sigit.io/src/controllers/NostrController.ts

import NDK, {
  NDKEvent,
  NDKNip46Signer,
  NDKPrivateKeySigner,
  NostrEvent
} from '@nostr-dev-kit/ndk'
import {
  Event,
  EventTemplate,
  Relay,
  UnsignedEvent,
  finalizeEvent,
  nip19
} from 'nostr-tools'
import { updateNsecbunkerPubkey } from '../store/actions'
import { AuthState, LoginMethods } from '../store/auth/types'
import store from '../store/store'
import { SignedEvent } from '../types'
import { getNsecBunkerDelegatedKey, verifySignedEvent } from '../utils'

export class NostrController {
  private static instance: NostrController

  private bunkerNDK: NDK | undefined
  private remoteSigner: NDKNip46Signer | undefined

  private constructor() {}

  public nsecBunkerInit = async (relays: string[]) => {
    // Don't reinstantiate bunker NDK if exists with same relays
    if (
      this.bunkerNDK &&
      this.bunkerNDK.explicitRelayUrls?.length === relays.length &&
      this.bunkerNDK.explicitRelayUrls?.every((relay) => relays.includes(relay))
    )
      return

    this.bunkerNDK = new NDK({
      explicitRelayUrls: relays
    })

    try {
      await this.bunkerNDK
        .connect(2000)
        .then(() => {
          console.log(
            `Successfully connected to the nsecBunker relays: ${relays.join(
              ','
            )}`
          )
        })
        .catch((err) => {
          console.error(
            `Error connecting to the nsecBunker relays: ${relays.join(
              ','
            )} ${err}`
          )
        })
    } catch (err) {
      console.error(err)
    }
  }

  /**
   * Creates nSecBunker signer instance for the given npub
   * Or if npub omitted it will return existing signer
   * If neither, error will be thrown
   * @param npub nPub / public key in hex format
   * @returns nsecBunker Signer instance
   */
  public createNsecBunkerSigner = async (
    npub: string | undefined
  ): Promise<NDKNip46Signer> => {
    const nsecBunkerDelegatedKey = getNsecBunkerDelegatedKey()

    return new Promise((resolve, reject) => {
      if (!nsecBunkerDelegatedKey) {
        reject('nsecBunker delegated key is not found in the browser.')
        return
      }
      const localSigner = new NDKPrivateKeySigner(nsecBunkerDelegatedKey)

      if (!npub) {
        if (this.remoteSigner) resolve(this.remoteSigner)

        const npubFromStorage = (store.getState().auth as AuthState)
          .nsecBunkerPubkey

        if (npubFromStorage) {
          npub = npubFromStorage
        } else {
          reject(
            'No signer instance present, no npub provided by user or found in the browser.'
          )
          return
        }
      } else {
        store.dispatch(updateNsecbunkerPubkey(npub))
      }

      // Pubkey of a key pair stored in nsecbunker that will be used to sign event with
      const appPubkeyOrToken = npub.includes('npub')
        ? npub
        : nip19.npubEncode(npub)

      /**
       * When creating and NDK instance we create new connection to the relay
       * To prevent too much connections and hitting rate limits, if npub against which we sign
       * we will reuse existing instance. Otherwise we will create new NDK and signer instance.
       */
      if (!this.remoteSigner || this.remoteSigner?.remotePubkey !== npub) {
        this.remoteSigner = new NDKNip46Signer(
          this.bunkerNDK!,
          appPubkeyOrToken,
          localSigner
        )
      }

      /**
       * when nsecbunker-delegated-key is regenerated we have to reinitialize the remote signer
       */
      if (this.remoteSigner.localSigner !== localSigner) {
        this.remoteSigner = new NDKNip46Signer(
          this.bunkerNDK!,
          appPubkeyOrToken,
          localSigner
        )
      }

      resolve(this.remoteSigner)
    })
  }

  /**
   * Signs the nostr event and returns the sig and id or full raw nostr event
   * @param npub stored in nsecBunker to sign with
   * @param event to be signed
   * @param returnFullEvent whether to return full raw nostr event or just SIG and ID values
   */
  public signWithNsecBunker = async (
    npub: string | undefined,
    event: NostrEvent,
    returnFullEvent = true
  ): Promise<{ id: string; sig: string } | NostrEvent> => {
    return new Promise((resolve, reject) => {
      this.createNsecBunkerSigner(npub)
        .then(async (signer) => {
          const ndkEvent = new NDKEvent(undefined, event)

