package charger

// LICENSE

// Copyright (c) evcc.io (andig, naltatis, premultiply)

// This module is NOT covered by the MIT license. All rights reserved.

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/cenkalti/backoff/v4"
	"github.com/evcc-io/evcc/api"
	"github.com/evcc-io/evcc/charger/easee"
	"github.com/evcc-io/evcc/core/loadpoint"
	"github.com/evcc-io/evcc/util"
	"github.com/evcc-io/evcc/util/request"
	"github.com/evcc-io/evcc/util/sponsor"
	"github.com/philippseith/signalr"
	"github.com/samber/lo"
	"golang.org/x/oauth2"
)

// Easee charger implementation
type Easee struct {
	*request.Helper
	charger               string
	site, circuit         int
	log                   *util.Logger
	mux                   sync.RWMutex
	maxChargerCurrent     float64
	dynamicChargerCurrent float64
	dynamicCircuitCurrent [3]float64
	current               float64
	chargerEnabled        bool
	smartCharging         bool
	authorize             bool
	enabled               bool
	opMode                int
	pilotMode             string
	reasonForNoCurrent    int
	phaseMode             int
	currentPower, sessionEnergy, totalEnergy,
	currentL1, currentL2, currentL3 float64
	rfid      string
	lp        loadpoint.API
	cmdC      chan easee.SignalRCommandResponse
	obsC      chan easee.Observation
	obsTime   map[easee.ObservationID]time.Time
	startDone func()
}

func init() {
	registry.AddCtx("easee", NewEaseeFromConfig)
}

// NewEaseeFromConfig creates a Easee charger from generic config
func NewEaseeFromConfig(ctx context.Context, other map[string]any) (api.Charger, error) {
	cc := struct {
		User      string
		Password  string
		Charger   string
		Timeout   time.Duration
		Authorize bool
	}{
		Timeout: request.Timeout,
	}

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

	if cc.User == "" || cc.Password == "" {
		return nil, api.ErrMissingCredentials
	}

	return NewEasee(ctx, cc.User, cc.Password, cc.Charger, cc.Timeout, cc.Authorize)
}

// NewEasee creates Easee charger
func NewEasee(ctx context.Context, user, password, charger string, timeout time.Duration, authorize bool) (*Easee, error) {
	log := util.NewLogger("easee").Redact(user, password)

	if !sponsor.IsAuthorized() {
		return nil, api.ErrSponsorRequired
	}

	done := make(chan struct{})

	c := &Easee{
		Helper:    request.NewHelper(log),
		charger:   charger,
		authorize: authorize,
		log:       log,
		current:   6, // default current
		startDone: sync.OnceFunc(func() { close(done) }),
		cmdC:      make(chan easee.SignalRCommandResponse),
		obsC:      make(chan easee.Observation),
		obsTime:   make(map[easee.ObservationID]time.Time),
	}

	c.Client.Timeout = timeout

	ts, err := easee.TokenSource(log, user, password)
	if err != nil {
		return nil, err
	}

	// replace client transport with authenticated transport
	c.Client.Transport = &oauth2.Transport{
		Source: ts,
		Base:   c.Client.Transport,
	}

	// find charger
	if charger == "" {
		chargers, err := c.chargers()
		if err != nil {
			return nil, err
		}

		if len(chargers) != 1 {
			return nil, fmt.Errorf("cannot determine charger id, found: %v", lo.Map(chargers, func(c easee.Charger, _ int) string { return c.ID }))
		}

		c.charger = chargers[0].ID
	}

	// find site
	site, err := c.chargerSite(c.charger)
	if err != nil {
		return nil, err
	}

