package cardata

import (
	"context"
	"fmt"
	"maps"
	"slices"
	"strings"
	"sync"
	"time"

	"github.com/evcc-io/evcc/api"
	"github.com/evcc-io/evcc/util"
	"github.com/spf13/cast"
	"golang.org/x/oauth2"
)

const StreamingURL = "tls://customer.streaming-cardata.bmwgroup.com:9000"

// Provider implements the vehicle api
type Provider struct {
	mu  sync.Mutex
	log *util.Logger
	api *API
	ts  oauth2.TokenSource

	vin       string
	container string

	rest      map[string]TelematicData
	streaming map[string]StreamingData
	updated   time.Time
	cache     time.Duration
}

// NewProvider creates a vehicle api provider
func NewProvider(ctx context.Context, log *util.Logger, api *API, ts oauth2.TokenSource, clientID, vin string, cache time.Duration) *Provider {
	v := &Provider{
		log:       log,
		api:       api,
		ts:        ts,
		vin:       vin,
		cache:     cache,
		rest:      make(map[string]TelematicData),
		streaming: make(map[string]StreamingData),
	}

	mqtt := NewMqttConnector(context.Background(), log, clientID, ts)
	recvC := mqtt.Subscribe(vin)

	go func() {
		<-ctx.Done()
		mqtt.Unsubscribe(vin, recvC)
	}()

	go func() {
		for msg := range recvC {
			v.mu.Lock()
			maps.Copy(v.streaming, msg.Data)
			v.updated = time.Now()
			v.mu.Unlock()
		}
	}()

	return v
}

func (v *Provider) findOrCreateContainer() (string, error) {
	containers, err := v.api.GetContainers()
	if err != nil {
		return "", err
	}

	// obsolete containers keep streaming, resulting in duplicate messages
	defer v.deleteObsoleteContainers(containers)

	if i := slices.IndexFunc(containers, func(c Container) bool {
		return c.Name == containerName && c.Purpose == requiredVersion
	}); i >= 0 {
		return containers[i].ContainerId, nil
	}

	res, err := v.api.CreateContainer(CreateContainer{
		Name:                 containerName,
		Purpose:              requiredVersion,
		TechnicalDescriptors: requiredKeys,
	})

	return res.ContainerId, err
}

func (v *Provider) deleteObsoleteContainers(containers []Container) {
	for _, c := range containers {
		if c.Name != containerName || c.Purpose == requiredVersion {
			continue
		}

		v.log.DEBUG.Printf("deleting obsolete container %s (%s)", c.ContainerId, c.Purpose)

		if err := v.api.DeleteContainer(c.ContainerId); err != nil {
			v.log.WARN.Printf("delete container %s: %v", c.ContainerId, err)
		}
	}
}

func (v *Provider) setupContainer() error {
	container, err := v.findOrCreateContainer()
	if err != nil {
		return fmt.Errorf("get container: %v", err)
	}

	v.container = container

	return nil
}

func (v *Provider) updateContainerData() error {
	res, err := v.api.GetTelematics(v.vin, v.container)
	if err != nil {
		return fmt.Errorf("get telematics: %v", err)
	}

	v.rest = res.TelematicData
	v.streaming = make(map[string]StreamingData) // reset streaming

	return nil
}

func (v *Provider) any(key string) (any, error) {
	v.mu.Lock()
	defer v.mu.Unlock()

	_, tokenErr := v.ts.Token()

	if tokenErr == nil && (v.updated.IsZero() || time.Since(v.updated) > v.cache) {
		if v.container == "" {
			if err := v.setupContainer(); err != nil {
				v.log.WARN.Println(err)
			}
		}

		if v.container != "" {
			if err := v.updateContainerData(); err != nil {
				v.log.WARN.Println(err)
			}
		}
		v.updated = time.Now()
	}

	if a, ok := v.streaming[key]; ok {
		return a.Value, nil
	}

	if el, ok := v.rest[key]; ok {
		return el.Value, nil
	}

	return nil, api.ErrNotAvailable
}

func isNilOrEmpty(val any) bool {
	return val == nil || val == ""
}

func (v *Provider) String(key string) (string, error) {
	res, err := v.any(key)
	if err != nil || isNilOrEmpty(res) {
		return "", api.ErrNotAvailable
	}

	return cast.ToStringE(res)
}

func (v *Provider) Int(key string) (int64, error) {
	res, err := v.any(key)
	if err != nil || isNilOrEmpty(res) {
		return 0, api.ErrNotAvailable
	}

	return cast.ToInt64E(res)
}

func (v *Provider) Float(key string) (float64, error) {
	res, err := v.any(key)
	if err != nil || isNilOrEmpty(res) {
		return 0, api.ErrNotAvailable
	}

	return cast.ToFloat64E(res)
}

var _ api.Battery = (*Provider)(nil)

