package charger

import (
	"errors"
	"fmt"
	"os"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/benbjohnson/clock"
	"github.com/evcc-io/evcc/api"
	"github.com/evcc-io/evcc/charger/ocpp"
	ocppapi "github.com/lorenzodonini/ocpp-go/ocpp"
	ocpp16 "github.com/lorenzodonini/ocpp-go/ocpp1.6"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/core"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/firmware"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/localauth"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/remotetrigger"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/reservation"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/smartcharging"
	"github.com/lorenzodonini/ocpp-go/ocpp1.6/types"
	"github.com/lorenzodonini/ocpp-go/ocppj"
	"github.com/lorenzodonini/ocpp-go/ws"
	"github.com/stretchr/testify/suite"
)

const ocppTestConnectTimeout = 10 * time.Second

// ocppTestUrl is derived from the actual bound port in SetupSuite: the central
// system binds an ephemeral port to avoid bind failures when the fixed default
// port is already in use on the CI runner.
var ocppTestUrl string

// testLogger receives all ocppj logging for this binary
var testLogger ocppLogger

// suiteRuns counts suite runs, see stationID
var suiteRuns atomic.Int64

func TestMain(m *testing.M) {
	ocpp.Timeout = 5 * time.Second

	// the simulated charge points never send a spontaneous BootNotification,
	// so shorten the proactive-trigger delay to avoid waiting 5s per charge point
	ocpp.TriggerBootDelay = 100 * time.Millisecond

	// bind the OCPP central system to an ephemeral port so this test binary
	// does not contend with the charger/ocpp package test binary for the fixed
	// default port when both run in parallel under `go test ./...`
	ocpp.NewServer(ocpp.Config{Port: 0}, "")

	// after NewServer, which registers the central system as ocppj logger itself
	ocppj.SetLogger(&testLogger)

	os.Exit(m.Run())
}

func TestOcpp(t *testing.T) {
	suite.Run(t, new(ocppTestSuite))
}

type ocppTestSuite struct {
	suite.Suite
	clock *clock.Mock
	run   int64
}

func (suite *ocppTestSuite) SetupSuite() {
	suite.run = suiteRuns.Add(1)

	cs, err := ocpp.Instance()
	suite.Require().NoError(err, "instance")
	suite.Require().NotNil(cs)

	testLogger.open(suite.T())

	suite.Require().NotZero(ocpp.Port(), "central system did not bind")
	ocppTestUrl = fmt.Sprintf("ws://localhost:%d", ocpp.Port())

	suite.clock = clock.NewMock()
}

func (suite *ocppTestSuite) TearDownSuite() {
	testLogger.close()
}

// stationID qualifies a charge point id with the suite run. The central system is
// a package global that keeps its registrations, so re-running the suite in the
// same binary (`go test -count>1`) would otherwise hand the second run the first
// run's stale, already disconnected charge points.
func (suite *ocppTestSuite) stationID(id string) string {
	return fmt.Sprintf("%s-%d", id, suite.run)
}

func (suite *ocppTestSuite) startChargePoint(id string, connectorId int) (ocpp16.ChargePoint, *ocppj.Client, func()) {
	// Buffered generously: the handlers in ocpp_test_handler.go send to
	// triggerC synchronously (via defer) on the charge point's WebSocket
	// read-loop goroutine. If that send blocks, the read loop cannot deliver
	// the CALL_RESULT for the CP→CS request the drain goroutine is waiting
	// on, deadlocking the test. The buffer keeps the send from blocking
	// until the drain catches up.
	handler := &ChargePointHandler{
		triggerC: make(chan remotetrigger.MessageTrigger, 16),
	}

	// ocppj endpoint with handler
	client := ws.NewClient()
	client.SetRequestedSubProtocol(types.V16Subprotocol)
	dispatcher := ocppj.NewDefaultClientDispatcher(ocppj.NewFIFOClientQueue(0))
	endpoint := ocppj.NewClient(id, client, dispatcher, nil, core.Profile, localauth.Profile, firmware.Profile, reservation.Profile, remotetrigger.Profile, smartcharging.Profile)

