@startuml

!include skinparams.puml

actor "Opponent" as opponent
actor "GUI Program" as program

boundary "Engine CLI" as cli
control "Play a stone" as playStone
control "Think next move" as think
entity "Board state" as state

loop until starting board is set
    program -> cli : play stone
    cli -> playStone
    playStone -> state
    cli <- state
end

loop until game ends
    program -> cli : ask for move
    cli -> think
    think -> state
    cli <- state : Show move
    opponent -> program : give input
    program -> cli : play stone
    cli -> playStone
    playStone -> state
    cli <- state
end

@enduml