local poweredClimb = 0
local glideClimb = 0
local lastAltitude
local playedAlarm = false

local engineSwitch
local resetSwitch
local alarmAlt
local altSensorIndex

local sensorIDs
local sensorParams
local sensorLabels

local function onEngineSwitchChanged(value)
    engineSwitch = system.getInputsVal(value) ~= 0 and value or nil
    system.pSave("enginesw", engineSwitch)
end

local function onAlarmAltChanged(value)
    alarmAlt = value
    system.pSave("alarmAlt", alarmAlt)
end

local function onResetSwitchChanged(value)
    resetSwitch = system.getInputsVal(value) ~= 0 and value or nil
    system.pSave("resetsw", resetSwitch)
end

local function onAltSensorIndexChanged(value)
    altSensorIndex = value - 1
    system.pSave("altidx", altSensorIndex)
end

local function initForm()
    form.addRow(2)
    form.addLabel({ label = "Engine" })
    form.addInputbox(engineSwitch, false, onEngineSwitchChanged)
    form.addRow(2)
    form.addLabel({ label = "Alarm" })
    form.addIntbox(alarmAlt, 1, 20000, 100, 0, 1, onAlarmAltChanged)
    form.addRow(2)
    form.addLabel({ label = "Altitude sensor" })
    form.addSelectbox(sensorLabels, altSensorIndex + 1, true, onAltSensorIndexChanged)
    form.addRow(2)
    form.addLabel({ label = "Reset" })
    form.addInputbox(resetSwitch, false, onResetSwitchChanged)
end

local function init()
    sensorIDs = {}
    sensorParams = {}
    sensorLabels = {"..."}
    for _,sensor in ipairs(system.getSensors()) do
        if sensor.param ~= 0 and sensor.type ~= 5 and sensor.type ~= 9 then
            sensorIDs[#sensorIDs+1] = sensor.id
            sensorParams[#sensorParams+1] = sensor.param
            sensorLabels[#sensorLabels+1] = string.format("%s: %s [%s]", sensor.sensorName, sensor.label, sensor.unit)
        end
    end
    engineSwitch = system.pLoad("enginesw")
    resetSwitch = system.pLoad("resetsw")
    alarmAlt = system.pLoad("alarmAlt", 100)
    altSensorIndex = system.pLoad("altidx", 0)
    if altSensorIndex > #sensorIDs then altSensorIndex = 0 end

    system.registerForm(1, MENU_APPS, "Calculated Capacity", initForm)
end

local function loop()
    if system.getInputsVal(resetSwitch) == 1 then
        poweredClimb = 0
        glideClimb = 0
        playedAlarm = false
    end
    local altitude = altSensorIndex ~= 0 and system.getSensorValueByID(sensorIDs[altSensorIndex], sensorParams[altSensorIndex]) or nil
    if altitude and altitude.valid and lastAltitude then
        if system.getInputsVal(engineSwitch) == 1 and altitude.value > lastAltitude then
            poweredClimb = poweredClimb + altitude.value - lastAltitude
            if poweredClimb >= alarmAlt and not playedAlarm then
                -- ALARM
                system.playBeep(3, 1000, 600)
                playedAlarm = true
            end
        elseif system.getInputsVal(engineSwitch) == -1 and altitude.value > lastAltitude then
            glideClimb = glideClimb + altitude.value - lastAltitude
        end
    end
    lastAltitude = (altitude and altitude.valid) and altitude.value or nil
end

return { init = init, loop = loop, author = "LeonAir RC", version = "1.0.0", name = "Calculated Capacity" }