	// create charge point with handler
	cp := ocpp16.NewChargePoint(id, endpoint, client)
	cp.SetCoreHandler(handler)
	cp.SetRemoteTriggerHandler(handler)
	cp.SetSmartChargingHandler(handler)

	// let cs handle the trigger messages; exit on done so we do not leak a
	// drain goroutine into subsequent subtests on the shared ocpp.Instance().
	// triggerC is deliberately left open: the handlers in ocpp_test_handler.go
	// send to it from the charge point's read loop, which we do not synchronize
	// with on shutdown, so closing it could panic on `send on closed channel`.
	done := make(chan struct{})
	finished := make(chan struct{})

	// mu keeps the drain from talking to a stopped charge point; it still
	// consumes triggerC afterwards so the read loop never blocks on a full buffer
	var mu sync.Mutex
	var stopped bool

	go func() {
		defer close(finished)
		for {
			select {
			case <-done:
				return
			case msg := <-handler.triggerC:
				mu.Lock()
				if !stopped {
					suite.handleTrigger(cp, connectorId, msg)
				}
				mu.Unlock()
			}
		}
	}()

	// quiesce the drain before disconnecting: stopping the charge point while a
	// request is in flight closes the dispatcher channel it is sending on
	stop := sync.OnceFunc(func() {
		mu.Lock()
		stopped = true
		mu.Unlock()

		if cp.IsConnected() {
			cp.Stop()
		}

		close(done)
		// wait for the drain goroutine to fully exit before the test method
		// returns: handleTrigger logs via suite.T(), which panics if called
		// after the test has completed.
		<-finished
	})

	suite.T().Cleanup(stop)

	return cp, endpoint, stop
}

func (suite *ocppTestSuite) handleTrigger(cp ocpp16.ChargePoint, connectorId int, msg remotetrigger.MessageTrigger) {
	switch msg {
	case core.BootNotificationFeatureName:
		if _, err := cp.BootNotification("model", "vendor"); err != nil {
			suite.T().Log("BootNotification:", err)
		}

	case core.ChangeAvailabilityFeatureName:
		fallthrough

	case core.StatusNotificationFeatureName:
		if _, err := cp.StatusNotification(connectorId, core.NoError, core.ChargePointStatusCharging); err != nil {
			suite.T().Log("StatusNotification:", err)
		}

	case core.MeterValuesFeatureName:
		if _, err := cp.MeterValues(connectorId, []types.MeterValue{
			{
				Timestamp: types.NewDateTime(suite.clock.Now()),
				SampledValue: []types.SampledValue{
					{Measurand: types.MeasurandPowerActiveImport, Value: "1000"},
					{Measurand: types.MeasurandEnergyActiveImportRegister, Value: "1.2", Unit: "kWh"},
				},
			},
		}); err != nil {
			suite.T().Log("MeterValues:", err)
		}
	}
}

func (suite *ocppTestSuite) TestConnect() {
	id1 := suite.stationID("test-1")

	// 1st charge point- remote
	cp1, _, _ := suite.startChargePoint(id1, 1)
	suite.Require().NoError(cp1.Start(ocppTestUrl))
	suite.Require().True(cp1.IsConnected())

	// 1st charge point- local
	c1, err := NewOCPP(suite.T().Context(), id1, 1, "", "", 0, false, false, false, true, false, ocppTestConnectTimeout)
	suite.Require().NoError(err)

	// status and meter values
	{
		suite.clock.Add(ocpp.Timeout)
		c1.conn.TestClock(suite.clock)

		// status
		_, err = c1.Status()
		suite.Require().NoError(err)
	}

	// takeover
	{
		expectedTxn := 99

		// always accept stopping unknown transaction, see https://github.com/evcc-io/evcc/pull/13990
		_, err := cp1.StopTransaction(0, types.NewDateTime(suite.clock.Now()), expectedTxn)
		suite.Require().NoError(err)