	// find single charger per circuit
	for _, circuit := range site.Circuits {
		if len(circuit.Chargers) > 1 {
			continue
		}

		for _, charger := range circuit.Chargers {
			if charger.ID == c.charger {
				c.site = site.ID
				c.circuit = circuit.ID
				break
			}
		}
	}

	client, err := signalr.NewClient(ctx,
		signalr.WithConnector(c.connect(ts)),
		signalr.WithBackoff(func() backoff.BackOff {
			return backoff.NewExponentialBackOff(backoff.WithMaxElapsedTime(0)) // prevents SignalR stack to silently give up after 15 mins
		}),
		signalr.WithReceiver(c),
		signalr.Logger(easee.SignalrLogger(c.log.TRACE), false),
	)

	if err == nil {
		c.subscribe(client)

		client.Start()

		ctx, cancel := context.WithTimeout(ctx, request.Timeout)
		defer cancel()
		err = <-client.WaitForState(ctx, signalr.ClientConnected)
	}

	// wait for first update
	select {
	case <-done:
	case <-ctx.Done():
		err = ctx.Err()
	case <-time.After(request.Timeout):
		err = os.ErrDeadlineExceeded
	}

	if err == nil {
		c.waitForOptionalState()
	}

	return c, err
}

func (c *Easee) waitForOptionalState() {
	for range 30 {
		if c.optionalStatePresent() {
			return
		}
		time.Sleep(100 * time.Millisecond)
	}
	c.log.WARN.Println("did not receive full state from cloud")
}

// check c.obsTime for presence of ALL of the following keys: easee.SESSION_ENERGY, easee.LIFETIME_ENERGY
func (c *Easee) optionalStatePresent() bool {
	c.mux.Lock()
	defer c.mux.Unlock()
	wanted := []easee.ObservationID{easee.SESSION_ENERGY, easee.LIFETIME_ENERGY, easee.TOTAL_POWER}
	return len(wanted) == len(lo.Intersect(wanted, lo.Keys(c.obsTime)))
}

func (c *Easee) chargerSite(charger string) (easee.Site, error) {
	var res easee.Site
	uri := fmt.Sprintf("%s/chargers/%s/site", easee.API, charger)
	err := c.GetJSON(uri, &res)
	return res, err
}

// connect creates an HTTP connection to the signalR hub
func (c *Easee) connect(ts oauth2.TokenSource) func() (signalr.Connection, error) {
	bo := backoff.NewExponentialBackOff(backoff.WithMaxInterval(time.Minute))

	return func() (conn signalr.Connection, err error) {
		defer func() {
			if err != nil {
				time.Sleep(bo.NextBackOff())
			} else {
				bo.Reset()
			}
		}()

		tok, err := ts.Token()
		if err != nil {
			return nil, err
		}

		ctx, cancel := context.WithTimeout(context.Background(), request.Timeout)
		defer cancel()

		return signalr.NewHTTPConnection(ctx, "https://streams.easee.com/hubs/chargers",
			signalr.WithHTTPClient(c.Client),
			signalr.WithHTTPHeaders(func() http.Header {
				return http.Header{
					"Authorization": []string{"Bearer " + tok.AccessToken},
				}
			}),
		)
	}
}

// subscribe listen to state changes and sends subscription requests when connection is established
func (c *Easee) subscribe(client signalr.Client) {
	stateC := make(chan signalr.ClientState, 1)
	_ = client.ObserveStateChanged(stateC)

	go func() {
		for state := range stateC {
			if state == signalr.ClientConnected {
				if err := <-client.Send("SubscribeWithCurrentState", c.charger, true); err != nil {
					c.log.ERROR.Printf("SubscribeWithCurrentState: %v", err)
				}
			}
		}
	}()
}

// ProductUpdate implements the signalr receiver
func (c *Easee) ProductUpdate(i json.RawMessage) {
	var res easee.Observation

	if err := json.Unmarshal(i, &res); err != nil {
		c.log.ERROR.Printf("invalid message: %s %v", i, err)
		return
	}

	value, err := res.TypedValue()
	if err != nil {
		c.log.ERROR.Println(err)
		return
	}

