <- prepareDB
      runRaw conn "DROP TABLE Person;"
      commit conn
      eitherEA <- try (select @Person conn allEntries)
      case eitherEA of
        Left (DatabaseError msg) -> msg `shouldContain` "does not exist"
        Left  _ -> expectationFailure "Expected DatabaseError"
        Right _ -> expectationFailure "Expected DatabaseError"  
      rollback conn
    it "persists new Entities using Generics" $ do
      conn <- prepareDB
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 0
      persist conn person
      commit conn
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 1
      person' <- selectById conn (123456 :: Int) :: IO (Maybe Person)
      person' `shouldBe` Just person
      commit conn
    it "persists new Entities using user implementation" $ do
      conn <- prepareDB
      allbooks <- select conn allEntries :: IO [Book]
      length allbooks `shouldBe` 0
      persist conn book
      commit conn
      allbooks' <- select conn allEntries :: IO [Book]
      length allbooks' `shouldBe` 1
      book' <- selectById conn (1 :: Int) :: IO (Maybe Book)
      book' `shouldBe` Just book
      commit conn
    it "persist throws an exception if things go wrong" $ do 
      conn <- prepareDB
      runRaw conn "DROP TABLE BOOK_TBL;"
      commit conn
      eitherEA <- try (persist conn book)
      case eitherEA of
        Left (DatabaseError msg) -> msg `shouldContain` "does not exist"
        Left  _ -> expectationFailure "Expected DatabaseError"
        Right _ -> expectationFailure "Expected DatabaseError" 
    it "persists existing Entities using Generics" $ do
      conn <- prepareDB
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 0
      persist conn person
      commit conn
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 1
      persist conn person {age = 26}
      commit conn
      person' <- selectById conn (123456 :: Int) :: IO (Maybe Person)
      person' `shouldBe` Just person {age = 26}
      commit conn
    it "persists existing Entities using user implementation" $ do
      conn <- prepareDB
      allbooks <- select conn allEntries :: IO [Book]
      length allbooks `shouldBe` 0
      persist conn book
      commit conn
      allbooks' <- select conn allEntries :: IO [Book]
      length allbooks' `shouldBe` 1
      eitherEA <- try $ persist conn book {year = 1938} :: IO (Either PersistenceException ())
      case eitherEA of
        Left  _ -> expectationFailure "should not throw an exception"
        Right x -> x `shouldBe` ()
      book' <- selectById conn (1 :: Int) :: IO (Maybe Book)
      book' `shouldBe` Just book {year = 1938}
      commit conn
    it "inserts Entities using Generics" $ do
      conn <- prepareDB
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 0
      _ <- insert conn person
      commit conn
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 1
      person' <- selectById conn (123456 :: Int) :: IO (Maybe Person)
      person' `shouldBe` Just person
      commit conn
    it "inserts Entities with autoincrement handling" $ do
      conn <- prepareDB
      myCar@(Car carId _) <- insert conn (Car 0 "Honda Jazz")
      myCar' <- selectById conn carId :: IO (Maybe Car)
      myCar' `shouldBe` Just myCar
      commit conn
    it "inserts many Entities re-using a single prepared stmt" $ do
      conn <- prepareDB
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 0
      insertMany conn manyPersons
      commit conn
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 6
      commit conn
    it "updates many Entities re-using a single prepared stmt" $ do
      conn <- prepareDB
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 0
      insertMany conn manyPersons
      commit conn
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 6
      let manyPersons' = map (\p -> p {name = "Bob"}) manyPersons
      updateMany conn manyPersons'
      commit conn
      allPersons'' <- select conn allEntries :: IO [Person]
      all (\p -> name p == "Bob") allPersons'' `shouldBe` True
      commit conn
    it "deletes many Entities re-using a single prepared stmt" $ do
      conn <- prepareDB
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 0
      insertMany conn manyPersons
      commit conn
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 6   
      deleteMany conn allPersons'
      commit conn
      allPersons'' <- select conn allEntries :: IO [Person]
      length allPersons'' `shouldBe` 0
      commit conn
    it "inserts Entities using user implementation" $ do
      conn <- prepareDB
      allbooks <- select conn allEntries :: IO [Book]
      length allbooks `shouldBe` 0
      _ <- insert conn book
      commit conn
      allbooks' <- select conn allEntries :: IO [Book]
      length allbooks' `shouldBe` 1
      book' <- selectById conn (1 :: Int) :: IO (Maybe Book)
      book' `shouldBe` Just book
      commit conn 
    it "updates Entities using Generics" $ do
      conn <- prepareDB
      _ <- insert conn person
      update conn person {name = "Bob"}
      commit conn
      person' <- selectById conn (123456 :: Int) :: IO (Maybe Person)
      person' `shouldBe` Just person {name = "Bob"}
      commit conn
    it "updates Entities using user implementation" $ do
      conn <- prepareDB
      _ <- insert conn book
      update conn book {title = "The Lord of the Rings"}
      commit conn
      book' <- selectById conn (1 :: Int) :: IO (Maybe Book)
      book' `shouldBe` Just book {title = "The Lord of the Rings"}
      commit conn
    it "deletes Entities using Generics" $ do
      conn <- prepareDB
      _ <- insert conn person
      allPersons <- select conn allEntries :: IO [Person]
      length allPersons `shouldBe` 1
      delete conn person
      allPersons' <- select conn allEntries :: IO [Person]
      length allPersons' `shouldBe` 0
      commit conn
    it "deletes Entities using user implementation" $ do
      conn <- prepareDB
      _ <- insert conn book
      allBooks <- select conn allEntries :: IO [Book]
      length allBooks `shouldBe` 1
      delete conn book
      allBooks' <- select conn allEntries :: IO [Book]
      length allBooks' `shouldBe` 0
      commit conn
    it "provides a Connection Pool" $ do
      connPool <- postgreSQLPool "host=localhost dbname=postgres user=postgres password=admin port=5431" 
      withResource connPool $ \conn -> do
        setupTableFor @Person Postgres conn
        _ <- insert conn person
        allPersons <- select conn allEntries :: IO [Person]
        length allPersons `shouldBe` 1
        commit conn

postgreSQLPool :: String -> IO ConnectionPool
postgreSQLPool connectString = createConnPool ExplicitCommit connectString connectPostgreSQL 10 100