From 147c7502dccd15fe0a07a0715e48f1660c0e2db8 Mon Sep 17 00:00:00 2001
From: Kieran <kieran@harkin.me>
Date: Thu, 19 Jan 2023 18:00:56 +0000
Subject: [PATCH] Hashtags (#92)

* feat: hashtags

* Show tag in header
---
 src/element/Hashtag.tsx    |  5 +++--
 src/element/Text.tsx       |  5 ++++-
 src/element/Timeline.tsx   | 12 +++++-------
 src/feed/EventPublisher.ts | 16 ++++++++++++----
 src/feed/TimelineFeed.ts   | 34 +++++++++++++++++++++-------------
 src/index.tsx              |  5 +++++
 src/nostr/Subscriptions.ts |  8 ++++++++
 src/nostr/Tag.ts           |  8 ++++++++
 src/nostr/index.ts         |  1 +
 src/pages/HashTagsPage.tsx | 16 ++++++++++++++++
 src/pages/ProfilePage.tsx  |  8 ++++----
 src/pages/Root.tsx         |  5 ++++-
 12 files changed, 91 insertions(+), 32 deletions(-)
 create mode 100644 src/pages/HashTagsPage.tsx

diff --git a/src/element/Hashtag.tsx b/src/element/Hashtag.tsx
index 8a6b7b32..78a5e5c3 100644
--- a/src/element/Hashtag.tsx
+++ b/src/element/Hashtag.tsx
@@ -1,9 +1,10 @@
+import { Link } from 'react-router-dom'
 import './Hashtag.css'
 
-const Hashtag = ({ children }: any) => {
+const Hashtag = ({ tag }: { tag: string }) => {
   return (
     <span className="hashtag">
-      {children}
+      <Link to={`/t/${tag}`} onClick={(e) => e.stopPropagation()}>#{tag}</Link>
     </span>
   )
 }
diff --git a/src/element/Text.tsx b/src/element/Text.tsx
index 9aeddeca..762143aa 100644
--- a/src/element/Text.tsx
+++ b/src/element/Text.tsx
@@ -100,6 +100,9 @@ function extractMentions(fragments: Fragment[], tags: Tag[], users: Map<string,
                                 let eText = hexToBech32("note", ref.Event!).substring(0, 12);
                                 return <Link key={ref.Event} to={eventLink(ref.Event!)} onClick={(e) => e.stopPropagation()}>#{eText}</Link>;
                             }
+                            case "t": {
+                                return <Hashtag tag={ref.Hashtag!} />
+                            }
                         }
                     }
                     return <b style={{ color: "var(--error)" }}>{matchTag[0]}?</b>;
@@ -132,7 +135,7 @@ function extractHashtags(fragments: Fragment[]) {
         if (typeof f === "string") {
             return f.split(HashtagRegex).map(i => {
                 if (i.toLowerCase().startsWith("#")) {
-                    return <Hashtag>{i}</Hashtag>
+                    return <Hashtag tag={i.substring(1)} />
                 } else {
                     return i;
                 }
diff --git a/src/element/Timeline.tsx b/src/element/Timeline.tsx
index 1d5cea10..184dec74 100644
--- a/src/element/Timeline.tsx
+++ b/src/element/Timeline.tsx
@@ -1,24 +1,22 @@
 import { useMemo } from "react";
-import useTimelineFeed from "../feed/TimelineFeed";
-import { HexKey, TaggedRawEvent, u256 } from "../nostr";
+import useTimelineFeed, { TimelineSubject } from "../feed/TimelineFeed";
+import { TaggedRawEvent } from "../nostr";
 import EventKind from "../nostr/EventKind";
 import LoadMore from "./LoadMore";
 import Note from "./Note";
 import NoteReaction from "./NoteReaction";
 
 export interface TimelineProps {
-    global: boolean,
     postsOnly: boolean,
-    pubkeys: HexKey[],
+    subject: TimelineSubject,
     method: "TIME_RANGE" | "LIMIT_UNTIL"
 }
 
