const fs = require("fs");
const { UA } = require("../data/constants");
const { fetchJSON } = require("./http-helpers");
const { Semaphore } = require("./ripe-stat");

const PEERINGDB_API_KEY = process.env.PEERINGDB_API_KEY || "";
const PEERINGDB_API_URL = process.env.PEERINGDB_API_URL || "https://www.peeringdb.com/api";

// Local PeeringDB SQLite (peeringdb-py sync, refreshed daily by cron)
const PEERINGDB_LOCAL_PATH = process.env.PEERINGDB_LOCAL_PATH || "/opt/peeringdb-data/peeringdb.sqlite3";
let _pdbLocal = null;
function getPdbLocal() {
  if (_pdbLocal) return _pdbLocal;
  try {
    const BetterSqlite3 = require("better-sqlite3");
    if (!fs.existsSync(PEERINGDB_LOCAL_PATH)) return null;
    _pdbLocal = new BetterSqlite3(PEERINGDB_LOCAL_PATH, { readonly: true, fileMustExist: true });
    console.log("[PeeringDB-local] SQLite opened:", PEERINGDB_LOCAL_PATH);
    return _pdbLocal;
  } catch (e) {
    console.warn("[PeeringDB-local] Could not open SQLite:", e.message);
    return null;
  }
}

// Map API path → SQLite result in { data: [...] } format, emulating the live PDB REST API.
function queryPeeringDBLocal(path) {
  const db = getPdbLocal();
  if (!db) return null;
  try {
    // /net?asn=X
    const netAsnMatch = path.match(/^\/net\?asn=(\d+)/);
    if (netAsnMatch) {
      const rows = db.prepare(
        "SELECT n.*, o.name AS org_name FROM peeringdb_network n " +
        "LEFT JOIN peeringdb_organization o ON n.org_id = o.id " +
        "WHERE n.asn = ? AND n.status = 'ok'"
      ).all(parseInt(netAsnMatch[1]));
      return { data: rows };
    }

    // /net?status=ok&depth=0  (coverage endpoint — all networks)
    if (path === "/net?status=ok&depth=0" || path.startsWith("/net?status=ok")) {
      const rows = db.prepare(
        "SELECT id, asn, name, aka, website, info_prefixes4, info_prefixes6, " +
        "info_type, info_traffic, info_unicast, info_ipv6, policy_general, org_id " +
        "FROM peeringdb_network WHERE status = 'ok' ORDER BY asn"
      ).all();
      return { data: rows };
    }

    // /netixlan?net_id=X&limit=...  or  /netixlan?asn=X&limit=...
    const netixlanNetId = path.match(/\/netixlan\?net_id=(\d+)/);
    if (netixlanNetId) {
      const rows = db.prepare(
        "SELECT ni.id, ni.net_id, ni.asn, ni.speed, ni.ipaddr4, ni.ipaddr6, ni.is_rs_peer, " +
        "ni.operational, ni.bfd_support, il.id AS ixlan_id, " +
        "ix.id AS ix_id, ix.name, ix.city, ix.country " +
        "FROM peeringdb_network_ixlan ni " +
        "LEFT JOIN peeringdb_ixlan il ON ni.ixlan_id = il.id " +
        "LEFT JOIN peeringdb_ix ix ON il.ix_id = ix.id " +
        "WHERE ni.net_id = ? AND ni.status = 'ok'"
      ).all(parseInt(netixlanNetId[1]));
      return { data: rows };
    }
    const netixlanAsn = path.match(/\/netixlan\?asn=(\d+)/);
    if (netixlanAsn) {
      const rows = db.prepare(
        "SELECT ni.id, ni.net_id, ni.asn, ni.speed, ni.ipaddr4, ni.ipaddr6, ni.is_rs_peer, " +
        "ni.operational, ni.bfd_support, il.id AS ixlan_id, " +
        "ix.id AS ix_id, ix.name, ix.city, ix.country " +
        "FROM peeringdb_network_ixlan ni " +
        "LEFT JOIN peeringdb_ixlan il ON ni.ixlan_id = il.id " +
        "LEFT JOIN peeringdb_ix ix ON il.ix_id = ix.id " +
        "WHERE ni.asn = ? AND ni.status = 'ok'"
      ).all(parseInt(netixlanAsn[1]));
      return { data: rows };
    }

    // /netixlan?ixlan_id=X
    const netixlanIxlanId = path.match(/\/netixlan\?ixlan_id=(\d+)/);
    if (netixlanIxlanId) {
      const rows = db.prepare(
        "SELECT ni.id, ni.net_id, ni.asn, ni.speed, ni.ipaddr4, ni.ipaddr6, ni.is_rs_peer, " +
        "n.name AS net_name " +
        "FROM peeringdb_network_ixlan ni " +
        "LEFT JOIN peeringdb_network n ON ni.net_id = n.id " +
        "WHERE ni.ixlan_id = ? AND ni.status = 'ok'"
      ).all(parseInt(netixlanIxlanId[1]));
      return { data: rows };
    }

