package main

import "math"

// daemonState contains all the state of the daemon. A copy of it can be
// requested for consumers, eg. the web view.
type daemonState struct {
	safety safetyStatus

	// adcPiraniVolts is a moving window of read ADC values, used to calculate a
	// moving average.
	adcPiraniVolts []float32
	rpOn           bool
	dpOn           bool

	vent       momentaryOutput
	pumpdown   momentaryOutput
	aboveRough thresholdOutput
	aboveHigh  thresholdOutput
}

type safetyStatus struct {
	// failsafe mode is enabled when the pirani gauge appears to be
	// disconnected, and is disabled only when an atmosphere is read.
	failsafe bool
	// highPressure mode is enabled when the pressure reading is above 1e-1
	// mbar, locking out the diffusion pump from being enabled.
	highPressure bool
}

type piraniDetection uint

const (
	// piraniDetectionUnknown means the system isn't yet sure whether the pirani
	// gauge is connected.
	piraniDetectionUnknown piraniDetection = iota
	// piraniDetectionConnected means the system assumes the pirani gauge is
	// connected.
	piraniDetectionConnected = iota
	// piraniDetectionDisconnected means the system assumes the pirani gauge is
	// disconnected.
	piraniDetectionDisconnected = iota
)

// piraniDetection guesses whether the pirani gauge is connected.
func (d *daemonState) piraniDetection() piraniDetection {
	if len(d.adcPiraniVolts) < 3 {
		return piraniDetectionUnknown
	}
	volts := float32(0.0)
	for _, v := range d.adcPiraniVolts[len(d.adcPiraniVolts)-3:] {
		volts += v
	}
	volts /= 3.0

	bar := math.Pow(10.0, float64(volts)-8.5)
	mbar := float32(bar * 1000.0)

	if mbar < 4e-6 {
		return piraniDetectionDisconnected
	}
	return piraniDetectionConnected
}

func (d *daemonState) pirani() (volts float32, mbar float32) {
	volts = 0.0
	for _, v := range d.adcPiraniVolts {
		volts += v
	}
	if len(d.adcPiraniVolts) != 0 {
		volts /= float32(len(d.adcPiraniVolts))
	}

	// Per Pirani probe docs.
	bar := math.Pow(10.0, float64(volts)-8.5)
	mbar = float32(bar * 1000.0)
	return
}

func (d *daemonState) vacuumStatus() (rough, high bool) {
	rough = !d.aboveRough.output
	high = !d.aboveHigh.output
	return
}