 /**
  * A list of notes by pubkeys
  */
-export default function Timeline({ global, pubkeys, postsOnly = false, method }: TimelineProps) {
-    const { main, others, loadMore } = useTimelineFeed(pubkeys, {
-        global,
+export default function Timeline({ subject, postsOnly = false, method }: TimelineProps) {
+    const { main, others, loadMore } = useTimelineFeed(subject, {
         method
     });
 
diff --git a/src/feed/EventPublisher.ts b/src/feed/EventPublisher.ts
index 388dd553..5f4b4f94 100644
--- a/src/feed/EventPublisher.ts
+++ b/src/feed/EventPublisher.ts
@@ -6,6 +6,7 @@ import Tag from "../nostr/Tag";
 import { RootState } from "../state/Store";
 import { HexKey, RawEvent, u256, UserMetadata } from "../nostr";
 import { bech32ToHex } from "../Util"
+import { HashtagRegex } from "../Const";
 
 declare global {
     interface Window {
@@ -41,7 +42,7 @@ export default function useEventPublisher() {
         return ev;
     }
 
-    function processMentions(ev: NEvent, msg: string) {
+    function processContent(ev: NEvent, msg: string) {
         const replaceNpub = (match: string) => {
             const npub = match.slice(1);
             try {
@@ -53,7 +54,14 @@ export default function useEventPublisher() {
                 return match
             }
         }
-        let content = msg.replace(/@npub[a-z0-9]+/g, replaceNpub)
+        const replaceHashtag = (match: string) => {
+            const tag = match.slice(1);
+            const idx = ev.Tags.length;
+            ev.Tags.push(new Tag(["t", tag.toLowerCase()], idx));
+            return `#[${idx}]`;
+        }
+        let content = msg.replace(/@npub[a-z0-9]+/g, replaceNpub);
+        content = content.replace(HashtagRegex, replaceHashtag);
         ev.Content = content;
     }
 
@@ -76,7 +84,7 @@ export default function useEventPublisher() {
             if (pubKey) {
                 let ev = NEvent.ForPubKey(pubKey);
                 ev.Kind = EventKind.TextNote;
-                processMentions(ev, msg);
+                processContent(ev, msg);
                 return await signEvent(ev);
             }
         },
@@ -113,7 +121,7 @@ export default function useEventPublisher() {
                         ev.Tags.push(new Tag(["p", replyTo.PubKey], ev.Tags.length));
                     }
                 }
-                processMentions(ev, msg);
+                processContent(ev, msg);
                 return await signEvent(ev);
             }
         },
diff --git a/src/feed/TimelineFeed.ts b/src/feed/TimelineFeed.ts
index 52b79ea9..a72c5d90 100644
--- a/src/feed/TimelineFeed.ts
+++ b/src/feed/TimelineFeed.ts
@@ -1,36 +1,44 @@
 import { useEffect, useMemo, useState } from "react";
-import { HexKey, u256 } from "../nostr";
+import { u256 } from "../nostr";
 import EventKind from "../nostr/EventKind";
 import { Subscriptions } from "../nostr/Subscriptions";
 import { unixNow } from "../Util";
 import useSubscription from "./Subscription";
 
 export interface TimelineFeedOptions {
-    global: boolean,
     method: "TIME_RANGE" | "LIMIT_UNTIL"
 }
 
-export default function useTimelineFeed(pubKeys: HexKey | Array<HexKey>, options: TimelineFeedOptions) {
+export interface TimelineSubject {
+    type: "pubkey" | "hashtag" | "global",
+    items: string[]
+}
+
+export default function useTimelineFeed(subject: TimelineSubject, options: TimelineFeedOptions) {
     const now = unixNow();
     const [window, setWindow] = useState<number>(60 * 60);
     const [until, setUntil] = useState<number>(now);
     const [since, setSince] = useState<number>(now - window);
     const [trackingEvents, setTrackingEvent] = useState<u256[]>([]);
 
