/** Client for the Albion Online Data Project (AODP) REST API. */
import { fetch as undiciFetch, ProxyAgent } from 'undici';
import { getMeta } from '../db/index.js';

/**
 * AODP is blocked in some regions. If the user's VPN is browser-only, they can
 * instead set a proxy (Settings page, or the HTTPS_PROXY env var) and the app
 * routes its market requests through it.
 */
function getProxyUrl(): string | null {
  return getMeta('proxy_url') || process.env.HTTPS_PROXY || process.env.HTTP_PROXY || null;
}

async function proxyAwareFetch(url: string, timeoutMs: number): Promise<{ ok: boolean; status: number; json(): Promise<unknown> }> {
  const proxyUrl = getProxyUrl();
  const signal = AbortSignal.timeout(timeoutMs);
  if (proxyUrl) {
    return undiciFetch(url, { signal, dispatcher: new ProxyAgent(proxyUrl) });
  }
  return fetch(url, { signal });
}

export const SERVER_HOSTS: Record<string, string> = {
  europe: 'europe.albion-online-data.com',
  americas: 'west.albion-online-data.com',
  asia: 'east.albion-online-data.com',
};

/** Locations with player markets we track by default. */
export const CITIES = [
  'Bridgewatch',
  'Caerleon',
  'Fort Sterling',
  'Lymhurst',
  'Martlock',
  'Thetford',
  'Brecilien',
  'Black Market',
] as const;

export interface AodpPriceRow {
  item_id: string;
  city: string;
  quality: number;
  sell_price_min: number;
  sell_price_min_date: string;
  sell_price_max: number;
  sell_price_max_date: string;
  buy_price_max: number;
  buy_price_max_date: string;
  buy_price_min: number;
  buy_price_min_date: string;
}

const CHUNK_SIZE = 100; // item ids per request (keeps URLs short)
const REQUEST_DELAY_MS = 500; // stay well under AODP's ~180 req/min limit
const REQUEST_TIMEOUT_MS = 20000;

/** AODP uses 0001-01-01T00:00:00 as "never observed". */
export function normalizeAodpDate(d: string | null | undefined): string | null {
  if (!d || d.startsWith('0001-')) return null;
  return d.endsWith('Z') ? d : `${d}Z`; // AODP timestamps are UTC without the Z
}

function sleep(ms: number): Promise<void> {
  return new Promise((r) => setTimeout(r, ms));
}

export class AodpUnreachableError extends Error {
  constructor(cause: unknown) {
    super(
      'Market data API (albion-online-data.com) is unreachable. ' +
        'If you are in a region where it is blocked, check that your VPN is on. ' +
        `(${cause instanceof Error ? cause.message : String(cause)})`,
    );
    this.name = 'AodpUnreachableError';
  }
}

export interface FetchPricesOptions {
  server: string; // key of SERVER_HOSTS
  items: string[];
  cities?: string[];
  qualities?: number[];
  onProgress?: (done: number, total: number) => void;
}

export async function fetchPrices(opts: FetchPricesOptions): Promise<AodpPriceRow[]> {
  const host = SERVER_HOSTS[opts.server] ?? SERVER_HOSTS.europe;
  const cities = opts.cities ?? [...CITIES];
  const qualities = opts.qualities ?? [1, 2, 3, 4, 5];

  const chunks: string[][] = [];
  for (let i = 0; i < opts.items.length; i += CHUNK_SIZE) {
    chunks.push(opts.items.slice(i, i + CHUNK_SIZE));
  }

  const all: AodpPriceRow[] = [];
  for (let i = 0; i < chunks.length; i++) {
    const url =
      `https://${host}/api/v2/stats/prices/${encodeURIComponent(chunks[i].join(','))}` +
      `?locations=${encodeURIComponent(cities.join(','))}` +
      `&qualities=${qualities.join(',')}`;
    try {
      const res = await proxyAwareFetch(url, REQUEST_TIMEOUT_MS);
      if (!res.ok) throw new Error(`HTTP ${res.status}`);
      const rows = (await res.json()) as AodpPriceRow[];
      all.push(...rows);
    } catch (e) {
      throw new AodpUnreachableError(e);
    }
    opts.onProgress?.(i + 1, chunks.length);
    if (i < chunks.length - 1) await sleep(REQUEST_DELAY_MS);
  }
  return all;
}