import { normalizeFilter } from './filter.js';
import { encodeIdSwitches, decodeIdSwitches } from '../../data/idSwitches.js';

/**
 * Provider params plus the filter. Custom switches share a stable ID-based
 * field; Mapillary retains its existing boolean and share token.
 * @param {{providers: Iterable<[string, boolean]>, filter: {pano: string, sinceDays: number}}} input
 */
export function encodeParams({ providers, filter }) {
  const params = {};
  const entries = [...providers];
  for (const [id, on] of entries) params[id] = on === true;
  const switches = encodeIdSwitches(
    entries.filter(([id]) => id !== 'mapillary'),
  );
  if (switches) params.providerSwitches = switches;
  params.pano = filter.pano;
  params.sinceDays = filter.sinceDays;
  return params;
}

/**
 * Read params back, ignoring unknown providers and malformed values so a link
 * from a build with more providers still applies.
 * @param {object} params
 * @param {{providerIds: Iterable<string>, filter: {pano: string, sinceDays: number}}} current
 * @returns {{providers: Map<string, boolean>, filter: {pano: string, sinceDays: number}}}
 */
export function decodeParams(params, { providerIds, filter }) {
  const providers = new Map();
  const source = params && typeof params === 'object' ? params : {};
  const switches = decodeIdSwitches(source.providerSwitches);
  switches.delete('mapillary');
  for (const id of providerIds) {
    if (switches.has(id)) providers.set(id, switches.get(id));
    else if (Object.hasOwn(source, id) && typeof source[id] === 'boolean')
      providers.set(id, source[id]);
  }
  const next = {};
  if ('pano' in source) next.pano = source.pano;
  if ('sinceDays' in source) next.sinceDays = source.sinceDays;
  return { providers, filter: normalizeFilter(next, filter) };
}