/**
 * @file unitAutomat.js
 * @description Manages allowable units of measure (Stück, kg, Liter, etc.)
 * for the active company.
 *
 * Upstream Triggers:
 * - `authAutomat`: Subscribes to auth state changes — calls `actions.load()` on
 *   `'authed'` with a `selectedCompanyId`, and `actions.reset()` on `'anon'`.
 * - UI / Settings: Mutating actions (`upsert`, `delete`).
 */

import { Automat } from 'react-automat';
import { unit as unitApi } from '../api';
import authAutomat from './authAutomat';

/**
 * @typedef {Object} UnitState
 * @property {Array<object>} units
 * @property {'idle'|'loading'|'succeeded'|'failed'} status
 * @property {string|null} error
 */

/** @type {UnitState} */
const initialState = {
  units: [],
  status: 'idle',
  error: null,
};

function sortUnits(units) {
  return [...units].sort((a, b) => {
    const left = a.symbol ?? a.si ?? '';
    const right = b.symbol ?? b.si ?? '';
    return String(left).localeCompare(String(right), 'de');
  });
}

let unitAutomat;

const actions = {
  /** Load all units for the selected company. */
  async load() {
    unitAutomat.setState({ status: 'loading', error: null });
    try {
      const res = await unitApi.list();
      const units = sortUnits(Array.isArray(res.units) ? res.units : []);
      unitAutomat.setState({ units, status: 'succeeded' });
      return units;
    } catch (err) {
      unitAutomat.setState({ status: 'failed', error: err?.message ?? String(err) });
      throw err;
    }
  },

  /**
   * Upsert (create or update) a unit.
   * @param {object} body
   */
  async upsert(body) {
    const res = await unitApi.upsert(body);
    const row = res.unit;
    const units = sortUnits([
      ...unitAutomat.state.units.filter((u) => u.si !== row.si),
      row,
    ]);
    unitAutomat.setState({ units });
    return units;
  },

  /**
   * Delete a unit by SI symbol.
   * @param {string} si
   */
  async delete(si) {
    await unitApi.delete(si);
    unitAutomat.setState({
      units: unitAutomat.state.units.filter((u) => u.si !== si),
    });
  },

  /** Reset to idle state (called on logout / company switch). */
  reset() {
    unitAutomat.setState(initialState);
  },
};

/**
 * Global unit state container.
 * Loads automatically when authAutomat reaches 'authed' with a selectedCompanyId.
 *
 * @type {Automat<UnitState>}
 */
unitAutomat = new Automat(initialState, actions, { name: 'unit' });

// Subscribe to auth changes
authAutomat.subscribe((auth) => {
  const companyId = auth.user?.selectedCompanyId;
  if (auth.status === 'authed' && companyId) {
    void unitAutomat.actions.load();
  } else if (auth.status === 'anon') {
    unitAutomat.actions.reset();
  }
});

export default unitAutomat;