snort/src/pages/MessagesPage.tsx

import { useMemo } from "react";
import { useSelector } from "react-redux"

import { HexKey, RawEvent } from "../nostr";
import ProfileImage from "../element/ProfileImage";
import { hexToBech32 } from "../Util";

type DmChat = {
    pubkey: HexKey,
    lastRead: number,
    unreadMessages: number,
    newestMessage: number
}

export default function MessagesPage() {
    const myPubKey = useSelector<any, string>(s => s.login.publicKey);
    const dms = useSelector<any, RawEvent[]>(s => s.login.dms);

    const chats = useMemo(() => {
        return extractChats(dms, myPubKey);
    }, [dms]);

    function person(chat: DmChat) {
        return (
            <div className="flex mb10" key={chat.pubkey}>
                <ProfileImage pubkey={chat.pubkey} className="f-grow" link={`/messages/${hexToBech32("npub", chat.pubkey)}`} />
                <span className="pill">
                    {chat.unreadMessages}
                </span>
            </div>
        )
    }

    return (
        <>
            <h3>Messages</h3>
            {chats.sort((a, b) => b.newestMessage - a.newestMessage).map(person)}
        </>
    )
}

export function lastReadDm(pk: HexKey) {
    let k = `dm:seen:${pk}`;
    return parseInt(window.localStorage.getItem(k) ?? "0");
}

export function setLastReadDm(pk: HexKey) {
    const now = Math.floor(new Date().getTime() / 1000);
    let current = lastReadDm(pk);
    if (current >= now) {
        return;
    }

    let k = `dm:seen:${pk}`;
    window.localStorage.setItem(k, now.toString());
}

export function totalUnread(dms: RawEvent[], myPubKey: HexKey) {
    return extractChats(dms, myPubKey).reduce((acc, v) => acc += v.unreadMessages, 0);
}

function unreadDms(dms: RawEvent[], myPubKey: HexKey, pk: HexKey) {
    let lastRead = lastReadDm(pk);
    return dms?.filter(a => a.pubkey === pk && a.pubkey !== myPubKey && a.created_at >= lastRead).length;
}

function newestMessage(dms: RawEvent[], myPubKey: HexKey, pk: HexKey) {
    return dms.filter(a => a.pubkey === pk && a.pubkey !== myPubKey).reduce((acc, v) => acc = v.created_at > acc ? v.created_at : acc, 0);
}


export function extractChats(dms: RawEvent[], myPubKey: HexKey) {
    const keys = dms.map(a => [a.pubkey, ...a.tags.filter(b => b[0] === "p").map(b => b[1])]).flat();
    const filteredKeys = Array.from(new Set<string>(keys));
    return filteredKeys.map(a => {
        return {
            pubkey: a,
            lastRead: lastReadDm(a),
            unreadMessages: unreadDms(dms, myPubKey, a),
            newestMessage: newestMessage(dms, myPubKey, a)
        } as DmChat;
    })
}