package sensor

import (
	"context"
	"fmt"
	"sync"

	"github.com/go-flucky/flucky/pkg/internal/collect"
	"github.com/go-flucky/flucky/pkg/internal/prittyprint"

	"github.com/go-flucky/flucky/pkg/types"
)

// Read measured values from sensors
func Read(ctx context.Context, sensors []Sensor) ([]*types.MeasuredValue, error) {

	measuredValuesChannel := make(chan []*types.MeasuredValue, len(sensors))
	errorChannel := make(chan error, len(sensors))

	ReadChannel(ctx, sensors, measuredValuesChannel, errorChannel)

	errors := collect.Errors(errorChannel)
	if len(errors) > 0 {
		return nil, prittyprint.FormatErrors(errors)
	}

	measuredValues := collect.MeasuredValues(measuredValuesChannel)

	return measuredValues, nil
}

// ReadChannel reads the measured values from sensors and writes them to a
// channel.
func ReadChannel(ctx context.Context, sensors []Sensor, measuredValuesChannel chan<- []*types.MeasuredValue, errorChannel chan<- error) {

	wg := new(sync.WaitGroup)
	wg.Add(len(sensors))

	for _, sensor := range sensors {
		go sensor.ReadChannel(measuredValuesChannel, errorChannel, wg)
	}

	wg.Wait()
}

// ReadContinuously reads the measured values continously from sensors and writes
// them to a channel.
func ReadContinuously(ctx context.Context, sensors []Sensor, measuredValuesChannel chan<- []*types.MeasuredValue, errorChannel chan<- error) {
	for {
		select {
		case <-ctx.Done():
			errorChannel <- fmt.Errorf("Context closed: %v", ctx.Err())
			return
		default:
			ReadChannel(ctx, sensors, measuredValuesChannel, errorChannel)
		}
	}
}