package server

import (
	"fmt"
	"math"
	"reflect"
	"strconv"
	"strings"
	"time"

	"github.com/evcc-io/evcc/api"
	"github.com/evcc-io/evcc/core/loadpoint"
	"github.com/evcc-io/evcc/core/site"
	"github.com/evcc-io/evcc/provider/mqtt"
	"github.com/evcc-io/evcc/util"
)

var deprecatedTopics = []string{
	"activePhases", "range", "socCharge", "vehicleSoC",
	"batterySoC", "bufferSoC", "minSoC", "prioritySoC",
	"targetSoC", "vehicleTargetSoC",
}

// MQTT is the MQTT server. It uses the MQTT client for publishing.
type MQTT struct {
	log     *util.Logger
	Handler *mqtt.Client
	root    string
}

// NewMQTT creates MQTT server
func NewMQTT(root string) *MQTT {
	return &MQTT{
		log:     util.NewLogger("mqtt"),
		Handler: mqtt.Instance,
		root:    root,
	}
}

func (m *MQTT) encode(v interface{}) string {
	// nil should erase the value
	if v == nil {
		return ""
	}

	switch val := v.(type) {
	case string:
		return val
	case float64:
		return fmt.Sprintf("%.5g", val)
	case time.Time:
		if val.IsZero() {
			return ""
		}
		return strconv.FormatInt(val.Unix(), 10)
	case time.Duration:
		// must be before stringer to convert to seconds instead of string
		return fmt.Sprintf("%d", int64(val.Seconds()))
	case fmt.Stringer:
		return val.String()
	default:
		return fmt.Sprintf("%v", val)
	}
}

func (m *MQTT) publishSingleValue(topic string, retained bool, payload interface{}) {
	token := m.Handler.Client.Publish(topic, m.Handler.Qos, retained, m.encode(payload))
	go m.Handler.WaitForToken("send", topic, token)
}

func (m *MQTT) publish(topic string, retained bool, payload interface{}) {
	// publish phase values
	if slice, ok := payload.([]float64); ok && len(slice) == 3 {
		var total float64
		for i, v := range slice {
			total += v
			m.publishSingleValue(fmt.Sprintf("%s/l%d", topic, i+1), retained, v)
		}

		// publish sum value
		payload = total
	}

	// publish slices of structs as sub topics
	if payload != nil {
		if typ := reflect.TypeOf(payload); typ.Kind() == reflect.Slice && typ.Elem().Kind() == reflect.Struct {
			val := reflect.ValueOf(payload)

			// loop slice
			for i := 0; i < val.Len(); i++ {
				val := val.Index(i)
				typ := val.Type()

				// loop struct
				for j := 0; j < typ.NumField(); j++ {
					n := typ.Field(j).Name
					v := val.Field(j).Interface()
					m.publishSingleValue(fmt.Sprintf("%s/%d/%s", topic, i+1, strings.ToLower(n[:1])+n[1:]), retained, v)
				}
			}

			// publish count
			payload = val.Len()
		}
	}

	// publish vehicles
	if slice, ok := payload.([]string); ok && strings.HasSuffix(topic, "vehicles") {
		// publish count
		payload = len(slice)

		for i, v := range slice {
			m.publishSingleValue(fmt.Sprintf("%s/%d", topic, i+1), retained, v)
		}
	}

	m.publishSingleValue(topic, retained, payload)
}

func (m *MQTT) listenSetters(topic string, site site.API, lp loadpoint.API) {
	m.Handler.ListenSetter(topic+"/mode", func(payload string) error {
		mode, err := api.ChargeModeString(payload)
		if err == nil {
			lp.SetMode(mode)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/minSoc", func(payload string) error {
		soc, err := strconv.Atoi(payload)
		if err == nil {
			lp.SetMinSoc(soc)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/targetEnergy", func(payload string) error {
		val, err := parseFloat(payload)
		if err == nil {
			lp.SetTargetEnergy(val)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/targetSoc", func(payload string) error {
		soc, err := strconv.Atoi(payload)
		if err == nil {
			lp.SetTargetSoc(soc)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/targetTime", func(payload string) error {
		val, err := time.Parse(time.RFC3339, payload)
		if err == nil {
			err = lp.SetTargetTime(val)
		} else if string(payload) == "null" {
			err = lp.SetTargetTime(time.Time{})
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/minCurrent", func(payload string) error {
		current, err := parseFloat(payload)
		if err == nil {
			lp.SetMinCurrent(current)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/maxCurrent", func(payload string) error {
		current, err := parseFloat(payload)
		if err == nil {
			lp.SetMaxCurrent(current)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/phases", func(payload string) error {
		phases, err := strconv.Atoi(payload)
		if err == nil {
			err = lp.SetPhases(phases)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/vehicle", func(payload string) error {
		vehicle, err := strconv.Atoi(payload)
		if err == nil {
			if vehicle > 0 {
				if vehicles := site.GetVehicles(); vehicle <= len(vehicles) {
					lp.SetVehicle(vehicles[vehicle-1])
				} else {
					err = fmt.Errorf("invalid vehicle: %d", vehicle)
				}
			} else {
				lp.SetVehicle(nil)
			}
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/enableThreshold", func(payload string) error {
		threshold, err := parseFloat(payload)
		if err == nil {
			lp.SetEnableThreshold(threshold)
		}
		return err
	})
	m.Handler.ListenSetter(topic+"/disableThreshold", func(payload string) error {
		threshold, err := parseFloat(payload)
		if err == nil {
			lp.SetDisableThreshold(threshold)
		}
		return err
	})
}

