package sensor

import (
	"github.com/volker-raschek/flucky/pkg/types"
)

func Read(sensors []Sensor, measuredValueType types.MeasuredValueType) ([]*types.MeasuredValue, error) {

	type result struct {
		measuredValues []*types.MeasuredValue
		err            error
	}

	resultChannel := make(chan *result, len(sensors))

	// producers
	// read measured values
	for _, s := range sensors {
		go func(s Sensor) {
			measuredValues, err := s.Read()
			resultChannel <- &result{
				measuredValues: measuredValues,
				err:            err,
			}
		}(s)
	}

	// consumer
	measuredValues := make([]*types.MeasuredValue, 0)
	counter := len(sensors)
	for {
		if counter == 0 {
			break
		}
		select {
		case result := <-resultChannel:
			counter--
			if result.err != nil {
				return nil, result.err
			}
			measuredValues = append(measuredValues, result.measuredValues...)
		}
	}

	return types.SelectMeasuredValues(measuredValueType, measuredValues), nil
}