	// https://github.com/evcc-io/evcc/issues/8009
	// logging might be slow or block, execute outside lock
	c.log.TRACE.Printf("ProductUpdate %s: (%v) %s %v", res.Mid, res.Timestamp, res.ID, value)

	c.mux.Lock()
	defer c.mux.Unlock()

	if prevTime, ok := c.obsTime[res.ID]; ok && prevTime.After(res.Timestamp) {
		// received observation is outdated, ignoring
		return
	}

	c.obsTime[res.ID] = res.Timestamp

	switch res.ID {
	case easee.USER_IDTOKEN:
		c.rfid = res.Value
	case easee.IS_ENABLED:
		c.chargerEnabled = value.(bool)
	case easee.SMART_CHARGING:
		c.smartCharging = value.(bool)
	case easee.TOTAL_POWER:
		c.currentPower = 1e3 * value.(float64)
	case easee.SESSION_ENERGY:
		// SESSION_ENERGY must not be set to 0 by Productupdates, they occur erratic
		// Reset to 0 is done in case CHARGER_OP_MODE
		if value.(float64) != 0 {
			c.sessionEnergy = value.(float64)
		}
	case easee.LIFETIME_ENERGY:
		c.totalEnergy = value.(float64)
	case easee.IN_CURRENT_T3:
		c.currentL1 = value.(float64)
	case easee.IN_CURRENT_T4:
		c.currentL2 = value.(float64)
	case easee.IN_CURRENT_T5:
		c.currentL3 = value.(float64)
	case easee.PHASE_MODE:
		c.phaseMode = value.(int)
	case easee.DYNAMIC_CIRCUIT_CURRENT_P1:
		c.dynamicCircuitCurrent[0] = value.(float64)
	case easee.DYNAMIC_CIRCUIT_CURRENT_P2:
		c.dynamicCircuitCurrent[1] = value.(float64)
	case easee.DYNAMIC_CIRCUIT_CURRENT_P3:
		c.dynamicCircuitCurrent[2] = value.(float64)
	case easee.MAX_CHARGER_CURRENT:
		c.maxChargerCurrent = value.(float64)
	case easee.DYNAMIC_CHARGER_CURRENT:
		c.dynamicChargerCurrent = value.(float64)
	case easee.CHARGER_OP_MODE:
		opMode := value.(int)

		// New charging session pending, reset internal value of SESSION_ENERGY to 0, and its observation timestamp to "now".
		// This should be done in a proper way by the api, but it's not.
		if c.opMode <= easee.ModeDisconnected && opMode >= easee.ModeAwaitingStart {
			c.sessionEnergy = 0
			c.obsTime[easee.SESSION_ENERGY] = time.Now()
		}

		c.opMode = opMode

		// startup completed
		c.startDone()

	case easee.REASON_FOR_NO_CURRENT:
		c.reasonForNoCurrent = value.(int)
	case easee.PILOT_MODE:
		c.pilotMode = value.(string)
	}

	select {
	case c.obsC <- res:
	default:
	}
}

// ChargerUpdate implements the signalr receiver
func (c *Easee) ChargerUpdate(i json.RawMessage) {
	c.log.TRACE.Printf("ChargerUpdate: %s", i)
}

// SubscribeToMyProduct implements the signalr receiver
func (c *Easee) SubscribeToMyProduct(i json.RawMessage) {
	c.log.TRACE.Printf("SubscribeToMyProduct: %s", i)
}

// CommandResponse implements the signalr receiver
func (c *Easee) CommandResponse(i json.RawMessage) {
	var res easee.SignalRCommandResponse

	if err := json.Unmarshal(i, &res); err != nil {
		c.log.ERROR.Printf("invalid message: %s %v", i, err)
		return
	}
	c.log.TRACE.Printf("CommandResponse %s: %+v", res.SerialNumber, res)

	select {
	case c.cmdC <- res:
	default:
	}
}

func (c *Easee) chargers() ([]easee.Charger, error) {
	var res []easee.Charger
	uri := fmt.Sprintf("%s/chargers", easee.API)
	err := c.GetJSON(uri, &res)
	return res, err
}

