package scripting import ( "errors" "sync" "git.kirsle.net/go/render/event" "github.com/robertkrimen/otto" ) // Event name constants. const ( CollideEvent = "OnCollide" // another doodad collides with us EnterEvent = "OnEnter" // a doodad is fully inside us LeaveEvent = "OnLeave" // a doodad no longer collides with us // Controllable (player character) doodad events KeypressEvent = "OnKeypress" // i.e. arrow keys ) // Event return errors. var ( ErrReturnFalse = errors.New("JS callback function returned false") ) // Events API for Doodad scripts. type Events struct { registry map[string][]otto.Value lock sync.RWMutex } // NewEvents initializes the Events API. func NewEvents() *Events { return &Events{ registry: map[string][]otto.Value{}, } } // OnCollide fires when another actor collides with yours. func (e *Events) OnCollide(call otto.FunctionCall) otto.Value { return e.register(CollideEvent, call.Argument(0)) } // RunCollide invokes the OnCollide handler function. func (e *Events) RunCollide(v interface{}) error { return e.run(CollideEvent, v) } // OnLeave fires when another actor stops colliding with yours. func (e *Events) OnLeave(call otto.FunctionCall) otto.Value { return e.register(LeaveEvent, call.Argument(0)) } // RunLeave invokes the OnLeave handler function. func (e *Events) RunLeave(v interface{}) error { return e.run(LeaveEvent, v) } // OnKeypress fires when another actor collides with yours. func (e *Events) OnKeypress(call otto.FunctionCall) otto.Value { return e.register(KeypressEvent, call.Argument(0)) } // RunKeypress invokes the OnCollide handler function. func (e *Events) RunKeypress(ev *event.State) error { return e.run(KeypressEvent, ev) } // register a named event. func (e *Events) register(name string, callback otto.Value) otto.Value { if !callback.IsFunction() { return otto.Value{} // TODO } e.lock.Lock() defer e.lock.Unlock() if _, ok := e.registry[name]; !ok { e.registry[name] = []otto.Value{} } e.registry[name] = append(e.registry[name], callback) return otto.Value{} } // Run an event handler. Returns an error only if there was a JavaScript error // inside the function. If there are no event handlers, just returns nil. func (e *Events) run(name string, args ...interface{}) error { e.lock.RLock() defer e.lock.RUnlock() if _, ok := e.registry[name]; !ok { return nil } for _, callback := range e.registry[name] { value, err := callback.Call(otto.Value{}, args...) if err != nil { return err } // If the event handler returned a boolean false, stop all other // callbacks and return the boolean. if value.IsBoolean() { if b, err := value.ToBoolean(); err == nil && b == false { return ErrReturnFalse } } } return nil }