/**
 * @file entityAutomat.js
 * @description Manages cached customer and contact entities (`GET /api/entity`)
 * for the active company. Follows the brand/warehouse/customergroup automat pattern
 * with filtering, deduplicated loads, silent reloads, and CRUD actions.
 *
 * Upstream Triggers:
 * - `authAutomat`: Triggers `actions.load()` on `'authed'` with a `selectedCompanyId`,
 *   and `actions.reset()` on `'anon'`.
 * - UI / Routes: Mutating actions (`create`, `update`, `remove`, `filter`).
 */

import { Automat } from 'react-automat';
import { entity as entityApi } from '../api';
import { requireArray, requireDefined, requireObject } from '../utils/apiShape';
import authAutomat from './authAutomat';
import customergroupAutomat from './customergroupAutomat';

/**
 * @typedef {Object} Entity
 * @property {string|number} id Entity id.
 * @property {string|number} customergroupId Owning customer group id.
 * @property {string} [number] Customer number.
 * @property {string|null} [firstName] First name.
 * @property {string} name Last / company name.
 * @property {string} [createdAt] Created timestamp.
 * @property {string} [updatedAt] Updated timestamp.
 */

/**
 * @typedef {Object} EntityState
 * @property {Array<Entity>} items Loaded records.
 * @property {Array<Entity>} filteredItems Records matching active search filter.
 * @property {string} filter Active search/filter string.
 * @property {'idle'|'loading'|'ready'|'failed'} status Load lifecycle state.
 * @property {Error|string|null} error Last load error.
 */

/** @type {EntityState} */
const initialState = {
  items: [],
  filteredItems: [],
  filter: '',
  status: 'idle',
  error: null,
};

const applyFilter = (entities, filter) => {
  const query = String(filter ?? '').trim().toLowerCase();
  if (!query) return entities;
  const groups = customergroupAutomat?.state?.items ?? [];
  const groupsById = Object.fromEntries(groups.map((g) => [g.id, g]));

  return entities.filter((e) => {
    const name = String(e.name ?? '').toLowerCase();
    const firstName = String(e.firstName ?? '').toLowerCase();
    const number = String(e.number ?? '').toLowerCase();
    const full1 = `${firstName} ${name}`.trim();
    const full2 = `${name} ${firstName}`.trim();
    const group = String(groupsById[e.customergroupId]?.name ?? '').toLowerCase();
    return (
      name.includes(query) ||
      firstName.includes(query) ||
      number.includes(query) ||
      full1.includes(query) ||
      full2.includes(query) ||
      group.includes(query)
    );
  });
};

const sortEntities = (items) =>
  [...items].sort((a, b) => {
    const byName = String(a.name ?? '').localeCompare(String(b.name ?? ''), 'de');
    if (byName !== 0) return byName;
    return String(a.firstName ?? '').localeCompare(String(b.firstName ?? ''), 'de');
  });

let entityAutomat;

const updateStateWithEntities = (entities, extra = {}) => {
  const list = sortEntities(Array.isArray(entities) ? entities : []);
  const filteredItems = applyFilter(list, entityAutomat.state.filter);
  entityAutomat.setState({ items: list, filteredItems, ...extra });
  return list;
};

async function fetchEntities() {
  const data = await entityApi.list();
  requireObject(data, 'GET /api/entity');
  return requireArray(data.entities, 'entities');
}

let inflightLoad = null;

function loadEntities() {
  if (inflightLoad) return inflightLoad;
  inflightLoad = (async () => {
    entityAutomat.setState({ status: 'loading', error: null });
    try {
      const entities = await fetchEntities();
      updateStateWithEntities(entities, { status: 'ready', error: null });
      return entities;
    } catch (error) {
      entityAutomat.setState({ status: 'failed', error });
      throw error;
    } finally {
      inflightLoad = null;
    }
  })();
  return inflightLoad;
}

const actions = {
  /** Sets the active search filter query and updates filteredItems. */
  filter(query) {
    const filter = String(query ?? '');
    entityAutomat.setState({
      filter,
      filteredItems: applyFilter(entityAutomat.state.items, filter),
    });
  },

  /** Loads the list, deduplicating concurrent callers. */
  load() {
    return loadEntities();
  },

  /** Silently refreshes the entities without flashing loading state. */
  async reload() {
    try {
      const entities = await fetchEntities();
      updateStateWithEntities(entities, { status: 'ready', error: null });
      return entities;
    } catch (error) {
      entityAutomat.setState({ error });
      throw error;
    }
  },

  /** Replaces the cached list without an API call. */
  replace(items) {
    return updateStateWithEntities(items, { status: 'ready', error: null });
  },

  /** Returns cached items if ready, otherwise loads. */
  ensureLoaded() {
    if (entityAutomat.state.status === 'ready') {
      return Promise.resolve(entityAutomat.state.items);
    }
    return actions.load();
  },

  /** Resets state to initial idle values. */
  reset() {
    inflightLoad = null;
    entityAutomat.setState(initialState);
  },

  /** Creates a customer entity and refreshes the cache. */
  async create(body) {
    const data = await entityApi.create(body);
    requireObject(data, 'POST /api/entity');
    requireObject(data.entity, 'entity');
    requireDefined(data.entity.id, 'entity.id');
    await entityAutomat.actions.reload();
    return data.entity;
  },

  /** Updates an entity name/fields and refreshes the cache. */
  async update(id, body) {
    const data = await entityApi.update(id, body);
    requireObject(data, 'PATCH /api/entity/:id');
    requireObject(data.entity, 'entity');
    requireDefined(data.entity.id, 'entity.id');
    await entityAutomat.actions.reload();
    return data.entity;
  },

  rename(id, body) {
    return actions.update(id, body);
  },

  /** Deletes an entity and refreshes the cache. */
  async remove(id) {
    await entityApi.delete(id);
    await entityAutomat.actions.reload();
  },
};

/**
 * Company customers and contacts (`GET /api/entity`).
 *
 * @type {Automat<EntityState>}
 */
entityAutomat = new Automat(initialState, actions, {
  name: 'entity',
});

export { entityAutomat };

// Load on session/company establishment, reset on logout.
authAutomat.subscribe((auth) => {
  const companyId = auth.user?.selectedCompanyId;
  if (auth.status === 'authed' && companyId) {
    void actions.load().catch(() => {});
  } else if (auth.status === 'anon') {
    actions.reset();
  }
});

export default entityAutomat;