package redistest

import (
	"fmt"
	"sync"
	"testing"
	"time"

	redigo "github.com/gomodule/redigo/redis"
	"github.com/mna/redisc"
	"github.com/mna/redisc/redistest"
	"github.com/stretchr/objx"
	"github.com/stretchr/testify/require"
	"src.dualinventive.com/go/dinet/rts"
	"src.dualinventive.com/go/lib/dilog"
)

// Redis contains a working redis cluster with functions to test data in Redis.
type Redis struct {
	Logger    dilog.Logger
	redisPort []string
	rc        *redisc.Cluster
	cleanup   func()
	wg        sync.WaitGroup
	event     chan bool
	isClosed  chan bool
}

// New creates a new Redis cluster.
func New(t *testing.T) *Redis {
	// Start redis cluster
	rcClose, rcPorts := redistest.StartCluster(t, nil)
	r := &Redis{
		Logger:    dilog.NewTestLogger(t),
		redisPort: []string{"127.0.0.1:" + rcPorts[0]},
		cleanup:   rcClose,
		event:     make(chan bool, 1),
		isClosed:  make(chan bool),
	}
	r.rc = &redisc.Cluster{
		StartupNodes: r.redisPort,
		DialOptions:  []redigo.DialOption{redigo.DialConnectTimeout(10 * time.Second)},
	}
	r.wg.Add(1)
	go r.eventListener(t)

	require.Nil(t, r.rc.Refresh())
	return r
}

// RedisPorts returns the testing redis ports
func (r *Redis) RedisPorts() []string {
	return r.redisPort
}

// getPubSubConn gets a new connection from the cluster and subscribes to ChanDevice and ChanProject
func (r *Redis) getPubSubConn() (*redigo.PubSubConn, error) {
	conn := r.rc.Get()

	psc := redigo.PubSubConn{Conn: conn}
	if err := psc.Subscribe(rts.ChanDevice, rts.ChanProject); err != nil {
		return nil, err
	}
	return &psc, nil
}

// eventListener listens for change events. This is necessary for the WaitForChange function
func (r *Redis) eventListener(t *testing.T) {
	defer r.wg.Done()

	psc, err := r.getPubSubConn()
	require.Nil(t, err)

	for {
		switch psc.Receive().(type) {
		case redigo.Message:
			select {
			case r.event <- true:
			default:
			}
		case error:
			// Check if servePublishEvents loop must be closed due to Close call
			select {
			case <-r.isClosed:
				return
			default:
			}
			// Reconnect a new PUBSUB connection on error
			require.Nil(t, psc.Close())
			time.Sleep(time.Second)
			psc, err = r.getPubSubConn()
			require.Nil(t, err)
		}
	}
}

// ClearEvent resets the event flag. WaitForChange will block till a new event is raised (or on a timeout).
func (r *Redis) ClearEvent() {
	select {
	case <-r.event:
	default:
	}
}

// WaitForChange blocks till a change is made in Redis (and return true) or when the timeout is reached (return false).
func (r *Redis) WaitForChange(timeout time.Duration) bool {
	select {
	case <-r.event:
		return true
	case <-time.After(timeout):
		return false
	}
}

func (r *Redis) field(t *testing.T, key, field string) interface{} {
	rply, err := r.do("HGET", key, field)
	require.Nil(t, err)
	return rply
}

// FieldUint64 gets the value for key and field and validates if it decodes into a uint64
func (r *Redis) FieldUint64(t *testing.T, key, field string) uint64 {
	u64, err := redigo.Uint64(r.do("HGET", key, field))
	require.Nil(t, err)
	return u64
}

// FieldExist checks if the field exist in redis via HGET
func (r *Redis) FieldExist(t *testing.T, key, field string) interface{} {
	rply := r.field(t, key, field)
	require.NotNil(t, rply, fmt.Sprintf("Expected field %s - %s found", key, field))
	return rply
}

// FieldNotExist checks if the field doesn't exist in redis via HGET
func (r *Redis) FieldNotExist(t *testing.T, key, field string) interface{} {
	rply := r.field(t, key, field)
	require.Nil(t, rply, fmt.Sprintf("Expected field %s - %s not found", key, field))
	return rply
}

// fieldJSON retrieves the json field value. If the field doesn't exist the test failes
func (r *Redis) fieldJSON(t *testing.T, key, field, jsonkey string) interface{} {
	value, err := redigo.String(r.FieldExist(t, key, field), nil)
	require.Nil(t, err)

	m := objx.MustFromJSON(value)
	return m.Get(jsonkey).Data()
}

// FieldJSONExist checks if the jsonkey exists in the field in Redis
func (r *Redis) FieldJSONExist(t *testing.T, key, field, jsonkey string) interface{} {
	value := r.fieldJSON(t, key, field, jsonkey)
	require.NotNil(t, value, fmt.Sprintf("Expected field %s - %s - %s found", key, field, jsonkey))
	return value
}

// FieldJSONNotExist checks if the jsonkey doesn't exists in the field in Redis. If the field doesn't exist the test
// failes
func (r *Redis) FieldJSONNotExist(t *testing.T, key, field, jsonkey string) {
	value := r.fieldJSON(t, key, field, jsonkey)
	require.Nil(t, value, fmt.Sprintf("Expected field %s - %s - %s not found", key, field, jsonkey))
}

// FieldJSONKeyValue checks if the value is the same as the value in the jsonkey in the field in Redis.
func (r *Redis) FieldJSONKeyValue(t *testing.T, key, field, jsonkey string, jsonvalue interface{}) {
	value := r.FieldJSONExist(t, key, field, jsonkey)
	require.Equal(t, jsonvalue, value)
}

// GPSRecordExists returns true when the DeviceUID contains a GEOHash
func (r *Redis) GPSRecordExists(t *testing.T, deviceUID string) bool {
	rply, err := redigo.Positions(r.do("GEOPOS", rts.SensorGeohashKey, deviceUID))
	require.Nil(t, err)

	// Length is 0 when rts.SensorGeohashKey doesn't exists in Redis (there are none GPS coordinates)
	// reply[0] is nil when the deviceUID is not in Redis (but there are other deviceUID's in Redis)
	return len(rply) > 0 && rply[0] != nil
}

// do execute a command on the redis cluster
func (r *Redis) do(commandName string, args ...interface{}) (reply interface{}, err error) {
	c, err := r.getConn()
	if err != nil {
		return nil, err
	}
	defer func() {
		closeerr := c.Close()
		// we are closing the connection so it is too late for errors.
		_ = closeerr
	}()

	return c.Do(commandName, args...)
}

func (r *Redis) getConn() (redigo.Conn, error) {
	conn := r.rc.Get()

	// create the retry connection - only Do, Close and Err are
	// supported on that connection. It will make up to 3 attempts
	// to get a valid response, and will wait 100ms before a retry
	// in case of a TRYAGAIN redis error.
	return redisc.RetryConn(conn, 3, time.Second)
}

// Close the connection to redis
func (r *Redis) Close() error {
	close(r.isClosed)
	err := r.rc.Close()
	r.cleanup()
	r.wg.Wait()
	return err
}