-    const subTab = options.global ? "global" : "follows";
     const sub = useMemo(() => {
-        if (!Array.isArray(pubKeys)) {
-            pubKeys = [pubKeys];
-        }
-
-        if (!options.global && (!pubKeys || pubKeys.length === 0)) {
+        if (subject.type !== "global" && subject.items.length == 0) {
             return null;
         }
 
         let sub = new Subscriptions();
-        sub.Id = `timeline:${subTab}`;
-        sub.Authors = options.global ? undefined : new Set(pubKeys);
+        sub.Id = `timeline:${subject.type}`;
         sub.Kinds = new Set([EventKind.TextNote, EventKind.Repost]);
+        switch (subject.type) {
+            case "pubkey": {
+                sub.Authors = new Set(subject.items);
+                break;
+            }
+            case "hashtag": {
+                sub.HashTags = new Set(subject.items);
+                break;
+            }
+        }
         if (options.method === "LIMIT_UNTIL") {
             sub.Until = until;
             sub.Limit = 10;
@@ -43,14 +51,14 @@ export default function useTimelineFeed(pubKeys: HexKey | Array<HexKey>, options
         }
 
         return sub;
-    }, [pubKeys, until, since, window]);
+    }, [subject, until, since, window]);
 
     const main = useSubscription(sub, { leaveOpen: true });
 
     const subNext = useMemo(() => {
         if (trackingEvents.length > 0) {
             let sub = new Subscriptions();
-            sub.Id = `timeline-related:${subTab}`;
+            sub.Id = `timeline-related:${subject.type}`;
             sub.Kinds = new Set([EventKind.Reaction, EventKind.Deletion, EventKind.Repost]);
             sub.ETags = new Set(trackingEvents);
             return sub;
diff --git a/src/index.tsx b/src/index.tsx
index 37dceb95..32d73d05 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -25,6 +25,7 @@ import VerificationPage from './pages/Verification';
 import MessagesPage from './pages/MessagesPage';
 import ChatPage from './pages/ChatPage';
 import DonatePage from './pages/DonatePage';
+import HashTagsPage from './pages/HashTagsPage';
 
 /**
  * HTTP query provider
@@ -81,6 +82,10 @@ const router = createBrowserRouter([
       {
         path: "/donate",
         element: <DonatePage />
+      },
+      {
+        path: "/t/:tag",
+        element: <HashTagsPage />
       }
     ]
   }
diff --git a/src/nostr/Subscriptions.ts b/src/nostr/Subscriptions.ts
index bf6fd9ba..676886c1 100644
--- a/src/nostr/Subscriptions.ts
+++ b/src/nostr/Subscriptions.ts
@@ -37,6 +37,11 @@ export class Subscriptions {
      */
     PTags?: Set<u256>;
 
+    /**
+     * A list of "t" tags to search 
+     */
+    HashTags?: Set<string>;
+
     /** 
      * a timestamp, events must be newer than this to pass
      */
@@ -125,6 +130,9 @@ export class Subscriptions {
         if (this.PTags) {
             ret["#p"] = Array.from(this.PTags);
         }
+        if(this.HashTags) {
+            ret["#t"] = Array.from(this.HashTags);
+        }
         if (this.Since !== null) {
             ret.since = this.Since;
         }
diff --git a/src/nostr/Tag.ts b/src/nostr/Tag.ts
index 2342914c..33e00417 100644
--- a/src/nostr/Tag.ts
+++ b/src/nostr/Tag.ts
@@ -7,6 +7,7 @@ export default class Tag {
     PubKey?: HexKey;
     Relay?: string;
     Marker?: string;
+    Hashtag?: string;
     Index: number;
     Invalid: boolean;
 