		_, err = cp1.MeterValues(1, []types.MeterValue{
			{
				Timestamp: types.NewDateTime(suite.clock.Now()),
				SampledValue: []types.SampledValue{
					{Measurand: types.MeasurandPowerActiveImport, Value: "1000"},
				},
			},
		}, func(request *core.MeterValuesRequest) {
			request.TransactionId = &expectedTxn
		})
		suite.Require().NoError(err)

		conn1 := c1.Connector()
		txnId, err := conn1.TransactionID()
		suite.Require().NoError(err)
		suite.Equal(expectedTxn, txnId)

		res, err := cp1.StopTransaction(0, types.NewDateTime(suite.clock.Now()), expectedTxn)
		suite.Require().NoError(err)
		suite.Equal(types.AuthorizationStatusAccepted, res.IdTagInfo.Status)
	}

	id2 := suite.stationID("test-2")

	// 2nd charge point - remote
	cp2, _, stopCp2 := suite.startChargePoint(id2, 1)
	suite.Require().NoError(cp2.Start(ocppTestUrl))
	suite.Require().True(cp2.IsConnected())

	// 2nd charge point - local
	c2, err := NewOCPP(suite.T().Context(), id2, 1, "", "", 0, false, false, false, true, false, ocppTestConnectTimeout)
	suite.Require().NoError(err)

	{
		suite.clock.Add(ocpp.Timeout)
		c2.conn.TestClock(suite.clock)

		// status
		_, err = c2.Status()
		suite.Require().NoError(err)
	}

	// error on unconfigured 2nd charge point
	cp3, _, _ := suite.startChargePoint(suite.stationID("unconfigured"), 1)
	_, err = cp3.BootNotification("model", "vendor")
	suite.Require().Error(err)

	// disconnect charge point
	stopCp2()
	suite.Require().False(cp2.IsConnected())

	t := time.NewTimer(100 * time.Millisecond)
WAIT_DISCONNECT:
	for {
		select {
		case <-t.C:
			suite.Fail("disconnect timeout")
		case <-time.After(10 * time.Millisecond):
			if _, err := c2.Status(); errors.Is(err, api.ErrTimeout) {
				break WAIT_DISCONNECT
			}
		}
	}
}

func (suite *ocppTestSuite) TestAutoStart() {
	id1 := suite.stationID("test-3")

	// 1st charge point- remote
	cp1, _, _ := suite.startChargePoint(id1, 1)
	suite.Require().NoError(cp1.Start(ocppTestUrl))
	suite.Require().True(cp1.IsConnected())

	// 1st charge point- local
	c1, err := NewOCPP(suite.T().Context(), id1, 1, "", "", 0, false, false, false, false, false, ocppTestConnectTimeout)
	suite.Require().NoError(err)

	// status and meter values
	{
		suite.clock.Add(ocpp.Timeout)
		c1.conn.TestClock(suite.clock)
	}

	// acquire
	{
		expectedIdTag := "tag"

		// always accept stopping unknown transaction, see https://github.com/evcc-io/evcc/pull/13990
		_, err := cp1.StartTransaction(1, expectedIdTag, 0, types.NewDateTime(suite.clock.Now()))
		suite.Require().NoError(err)

		id, err := c1.Identify()
		suite.Require().NoError(err)
		suite.Require().Equal([]string{expectedIdTag}, id)

		conn1 := c1.Connector()
		_, err = conn1.TransactionID()
		suite.Require().NoError(err)
	}

	err = c1.Enable(true)
	suite.Require().NoError(err)

	err = c1.Enable(false)
	suite.Require().NoError(err)
}

func (suite *ocppTestSuite) TestTimeout() {
	id1 := suite.stationID("test-4")

	// 1st charge point- remote
	cp1, ocppjClient, _ := suite.startChargePoint(id1, 1)
	suite.Require().NoError(cp1.Start(ocppTestUrl))
	suite.Require().True(cp1.IsConnected())

	handler := ocppjClient.GetRequestHandler()
	ocppjClient.SetRequestHandler(func(request ocppapi.Request, requestId string, action string) {
		if action != core.ChangeAvailabilityFeatureName {
			handler(request, requestId, action)
		}
	})

	// 1st charge point- local
	_, err := NewOCPP(suite.T().Context(), id1, 1, "", "", 0, false, false, false, false, false, ocppTestConnectTimeout)

	suite.Require().NoError(err)
}