// update.js
// Pure update function

/**
 * @param {object} state - Current state
 * @param {object} action - { type, payload }
 * @returns {object} new state
 */
export function update(state, action) {
  switch (action.type) {
    case 'UPDATE_QUERY':
      return { ...state, query: action.payload, error: null };
    case 'FETCH_START':
      return { ...state, loading: true, error: null, pokemon: null };
    case 'FETCH_SUCCESS':
      return { ...state, loading: false, error: null, pokemon: action.payload };
    case 'FETCH_ERROR':
      return { ...state, loading: false, error: action.payload, pokemon: null };
    default:
      return state;
  }
}