import { leaderboardReport } from '$lib/server/reports/index.js';
import { json } from '@sveltejs/kit';
import { isLeaderboardMetric, MAX_LEADERBOARD_OFFSET } from '$lib/server/fleet/leaderboard.js';
import type { LeaderboardPlayerCount } from '$lib/leaderboard.js';

export async function GET({ url }: { url: URL }) {
    const params = url.searchParams;
    const game = params.get('game');
    const map = params.get('map');
    const metric = params.get('metric');
    const q = params.get('q');
    const players = params.get('players');
    const rawLimit = params.get('limit');
    const rawOffset = params.get('offset');
    const integer = (value: string | null, fallback: number) =>
        value === null
            ? fallback
            : /^\d+$/.test(value) && Number.isSafeInteger(Number(value))
              ? Number(value)
              : NaN;
    const limit = integer(rawLimit, 50);
    const offset = integer(rawOffset, 0);
    if (
        (game !== null && game !== 't5' && game !== 't6') ||
        (map !== null && map.length > 1024) ||
        (q !== null && q.length > 100) ||
        (metric !== null && !isLeaderboardMetric(metric)) ||
        (players !== null && !/^[1-4]$/.test(players)) ||
        !Number.isFinite(limit) ||
        limit < 1 ||
        limit > 100 ||
        !Number.isFinite(offset) ||
        offset < 0 ||
        offset > MAX_LEADERBOARD_OFFSET
    ) {
        return json(
            {
                ok: false,
                kind: 'bad-request',
                error: 'Use game t5 or t6, a supported metric, players 1–4, map key up to 1024 characters, q up to 100 characters, limit 1–100, and offset 0–1000000.'
            },
            { status: 400 }
        );
    }
    return json(
        await leaderboardReport({
            game: game ?? undefined,
            map: map || undefined,
            metric: metric !== null && isLeaderboardMetric(metric) ? metric : undefined,
            players: players === null ? undefined : (Number(players) as LeaderboardPlayerCount),
            q: q ?? undefined,
            limit,
            offset
        })
    );
}