// Soc implements the api.Vehicle interface
func (v *Provider) Soc() (float64, error) {
	if res, err := v.Float("vehicle.drivetrain.batteryManagement.header"); err == nil {
		return res, nil
	}
	return v.Float("vehicle.powertrain.electric.battery.stateOfCharge.displayed")
}

var _ api.ChargeState = (*Provider)(nil)

// Status implements the api.ChargeState interface
func (v *Provider) Status() (api.ChargeStatus, error) {
	// evaluate status first, since it's usually available through
	// mqtt, while hvStatus might only be available through rest
	// (https://github.com/evcc-io/evcc/pull/26235)
	cs, err := v.String("vehicle.drivetrain.electricEngine.charging.status")
	if err != nil {
		cs, _ = v.String("vehicle.drivetrain.electricEngine.charging.hvStatus")
	}

	if slices.Contains([]string{
		"INITIALIZATION",         // vehicle.drivetrain.electricEngine.charging.status
		"CHARGINGPAUSED",         // vehicle.drivetrain.electricEngine.charging.status
		"CHARGINGENDED",          // vehicle.drivetrain.electricEngine.charging.status
		"WAITING_FOR_CHARGING",   // vehicle.drivetrain.electricEngine.charging.hvStatus
		"FINISHED_FULLY_CHARGED", // vehicle.drivetrain.electricEngine.charging.hvStatus
		"FINISHED_NOT_FULL",      // vehicle.drivetrain.electricEngine.charging.hvStatus
	}, cs) {
		return api.StatusB, nil
	}

	if slices.Contains([]string{
		"CHARGINGACTIVE", // vehicle.drivetrain.electricEngine.charging.status
		"CHARGING",       // vehicle.drivetrain.electricEngine.charging.hvStatus
	}, cs) {
		return api.StatusC, nil
	}

	port, err := v.String("vehicle.body.chargingPort.status")
	if err != nil {
		port, err = v.String("vehicle.body.chargingPort.combinedStatus")
		if err != nil {
			return api.StatusNone, err
		}
	}

	status := api.StatusA // disconnected
	if port == "CONNECTED" {
		status = api.StatusB
	}

	return status, err
}

var _ api.VehicleFinishTimer = (*Provider)(nil)

// FinishTime implements the api.VehicleFinishTimer interface
func (v *Provider) FinishTime() (time.Time, error) {
	res, err := v.Int("vehicle.drivetrain.electricEngine.charging.timeRemaining")
	if err != nil {
		return time.Time{}, err
	}
	return time.Now().Add(time.Duration(res) * time.Minute), nil
}

var _ api.VehicleRange = (*Provider)(nil)

// Range implements the api.VehicleRange interface
func (v *Provider) Range() (int64, error) {
	if res, err := v.Int("vehicle.drivetrain.electricEngine.kombiRemainingElectricRange"); err == nil {
		return res, nil
	}
	return v.Int("vehicle.drivetrain.lastRemainingRange")
}

var _ api.VehicleOdometer = (*Provider)(nil)

// Odometer implements the api.VehicleOdometer interface
func (v *Provider) Odometer() (float64, error) {
	return v.Float("vehicle.vehicle.travelledDistance")
}

var _ api.SocLimiter = (*Provider)(nil)

// GetLimitSoc implements the api.SocLimiter interface
func (v *Provider) GetLimitSoc() (int64, error) {
	return v.Int("vehicle.powertrain.electric.battery.stateOfCharge.target")
}

var _ api.VehicleClimater = (*Provider)(nil)

// Climater implements the api.VehicleClimater interface
func (v *Provider) Climater() (bool, error) {
	activeStates := []string{"HEATING", "COOLING", "VENTILATION", "DEFROST"}

	res, err := v.String("vehicle.cabin.hvac.preconditioning.status.comfortState")
	if err == nil {
		return slices.Contains(activeStates, strings.TrimPrefix(strings.ToUpper(res), "COMFORT_")), nil
	}

	if res, err = v.String("vehicle.vehicle.preConditioning.activity"); err == nil {
		return slices.Contains(activeStates, strings.ToUpper(res)), nil
	}

	return false, err
}

var _ api.VehiclePosition = (*Provider)(nil)

// Position implements the api.VehiclePosition interface
func (v *Provider) Position() (float64, float64, error) {
	lat, err := v.Float("vehicle.cabin.infotainment.navigation.currentLocation.latitude")
	if err != nil {
		return 0, 0, err
	}

	lon, err := v.Float("vehicle.cabin.infotainment.navigation.currentLocation.longitude")
	if err != nil {
		return 0, 0, err
	}

	return lat, lon, nil
}