{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE QuasiQuotes                #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE DeriveDataTypeable         #-}
{-# OPTIONS_GHC -XNoCPP -fno-warn-unused-binds  #-}

module Data.API.Test.Migration
    ( migrationTests
    ) where

import           Data.API.Changes
import           Data.API.PP
import           Data.API.Tools
import           Data.API.Test.MigrationData
import           Data.API.Types
import           Data.API.Utils

import qualified Data.Aeson               as JS
import qualified Data.Aeson.Encode.Pretty as JS
import qualified Data.ByteString.Char8    as B
import qualified Data.ByteString.Base64   as B64
import qualified Data.ByteString.Lazy.Char8 as BL
import qualified Data.HashMap.Strict      as HMap
import qualified Data.Map                 as Map
import qualified Data.Text                as T
import           Data.Version
import           Test.Tasty               as Test
import           Test.Tasty.HUnit
import qualified Test.Tasty.QuickCheck    as QC
import           Test.QuickCheck.Property as P


$(generateMigrationKinds changelog "TestDatabaseMigration" "TestRecordMigration" "TestFieldMigration")


-- Test of a whole-database migration: copy data between tables
testDatabaseMigration :: TestDatabaseMigration -> JS.Object -> Either ValueError JS.Object
testDatabaseMigration DuplicateBar x = do
    bar <- HMap.lookup "bar" x ?! CustomMigrationError "missing bar" (JS.Object x)
    return $ HMap.insert "bar2" bar x
testDatabaseMigration DuplicateRecursive x = do
    recur <- HMap.lookup "recur" x ?! CustomMigrationError "missing recur" (JS.Object x)
    return $ HMap.insert "recur2" recur x

testDatabaseMigrationSchema :: TestDatabaseMigration -> NormAPI -> Either ApplyFailure (Maybe NormAPI)
testDatabaseMigrationSchema DuplicateBar _ = Right Nothing
testDatabaseMigrationSchema DuplicateRecursive napi =
    let Just recur = Map.lookup (TypeName "Recursive") napi
        Just (NRecordType dbs) = Map.lookup root_ napi
        dbs' = Map.insert (FieldName "recur2") (TyMaybe (TyList (TyName "DuplicateRecursive"))) dbs
    in Right $ Just $ Map.insert (TypeName "DuplicateRecursive") recur $
                      Map.insert root_ (NRecordType dbs') napi


-- Test of a single-record migration: copy the value in the id field
-- onto the end of the c field
testRecordMigration :: TestRecordMigration -> JS.Value -> Either ValueError JS.Value
testRecordMigration CopyIDtoC = mkRecordMigration $ \ x -> do
    i <- HMap.lookup "id" x ?! CustomMigrationError "missing id" (JS.Object x)
    b <- HMap.lookup "c" x  ?! CustomMigrationError "missing b" (JS.Object x)
    r <- case (i, b) of
        (JS.Number j, JS.String t)
            -> return $ JS.String $ t `T.append` T.pack (show (round j :: Int))
        _   -> Left $ CustomMigrationError "bad data" (JS.Object x)
    return $ HMap.insert "c" r x
testRecordMigration DuplicateNew = mkRecordMigration $ \ x -> do
    new <- HMap.lookup "new" x ?! CustomMigrationError "missing new" (JS.Object x)
    return $ HMap.insert "newnew" new x

testRecordMigrationSchema :: TestRecordMigration -> NormTypeDecl -> Either ApplyFailure (Maybe NormTypeDecl)
testRecordMigrationSchema CopyIDtoC    = noSchemaChanges
testRecordMigrationSchema DuplicateNew = mkRecordMigrationSchema "Recursive" $ \ r ->
    return $ Just $ Map.insert (FieldName "newnew") (TyBasic BTstring) r

