/*
 This file is part of GNU Taler
 (C) 2019 Taler Systems S.A.

 GNU Taler is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

/**
 * Helpers to create headless wallets.
 * @author Florian Dold <dold@taler.net>
 */

/**
 * Imports.
 */
import type { IDBFactory } from "@gnu-taler/idb-bridge";
// eslint-disable-next-line no-duplicate-imports
import {
  AccessStats,
  BridgeIDBFactory,
  MemoryBackend,
  createSqliteBackend,
  shimIndexedDB,
} from "@gnu-taler/idb-bridge";
import { createNodeSqlite3Impl } from "@gnu-taler/idb-bridge/node-sqlite3-bindings";
import {
  Logger,
  SetTimeoutTimerAPI,
  WalletRunConfig,
} from "@gnu-taler/taler-util";
import { createPlatformHttpLib } from "@gnu-taler/taler-util/http";
import * as fs from "fs";
import { NodeThreadCryptoWorkerFactory } from "./crypto/workers/nodeThreadWorker.js";
import { SynchronousCryptoWorkerFactoryPlain } from "./crypto/workers/synchronousWorkerFactoryPlain.js";
import { DefaultNodeWalletArgs, makeTempfileId } from "./host-common.js";
import { Wallet } from "./wallet.js";

const logger = new Logger("host-impl.node.ts");

interface MakeDbResult {
  idbFactory: BridgeIDBFactory;
  getStats: () => AccessStats;
}

async function makeFileDb(
  args: DefaultNodeWalletArgs = {},
): Promise<MakeDbResult> {
  const myBackend = new MemoryBackend();
  myBackend.enableTracing = false;
  const storagePath = args.persistentStoragePath;
  if (storagePath) {
    try {
      const dbContentStr: string = fs.readFileSync(storagePath, {
        encoding: "utf-8",
      });
      const dbContent = JSON.parse(dbContentStr);
      myBackend.importDump(dbContent);
    } catch (e: any) {
      const code: string = e.code;
      if (code === "ENOENT") {
        logger.trace("wallet file doesn't exist yet");
      } else {
        logger.error("could not open wallet database file");
        throw Error(
          "could not open wallet database file",
          // @ts-expect-error no support for options.cause yet
          { cause: e },
        );
      }
    }

    myBackend.afterCommitCallback = async () => {
      logger.trace("committing database");
      // Allow caller to stop persisting the wallet.
      if (args.persistentStoragePath === undefined) {
        return;
      }
      const tmpPath = `${args.persistentStoragePath}-${makeTempfileId(5)}.tmp`;
      logger.trace("exported DB dump");
      const dbContent = myBackend.exportDump();
      fs.writeFileSync(tmpPath, JSON.stringify(dbContent, undefined, 2), {
        encoding: "utf-8",
      });
      // Atomically move the temporary file onto the DB path.
      fs.renameSync(tmpPath, args.persistentStoragePath);
      logger.trace("committing database done");
    };
  }

  BridgeIDBFactory.enableTracing = false;

  const myBridgeIdbFactory = new BridgeIDBFactory(myBackend);
  return {
    idbFactory: myBridgeIdbFactory,
    getStats: () => myBackend.accessStats,
  };
}

async function makeSqliteDb(
  args: DefaultNodeWalletArgs,
): Promise<MakeDbResult> {
  BridgeIDBFactory.enableTracing = false;
  const imp = await createNodeSqlite3Impl();
  const dbFilename = args.persistentStoragePath ?? ":memory:";
  logger.info(`using database ${dbFilename}`);
  const myBackend = await createSqliteBackend(imp, {
    filename: dbFilename,
  });
  myBackend.enableTracing = false;
  if (process.env.TALER_WALLET_DBSTATS) {
    myBackend.trackStats = true;
  }
  const myBridgeIdbFactory = new BridgeIDBFactory(myBackend);
  return {
    getStats() {
      return myBackend.accessStats;
    },
    idbFactory: myBridgeIdbFactory,
  };
}

/**
 * Get a wallet instance with default settings for node.
 *
 * Extended version that allows getting DB stats.
 */
export async function createNativeWalletHost2(
  args: DefaultNodeWalletArgs = {},
): Promise<{
  wallet: Wallet;
  getDbStats: () => AccessStats;
}> {
  const myHttpFactory = (config: WalletRunConfig) => {
    let myHttpLib;
    if (args.httpLib) {
      myHttpLib = args.httpLib;
    } else {
      myHttpLib = createPlatformHttpLib({
        enableThrottling: true,
        requireTls: !config.features.allowHttp,
      });
    }
    return myHttpLib;
  };

  let dbResp: MakeDbResult;

  if (
    args.persistentStoragePath &&
    args.persistentStoragePath.endsWith(".json")
  ) {
    logger.info("using JSON file DB backend (slow, only use for testing)");
    dbResp = await makeFileDb(args);
  } else {
    logger.info(`using sqlite3 DB backend`);
    dbResp = await makeSqliteDb(args);
  }

  const myIdbFactory: IDBFactory = dbResp.idbFactory as any as IDBFactory;

  shimIndexedDB(dbResp.idbFactory);

  let workerFactory;
  const cryptoWorkerType = args.cryptoWorkerType ?? "node-worker-thread";
  if (cryptoWorkerType === "sync") {
    logger.info("using synchronous crypto worker");
    workerFactory = new SynchronousCryptoWorkerFactoryPlain();
  } else if (cryptoWorkerType === "node-worker-thread") {
    try {
      // Try if we have worker threads available, fails in older node versions.
      const _r = "require";
      // eslint-disable-next-line no-unused-vars
      const worker_threads = module[_r]("worker_threads");
      // require("worker_threads");
      workerFactory = new NodeThreadCryptoWorkerFactory();
      logger.info("using node thread crypto worker");
    } catch (e) {
      logger.warn(
        "worker threads not available, falling back to synchronous workers",
      );
      workerFactory = new SynchronousCryptoWorkerFactoryPlain();
    }
  } else {
    throw Error(`unsupported crypto worker type '${cryptoWorkerType}'`);
  }

  const timer = new SetTimeoutTimerAPI();

  const w = await Wallet.create(
    myIdbFactory,
    myHttpFactory,
    timer,
    workerFactory,
  );

  if (args.notifyHandler) {
    w.addNotificationListener(args.notifyHandler);
  }
  return {
    wallet: w,
    getDbStats: dbResp.getStats,
  };
}