@@ -35,6 +36,10 @@ export default class Tag {
                 }
                 break;
             }
+            case "t": {
+                this.Hashtag = tag[1];
+                break;
+            }
             case "delegation": {
                 this.PubKey = tag[1];
                 break;
@@ -53,6 +58,9 @@ export default class Tag {
             case "p": {
                 return this.PubKey ? ["p", this.PubKey] : null;
             }
+            case "t": {
+                return ["t", this.Hashtag!];
+            }
             default: {
                 return this.Original;
             }
diff --git a/src/nostr/index.ts b/src/nostr/index.ts
index 62da4517..cac6946e 100644
--- a/src/nostr/index.ts
+++ b/src/nostr/index.ts
@@ -34,6 +34,7 @@ export type RawReqFilter = {
     kinds?: number[],
     "#e"?: u256[],
     "#p"?: u256[],
+    "#t"?: string[],
     since?: number,
     until?: number,
     limit?: number
diff --git a/src/pages/HashTagsPage.tsx b/src/pages/HashTagsPage.tsx
new file mode 100644
index 00000000..0609e8e5
--- /dev/null
+++ b/src/pages/HashTagsPage.tsx
@@ -0,0 +1,16 @@
+import { useParams } from "react-router-dom";
+import Timeline from "../element/Timeline";
+
+const HashTagsPage = () => {
+    const params = useParams();
+    const tag = params.tag!.toLowerCase();
+
+    return (
+        <>
+            <h2>#{tag}</h2>
+            <Timeline subject={{ type: "hashtag", items: [tag] }} postsOnly={false} method={"TIME_RANGE"} />
+        </>
+    )
+}
+
+export default HashTagsPage;
\ No newline at end of file
diff --git a/src/pages/ProfilePage.tsx b/src/pages/ProfilePage.tsx
index de29dbec..d697d63e 100644
--- a/src/pages/ProfilePage.tsx
+++ b/src/pages/ProfilePage.tsx
@@ -49,15 +49,15 @@ export default function ProfilePage() {
         return (
             <div className="name">
                 <h2>
-                  {user?.display_name || user?.name || 'Nostrich'}
-                  <FollowsYou pubkey={id} />
+                    {user?.display_name || user?.name || 'Nostrich'}
+                    <FollowsYou pubkey={id} />
                 </h2>
                 <Copy text={params.id || ""} />
                 {user?.nip05 && <Nip05 nip05={user.nip05} pubkey={user.pubkey} />}
             </div>
         )
     }
-    
+
     function bio() {
         const lnurl = extractLnAddress(user?.lud16 || user?.lud06 || "");
         return (
@@ -88,7 +88,7 @@ export default function ProfilePage() {
     function tabContent() {
         switch (tab) {
             case ProfileTab.Notes:
-                return <Timeline key={id} pubkeys={[id]} global={false} postsOnly={false} method={"LIMIT_UNTIL"} />;
+                return <Timeline key={id} subject={{ type: "pubkey", items: [id] }} postsOnly={false} method={"LIMIT_UNTIL"} />;
             case ProfileTab.Follows: {
                 if (isMe) {
                     return (
diff --git a/src/pages/Root.tsx b/src/pages/Root.tsx
index 4b496cc9..d5f8a12d 100644
--- a/src/pages/Root.tsx
+++ b/src/pages/Root.tsx
@@ -6,6 +6,7 @@ import Timeline from "../element/Timeline";
 import { useState } from "react";
 import { RootState } from "../state/Store";
 import { HexKey } from "../nostr";
+import { TimelineSubject } from "../feed/TimelineFeed";
 
 const RootTab = {
     Posts: 0,
@@ -25,6 +26,8 @@ export default function RootPage() {
         }
     }
 
+    const isGlobal = loggedOut || tab === RootTab.Global;
+    const timelineSubect: TimelineSubject = isGlobal ? { type: "global", items: [] } : { type: "pubkey", items: follows };
     return (
         <>
             {pubKey ? <>
@@ -41,7 +44,7 @@ export default function RootPage() {
                     </div>
                 </div></> : null}
             {followHints()}
-            <Timeline key={tab} pubkeys={follows} global={loggedOut || tab === RootTab.Global} postsOnly={tab === RootTab.Posts} method={"TIME_RANGE"} />
+            <Timeline key={tab} subject={timelineSubect} postsOnly={tab === RootTab.Posts} method={"TIME_RANGE"} />
         </>
     );
 }
\ No newline at end of file