-- Test of a single-field migration: change the type of the field from
-- binary to string by base64-decoding the contents
testFieldMigration :: TestFieldMigration -> JS.Value -> Either ValueError JS.Value
testFieldMigration ConvertBinaryToString v@(JS.String s) =
    case B64.decode (B.pack (T.unpack s)) of
        Left err  -> Left (CustomMigrationError err v)
        Right x -> return (JS.String (T.pack (B.unpack x)))
testFieldMigration ConvertBinaryToString v = Left $ CustomMigrationError "bad data" v


testMigration :: CustomMigrations TestDatabaseMigration TestRecordMigration TestFieldMigration
testMigration = CustomMigrations testDatabaseMigration
                                 testDatabaseMigrationSchema
                                 testRecordMigration
                                 testRecordMigrationSchema
                                 testFieldMigration


assertMatchesAPI :: String -> API -> JS.Value -> Assertion
assertMatchesAPI x a v = case dataMatchesAPI root_ a v of
    Right () -> return ()
    Left err -> assertFailure (x ++ ": " ++ prettyValueErrorPosition err)

basicMigrationTest :: Assertion
basicMigrationTest = do
    assertMatchesAPI "Start data does not match start API" startSchema startData
    assertMatchesAPI "End data does not match end API"     endSchema   endData
    case migrateDataDump (startSchema, startVersion) (endSchema, DevVersion)
                         changelog testMigration root_ CheckAll startData of
      Right (v, []) | endData == v -> return ()
                    | otherwise    -> assertFailure $ "expected:\n"
                                      ++ BL.unpack (JS.encodePretty endData)
                                      ++ "\nbut got:\n"
                                      ++ BL.unpack (JS.encodePretty v)
      Right (_, ws) -> assertFailure $ "Unexpcted warnings: " ++ show ws
      Left err      -> assertFailure (prettyMigrateFailure err)

applyFailureTest :: (Version, Version, ApplyFailure) -> Test.TestTree
applyFailureTest (ver, ver', expected) =
    testCase (showVersion ver ++ " -> " ++ showVersion ver') $
          case migrateDataDump (startSchema, ver) (endSchema, Release ver')
                               badChangelog testMigration root_ CheckAll startData of
            Right _ -> assertFailure $ "Successful migration!"
            Left (ValidateFailure (ChangelogEntryInvalid _ _ err))
                | err == expected -> return ()
            Left err -> assertFailure $ unlines $ ["Unexpected failure:"]
                        ++ indent (ppLines err) ++ ["Expecting:"]
                        ++ indent (ppLines expected)

migrateFailureTest :: MigrateFailureTest
                    -> Test.TestTree
migrateFailureTest (s, start, end, clog, db, expected) =
    testCase s $ case migrateDataDump start end clog testMigration root_ CheckAll db of
        Right _                 -> assertFailure $ "Successful migration!"
        Left err | expected err -> return ()
                 | otherwise    -> assertFailure $ unlines $ ["Unexpected failure:"]
                                                             ++ indent (ppLines err)


$(generate         startSchema)
$(generateAPITools startSchema
                   [ enumTool
                   , jsonTool'
                   , quickCheckTool
                   ])

validMigrationProperty :: DatabaseSnapshot -> P.Result
validMigrationProperty db =
    case migrateDataDump (startSchema, startVersion) (endSchema, DevVersion)
                         changelog testMigration root_ CheckStartAndEnd (JS.toJSON db) of
    Right (v, []) -> case dataMatchesAPI root_ endSchema v of
        Right _   -> succeeded
        Left  err -> failedBecause ("end data does not match API: "
                                    ++ prettyValueErrorPosition err)
    Right (_, ws) -> failedBecause ("migration generated warnings: " ++ show ws)
    Left err      -> failedBecause ("migration failed: " ++ prettyMigrateFailure err)
  where
    failedBecause e = failed { reason = e }


migrationTests :: TestTree
migrationTests = testGroup "Migration"
  [ testCase     "Basic migration using sample changelog" basicMigrationTest
  , testGroup    "Invalid changes"    $ map applyFailureTest   expectedApplyFailures
  , testGroup    "Invalid migrations" $ map migrateFailureTest expectedMigrateFailures
  , QC.testProperty "Valid migrations" validMigrationProperty
  ]