// Run starts the MQTT publisher for the MQTT API
func (m *MQTT) Run(site site.API, in <-chan util.Param) {
	// alive
	topic := fmt.Sprintf("%s/status", m.root)
	m.publish(topic, true, "online")

	// site setters
	m.Handler.ListenSetter(m.root+"/site/prioritySoc", func(payload string) error {
		val, err := parseFloat(payload)
		if err == nil {
			err = site.SetPrioritySoc(val)
		}
		return err
	})

	m.Handler.ListenSetter(m.root+"/site/bufferSoc", func(payload string) error {
		val, err := parseFloat(payload)
		if err == nil {
			err = site.SetBufferSoc(val)
		}
		return err
	})

	m.Handler.ListenSetter(m.root+"/site/bufferStartSoc", func(payload string) error {
		val, err := parseFloat(payload)
		if err == nil {
			err = site.SetBufferStartSoc(val)
		}
		return err
	})

	m.Handler.ListenSetter(m.root+"/site/residualPower", func(payload string) error {
		val, err := parseFloat(payload)
		if err == nil {
			err = site.SetResidualPower(val)
		}
		return err
	})

	m.Handler.ListenSetter(m.root+"/site/smartCostLimit", func(payload string) error {
		val, err := parseFloat(payload)
		if err == nil {
			err = site.SetSmartCostLimit(val)
		}
		return err
	})

	// number of loadpoints
	topic = fmt.Sprintf("%s/loadpoints", m.root)
	m.publish(topic, true, len(site.Loadpoints()))

	// loadpoint setters
	for id, lp := range site.Loadpoints() {
		topic := fmt.Sprintf("%s/loadpoints/%d", m.root, id+1)
		m.listenSetters(topic, site, lp)
	}

	// TODO remove deprecated topics
	for _, dep := range deprecatedTopics {
		m.publish(fmt.Sprintf("%s/site/%s", m.root, dep), true, nil)
	}

	for id := range site.Loadpoints() {
		topic := fmt.Sprintf("%s/loadpoints/%d", m.root, id+1)
		for _, dep := range deprecatedTopics {
			m.publish(fmt.Sprintf("%s/%s", topic, dep), true, nil)
		}
	}

	for i := 0; i < 10; i++ {
		m.publish(fmt.Sprintf("%s/site/pv/%d", m.root, i), true, nil)
		m.publish(fmt.Sprintf("%s/site/battery/%d", m.root, i), true, nil)
		m.publish(fmt.Sprintf("%s/site/vehicles/%d", m.root, i), true, nil)
	}

	// alive indicator
	var updated time.Time

	// publish
	for p := range in {
		topic := fmt.Sprintf("%s/site", m.root)
		if p.Loadpoint != nil {
			id := *p.Loadpoint + 1
			topic = fmt.Sprintf("%s/loadpoints/%d", m.root, id)
		}

		// alive indicator
		if time.Since(updated) > time.Second {
			updated = time.Now()
			m.publish(fmt.Sprintf("%s/updated", m.root), true, updated.Unix())
		}

		// value
		topic += "/" + p.Key
		m.publish(topic, true, p.Val)
	}
}

// parseFloat rejects NaN and Inf values
func parseFloat(payload string) (float64, error) {
	f, err := strconv.ParseFloat(payload, 64)
	if err == nil && (math.IsNaN(f) || math.IsInf(f, 0)) {
		err = fmt.Errorf("invalid float value: %s", payload)
	}
	return f, err
}