import type { SearchResults } from 'algoliasearch-helper';
import {
  uniq,
  find,
  createDocumentationMessageGenerator,
  warning,
} from '../utils';
import type {
  Hit,
  InsightsClient,
  InsightsClientMethod,
  InsightsClientPayload,
  Connector,
} from '../../types';

const getSelectedHits = (hits: Hit[], selectedObjectIDs: string[]): Hit[] => {
  return selectedObjectIDs.map((objectID) => {
    const hit = find(hits, (h) => h.objectID === objectID);
    if (typeof hit === 'undefined') {
      throw new Error(
        `Could not find objectID "${objectID}" passed to \`clickedObjectIDsAfterSearch\` in the returned hits. This is necessary to infer the absolute position and the query ID.`
      );
    }
    return hit;
  });
};

const getQueryID = (selectedHits: Hit[]): string => {
  const queryIDs = uniq(selectedHits.map((hit) => hit.__queryID));
  if (queryIDs.length > 1) {
    throw new Error(
      'Insights currently allows a single `queryID`. The `objectIDs` provided map to multiple `queryID`s.'
    );
  }
  const queryID = queryIDs[0];
  if (typeof queryID !== 'string') {
    throw new Error(
      `Could not infer \`queryID\`. Ensure InstantSearch \`clickAnalytics: true\` was added with the Configure widget.

See: https://alg.li/lNiZZ7`
    );
  }
  return queryID;
};

const getPositions = (selectedHits: Hit[]): number[] =>
  selectedHits.map((hit) => hit.__position);

export const inferPayload = ({
  method,
  results,
  hits,
  objectIDs,
}: {
  method: InsightsClientMethod;
  results: SearchResults;
  hits: Hit[];
  objectIDs: string[];
}): Omit<InsightsClientPayload, 'eventName'> => {
  const { index } = results;
  const selectedHits = getSelectedHits(hits, objectIDs);
  const queryID = getQueryID(selectedHits);

  switch (method) {
    case 'clickedObjectIDsAfterSearch': {
      const positions = getPositions(selectedHits);
      return { index, queryID, objectIDs, positions };
    }

    case 'convertedObjectIDsAfterSearch':
      return { index, queryID, objectIDs };

    default:
      throw new Error(`Unsupported method passed to insights: "${method}".`);
  }
};

const wrapInsightsClient =
  (
    aa: InsightsClient | null,
    results: SearchResults,
    hits: Hit[]
  ): InsightsClient =>
  (method, ...payloads) => {
    const [payload] = payloads;
    warning(
      false,
      `\`insights\` function has been deprecated. It is still supported in 4.x releases, but not further. It is replaced by the \`insights\` middleware.

For more information, visit https://www.algolia.com/doc/guides/getting-insights-and-analytics/search-analytics/click-through-and-conversions/how-to/send-click-and-conversion-events-with-instantsearch/js/`
    );
    if (!aa) {
      const withInstantSearchUsage = createDocumentationMessageGenerator({
        name: 'instantsearch',
      });
      throw new Error(
        withInstantSearchUsage(
          'The `insightsClient` option has not been provided to `instantsearch`.'
        )
      );
    }
    if (!Array.isArray(payload.objectIDs)) {
      throw new TypeError('Expected `objectIDs` to be an array.');
    }
    const inferredPayload = inferPayload({
      method,
      results,
      hits,
      objectIDs: payload.objectIDs,
    });
    aa(method, { ...inferredPayload, ...payload });
  };

/**
 * @deprecated This function will be still supported in 4.x releases, but not further. It is replaced by the `insights` middleware. For more information, visit https://www.algolia.com/doc/guides/getting-insights-and-analytics/search-analytics/click-through-and-conversions/how-to/send-click-and-conversion-events-with-instantsearch/js/
 * It passes `insights` to `HitsWithInsightsListener` and `InfiniteHitsWithInsightsListener`.
 */
export default function withInsights<TConnector extends Connector<any, any>>(
  connector: TConnector
): TConnector {
  return ((renderFn, unmountFn) =>
    connector((renderOptions, isFirstRender) => {
      const { results, hits, instantSearchInstance } = renderOptions;
      if (results && hits && instantSearchInstance) {
        const insights = wrapInsightsClient(
          instantSearchInstance.insightsClient,
          results,
          hits
        );
        return renderFn({ ...renderOptions, insights }, isFirstRender);
      }
      return renderFn(renderOptions, isFirstRender);
    }, unmountFn)) as TConnector;
}