package v1

import (
	"context"
	"sync"

	"forge.cadoles.com/cadoles/go-emlid/reach/client/protocol"
	"forge.cadoles.com/cadoles/go-emlid/reach/client/protocol/v1/model"
	"forge.cadoles.com/cadoles/go-emlid/reach/client/socketio"
	"github.com/mitchellh/mapstructure"
	"github.com/pkg/errors"
)

const (
	eventGetConfiguration       = "get configuration"
	eventCurrentConfiguration   = "current configuration"
	eventApplyConfiguration     = "apply configuration"
	eventConfigurationApplied   = "configuration applied"
	eventResetConfiguration     = "reset configuration to default"
	eventSettingsResetToDefault = "settings reset to default"
)

type configurationApplied struct {
	Configuration *model.Configuration `mapstructure:"configuration,omitempty"`
	Result        string               `mapstructure:"result"`
	Constraints   *model.Constraints   `mapstructure:"constraints,omitempty"`
}

func (o *Operations) ApplyConfiguration(ctx context.Context, config *model.Configuration) (string, *model.Configuration, error) {
	res := &configurationApplied{}
	if err := o.ReqResp(ctx, eventApplyConfiguration, config, eventConfigurationApplied, res); err != nil {
		return configurationApplyFailed, nil, err
	}
	return res.Result, res.Configuration, nil
}

func (o *Operations) RequestConfiguration(ctx context.Context) (*model.Configuration, error) {
	configuration := &model.Configuration{}
	if err := o.ReqResp(ctx, eventGetConfiguration, nil, eventCurrentConfiguration, configuration); err != nil {
		return nil, err
	}
	return configuration, nil
}

// ReqResp emits an event with the given data and waits for a response
func (o *Operations) ReqResp(ctx context.Context,
	requestEvent string, requestData any,
	responseEvent string, res any) error {
	o.mutex.RLock()
	defer o.mutex.RUnlock()

	if o.client == nil || !o.client.Alive() {
		return errors.WithStack(protocol.ErrClosed)
	}

	var err error
	var wg sync.WaitGroup
	var once sync.Once

	done := func() {
		o.client.Off(responseEvent)
		wg.Done()
	}

	wg.Add(1)

	go func() {
		<-ctx.Done()
		err = ctx.Err()
		once.Do(done)
	}()

	err = o.client.On(responseEvent, func(_ *socketio.Channel, data interface{}) {
		if res != nil {
			err = mapstructure.WeakDecode(data, res)
		}

		once.Do(done)
	})
	if err != nil {
		return errors.Wrapf(err, "error while binding to '%s' event", responseEvent)
	}

	if err = o.client.Emit(requestEvent, requestData); err != nil {
		return errors.Wrapf(err, "error while emitting event '%s'", requestEvent)
	}

	wg.Wait()

	return err
}