// Status implements the api.Charger interface
func (c *Easee) Status() (api.ChargeStatus, error) {
	c.updateSmartCharging()

	c.mux.RLock()
	defer c.mux.RUnlock()

	res := api.StatusNone

	switch c.opMode {
	case easee.ModeDisconnected:
		res = api.StatusA
	case easee.ModeAwaitingStart, easee.ModeCompleted, easee.ModeReadyToCharge,
		easee.ModeAwaitingAuthentication, easee.ModeDeauthenticating:
		res = api.StatusB
	case easee.ModeCharging:
		res = api.StatusC
	default:
		return res, fmt.Errorf("invalid opmode: %d", c.opMode)
	}

	return res, nil
}

// Enabled implements the api.Charger interface
func (c *Easee) Enabled() (bool, error) {
	c.mux.RLock()
	defer c.mux.RUnlock()
	return c.enabled, nil
}

// Enable implements the api.Charger interface
func (c *Easee) Enable(enable bool) (err error) {
	c.mux.Lock()
	enablingRequired := enable && !c.chargerEnabled
	opMode := c.opMode
	c.mux.Unlock()

	defer func() {
		if err == nil {
			c.enabled = enable
		}
	}()

	// enable charger once if it's switched off
	if enablingRequired {
		data := easee.ChargerSettings{
			Enabled: &enable,
		}

		uri := fmt.Sprintf("%s/chargers/%s/settings", easee.API, c.charger)
		if _, err := c.postJSONAndWait(uri, data); err != nil {
			return err
		}
	}

	// do not send pause/resume if disconnected or unauthenticated without automatic authorization
	if opMode == easee.ModeDisconnected || (opMode == easee.ModeAwaitingAuthentication && !(enable && c.authorize)) {
		return nil
	}

	// resume/stop charger
	action := easee.ChargePause
	var targetCurrent float64
	if enable {
		action = easee.ChargeResume
		if opMode == easee.ModeAwaitingAuthentication && c.authorize {
			action = easee.ChargeStart
		}
		targetCurrent = 32
	}

	uri := fmt.Sprintf("%s/chargers/%s/commands/%s", easee.API, c.charger, action)
	if _, err := c.postJSONAndWait(uri, nil); err != nil {
		return err
	}

	if err := c.waitForChargerEnabledState(enable); err != nil {
		return err
	}

	if action == easee.ChargeStart { // ChargeStart does not mingle with DCC, no need for below operations
		return nil
	}

	if err := c.waitForDynamicChargerCurrent(targetCurrent); err != nil {
		return err
	}

	if enable {
		// reset currents after enable, as easee automatically resets to maxA
		return c.MaxCurrent(int64(c.current))
	}

	return nil
}

func (c *Easee) inExpectedOpMode(enable bool) bool {
	c.mux.RLock()
	defer c.mux.RUnlock()

	// start/resume
	if enable {
		return c.opMode == easee.ModeCharging ||
			c.opMode == easee.ModeCompleted ||
			c.opMode == easee.ModeAwaitingStart ||
			c.opMode == easee.ModeReadyToCharge
	}

	// paused/stopped
	return c.opMode == easee.ModeAwaitingStart || c.opMode == easee.ModeAwaitingAuthentication
}

// posts JSON to the Easee API endpoint and waits for the async response
func (c *Easee) postJSONAndWait(uri string, data any) (bool, error) {
	resp, err := c.Post(uri, request.JSONContent, request.MarshalJSON(data))
	if err != nil {
		return false, err
	}
	defer resp.Body.Close()

	if resp.StatusCode == 200 { // sync call
		return false, nil
	}

	if resp.StatusCode == 202 { // async call, wait for response
		var cmd easee.RestCommandResponse

		if strings.Contains(uri, "/commands/") { // command endpoint
			if err := json.NewDecoder(resp.Body).Decode(&cmd); err != nil {
				return false, err
			}
		} else { // settings endpoint
			var cmdArr []easee.RestCommandResponse
			if err := json.NewDecoder(resp.Body).Decode(&cmdArr); err != nil {
				return false, err
			}

			if len(cmdArr) != 0 {
				cmd = cmdArr[0]
			}
		}

		if cmd.Ticks == 0 { // api thinks this was a noop
			return true, nil
		}

		return false, c.waitForTickResponse(cmd.Ticks)
	}

	// all other response codes lead to an error
	return false, fmt.Errorf("invalid status: %d", resp.StatusCode)
}

func (c *Easee) waitForTickResponse(expectedTick int64) error {
	for {
		select {
		case cmdResp := <-c.cmdC:
			if cmdResp.Ticks == expectedTick {
				if !cmdResp.WasAccepted {
					return fmt.Errorf("command rejected: %d", cmdResp.Ticks)
				}
				return nil
			}
		case <-time.After(c.Client.Timeout):
			return api.ErrTimeout
		}
	}
}

