5 changed files with 284 additions and 13 deletions
--- a/src/pages/create/index.tsx
+++ b/src/pages/create/index.tsx
@ -39,7 +39,9 @@ import {
  updateUsersAppData,
  uploadToFileStorage,
  DEFAULT_TOOLBOX,
-  settleAllFullfilfedPromises
+  settleAllFullfilfedPromises,
+  sendPrivateDirectMessage,
+  parseNostrEvent
 } from '../../utils'
 import { Container } from '../../components/Container'
 import fileListStyles from '../../components/FileList/style.module.scss'
@ -62,6 +64,7 @@ import {
 } from '@fortawesome/free-solid-svg-icons'
 import { getSigitFile, SigitFile } from '../../utils/file.ts'
 import _ from 'lodash'
+import { SendDMError } from '../../types/errors/SendDMError.ts'

 export const CreatePage = () => {
  const navigate = useNavigate()
@ -713,6 +716,31 @@ export const CreatePage = () => {
            toast.error('Failed to publish notifications')
          })

+        // Send DM to the next signer
+        setLoadingSpinnerDesc('Sending DMs')
+        if (signers.length > 0 && signers[0].pubkey !== usersPubkey) {
+          // No need to send notification to self so remove it from the list
+          const nextSigner = signers[0].pubkey
+
+          if (nextSigner) {
+            const createSignatureEvent = await parseNostrEvent(
+              meta.createSignature
+            )
+            const { id } = createSignatureEvent
+            try {
+              await sendPrivateDirectMessage(
+                `Sigit created, visit ${window.location.origin}/#/sign/${id}`,
+                npubToHex(nextSigner)!
+              )
+            } catch (error) {
+              if (error instanceof SendDMError) {
+                toast.error(error.message)
+              }
+              console.error(error)
+            }
+          }
+        }
+
        navigate(appPrivateRoutes.sign, { state: { meta } })
      } else {
        const zip = new JSZip()
--- a/src/pages/sign/index.tsx
+++ b/src/pages/sign/index.tsx
@ -33,7 +33,9 @@ import {
  signEventForMetaFile,
  updateUsersAppData,
  findOtherUserMarks,
-  timeout
+  timeout,
+  sendPrivateDirectMessage,
+  parseNostrEvent
 } from '../../utils'
 import { Container } from '../../components/Container'
 import { DisplayMeta } from './internal/displayMeta'
@ -53,6 +55,7 @@ import {
  SigitFile
 } from '../../utils/file.ts'
 import { ARRAY_BUFFER, DEFLATE } from '../../utils/const.ts'
+import { SendDMError } from '../../types/errors/SendDMError.ts'

 enum SignedStatus {
  Fully_Signed,
@ -720,6 +723,65 @@ export const SignPage = () => {
        toast.error('Failed to publish notifications')
      })

+    // Send DMs
+    setLoadingSpinnerDesc('Sending DMs')
+    const createSignatureEvent = await parseNostrEvent(meta.createSignature)
+    const { id } = createSignatureEvent
+
+    if (isLastSigner) {
+      // Final sign sends to everyone (creator, signers, viewers - /verify)
+      const areSent: boolean[] = Array(users.length).fill(false)
+      for (let i = 0; i < users.length; i++) {
+        try {
+          areSent[i] = await sendPrivateDirectMessage(
+            `Sigit completed, visit ${window.location.origin}/#/verify/${id}`,
+            npubToHex(users[i])!
+          )
+        } catch (error) {
+          if (error instanceof SendDMError) {
+            toast.error(error.message)
+          }
+          console.error(error)
+        }
+      }
+
+      if (areSent.some((r) => r)) {
+        toast.success(
+          `DMs sent ${areSent.filter((r) => r).length}/${users.length}`
+        )
+      }
+    } else {
+      // Notify the creator and the next signer (/sign).
+      try {
+        await sendPrivateDirectMessage(
+          `Sigit signed by ${usersNpub}, visit ${window.location.origin}/#/sign/${id}`,
+          npubToHex(submittedBy!)!
+        )
+      } catch (error) {
+        if (error instanceof SendDMError) {
+          toast.error(error.message)
+        }
+        console.error(error)
+      }
+
+      // No need to notify creator twice, skipping
+      const currentSignerIndex = signers.indexOf(usersNpub)
+      const nextSigner = signers[currentSignerIndex + 1]
+      if (nextSigner !== submittedBy) {
+        try {
+          await sendPrivateDirectMessage(
+            `You're the next signer, visit ${window.location.origin}/#/sign/${id}`,
+            npubToHex(nextSigner)!
+          )
+        } catch (error) {
+          if (error instanceof SendDMError) {
+            toast.error(error.message)
+          }
+          console.error(error)
+        }
+      }
+    }
+
    setIsLoading(false)
  }

