sendou.ink/app/features/team/loaders/t.server.ts

import type { LoaderFunctionArgs } from "@remix-run/node";
import type { UserWithPlusTier } from "~/db/types";
import { getUserId } from "~/features/auth/core/user.server";
import { sumArray } from "~/utils/number";
import * as TeamRepository from "../TeamRepository.server";

export const loader = async ({ request }: LoaderFunctionArgs) => {
	const user = await getUserId(request);

	const unsortedTeams = await TeamRepository.findAllUndisbanded();

	const teams = unsortedTeams.sort((teamA, teamB) => {
		// show own team first always
		if (user && teamA.members.some((m) => m.id === user.id)) {
			return -1;
		}

		if (user && teamB.members.some((m) => m.id === user.id)) {
			return 1;
		}

		// then full teams
		if (teamA.members.length >= 4 && teamB.members.length < 4) {
			return -1;
		}

		if (teamA.members.length < 4 && teamB.members.length >= 4) {
			return 1;
		}

		const teamAPlusTierRating = membersToCommonPlusTierRating(teamA.members);
		const teamBPlusTierRating = membersToCommonPlusTierRating(teamB.members);

		// and as tiebreaker teams with a higher plus server tier member first (4 best considered)
		if (teamAPlusTierRating > teamBPlusTierRating) {
			return 1;
		}

		if (teamAPlusTierRating < teamBPlusTierRating) {
			return -1;
		}

		return 0;
	});

	return {
		teams,
		teamMemberOfCount: user
			? teams.filter((team) => team.members.some((m) => m.id === user.id))
					.length
			: 0,
	};
};

const membersToCommonPlusTierRating = (
	members: Pick<UserWithPlusTier, "plusTier">[],
) => {
	return sumArray(
		members
			.map((m) => m.plusTier ?? 100)
			.sort((a, b) => a - b)
			.slice(0, 4),
	);
};