// wait for opMode become expected op mode
func (c *Easee) waitForChargerEnabledState(expEnabled bool) error {
	// check any updates received meanwhile
	if c.inExpectedOpMode(expEnabled) {
		return nil
	}

	timer := time.NewTimer(c.Client.Timeout)
	for {
		select {
		case obs := <-c.obsC:
			if obs.ID != easee.CHARGER_OP_MODE {
				continue
			}
			if c.inExpectedOpMode(expEnabled) {
				return nil
			}
		case <-timer.C: // time is up, bail after one final check
			if c.inExpectedOpMode(expEnabled) {
				return nil
			}
			return api.ErrTimeout
		}
	}
}

// wait for current become targetCurrent
func (c *Easee) waitForDynamicChargerCurrent(targetCurrent float64) error {
	// check any updates received meanwhile
	c.mux.RLock()
	if c.dynamicChargerCurrent == targetCurrent {
		c.mux.RUnlock()
		return nil
	}
	c.mux.RUnlock()

	timer := time.NewTimer(c.Client.Timeout)
	for {
		select {
		case obs := <-c.obsC:
			if obs.ID != easee.DYNAMIC_CHARGER_CURRENT {
				continue
			}
			value, err := obs.TypedValue()
			if err != nil {
				continue
			}
			if value.(float64) == targetCurrent {
				return nil
			}
		case <-timer.C: // time is up, bail after one final check
			c.mux.RLock()
			defer c.mux.RUnlock()
			if c.dynamicChargerCurrent == targetCurrent {
				return nil
			}
			return api.ErrTimeout
		}
	}
}

// MaxCurrent implements the api.Charger interface
func (c *Easee) MaxCurrent(current int64) error {
	cur := float64(current)
	if c.maxChargerCurrent != 0 {
		cur = min(cur, c.maxChargerCurrent)
	}
	data := easee.ChargerSettings{
		DynamicChargerCurrent: &cur,
	}

	uri := fmt.Sprintf("%s/chargers/%s/settings", easee.API, c.charger)
	noop, err := c.postJSONAndWait(uri, data)
	if err != nil {
		return err
	}

	if !noop {
		if err := c.waitForDynamicChargerCurrent(float64(current)); err != nil {
			return err
		}
	}

	c.mux.Lock()
	defer c.mux.Unlock()
	c.current = cur

	return nil
}

var _ api.CurrentGetter = (*Easee)(nil)

// GetMaxCurrent implements the api.CurrentGetter interface
func (c *Easee) GetMaxCurrent() (float64, error) {
	c.mux.RLock()
	defer c.mux.RUnlock()
	return c.dynamicChargerCurrent, nil
}

var _ api.Meter = (*Easee)(nil)

// CurrentPower implements the api.Meter interface
func (c *Easee) CurrentPower() (float64, error) {
	if status, err := c.Status(); err != nil || status == api.StatusA {
		return 0, err
	}

	c.mux.RLock()
	defer c.mux.RUnlock()

	return c.currentPower, nil
}

var _ api.ChargeRater = (*Easee)(nil)

// ChargedEnergy implements the api.ChargeRater interface
func (c *Easee) ChargedEnergy() (float64, error) {
	c.mux.RLock()
	defer c.mux.RUnlock()
	return c.sessionEnergy, nil
}

var _ api.PhaseCurrents = (*Easee)(nil)

// Currents implements the api.PhaseCurrents interface
func (c *Easee) Currents() (float64, float64, float64, error) {
	c.mux.RLock()
	defer c.mux.RUnlock()
	return c.currentL1, c.currentL2, c.currentL3, nil
}

var _ api.MeterEnergy = (*Easee)(nil)

