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

	piraniVolts100 ringbufferInput
	piraniVolts3   ringbufferInput

	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
)

func piraniVoltsToMbar(v float32) float32 {
	// Per Pirani probe docs.
	bar := math.Pow(10.0, float64(v)-8.5)
	return float32(bar * 1000.0)
}

// piraniDetection guesses whether the pirani gauge is connected.
func (d *daemonState) piraniDetection() piraniDetection {
	if !d.piraniVolts3.saturated() {
		return piraniDetectionUnknown
	}
	mbar := piraniVoltsToMbar(d.piraniVolts3.avg)
	if mbar < 4e-6 {
		return piraniDetectionDisconnected
	}
	return piraniDetectionConnected
}

func (d *daemonState) pirani() (volts float32, mbar float32) {
	volts = d.piraniVolts100.avg
	mbar = piraniVoltsToMbar(volts)
	return
}

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