'use client';
import type { RankingResponse } from './types';
import type { CompareMode, CompareResponse, IndicatorsResponse, RankHistoryResponse } from './types-compare';

/** Browser-side fetches for the compare / rankings pages (same-origin `/api/v1`, rewritten to the API). */
export class ClientCompareError extends Error {
  constructor(
    readonly status: number,
    message: string,
  ) {
    super(message);
    this.name = 'ClientCompareError';
  }
}

async function get<T>(path: string, signal?: AbortSignal): Promise<T> {
  const res = await fetch(`/api/v1${path}`, { headers: { accept: 'application/json' }, signal });
  if (!res.ok) throw new ClientCompareError(res.status, `API ${res.status}`);
  return (await res.json()) as T;
}

function qs(obj: Record<string, string | number | boolean | null | undefined>): string {
  const p = new URLSearchParams();
  for (const [k, v] of Object.entries(obj)) if (v !== undefined && v !== null && v !== '') p.set(k, String(v));
  const s = p.toString();
  return s ? `?${s}` : '';
}

export const clientCompare = {
  compare: (countries: string[], indicators: string[], q: { from?: number | null; to?: number | null; mode?: CompareMode } = {}, signal?: AbortSignal) =>
    get<CompareResponse>(`/compare${qs({ countries: countries.join(','), indicators: indicators.join(','), from: q.from, to: q.to, mode: q.mode ?? 'absolute' })}`, signal),

  indicators: (signal?: AbortSignal) => get<IndicatorsResponse>('/indicators', signal),

  rankingTop: (slug: string, limit = 3, signal?: AbortSignal) => get<RankingResponse>(`/rankings/${encodeURIComponent(slug)}${qs({ limit, sparkline: false })}`, signal),

  rankHistory: (slug: string, countries: string[], signal?: AbortSignal) => get<RankHistoryResponse>(`/rankings/${encodeURIComponent(slug)}/history${qs({ countries: countries.join(',') })}`, signal),
};