const API_BASE = process.env.NEXT_PUBLIC_API_URL ?? "";

export interface RateData {
  symbol: string;
  markPrice: number;
  indexPrice: number;
  lastFundingRate: number;
  nextFundingTime: number;
  timestamp: number;
}

export interface RatesResponse {
  BTC: RateData;
  ETH: RateData;
}

export interface HistoryPoint {
  fundingTime: number;
  fundingRate: number;
  timestamp: string;
}

export interface HistoryResponse {
  BTC: HistoryPoint[];
  ETH: HistoryPoint[];
}

export interface AssetStats {
  mean7d: number;
  annualized: number;
  count: number;
}

export interface StatsResponse {
  BTC: AssetStats;
  ETH: AssetStats;
  combo: { mean7d: number; annualized: number };
}

async function fetchAPI<T>(path: string): Promise<T> {
  const res = await fetch(`${API_BASE}${path}`, { cache: "no-store" });
  if (!res.ok) throw new Error(`API error ${res.status}`);
  return res.json();
}

export const api = {
  rates: () => fetchAPI<RatesResponse>("/api/rates"),
  history: () => fetchAPI<HistoryResponse>("/api/history"),
  stats: () => fetchAPI<StatsResponse>("/api/stats"),
  health: () => fetchAPI<{ status: string }>("/api/health"),
};