import { Action } from "../types";
import { getType } from "typesafe-actions";
import {
  fetchRecipesFulfill,
  postCookingSessionFulfill,
  postRecipeFulfill,
} from "../actions";
import { Dict, Entities } from "../entities";

const initialState: Entities = {
  recipes: {},
  cookingSessions: {},
  ingredients: {},
};

export default function entitiesReducer(state = initialState, action: Action) {
  switch (action.type) {
    case getType(fetchRecipesFulfill):
    case getType(postRecipeFulfill):
    case getType(postCookingSessionFulfill): {
      const { entities } = action.meta;
      return Object.keys(state).reduce(
        (state, key) => ({
          ...state,
          [key]: mergeEntities(state[key], entities[key]),
        }),
        state
      );
    }
    default:
      return state;
  }
}

function mergeEntities<T>(entitiesA: Dict<T> = {}, entitiesB: Dict<T> = {}) {
  return Object.keys(entitiesB).reduce(
    (acc, key) => ({
      ...acc,
      [key]: acc[key]
        ? {
            ...acc[key],
            ...entitiesB[key],
          }
        : entitiesB[key],
    }),
    entitiesA
  );
}