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import { Client } from "https://deno.land/x/postgres/mod.ts";
import { Adapter, AdapterParams, adapters } from './mod.ts';
const CREATE = 'CREATE TABLE IF NOT EXISTS kv_storage (area TEXT, key TEXT, value TEXT, PRIMARY KEY (area, key))';const GET = 'SELECT value FROM kv_storage WHERE key=$2 AND area=$1';const UPSERT = 'INSERT INTO kv_storage (area, key, value) VALUES ($1, $2, $3) ON CONFLICT(area, key) DO UPDATE SET value=$3';const DELETE = 'DELETE FROM kv_storage WHERE key=$2 AND area=$1';const CLEAR = 'DELETE FROM kv_storage WHERE area=$1';const KEYS = 'SELECT key FROM kv_storage WHERE area=$1';const VALUES = 'SELECT value FROM kv_storage WHERE area=$1';const ENTRIES = 'SELECT key, value FROM kv_storage WHERE area=$1';
export class PostgresAdapter implements Adapter {  private area: string;  private url: string;  private ready: Promise<void>;
  constructor({ area, url }: AdapterParams) {    this.area = area;    this.url = url;
    this.ready = (async () => {      // TODO error??      const client = new Client(url);      await client.connect();      // https://stackoverflow.com/questions/26150758/suppressing-notice-relation-exists-when-using-create-if-not-exists      await client.queryArray(`SET client_min_messages = warning`);      await client.queryArray(CREATE);      await client.end();    })();  }
  private async query(query: string, { key, value }: { key?: string, value?: string } = {}) {    await this.ready;    const client = new Client(this.url);    await client.connect();    const ret =  (await client.queryArray<any>({       text: query,       args: [this.area, ...key ? [key] : [], ...value ? [value]: []],     })).rows;    await client.end();    return ret;  }
  async get(key: string): Promise<string | undefined> {    return (await this.query(GET, { key }))[0]?.[0];  }
  async set(key: string, value: string) {    await this.query(UPSERT, { key, value });  }
  async delete(key: string) {    await this.query(DELETE, { key });  }
  async clear() {    await this.query(CLEAR);  }
  async *keys() {    for (const [key] of await this.query(KEYS)) {      yield key;    }  }
  async *values() {    for (const [value] of await this.query(VALUES)) {      yield value;    }  }
  async *entries() {    for (const [key, value] of await this.query(ENTRIES)) {      yield [key, value] as [string, string];    }  }
  backingStore() {    return new Client(this.url);  }}
adapters.set('postgres:', PostgresAdapter);