// Backend API client.
// NEXT_PUBLIC_API_BASE 는 docker-compose 에서 http://localhost:8000 으로 주입됨.

const RAW_BASE = process.env.NEXT_PUBLIC_API_BASE ?? "http://localhost:8000";
export const API_BASE = RAW_BASE.replace(/\/$/, "");

export type Symbol = {
  code: string;
  name: string;
  market: string;
  sector: string | null;
  is_seed: boolean;
};

export type SymbolSearch = {
  q: string;
  count: number;
  items: Symbol[];
};

export type OhlcvPoint = {
  date: string;
  open: number | null;
  high: number | null;
  low: number | null;
  close: number | null;
  volume: number | null;
};

export type SentimentPoint = {
  date: string;
  n_articles: number;
  mean_score: number | null;
  weighted_score: number | null;
};

export type TradingValuePoint = {
  date: string;
  foreign_net: number | null;
  institution_net: number | null;
  individual_net: number | null;
};

export type ChartPayload = {
  code: string;
  name: string;
  market: string;
  range: { from: string; to: string };
  ohlcv: OhlcvPoint[];
  sentiment: SentimentPoint[];
  trading_value: TradingValuePoint[];
};

export type PredictionStep = {
  horizon: number;
  target_idx?: number;
  point_close: number;
  ci_low: number;
  ci_high: number;
  prob_up: number;
  prob_flat: number;
  prob_down: number;
  direction: "up" | "flat" | "down";
  expected_return: number;
  target_date?: string;
};

export type PredictResponse = {
  code: string;
  base_date: string;
  base_close: number;
  sources_used: string[];
  steps: PredictionStep[];
  saved_prediction_ids: number[];
  user_triggered: boolean;
};

export type LatestPredictionStep = {
  predicted_at: string | null;
  target_date: string;
  horizon: number;
  direction: "up" | "flat" | "down" | string;
  prob_up: number | null;
  prob_flat: number | null;
  prob_down: number | null;
  expected_return: number | null;
  point_close: number | null;
  ci_low: number | null;
  ci_high: number | null;
  user_triggered: boolean;
  features_snapshot: unknown;
};

export type LatestPredictionResponse = {
  code: string;
  name?: string;
  found: boolean;
  base_date?: string;
  base_close?: number | null;
  steps: LatestPredictionStep[];
};

export type MetricsRow = {
  model: string;
  horizon: number;
  n: number;
  hit_rate: number | null;
  mae: number | null;
};

export type MetricsResponse = {
  code?: string;
  name?: string;
  window_days: number;
  range: { from: string; to: string };
  by_model_horizon: MetricsRow[];
};

export type NewsItem = {
  source: string;
  published_at: string | null;
  title: string;
  url: string;
  sentiment_score: number | null;
  sentiment_label: string | null;
};

export type NewsResponse = {
  code: string;
  name: string;
  count: number;
  items: NewsItem[];
};

async function getJson<T>(path: string, init?: RequestInit): Promise<T> {
  const res = await fetch(`${API_BASE}${path}`, {
    ...init,
    headers: {
      Accept: "application/json",
      ...(init?.headers ?? {}),
    },
    cache: "no-store",
  });
  if (!res.ok) {
    const text = await res.text().catch(() => "");
    throw new Error(`API ${path} → ${res.status} ${text || res.statusText}`);
  }
  return (await res.json()) as T;
}

export const api = {
  search: (q: string, seedOnly = false, limit = 20) =>
    getJson<SymbolSearch>(
      `/api/symbols/search?q=${encodeURIComponent(q)}&limit=${limit}&seed_only=${seedOnly}`,
    ),
  getSymbol: (code: string) => getJson<Symbol>(`/api/symbols/${encodeURIComponent(code)}`),
  getChart: (code: string, days = 180) =>
    getJson<ChartPayload>(`/api/chart/${encodeURIComponent(code)}?days=${days}`),
  predict: (code: string, horizons = "1,3,5") =>
    getJson<PredictResponse>(
      `/api/predict/${encodeURIComponent(code)}?horizons=${encodeURIComponent(horizons)}`,
      { method: "POST" },
    ),
  latestPrediction: (code: string) =>
    getJson<LatestPredictionResponse>(`/api/predict/${encodeURIComponent(code)}/latest`),
  metrics: (code: string, windowDays = 30) =>
    getJson<MetricsResponse>(
      `/api/metrics/${encodeURIComponent(code)}?window_days=${windowDays}`,
    ),
  overallMetrics: (windowDays = 30) =>
    getJson<MetricsResponse>(`/api/metrics?window_days=${windowDays}`),
  news: (code: string, limit = 20, source?: string) =>
    getJson<NewsResponse>(
      `/api/news/${encodeURIComponent(code)}?limit=${limit}${
        source ? `&source=${encodeURIComponent(source)}` : ""
      }`,
    ),
};