import { type Timestamp } from "../timestamp";
import buildDocFromHash from "./buildDocFromHash";
import { type DocumentHash } from "./buildDocFromHash.model";
import {
  type MockedQuerySnapshot,
  type QueryFilter,
} from "./buildQuerySnapShot.model";

/**
 * Builds a query result from the given array of record objects.
 *
 * @param requestedRecords
 * @param filters
 */
export default function buildQuerySnapShot(
  requestedRecords: DocumentHash[],
  filters?: QueryFilter[],
  selectFields?: string[]
): MockedQuerySnapshot {
  const definiteRecords = requestedRecords.filter((rec) => !!rec);
  const results = _filteredDocuments(definiteRecords, filters);
  const docs = results.map((doc) =>
    buildDocFromHash(doc, "abc123", selectFields)
  );

  return {
    empty: results.length < 1,
    size: results.length,
    docs,
    forEach(callback) {
      docs.forEach(callback);
    },
    docChanges() {
      return [];
    },
  };
}

/**
 * @typedef DocumentHash
 * @type {import('./buildDocFromHash').DocumentHash}
 */

/**
 * @typedef Comparator
 * @type {import('./buildQuerySnapShot').Comparator}
 */

/**
 * Applies query filters to an array of mock document data.
 *
 * @param {Array<DocumentHash>} records The array of records to filter.
 * @param {Array<{ key: string; comp: Comparator; value: unknown }>=} filters The filters to apply.
 * If no filters are provided, then the records array is returned as-is.
 *
 * @returns {Array<import('./buildDocFromHash').DocumentHash>} The filtered documents.
 */
function _filteredDocuments(
  records: DocumentHash[],
  filters?: QueryFilter[]
): DocumentHash[] {
  if (filters == null || !Array.isArray(filters) || filters.length === 0) {
    return records;
  }

  filters.forEach(({ key, comp, value }) => {
    // https://firebase.google.com/docs/reference/js/firebase.firestore#wherefilterop
    // Convert values to string to make Array comparisons work
    // See https://jsbin.com/bibawaf/edit?js,console

    if (!(typeof key === 'string')) {
      key = 'id';
    }

    switch (comp) {
      // https://firebase.google.com/docs/firestore/query-data/queries#query_operators
      case "<":
        records = _recordsLessThanValue(records, key, value);
        break;

      case "<=":
        records = _recordsLessThanOrEqualToValue(records, key, value);
        break;

      case "==":
        records = _recordsEqualToValue(records, key, value);
        break;

      case "!=":
        records = _recordsNotEqualToValue(records, key, value);
        break;

      case ">=":
        records = _recordsGreaterThanOrEqualToValue(records, key, value);
        break;

      case ">":
        records = _recordsGreaterThanValue(records, key, value);
        break;

      case "array-contains":
        records = _recordsArrayContainsValue(records, key, value);
        break;

      case "in":
        records = _recordsWithValueInList(records, key, value);
        break;

      case "not-in":
        records = _recordsWithValueNotInList(records, key, value);
        break;

      case "array-contains-any":
        records = _recordsWithOneOfValues(records, key, value);
        break;
    }
  });

  return records;
}

function byString(o: any, s: string) {
  s = s.replace(/\[(\w+)\]/g, '.$1'); // convert indexes to properties
  s = s.replace(/^\./, '');           // strip a leading dot
  var a = s.split('.');
  for (var i = 0, n = a.length; i < n; ++i) {
    var k = a[i];
    if (k in o) {
      o = o[k];
    } else {
      return;
    }
  }
  return o;
}


function _recordsWithKey(records: DocumentHash[], key: string): DocumentHash[] {
  return records.filter((record) => byString(record, key) !== undefined);
}

function _recordsWithNonNullKey(
  records: DocumentHash[],
  key: string
): DocumentHash[] {
  return records.filter((record) => record?.[key] != null);
}

function _shouldCompareTimestamp(a: unknown, b: unknown): a is Timestamp {
  // We check whether toMillis method exists to support both Timestamp mock and Firestore Timestamp object
  // B is expected to be Date, not Timestamp, just like Firestore does
  return (
    typeof a === "object" &&
    a !== null &&
    typeof (a as Record<string, unknown>).toMillis === "function" &&
    b instanceof Date
  );
}

