package configure

import (
	"context"
	"errors"
	"time"

	"github.com/evcc-io/evcc/api"
	"github.com/evcc-io/evcc/charger"
	"github.com/evcc-io/evcc/meter"
	"github.com/evcc-io/evcc/util/templates"
	"github.com/evcc-io/evcc/vehicle"
	"go.yaml.in/yaml/v4"
)

type DeviceTestResult string

const (
	DeviceTestResultValid             DeviceTestResult = "Valid"
	DeviceTestResultValidMissingMeter DeviceTestResult = "Valid_MissingMeter"
	DeviceTestResultInvalid           DeviceTestResult = "Invalid"
)

type DeviceTest struct {
	DeviceCategory DeviceCategory
	Template       templates.Template
	ConfigValues   map[string]any
}

// Test returns:
// - DeviceTestResult: Valid, Valid_MissingMeter, Invalid
// - error: != nil if the device is invalid and can not be configured with the provided settings
func (d *DeviceTest) Test() (DeviceTestResult, error) {
	v, err := d.configure()
	if err != nil {
		return DeviceTestResultInvalid, err
	}

	switch DeviceCategories[d.DeviceCategory].class {
	case templates.Charger:
		return d.testCharger(v)

	case templates.Meter:
		return d.testMeter(d.DeviceCategory, v)

	case templates.Vehicle:
		return d.testVehicle(v)

	default:
		panic("invalid class for category: " + d.DeviceCategory)
	}
}

// configure creates a configured device from a template so we can test it
func (d *DeviceTest) configure() (any, error) {
	b, _, err := d.Template.RenderResult(templates.RenderModeInstance, d.ConfigValues)
	if err != nil {
		return nil, err
	}

	var instance struct {
		Type  string
		Other map[string]any `yaml:",inline"`
	}

	if err := yaml.Unmarshal(b, &instance); err != nil {
		return nil, err
	}

	var v any

	ctx := context.TODO()
	switch DeviceCategories[d.DeviceCategory].class {
	case templates.Meter:
		v, err = meter.NewFromConfig(ctx, instance.Type, instance.Other)
	case templates.Charger:
		v, err = charger.NewFromConfig(ctx, instance.Type, instance.Other)
	case templates.Vehicle:
		v, err = vehicle.NewFromConfig(ctx, instance.Type, instance.Other)
	}

	return v, err
}

// testCharger tests a charger device
func (d *DeviceTest) testCharger(v any) (DeviceTestResult, error) {
	c, ok := v.(api.Charger)
	if !ok {
		return DeviceTestResultInvalid, errors.New("selected device is not a wallbox")
	}

	if _, err := c.Status(); err != nil {
		return DeviceTestResultInvalid, err
	}

	m, ok := v.(api.Meter)
	if !ok {
		return DeviceTestResultValidMissingMeter, nil
	}
	if _, err := m.CurrentPower(); err != nil {
		return DeviceTestResultInvalid, err
	}

	return DeviceTestResultValid, nil
}

// testMeter tests a meter device
func (d *DeviceTest) testMeter(deviceCategory DeviceCategory, v any) (DeviceTestResult, error) {
	m, ok := v.(api.Meter)
	if !ok {
		return DeviceTestResultInvalid, errors.New("selected device is not a meter")
	}

	power, err := m.CurrentPower()
	if err != nil {
		return DeviceTestResultInvalid, err
	}

	// check if the grid meter reports power 0, which should be impossible
	// happens with Kostal Piko charger that do not have a grid meter attached
	// but we can't determine this
	if power == 0 && deviceCategory == DeviceCategoryGridMeter {
		return DeviceTestResultInvalid, errors.New("grid meter reports power 0")
	}

	if deviceCategory == DeviceCategoryBatteryMeter {
		b, ok := v.(api.Battery)
		if !ok {
			return DeviceTestResultInvalid, errors.New("selected device is not a battery meter")
		}

		_, err := b.Soc()

		for err != nil && errors.Is(err, api.ErrMustRetry) {
			time.Sleep(3 * time.Second)
			_, err = b.Soc()
		}

		if err != nil {
			return DeviceTestResultInvalid, err
		}
	}

	return DeviceTestResultValid, nil
}

// testVehicle tests a vehicle device
func (d *DeviceTest) testVehicle(v any) (DeviceTestResult, error) {
	vv, ok := v.(api.Vehicle)
	if !ok {
		return DeviceTestResultInvalid, errors.New("selected device is not a vehicle")
	}

	if _, err := vv.Soc(); err != nil {
		return DeviceTestResultInvalid, err
	}

	return DeviceTestResultValid, nil
}