    // /netfac?net_id=X
    const netfacNetId = path.match(/\/netfac\?net_id=(\d+)/);
    if (netfacNetId) {
      const rows = db.prepare(
        "SELECT nf.id, nf.net_id, f.id AS fac_id, f.name, f.city, f.state, " +
        "f.country, f.latitude, f.longitude, f.website " +
        "FROM peeringdb_network_facility nf " +
        "LEFT JOIN peeringdb_facility f ON nf.fac_id = f.id " +
        "WHERE nf.net_id = ? AND nf.status = 'ok'"
      ).all(parseInt(netfacNetId[1]));
      return { data: rows };
    }

    // /fac?id__in=X,Y,Z&fields=...
    const facIdIn = path.match(/\/fac\?id__in=([\d,]+)/);
    if (facIdIn) {
      const ids = facIdIn[1].split(",").map(Number).filter(Boolean);
      if (ids.length === 0) return { data: [] };
      const placeholders = ids.map(() => "?").join(",");
      const rows = db.prepare(
        "SELECT id, name, city, country, latitude, longitude, website " +
        "FROM peeringdb_facility WHERE id IN (" + placeholders + ") AND status = 'ok'"
      ).all(...ids);
      return { data: rows };
    }

    // /ixfac?ix_id__in=X,Y,Z
    const ixfacIxIdIn = path.match(/\/ixfac\?ix_id__in=([\d,]+)/);
    if (ixfacIxIdIn) {
      const ids = ixfacIxIdIn[1].split(",").map(Number).filter(Boolean);
      if (ids.length === 0) return { data: [] };
      const placeholders = ids.map(() => "?").join(",");
      const rows = db.prepare(
        "SELECT ixf.id, ixf.ix_id, ixf.fac_id, f.latitude, f.longitude, f.city, f.country " +
        "FROM peeringdb_ix_facility ixf " +
        "LEFT JOIN peeringdb_facility f ON ixf.fac_id = f.id " +
        "WHERE ixf.ix_id IN (" + placeholders + ") AND ixf.status = 'ok'"
      ).all(...ids);
      return { data: rows };
    }

    // /ix?name__contains=X
    const ixNameContains = path.match(/\/ix\?name__contains=([^&]+)/);
    if (ixNameContains) {
      const term = "%" + decodeURIComponent(ixNameContains[1]) + "%";
      const rows = db.prepare(
        "SELECT id, name, name_long, city, country, website, region_continent " +
        "FROM peeringdb_ix WHERE (name LIKE ? OR name_long LIKE ?) AND status = 'ok' LIMIT 20"
      ).all(term, term);
      return { data: rows };
    }

    // /ixlan?ix_id=X
    const ixlanIxId = path.match(/\/ixlan\?ix_id=(\d+)/);
    if (ixlanIxId) {
      const rows = db.prepare(
        "SELECT id, ix_id, name, rs_asn, arp_sponge, mtu FROM peeringdb_ixlan " +
        "WHERE ix_id = ? AND status = 'ok'"
      ).all(parseInt(ixlanIxId[1]));
      return { data: rows };
    }

    // /net/X  (single network by PDB id)
    const netById = path.match(/^\/net\/(\d+)$/);
    if (netById) {
      const row = db.prepare(
        "SELECT n.*, o.name AS org_name FROM peeringdb_network n " +
        "LEFT JOIN peeringdb_organization o ON n.org_id = o.id " +
        "WHERE n.id = ? AND n.status = 'ok'"
      ).get(parseInt(netById[1]));
      return row ? { data: [row] } : { data: [] };
    }

    return null; // path not handled locally — fall through to live API
  } catch (e) {
    console.warn("[PeeringDB-local] Query error for", path, ":", e.message);
    return null;
  }
}

// PeeringDB semaphore — limits concurrent PDB requests to avoid 429 rate-limits
const pdbSemaphore = new Semaphore(5);

// PeeringDB authenticated fetch helper — tries local SQLite first, falls back to live API
async function fetchPeeringDB(path, options) {
  // Try local SQLite (instant, no rate-limits) — skip large "all networks" calls to live API
  const localResult = queryPeeringDBLocal(path);
  if (localResult !== null) return localResult;

  // Fallback: live PeeringDB API (throttled via semaphore)
  const url = PEERINGDB_API_URL + path;
  const headers = { "User-Agent": UA };
  if (PEERINGDB_API_KEY) {
    headers["Authorization"] = "Api-Key " + PEERINGDB_API_KEY;
  }
  await pdbSemaphore.acquire();
  try {
    return await fetchJSON(url, { ...options, headers: { ...(options && options.headers || {}), ...headers } });
  } finally {
    pdbSemaphore.release();
  }
}

// PeeringDB fetch with exponential backoff retries (handles rate-limits under concurrent load).
// Up to 3 attempts: immediate → 2s → 5s. Returns null only after all attempts exhausted.
async function fetchPeeringDBWithRetry(path, options) {
  const delays = [2000, 5000];
  let result = await fetchPeeringDB(path, options);
  for (let i = 0; i < delays.length && result === null; i++) {
    await new Promise(r => setTimeout(r, delays[i]));
    result = await fetchPeeringDB(path, options);
  }
  return result;
}

module.exports = {
  PEERINGDB_API_KEY,
  PEERINGDB_API_URL,
  getPdbLocal,
  queryPeeringDBLocal,
  pdbSemaphore,
  fetchPeeringDB,
  fetchPeeringDBWithRetry,
};