@startuml Storage_Popup

    participant SW                  as SW
    participant UI                  as UI
    actor       USER                as US

    'Possible actions and interaction types
    ' External on CANBus
    ' TD -> SW: MSG: Message
    ' SW -> TD: MSG: Message

    ' Internal to the application
    ' XX -> YY: CMD: Command
    ' XX -> XX: ACT: Action

    ' External on OS/FS
    ' SW -> Script: ACT: Command
    ' Script -> OS: CMD: Command
    ' Script -> SW: MSG: Message
    ' OS -> Script: MSG: Message

    ' US -> UI: User actions are:
    '   ASK: Display a <message>
    '   ENT: User enters a value or string
    '   TCH: User touches a button (RadioButton, CheckBox, ...)
    '   SCL: User scrolls a flip-able area

    == Storage Popup ==
    loop QTimerEvent
        SW ->o SW: ⟲: ACT: sdcardSpaceCheck()\
                    \n\t Checks for the SD-Card drive space
    
        alt SD-Card is mounted and ready 
            SW -> UI: MSG: emit didSDCardSpaceChange()  \
                    \n\tReady                           \
                    \n\tTotal                           \
                    \n\tAvailable                       \
                    \n\tPercentage                       

        else SD-Card Not Ready
            SW -> UI: MSG: emit didSDCardSpaceChange()  \
                    \n\tReady                           \
                    \n\tTotal                           \
                    \n\tAvailable = 0                   \
                    \n\tPercentage = 0      
        end
    end

    US -> UI: TCH: User touches a storage button
    UI -> UI: ACT: Display SD-Card Information: \
                \n\t\tReady Status                \
                \n\t\tPercentage of Free Space    \
                \n\t\tAvailable Space (MB)        \
                \n\t\tTotal Space (MB)   
@enduml