// TotalEnergy implements the api.MeterEnergy interface
func (c *Easee) TotalEnergy() (float64, error) {
	c.mux.RLock()
	defer c.mux.RUnlock()
	// updates for this are only sent once an hour, so inaccurate by design
	// see also https://github.com/evcc-io/evcc/issues/20594
	return c.totalEnergy, nil
}

var _ api.PhaseSwitcher = (*Easee)(nil)

// Phases1p3p implements the api.PhaseSwitcher interface
func (c *Easee) Phases1p3p(phases int) error {
	var err error
	if c.circuit != 0 {
		// circuit level
		uri := fmt.Sprintf("%s/sites/%d/circuits/%d/settings", easee.API, c.site, c.circuit)

		var res easee.CircuitSettings
		if err := c.GetJSON(uri, &res); err != nil {
			return err
		}

		if res.MaxCircuitCurrentP1 == nil || res.MaxCircuitCurrentP2 == nil || res.MaxCircuitCurrentP3 == nil {
			return errors.New("MaxCircuitCurrent must not be nil")
		}

		var zero float64
		max1 := *res.MaxCircuitCurrentP1
		max2 := *res.MaxCircuitCurrentP2
		max3 := *res.MaxCircuitCurrentP3

		data := easee.CircuitSettings{
			DynamicCircuitCurrentP1: &max1,
			DynamicCircuitCurrentP2: &zero,
			DynamicCircuitCurrentP3: &zero,
		}

		if phases > 1 {
			data.DynamicCircuitCurrentP2 = &max2
			data.DynamicCircuitCurrentP3 = &max3
		}

		_, err = c.postJSONAndWait(uri, data)
	} else {
		// charger level
		if phases == 3 {
			phases = 2 // mode 2 means auto
		}

		// change phaseMode only if necessary
		if phases != c.phaseMode {
			data := easee.ChargerSettings{
				PhaseMode: &phases,
			}

			uri := fmt.Sprintf("%s/chargers/%s/settings", easee.API, c.charger)

			if _, err = c.postJSONAndWait(uri, data); err != nil {
				return err
			}
		}
		// disable charger to activate changed settings (loadpoint will reenable it)
		err = c.Enable(false)
	}

	return err
}

var _ api.PhaseGetter = (*Easee)(nil)

// GetPhases implements the api.PhaseGetter interface
func (c *Easee) GetPhases() (int, error) {
	c.mux.RLock()
	defer c.mux.RUnlock()
	var phases int
	if c.circuit != 0 {
		// circuit level controlled charger
		for _, dcc := range c.dynamicCircuitCurrent {
			if dcc > 0 {
				phases++
			}
		}
	} else {
		// charger level
		phases = c.phaseMode
		if phases == 2 { // map automatic to 3p
			phases = 3
		}
	}
	return phases, nil
}

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

// Currents implements the api.PhaseCurrents interface
func (c *Easee) Identify() (string, error) {
	c.mux.Lock()
	defer c.mux.Unlock()

	return c.rfid, nil
}

// Set smart charging status to update the chargers led (smart=blue, fast=white)
func (c *Easee) updateSmartCharging() {
	if c.lp == nil {
		return
	}

	mode := c.lp.GetMode()
	isSmartCharging := mode == api.ModePV || mode == api.ModeMinPV

	c.mux.Lock()
	updateNeeded := c.opMode != easee.ModeDisconnected && isSmartCharging != c.smartCharging
	c.mux.Unlock()

	if updateNeeded {
		data := easee.ChargerSettings{
			SmartCharging: &isSmartCharging,
		}

		uri := fmt.Sprintf("%s/chargers/%s/settings", easee.API, c.charger)

		if _, err := c.postJSONAndWait(uri, data); err != nil {
			c.log.WARN.Printf("smart charging: %v", err)
			return
		}

		c.mux.Lock()
		c.smartCharging = isSmartCharging
		c.mux.Unlock()
	}
}

var _ loadpoint.Controller = (*Easee)(nil)

// LoadpointControl implements loadpoint.Controller
func (c *Easee) LoadpointControl(lp loadpoint.API) {
	c.lp = lp
}