typescript source code of SingleAccountSigner

// Copyright 2017-2020 @polkadot/api authors & contributors
// SPDX-License-Identifier: Apache-2.0

import { Signer, SignerResult } from "@polkadot/api/types";
import { KeyringPair } from "@polkadot/keyring/types";
import { Registry, SignerPayloadJSON, SignerPayloadRaw } from "@polkadot/types/types";

import { hexToU8a, u8aToHex } from "@polkadot/util";

let id = 0;

export class SingleAccountSigner implements Signer {
  readonly #keyringPair: KeyringPair;

  readonly #registry: Registry;

  readonly #signDelay: number;

  constructor (registry: Registry, keyringPair: KeyringPair, signDelay = 0) {
      this.#keyringPair = keyringPair;
      this.#registry = registry;
      this.#signDelay = signDelay;
  }

  public async signPayload (payload: SignerPayloadJSON): Promise<SignerResult> {
      if (payload.address !== this.#keyringPair.address) {
          throw new Error("does not have the keyringPair");
      }

      return new Promise((resolve): void => {
          setTimeout((): void => {
              const signed = this.#registry.createType("ExtrinsicPayload", payload, { version: payload.version }).sign(this.#keyringPair);

              resolve({
                  id: ++id,
                  ...signed
              });
          }, this.#signDelay);
      });
  }

  public async signRaw ({ address, data }: SignerPayloadRaw): Promise<SignerResult> {
      if (address !== this.#keyringPair.address) {
          throw new Error("does not have the keyringPair");
      }

      return new Promise((resolve): void => {
          setTimeout((): void => {
              const signature = u8aToHex(this.#keyringPair.sign(hexToU8a(data)));

              resolve({
                  id: ++id,
                  signature
              });
          }, this.#signDelay);
      });
  }
}