Autocomplete Cache

cache.ts

import { Client } from "@ideal-postcodes/core-browser";
import { AddressSuggestion, Address } from "@ideal-postcodes/api-typings";

export class ApiCache {
  private client: Client;
  private cache: Record<string, AddressSuggestion[]>;
  private prefix = "!";

  constructor(client: Client) {
    this.client = client;
    this.cache = {};
  }
  
  key(query: string): string {
    return `${this.prefix}${query.toLowerCase()}`;
  }

  retrieve(query: string): AddressSuggestion[] | undefined {
    return this.cache[this.key(query)];
  }

  store(query: string, data: AddressSuggestion[]) {
    this.cache[this.key(query)] = data;
  }

  clear() {
    this.cache = {};
  }
  /**
   * Retrieve a list of address suggestions given a query
   *
   * Write and read from cache if previously requested
   */
  query(query: string): Promise<AddressSuggestion[]> {
    const cachedValue = this.retrieve(query);
    if (cachedValue) return Promise.resolve(cachedValue);

    return this.client.autocomplete
      .list({ query: { query, api_key: this.client.api_key } })
      .then((response) => {
        const suggestions = response.body.result.hits;
        this.store(query, suggestions);
        return suggestions;
      });
  }

  resolve(suggestion: AddressSuggestion): Promise<Address | null> {
    const { umprn, udprn } = suggestion;
    if (umprn !== undefined) return this.client.lookupUmprn({ umprn });
    return this.client.lookupUdprn({ udprn });
  }
}