--- a/src/types/errors/SendDMError.ts
+++ b/src/types/errors/SendDMError.ts
@ -0,0 +1,24 @@
+import { Jsonable } from '.'
+
+export enum SendDMErrorType {
+  'METADATA_FETCH_FAILED' = 'Sending DM failed. An error occured while fetching user metadata.',
+  'RELAY_READ_EMPTY' = `Sending DM failed. The user's relay read set is empty.`,
+  'ENCRYPTION_FAILED' = 'Sending DM failed. An error occurred in encrypting dm message.',
+  'RELAY_PUBLISH_FAILED' = 'Sending DM failed. Publishing events failed.'
+}
+
+export class SendDMError extends Error {
+  public readonly context?: Jsonable
+
+  constructor(
+    message: string,
+    options: { cause?: Error; context?: Jsonable } = {}
+  ) {
+    const { cause, context } = options
+
+    super(message, { cause })
+    this.name = this.constructor.name
+
+    this.context = context
+  }
+}
--- a/src/utils/nostr.ts
+++ b/src/utils/nostr.ts
@ -6,6 +6,7 @@ import {
  EventTemplate,
  Filter,
  UnsignedEvent,
+  VerifiedEvent,
  finalizeEvent,
  generateSecretKey,
  getEventHash,
@ -21,7 +22,8 @@ import { NIP05_REGEX } from '../constants'
 import {
  MetadataController,
  NostrController,
-  relayController
+  relayController,
+  RelayController
 } from '../controllers'
 import {
  updateProcessedGiftWraps,
@ -35,6 +37,7 @@ import { parseJson, removeLeadingSlash } from './string'
 import { timeout } from './utils'
 import { getHash } from './hash'
 import { SIGIT_BLOSSOM } from './const.ts'
+import { SendDMError, SendDMErrorType } from '../types/errors/SendDMError.ts'

 /**
 * Generates a `d` tag for userAppData
@ -248,6 +251,12 @@ export const toUnixTimestamp = (date: number | Date) => {
 export const fromUnixTimestamp = (unix: number) => {
  return unix * 1000
 }
+export const randomTimeUpTo2DaysInThePast = (): number => {
+  const now = Date.now()
+  const twoDaysInMilliseconds = 2 * 24 * 60 * 60 * 1000
+  const randomPastTime = now - Math.floor(Math.random() * twoDaysInMilliseconds)
+  return toUnixTimestamp(randomPastTime)
+}

 /**
 * Generate nip44 conversation key
@ -297,19 +306,21 @@ export const countLeadingZeroes = (hex: string) => {

 /**
 * Function to create a wrapped event with PoW
- * @param event Original event to be wrapped
+ * @param event  Original event to be wrapped (can be unsigned or verified)
 * @param receiver Public key of the receiver
- * @param difficulty PoW difficulty level (default is 20)
 * @returns
 */
 //
-export const createWrap = (unsignedEvent: UnsignedEvent, receiver: string) => {
+export const createWrap = (
+  event: UnsignedEvent | VerifiedEvent,
+  receiver: string
+) => {
  // Generate a random secret key and its corresponding public key
  const randomKey = generateSecretKey()
  const pubkey = getPublicKey(randomKey)

  // Encrypt the event content using nip44 encryption
-  const content = nip44Encrypt(unsignedEvent, randomKey, receiver)
+  const content = nip44Encrypt(event, randomKey, receiver)

