move to pkg

packages/system/src/EventBuilder.ts

@@ -0,0 +1,108 @@
+import { EventKind, HexKey, NostrPrefix, NostrEvent } from ".";
+import { HashtagRegex } from "./Const";
+import { getPublicKey, unixNow } from "./Util";
+import { EventExt } from "./EventExt";
+import { parseNostrLink } from "./NostrLink";
+
+export class EventBuilder {
+  #kind?: EventKind;
+  #content?: string;
+  #createdAt?: number;
+  #pubkey?: string;
+  #tags: Array<Array<string>> = [];
+
+  kind(k: EventKind) {
+    this.#kind = k;
+    return this;
+  }
+
+  content(c: string) {
+    this.#content = c;
+    return this;
+  }
+
+  createdAt(n: number) {
+    this.#createdAt = n;
+    return this;
+  }
+
+  pubKey(k: string) {
+    this.#pubkey = k;
+    return this;
+  }
+
+  tag(t: Array<string>): EventBuilder {
+    const duplicate = this.#tags.some(a => a.length === t.length && a.every((b, i) => b !== a[i]));
+    if (duplicate) return this;
+    this.#tags.push(t);
+    return this;
+  }
+
+  /**
+   * Extract mentions
+   */
+  processContent() {
+    if (this.#content) {
+      this.#content = this.#content.replace(/@n(pub|profile|event|ote|addr|)1[acdefghjklmnpqrstuvwxyz023456789]+/g, m =>
+        this.#replaceMention(m)
+      );
+
+      const hashTags = [...this.#content.matchAll(HashtagRegex)];
+      hashTags.map(hashTag => {
+        this.#addHashtag(hashTag[0]);
+      });
+    }
+    return this;
+  }
+
+  build() {
+    this.#validate();
+    const ev = {
+      id: "",
+      pubkey: this.#pubkey ?? "",
+      content: this.#content ?? "",
+      kind: this.#kind,
+      created_at: this.#createdAt ?? unixNow(),
+      tags: this.#tags,
+    } as NostrEvent;
+    ev.id = EventExt.createId(ev);
+    return ev;
+  }
+
+  /**
+   * Build and sign event
+   * @param pk Private key to sign event with
+   */
+  async buildAndSign(pk: HexKey) {
+    const ev = this.pubKey(getPublicKey(pk)).build();
+    await EventExt.sign(ev, pk);
+    return ev;
+  }
+
+  #validate() {
+    if (this.#kind === undefined) {
+      throw new Error("Kind must be set");
+    }
+    if (this.#pubkey === undefined) {
+      throw new Error("Pubkey must be set");
+    }
+  }
+
+  #replaceMention(match: string) {
+    const npub = match.slice(1);
+    const link = parseNostrLink(npub);
+    if (link) {
+      if (link.type === NostrPrefix.Profile || link.type === NostrPrefix.PublicKey) {
+        this.tag(["p", link.id]);
+      }
+      return `nostr:${link.encode()}`;
+    } else {
+      return match;
+    }
+  }
+
+  #addHashtag(match: string) {
+    const tag = match.slice(1);
+    this.tag(["t", tag.toLowerCase()]);
+  }
+}