@startuml

start
note left
    Do this for each item in the list.
    An item has a name, a sell in value and a quality value
end note

if (not "Aged Brie" and not "Backstage passes to a TAFKAL80ETC concert") then (yes)
    if (quality > 0) then (yes)
        if (not "Sulfuras, Hand of Ragnaros") then (yes)
            -lower quality with 1
        endif
    endif
else (no)
    if (quality < 50) then (yes)
        -increase quality with 1
        if ("Backstage passes to a TAFKAL80ETC concert") then (yes)
            if (sell in < 11) then (yes)
                if (quality < 50) then (yes)
                    -increase quality with 1
                endif
            endif
            if (sell in < 6) then (yes)
                if (quality < 50) then (yes)
                    -increase quality with 1
                endif
            endif
        endif
    endif
endif

if (not "Sulfuras, Hand of Ragnaros") then (yes)
    -lower quality with 1
endif

if (sell in < 0) then (yes)
    if (not "Aged Brie") then (yes)
        if (not "Backstage passes to a TAFKAL80ETC concert") then (yes)
            if (quality > 0) then (yes)
                if (not "Sulfuras, Hand of Ragnaros") then (yes)
                    -lower quality with 1
                endif
            endif
        else (no)
            -lower quality with quality
        endif
    else (no)
        if (quality < 50) then (yes)
            -increase quality with 1
        endif
    endif
endif

stop

@enduml