const API_BASE = "https://api.dongfeng-systems.org";

// ── Raw shape returned by the API ────────────────────────────────────────────
export interface LiveQuote {
  symbol: string;
  lastPrice: number;
  volume: number | null;
  previousClose: number;
  openPrice: number | null;
  marketOpen?: boolean;
}

// ── Derived/mapped shape used by every UI component ──────────────────────────
export interface MappedQuote {
  symbol: string;
  lastPrice: number;
  volume: number | null;
  previousClose: number;
  openPrice: number | null;
  marketOpen: boolean;
  /** lastPrice - previousClose */
  priceChange: number;
  /** ((lastPrice - previousClose) / previousClose) * 100 */
  percentChange: number;
}

/**
 * Format a value that may be null when markets are closed.
 * Returns "Markets closed" if marketOpen is false or value is null/undefined.
 */
export function formatMarketValue(
  value: number | null | undefined,
  marketOpen: boolean,
  formatter: (v: number) => string
): string {
  if (!marketOpen || value == null) {
    return "Markets closed";
  }
  return formatter(value);
}

/** Single transformation applied once; all components share this output type. */
export function mapQuote(raw: LiveQuote): MappedQuote {
  const priceChange = raw.lastPrice - raw.previousClose;
  const percentChange =
    raw.previousClose !== 0
      ? (priceChange / raw.previousClose) * 100
      : 0;
  return {
    ...raw,
    marketOpen: raw.marketOpen ?? true,
    priceChange,
    percentChange,
  };
}

// ── Fetch helpers ─────────────────────────────────────────────────────────────
export async function getLiveQuote(symbol: string): Promise<MappedQuote> {
  const res = await fetch(`${API_BASE}/api/market/live/${symbol}`, {
    cache: "no-store",
  });
  if (!res.ok) throw new Error("Failed to fetch live quote");
  const raw: LiveQuote = await res.json();
  return mapQuote(raw);
}

// Alias kept so InterestsPage import is unchanged
export const getWatchlistQuote = getLiveQuote;
export type WatchlistQuote = MappedQuote;