          const timeout = setTimeout(() => {
            reject('Timeout occurred while waiting for event signing')
          }, 60000) // 60000 ms (1 min) = 1000 * 60

          await ndkEvent.sign(signer).catch((err) => {
            clearTimeout(timeout)
            reject(err)
            return
          })

          clearTimeout(timeout)

          if (returnFullEvent) {
            resolve(ndkEvent.rawEvent())
          } else {
            resolve({
              id: ndkEvent.id,
              sig: ndkEvent.sig!
            })
          }
        })
        .catch((err) => {
          reject(err)
        })
    })
  }

  public static getInstance(): NostrController {
    if (!NostrController.instance) {
      NostrController.instance = new NostrController()
    }
    return NostrController.instance
  }

  /**
   * Function will publish provided event to the provided relay
   */
  publishEvent = async (event: Event, relayUrl: string) => {
    const relay = await Relay.connect(relayUrl)
    await relay.publish(event)
    relay.close()

    return `event published to relay: ${relayUrl}`
  }

  /**
   * Signs an event with private key (if it is present in local storage) or
   * with browser extension (if it is present) or
   * with nSecBunker instance.
   * @param event - unsigned nostr event.
   * @returns - a promised that is resolved with signed nostr event.
   */
  signEvent = async (
    event: UnsignedEvent | EventTemplate
  ): Promise<SignedEvent> => {
    const loginMethod = (store.getState().auth as AuthState).loginMethod

    if (!loginMethod) {
      return Promise.reject('No login method found in the browser storage')
    }

    if (loginMethod === LoginMethods.nsecBunker) {
      // Check if nsecBunker is available
      if (!this.bunkerNDK) {
        return Promise.reject(
          `Login method is ${loginMethod} but bunkerNDK is not created`
        )
      }

      if (!this.remoteSigner) {
        return Promise.reject(
          `Login method is ${loginMethod} but bunkerNDK is not created`
        )
      }

      const signedEvent = await this.signWithNsecBunker(
        '',
        event as NostrEvent
      ).catch((err) => {
        throw err
      })

      return Promise.resolve(signedEvent as SignedEvent)
    } else if (loginMethod === LoginMethods.privateKey) {
      const keys = (store.getState().auth as AuthState).keyPair

      if (!keys) {
        return Promise.reject(
          `Login method is ${loginMethod}, but keys are not found`
        )
      }

      const { private: nsec } = keys
      const privateKey = nip19.decode(nsec).data as Uint8Array

      const signedEvent = finalizeEvent(event, privateKey)

      verifySignedEvent(signedEvent)

      return Promise.resolve(signedEvent)
    } else if (loginMethod === LoginMethods.extension) {
      if (!window.nostr) {
        return Promise.reject(
          `Login method is ${loginMethod} but window.nostr is not present. Make sure extension is working properly`
        )
      }

      return (await window.nostr
        .signEvent(event as NostrEvent)
        .catch((err: any) => {
          console.log('Error while signing event: ', err)

          throw err
        })) as Event
    } else {
      return Promise.reject(
        `We could not sign the event, none of the signing methods are available`
      )
    }
  }

  /**
   * Function will capture the public key from the nostr extension or if no extension present
   * function wil capture the public key from the local storage
   */
  capturePublicKey = async (): Promise<string> => {
    if (window.nostr) {
      const pubKey = await window.nostr.getPublicKey().catch((err: any) => {
        return Promise.reject(err.message)
      })

      if (!pubKey) {
        return Promise.reject('Error getting public key, user canceled')
      }

      return Promise.resolve(pubKey)
    }

    return Promise.reject(
      'window.nostr object not present. Make sure you have an nostr extension installed.'
    )
  }

  /**
   * Generates NDK Private Signer
   * @returns nSecBunker delegated key
   */
  generateDelegatedKey = (): string => {
    return NDKPrivateKeySigner.generate().privateKey!
  }
}