import { type OverlayItem } from './context';

export type OverlayReducerState = {
  overlayList: OverlayItem[];
  current: OverlayItem | null;
};

export type OverlayReducerAction =
  | { type: 'OPEN'; overlay: OverlayItem }
  | { type: 'CLOSE'; overlayId: string }
  | { type: 'CLOSE_ALL' };

export function overlayReducer(
  state: OverlayReducerState,
  action: OverlayReducerAction
): OverlayReducerState {
  switch (action.type) {
    case 'OPEN': {
      return {
        current: action.overlay,
        overlayList: [...state.overlayList, action.overlay],
      };
    }
    case 'CLOSE': {
      const remainingOverlays = state.overlayList.filter((item) => item.id !== action.overlayId);
      if (state.overlayList.length === remainingOverlays.length) return state;

      return {
        current: remainingOverlays[remainingOverlays.length - 1] || state.current,
        overlayList: remainingOverlays,
      };
    }
    case 'CLOSE_ALL': {
      if (state.overlayList.length === 0) return state;

      return {
        current: state.current,
        overlayList: [],
      };
    }
  }
}