@Override
public DevToolsState<S> reduce(DevToolsState<S> state, Action action) {
if (!(action instanceof DevToolsAction)) {
throw new IllegalArgumentException(
"When using the Dev Tools, all actions must be wrapped as a DevToolsAction");
}
DevToolsAction devToolsAction = (DevToolsAction) action;
switch (devToolsAction.getType()) {
case DevToolsAction.INIT:
final S initialState = appReducer.reduce(state.getCurrentAppState(), action);
return new DevToolsState<>(
Collections.singletonList(initialState), Collections.singletonList(action), 0);
case DevToolsAction.PERFORM_ACTION:
final boolean addToEnd = state.getCurrentPosition() == state.getComputedStates().size() - 1;
return performAction(
state,
devToolsAction,
addToEnd
? state.getComputedStates()
: state.getComputedStates().subList(0, state.getCurrentPosition() + 1),
addToEnd
? state.getStagedActions()
: state.getStagedActions().subList(0, state.getCurrentPosition() + 1));
case DevToolsAction.RESET:
return new DevToolsState<>(
Collections.singletonList(state.getCommittedState()),
Collections.<Action>singletonList(devToolsAction),
0);
case DevToolsAction.SAVE:
return new DevToolsState<>(
Collections.singletonList(state.getCurrentAppState()),
Collections.singletonList(action),
0);
case DevToolsAction.JUMP_TO_STATE:
return new DevToolsState<>(
state.getComputedStates(), state.getStagedActions(), devToolsAction.getPosition());
case DevToolsAction.RECOMPUTE:
return new DevToolsState<>(
recomputeStates(state.getComputedStates(), state.getStagedActions()),
state.getStagedActions(),
state.getStagedActions().size() - 1);
default:
return state;
}
}
private List<S> recomputeStates(List<S> computedStates, List<Action> stagedActions) {
List<S> recomputedStates = new ArrayList<>(computedStates.size());
S currentState = computedStates.get(0);
for (int i = 0; i < computedStates.size(); i++) {
Action currentAction = stagedActions.get(i);
currentState = appReducer.reduce(currentState, currentAction);
recomputedStates.add(currentState);
}
return recomputedStates;
}
private DevToolsState<S> performAction(
DevToolsState<S> state,
DevToolsAction devToolsAction,
List<S> computedStates,
List<Action> stagedActions) {
List<S> newStates = new ArrayList<>(computedStates);
List<Action> newActions = new ArrayList<>(stagedActions);
newStates.add(appReducer.reduce(state.getCurrentAppState(), devToolsAction.getAppAction()));
newActions.add(devToolsAction.getAppAction());
return new DevToolsState<>(newStates, newActions, newStates.size() - 1);
}