package charger

import (
	"context"
	"fmt"
	"time"

	"github.com/evcc-io/evcc/api"
	"github.com/evcc-io/evcc/util"
	"github.com/evcc-io/evcc/util/modbus"
	"github.com/volkszaehler/mbmd/encoding"
)

const (
	// holding and input return same values
	charxRegName           = 100
	charxRegSwVersion      = 110
	charxRegNumControllers = 114

	// per-unit registers
	charxOffset = 1000

	charxRegMeter          = 112
	charxRegVoltages       = 232 // mV
	charxRegCurrents       = 238 // mA
	charxRegPower          = 244 // mW
	charxRegEnergy         = 250 // Wh
	charxRegSoc            = 264 // %
	charxRegEvid           = 265 // 10
	charxRegRfid           = 275 // 10
	charxRegConnectionTime = 285 // s
	charxRegChargeTime     = 287 // s
	charxRegChargeEnergy   = 289 // Wh
	charxRegStatus         = 299 // IEC 61851-1
	charxRegEnable         = 300
	charxRegMaxCurrent     = 301 // A
)

// PhoenixCharx is an api.Charger implementation for Phoenix CHARX controller
type PhoenixCharx struct {
	conn      *modbus.Connection
	connector uint16
	current   uint16
}

func init() {
	registry.AddCtx("phoenix-charx", NewPhoenixCharxFromConfig)
}

//go:generate go tool decorate -f decoratePhoenixCharx -b *PhoenixCharx -r api.Charger -t api.Meter,api.MeterEnergy,api.PhaseCurrents,api.PhaseVoltages

// NewPhoenixCharxFromConfig creates a Phoenix charger from generic config
func NewPhoenixCharxFromConfig(ctx context.Context, other map[string]any) (api.Charger, error) {
	cc := struct {
		modbus.TcpSettings `mapstructure:",squash"`
		Connector          uint16
	}{
		TcpSettings: modbus.TcpSettings{
			ID: 1, // default
		},
		Connector: 1,
	}

	if err := util.DecodeOther(other, &cc); err != nil {
		return nil, err
	}

	wb, err := NewPhoenixCharx(ctx, cc.URI, cc.ID, cc.Connector)
	if err != nil {
		return nil, err
	}

	meter, err := wb.meter()
	if err != nil {
		return nil, err
	}

	if meter > 0 && meter != 65535 {
		return decoratePhoenixCharx(wb, wb.currentPower, wb.totalEnergy, wb.currents, wb.voltages), nil
	}

	return wb, nil
}

// NewPhoenixCharx creates a Phoenix charger
func NewPhoenixCharx(ctx context.Context, uri string, id uint8, connector uint16) (*PhoenixCharx, error) {
	conn, err := modbus.NewConnection(ctx, uri, "", "", 0, modbus.Tcp, id)
	if err != nil {
		return nil, err
	}

	log := util.NewLogger("charx")
	conn.Logger(log.TRACE)

	wb := &PhoenixCharx{
		conn:      conn,
		connector: connector,
		current:   6, // assume min current
	}

	controllers, err := wb.controllers()
	if err != nil {
		return nil, err
	}

	if connector > controllers {
		return nil, fmt.Errorf("invalid connector: %d", connector)
	}

	// Initialize current with the actual register value
	if b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegMaxCurrent), 1); err == nil {
		if current := encoding.Uint16(b); current >= wb.current {
			wb.current = current
		}
	}

	return wb, nil
}

func (wb *PhoenixCharx) controllers() (uint16, error) {
	b, err := wb.conn.ReadHoldingRegisters(charxRegNumControllers, 1)
	if err != nil {
		return 0, err
	}

	return encoding.Uint16(b), nil
}

func (wb *PhoenixCharx) register(reg uint16) uint16 {
	return wb.connector*charxOffset + reg
}

func (wb *PhoenixCharx) meter() (uint16, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegMeter), 1)
	if err != nil {
		return 0, err
	}

	return encoding.Uint16(b), nil
}

// Status implements the api.Charger interface
func (wb *PhoenixCharx) Status() (api.ChargeStatus, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegStatus), 1)
	if err != nil {
		return api.StatusNone, err
	}

