import { leaderboardMetrics } from './leaderboard.js';

const origin = 'https://electric-cherry.invalid';
const contextKeys = ['game', 'map', 'players', 'metric', 'q', 'offset'] as const;

/** Only retain a local leaderboard destination and its supported view state. */
export function leaderboardReturnHref(value: string | null | undefined): string {
    if (!value?.startsWith('/leaderboard')) return '/leaderboard';
    try {
        const url = new URL(value, origin);
        if (url.origin !== origin || url.pathname !== '/leaderboard') return '/leaderboard';
        const params = new URLSearchParams();
        for (const key of contextKeys) {
            const entry = url.searchParams.get(key);
            if (entry || (key === 'map' && entry !== null)) params.set(key, entry!);
        }
        return `/leaderboard${params.size ? `?${params}` : ''}`;
    } catch {
        return '/leaderboard';
    }
}

export function playerContextHref(guid: string, source: string): string {
    const returnTo = leaderboardReturnHref(source);
    const original = new URL(returnTo, origin).searchParams;
    const params = new URLSearchParams({ returnTo });
    // History pagination is independent of the originating leaderboard page.
    const game = original.get('game');
    const map = original.get('map');
    const metric = original.get('metric');
    const players = original.get('players');
    // Match the leaderboard's displayed defaults for older or hand-edited URLs.
    if (game === 't5' || game === 't6') params.set('game', game);
    if (map !== null && map.length <= 1024) params.set('map', map);
    if (players && /^[1-4]$/.test(players)) params.set('players', players);
    if (metric && leaderboardMetrics.some((item) => item.key === metric))
        params.set('metric', metric);
    return `/leaderboard/players/${encodeURIComponent(guid)}?${params}`;
}

export function profileViewHref(current: URL, changes: Record<string, string>): string {
    const params = new URLSearchParams(current.search);
    params.delete('offset');
    for (const [key, value] of Object.entries(changes)) {
        if (value || key === 'map') params.set(key, value);
        else params.delete(key);
    }
    return `${current.pathname}${params.size ? `?${params}` : ''}`;
}