  // Initialize nonce and leadingZeroes for PoW calculation
  let nonce = 0
@ -320,11 +331,12 @@ export const createWrap = (unsignedEvent: UnsignedEvent, receiver: string) => {
  // eslint-disable-next-line no-constant-condition
  while (true) {
    // Create an unsigned event with the necessary fields
+    // TODO: kinds.GiftWrap (wrong kind number in nostr-tools 10/11/2024 at v2.7.2)
    const event: UnsignedEvent = {
      kind: 1059, // Event kind
      content, // Encrypted content
      pubkey, // Public key of the creator
-      created_at: unixNow(), // Current timestamp
+      created_at: randomTimeUpTo2DaysInThePast(),
      tags: [
        // Tags including receiver and nonce
        ['p', receiver],
@ -989,3 +1001,145 @@ export const getProfileUsername = (
  truncate(profile?.display_name || profile?.name || hexToNpub(npub), {
    length: 16
  })
+
+/**
+ * Modified {@link UnsignedEvent Unsigned Event} that includes an id
+ *
+ * Fields id and created_at are required.
+ * @see {@link UnsignedEvent}
+ * @see {@link https://github.com/nostr-protocol/nips/blob/master/17.md#direct-message-kind}
+ */
+type UnsignedEventWithId = UnsignedEvent & {
+  id?: string
+}
+export const sendPrivateDirectMessage = async (
+  message: string,
+  receiver: string,
+  subject?: string
+) => {
+  // Instantiate the MetadataController to retrieve relay list metadata to look for preferred DM relays
+  const metadataController = MetadataController.getInstance()
+  const relaySet = await metadataController
+    .findRelayListMetadata(receiver)
+    .catch((err) => {
+      // Log an error if retrieving relay list metadata fails
+      console.log(
+        `An error occurred while finding relay list metadata for ${hexToNpub(receiver)}`,
+        err
+      )
+      return null
+    })
+
+  // Throw if metadata retrieval failed
+  if (!relaySet) {
+    throw new SendDMError(SendDMErrorType.METADATA_FETCH_FAILED, {
+      context: {
+        receiver
+      }
+    })
+  }
+
+  // Ensure relay list is not empty
+  if (relaySet.read.length === 0) {
+    throw new SendDMError(SendDMErrorType.RELAY_READ_EMPTY, {
+      context: {
+        receiver,
+        relaySet: JSON.stringify(relaySet)
+      }
+    })
+  }
+  // Get the direct message preferred relays list
+  // TODO: kinds.DirectMessageRelaysList  (unavailabe in nostr-tools 10/10/2024 at v2.7.0)
+  // https://github.com/nostr-protocol/nips/blob/master/17.md#publishing
+  const eventFilter: Filter = {
+    kinds: [10050],
+    authors: [receiver]
+  }
+  const preferredRelaysListEvents =
+    await RelayController.getInstance().fetchEvents(eventFilter, relaySet.read)
+
+  const isRelayTag = (tag: string[]): boolean => tag[0] === 'relay'
+  const preferredRelaysList = preferredRelaysListEvents.reduce(
+    (previous: string[], current: Event) => {
+      const relaysList = current.tags
+        .filter((t) => isRelayTag(t) && !previous.includes(t[1]))
+        .map((t) => t[1])
+
+      return [...previous, ...relaysList]
+    },
+    []
+  )
+  // Empty preferred relays list
+  const finalRelaysList: string[] =
+    preferredRelaysList?.length > 0 ? preferredRelaysList : [...relaySet.write]
+
+  // Generate "sender"
+  const senderSecret = generateSecretKey()
+  const senderPubkey = getPublicKey(senderSecret)
+
+  // Prepare tags for the message
+  const tags: string[][] = [['p', receiver]]
+
+  // Conversation title
+  if (subject) tags.push(['subject', subject])
+
+  // Create private DM event containing the message and relevant metadata
+  // TODO: kinds.PrivateDirectMessage (unavailabe in nostr-tools 10/10/2024 at v2.7.0)
+  const dm: UnsignedEventWithId = {
+    pubkey: senderPubkey,
+    created_at: unixNow(),
+    kind: 14,
+    tags,
+    content: message
+  }
+
+  // Calculate the hash based on the UnverifiedEvent
+  dm.id = getEventHash(dm)
+
+  // Encrypt the private dm using the sender secret and the receiver's public key
+  const encryptedDm = nip44Encrypt(dm, senderSecret, receiver)
+  if (!encryptedDm) {
+    throw new SendDMError(SendDMErrorType.ENCRYPTION_FAILED, {
+      context: {
+        receiver,
+        message,
+        kind: dm.kind
+      }
+    })
+  }
+
+  // Seal the message
+  // TODO: kinds.Seal (unavailabe in nostr-tools 10/10/2024 at v2.7.0)
+  const sealedMessage: UnsignedEvent = {
+    kind: 13, // seal
+    pubkey: senderPubkey,
+    content: encryptedDm,
+    created_at: randomTimeUpTo2DaysInThePast(),
+    tags: [] // no tags
+  }
+
+  // Finalize and sign the sealed event
+  const finalizedSeal = finalizeEvent(sealedMessage, senderSecret)
+
+  // Encrypt the seal and gift wrap
+  const finalizedGiftWrap = createWrap(finalizedSeal, receiver)
+
+  // Publish the finalized gift wrap event (the encrypted DM) to the relays
+  const publishedOnRelays = await relayController.publish(
+    finalizedGiftWrap,
+    finalRelaysList
+  )
+
+  // Handle cases where publishing to the relays failed
+  if (publishedOnRelays.length === 0) {
+    throw new SendDMError(SendDMErrorType.ENCRYPTION_FAILED, {
+      context: {
+        receiver,
+        count: publishedOnRelays.length
+      }
+    })
+  }
+
+  // Return true indicating that the DM was successfully sent
+  return true
+}
--- a/src/utils/relays.ts
+++ b/src/utils/relays.ts
@ -97,20 +97,23 @@ const isOlderThanOneDay = (cachedAt: number) => {
 }

 const isRelayTag = (tag: string[]): boolean => tag[0] === 'r'
-
+const addRelay = (list: string[], relay: string) => {
+  // Only add if the list doesn't already include the relay
+  if (!list.includes(relay)) list.push(relay)
+}
 const toRelaySet = (obj: RelaySet, tag: string[]): RelaySet => {
  if (tag.length >= 3) {
    const marker = tag[2]

    if (marker === READ_MARKER) {
-      obj.read.push(tag[1])
+      addRelay(obj.read, tag[1])
    } else if (marker === WRITE_MARKER) {
-      obj.write.push(tag[1])
+      addRelay(obj.write, tag[1])
    }
  }
  if (tag.length === 2) {
-    obj.read.push(tag[1])
-    obj.write.push(tag[1])
+    addRelay(obj.read, tag[1])
+    addRelay(obj.write, tag[1])
  }

  return obj