	// TODO check IEC 61851-1 C1 state
	state := string(b[0])

	return api.ChargeStatusString(state)
}

// Enabled implements the api.Charger interface
func (wb *PhoenixCharx) Enabled() (bool, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegMaxCurrent), 1)
	if err != nil {
		return false, err
	}

	return encoding.Uint16(b) != 0, nil
}

// Enable implements the api.Charger interface
func (wb *PhoenixCharx) Enable(enable bool) error {
	b := make([]byte, 2)
	if enable {
		encoding.PutUint16(b, wb.current)
	}

	_, err := wb.conn.WriteMultipleRegisters(wb.register(charxRegMaxCurrent), 1, b)

	return err
}

// MaxCurrent implements the api.Charger interface
func (wb *PhoenixCharx) MaxCurrent(current int64) error {
	if current < 6 {
		return fmt.Errorf("invalid current %d", current)
	}

	b := make([]byte, 2)
	encoding.PutUint16(b, uint16(current))

	_, err := wb.conn.WriteMultipleRegisters(wb.register(charxRegMaxCurrent), 1, b)
	if err == nil {
		wb.current = uint16(current)
	}

	return err
}

var _ api.ChargeTimer = (*PhoenixCharx)(nil)

// ChargeDuration implements the api.ChargeTimer interface
func (wb *PhoenixCharx) ChargeDuration() (time.Duration, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegChargeTime), 2)
	if err != nil {
		return 0, err
	}

	return time.Duration(encoding.Uint32(b)) * time.Second, nil
}

var _ api.ConnectionTimer = (*PhoenixCharx)(nil)

// ConnectionDuration implements the api.ConnectionTimer interface
func (wb *PhoenixCharx) ConnectionDuration() (time.Duration, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegConnectionTime), 2)
	if err != nil {
		return 0, err
	}

	return time.Duration(encoding.Uint32(b)) * time.Second, nil
}

// currentPower implements the api.Meter interface
func (wb *PhoenixCharx) currentPower() (float64, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegPower), 2)
	if err != nil {
		return 0, err
	}

	return float64(encoding.Int32(b)) / 1e3, nil
}

// totalEnergy implements the api.MeterEnergy interface
func (wb *PhoenixCharx) totalEnergy() (float64, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegEnergy), 4)
	if err != nil {
		return 0, err
	}

	return float64(encoding.Int64(b)) / 1e3, nil
}

// currents implements the api.PhaseCurrents interface
func (wb *PhoenixCharx) currents() (float64, float64, float64, error) {
	return wb.getPhaseValues(charxRegCurrents)
}

// voltages implements the api.PhaseVoltages interface
func (wb *PhoenixCharx) voltages() (float64, float64, float64, error) {
	return wb.getPhaseValues(charxRegVoltages)
}

// getPhaseValues returns 3 sequential phase values
func (wb *PhoenixCharx) getPhaseValues(reg uint16) (float64, float64, float64, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(reg), 6)
	if err != nil {
		return 0, 0, 0, err
	}

	var res [3]float64
	for i := range res {
		res[i] = float64(encoding.Int32(b[4*i:])) / 1e3
	}

	return res[0], res[1], res[2], nil
}

var _ api.Identifier = (*PhoenixCharx)(nil)

// Identify implements the api.Identifier interface
func (wb *PhoenixCharx) Identify() (string, error) {
	b, err := wb.conn.ReadHoldingRegisters(wb.register(charxRegEvid), 10)
	if err != nil {
		return "", err
	}

	if res := bytesAsString(b); res != "" {
		return res, nil
	}

	b, err = wb.conn.ReadHoldingRegisters(wb.register(charxRegRfid), 10)
	if err != nil {
		return "", err
	}

	return bytesAsString(b), nil
}

var _ api.Diagnosis = (*PhoenixCharx)(nil)

// Diagnose implements the api.Diagnosis interface
func (wb *PhoenixCharx) Diagnose() {
	if b, err := wb.conn.ReadHoldingRegisters(charxRegName, 10); err == nil {
		fmt.Printf("Name: %s\n", b)
	}
	if b, err := wb.conn.ReadHoldingRegisters(charxRegSwVersion, 4); err == nil {
		fmt.Printf("Software version: %s\n", b)
	}

	controllers, err := wb.controllers()
	if err == nil {
		fmt.Printf("Controllers: %d\n", controllers)
	}

	meter, err := wb.meter()
	if err == nil {
		fmt.Printf("Meter: %d\n", meter)
	}
}