import { BUILD_KANBOARD_SUCCESS, MOVE_CARD } from "../actions/kanboards";

export const defaultState = {
  byID: {},
};

export function kanboardsReducer(state = defaultState, action) {
  switch(action.type) {
    case BUILD_KANBOARD_SUCCESS:
      return handleBuildKanboardSuccess(state, action);
    case MOVE_CARD:
      return handleMoveCard(state, action);
    default:
      return state;
  }
}

function handleBuildKanboardSuccess(state, action) {
  return {
    ...state,
    byID: {
      ...state.byID,
      [action.kanboard.id]: {
        ...action.kanboard,
      }
    }
  };
}

function handleMoveCard(state, action) {
  const { 
    boardID, fromLaneID, 
    fromPosition, toLaneID, 
    toPosition 
  } = action;

  const kanboard = state.byID[boardID];

  const lanes = [ ...kanboard.lanes ];
  const fromLane = lanes[fromLaneID];
  const toLane = lanes[toLaneID];
  const card = fromLane.cards[fromPosition];

  const fromCards = [ ...fromLane.cards ];
  if (fromLaneID !== toLaneID) {
    fromCards.splice(fromPosition, 1);
    lanes[fromLaneID] = {
      ...fromLane,
      cards: fromCards,
    };
  
    const toCards = [ ...toLane.cards ];
    toCards.splice(toPosition, 0, card);
    lanes[toLaneID] = {
      ...toLane,
      cards: toCards,
    };
  } else {
    fromCards.splice(fromPosition, 1);
    fromCards.splice(toPosition, 0, card);
  }

  return {
    ...state,
    byID: {
      ...state.byID,
      [boardID]: {
        ...state.byID[boardID],
        lanes,
      },
    }
  };
}