function _recordsLessThanValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return _recordsWithNonNullKey(records, key).filter((record) => {
    const recordValue = byString(record, key);
    if (typeof recordValue === "number" && typeof value === "number") {
      return recordValue < value;
    }
    if (_shouldCompareTimestamp(recordValue, value)) {
      return recordValue.toMillis() < (value as Date).getTime();
    }
    return String(byString(record, key)) < String(value);
  });
}

function _recordsLessThanOrEqualToValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return _recordsWithNonNullKey(records, key).filter((record) => {
    const recordValue = byString(record, key);
    if (typeof recordValue === "number" && typeof value === "number") {
      return recordValue <= value;
    }
    if (_shouldCompareTimestamp(recordValue, value)) {
      return recordValue.toMillis() <= (value as Date).getTime();
    }
    return String(byString(record, key)) <= String(value);
  });
}

function _recordsEqualToValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return _recordsWithKey(records, key).filter((record) => {
    const recordValue = byString(record, key);
    if (_shouldCompareTimestamp(recordValue, value)) {
      // NOTE: for equality, we must compare numbers!
      return recordValue.toMillis() === (value as Date).getTime();
    }
    return String(byString(record, key)) === String(value);
  });
}

function _recordsNotEqualToValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return _recordsWithKey(records, key).filter((record) => {
    const recordValue = byString(record, key);
    if (_shouldCompareTimestamp(recordValue, value)) {
      // NOTE: for equality, we must compare numbers!
      return recordValue.toMillis() !== (value as Date).getTime();
    }
    return String(byString(record, key)) !== String(value);
  });
}

function _recordsGreaterThanOrEqualToValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return _recordsWithNonNullKey(records, key).filter((record) => {
    const recordValue = byString(record, key);
    if (typeof recordValue === "number" && typeof value === "number") {
      return recordValue >= value;
    }
    if (_shouldCompareTimestamp(recordValue, value)) {
      return recordValue.toMillis() >= (value as Date).getTime();
    }
    return String(byString(record, key)) >= String(value);
  });
}

function _recordsGreaterThanValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return _recordsWithNonNullKey(records, key).filter((record) => {
    const recordValue = byString(record, key);
    if (typeof recordValue === "number" && typeof value === "number") {
      return recordValue > value;
    }
    if (_shouldCompareTimestamp(recordValue, value)) {
      return recordValue.toMillis() > (value as Date).getTime();
    }
    return String(byString(record, key)) > String(value);
  });
}

/**
 * @see https://firebase.google.com/docs/firestore/query-data/queries#array_membership
 */
function _recordsArrayContainsValue(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  return records.filter(
    (record) =>
      record?.[key] &&
      Array.isArray(byString(record, key)) &&
      (byString(record, key) as unknown[]).includes(value)
  );
}

/**
 * @see https://firebase.google.com/docs/firestore/query-data/queries#in_not-in_and_array-contains-any
 */
function _recordsWithValueInList(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  // TODO: Throw an error when a value is passed that contains more than 10 values
  return records.filter((record) => {
    if (!record || byString(record, key) === undefined) {
      return false;
    }
    return value && Array.isArray(value) && value.includes(byString(record, key));
  });
}

/**
 * @see https://firebase.google.com/docs/firestore/query-data/queries#not-in
 */
function _recordsWithValueNotInList(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  // TODO: Throw an error when a value is passed that contains more than 10 values
  return _recordsWithKey(records, key).filter(
    (record) => value && Array.isArray(value) && !value.includes(byString(record, key))
  );
}

/**
 * @see https://firebase.google.com/docs/firestore/query-data/queries#in_not-in_and_array-contains-any
 */
function _recordsWithOneOfValues(
  records: DocumentHash[],
  key: string,
  value: unknown
): DocumentHash[] {
  // TODO: Throw an error when a value is passed that contains more than 10 values
  return records.filter(
    (record) =>
      record?.[key] &&
      Array.isArray(byString(record, key)) &&
      value &&
      Array.isArray(value) &&
      (byString(record, key) as unknown[]).some((v) => value.includes(v))
  );
}