import type { StockDatabase, StockKey } from "./interfaces.js";
import { open } from "lmdbx";

const stockAggregatesDb = open({
  path: "./stock-aggregates.db",
  // any options go here, we can turn on compression like this:
  compression: true,
});

const stockExistenceDb = open({
  path: "./stock-existence.db",
  // any options go here, we can turn on compression like this:
  compression: true,
});

/** Largest possible key according to the `ordered-binary` (used by lmdbx) docs. */
const MAXIMUM_KEY = Buffer.from([0xff]);

function makeStockDatabase(): StockDatabase {
  const stockDatabase: Omit<StockDatabase, "getSymbols"> = {
    getKeys: async ({ date, key }) => {
      if (key?.symbol) {
        return [key as StockKey];
      }
      return stockExistenceDb
        .getRange({
          start: [date],
          end: [date, MAXIMUM_KEY],
        })
        .map(({ key }) => ({ symbol: key[1] })).asArray;
    },
    getAggregates: async ({ key: { symbol }, date }) => {
      const startOfDayUnix = new Date(`${date}T00:00:00Z`).valueOf();
      const endOfDayUnix = startOfDayUnix + 3600 * 24 * 1000;
      return stockAggregatesDb
        .getRange({
          start: [symbol, startOfDayUnix],
          end: [symbol, endOfDayUnix],
        })
        .map(({ key, value }) => ({
          tsStart: key[1],
          open: value.open,
          close: value.close,
          high: value.high,
          low: value.low,
        })).asArray;
    },
    getAggregate: async ({ key: { symbol }, tsStart }) => {
      return stockAggregatesDb.get([symbol, tsStart]);
    },
    insertAggregates: async (aggregates) => {
      await stockExistenceDb.batch(() => {
        for (const aggregate of aggregates) {
          stockExistenceDb.put(
            [
              new Date(aggregate.tsStart).toISOString().substring(0, 10),
              aggregate.key.symbol,
            ],
            null
          );
        }
      });
      await stockAggregatesDb.batch(() => {
        for (const aggregate of aggregates) {
          stockAggregatesDb.put([aggregate.key.symbol, aggregate.tsStart], {
            open: aggregate.open,
            close: aggregate.close,
            high: aggregate.high,
            low: aggregate.low,
          });
        }
      });
    },
    getClosingPrice: async ({ key }) => {
      // no-op: not used since stocks don't have a "closing" price, unlike options.
      return 0;
    },
  };

  return {
    ...stockDatabase,
    getSymbols: stockDatabase.getKeys,
  };
}

export const database: StockDatabase = makeStockDatabase();