// /home/def/monitor/backend/server.js
//
// Express backend for monitor.outsidethebox.top
// - Reads /home/def/monitor/config/lines.json
// - Rotating refresh (one line per interval)
// - Supports sources:
//     * CoinGecko: line.source omitted or "coingecko" + coingecko_id (slug)
//     * KlingEx:   line.source === "klingex" + klingex_pair ("ETHO-USDT", "EGAZ-USDT")
//
// Fiat sources (USD base):
//   * USD: fixed 1.0
//   * CAD: Bank of Canada FXUSDCAD (1 USD = X CAD) -> invert to get CAD in USD
//   * EUR: Frankfurter API EUR->USD (timeseries + latest)
//
// Endpoints:
//   GET /health
//   GET /api/lines

const fs = require("fs");
const path = require("path");
const express = require("express");
const { fetchPair } = require("./providers/klingex");
const oracleRoutes = require("../oracle/routes");

const app = express();
app.use("/api/oracle", oracleRoutes);

const PORT = process.env.PORT ? Number(process.env.PORT) : 4010;
const ROTATE_SECONDS = process.env.ROTATE_SECONDS ? Number(process.env.ROTATE_SECONDS) : 60;

const ROOT = "/home/def/monitor";
const CONFIG_PATH = path.join(ROOT, "config", "lines.json");

// Bank of Canada: USD/CAD (1 USD = X CAD). We invert to show CAD in USD base.
const BOC_USDCAD = "https://www.bankofcanada.ca/valet/observations/FXUSDCAD/json";

// Frankfurter FX API (ECB-based). We'll use EUR->USD for Euro.
const FRANKFURTER = "https://api.frankfurter.app";

function nowMs() { return Date.now(); }

async function fetchJson(url, { timeoutMs = 15000 } = {}) {
  const ctrl = new AbortController();
  const t = setTimeout(() => ctrl.abort(), timeoutMs);
  try {
    const res = await fetch(url, {
      headers: {
        "accept": "application/json",
        "user-agent": "monitor.outsidethebox.top/1.0"
      },
      signal: ctrl.signal
    });
    if (!res.ok) {
      const txt = await res.text().catch(() => "");
      const err = new Error(`HTTP ${res.status} for ${url} :: ${txt.slice(0, 250)}`);
      err.status = res.status;
      throw err;
    }
    return await res.json();
  } finally {
    clearTimeout(t);
  }
}

function normalizeTo7(points) {
  const cleaned = points.filter(v => typeof v === "number" && isFinite(v));
  if (cleaned.length <= 7) return cleaned;
  const out = [];
  for (let i = 0; i < 7; i++) {
    const idx = Math.round((i * (cleaned.length - 1)) / 6);
    out.push(cleaned[idx]);
  }
  return out;
}

function formatDisplay(v) {
  if (v == null || !isFinite(v)) return "—";
  if (v >= 1000) return v.toFixed(0);
  if (v >= 1) return v.toFixed(4);
  return v.toFixed(6);
}

function isoDate(d) { return d.toISOString().slice(0, 10); }

function dateRange(days) {
  const end = new Date();
  const start = new Date();
  start.setDate(end.getDate() - (days + 3)); // small buffer
  return { start: isoDate(start), end: isoDate(end) };
}

function cgMarketChartUrl(coinId, vs, days = 7) {
  return `https://api.coingecko.com/api/v3/coins/${encodeURIComponent(coinId)}/market_chart?vs_currency=${encodeURIComponent(vs)}&days=${days}&interval=daily`;
}

/* --------------------- state --------------------- */
let cfg = null;
let cfgMtime = 0;

let queue = []; // rotating items (fiat lines + crypto lines)
let state = {
  fiat: [],
  crypto: [],
  errors: [],
  progress: { total: 0, done: 0, current: null, cycle: 0 }
};

let backoffUntilMs = 0;
let consecutive429 = 0;

/* --------------------- config load --------------------- */
function loadConfig() {
  const st = fs.statSync(CONFIG_PATH);
  if (st.mtimeMs <= cfgMtime && cfg) return cfg;

  const raw = fs.readFileSync(CONFIG_PATH, "utf8");
  const parsed = JSON.parse(raw);
  cfg = parsed;
  cfgMtime = st.mtimeMs;

  // Flatten into one rotating queue in the order we want to update
  const fiatLines = (cfg?.fiat?.lines || []).map(x => ({ ...x, group: "fiat" }));
  const cryptoLines = (cfg?.crypto?.lines || []).map(x => ({ ...x, group: "crypto" }));

  queue = [...fiatLines, ...cryptoLines];

  // init visible state arrays (keep ordering)
  state.fiat = fiatLines.map(x => ({
    ...x,
    value: null,
    display: "—",
    vs: cfg?.fiat?.base || "USD",
    spark: [],
    spark_points: [],
    source: "init"
  }));

  state.crypto = cryptoLines.map(x => ({
    ...x,
    value: null,
    display: "—",
    vs: (cfg?.crypto?.vs_currency || "usd").toUpperCase(),
    spark: [],
    spark_points: [],
    source: "init"
  }));

  state.errors = [];
  state.progress.total = queue.length;
  state.progress.done = 0;
  state.progress.current = null;

  return cfg;
}

function findLineInState(group, key) {
  const arr = group === "fiat" ? state.fiat : state.crypto;
  return arr.find(x => x.key === key);
}

function setError(msg) {
  state.errors.push(msg);
  // keep last 20 errors max
  if (state.errors.length > 20) state.errors = state.errors.slice(-20);
}

function setProgress(currentKey = null) {
  state.progress.current = currentKey;
}

function nextCycle() {
  state.progress.cycle += 1;
  state.progress.done = 0;
  state.progress.current = null;
}

/* --------------------- fiat fetchers --------------------- */

// CAD in USD base using BoC FXUSDCAD (1 USD = X CAD) -> invert for CADUSD
async function fetchCadUsdFromBoC() {
  const j = await fetchJson(BOC_USDCAD, { timeoutMs: 15000 });

  const obs = Array.isArray(j?.observations) ? j.observations : [];
  // obs entries: { d: "YYYY-MM-DD", FXUSDCAD: { v: "1.34" } }
  const points = [];
  const sparkPoints = [];

  for (const o of obs) {
    const d = o?.d;
    const v = o?.FXUSDCAD?.v;
    const num = v != null ? Number(v) : NaN;
    if (!d || !isFinite(num) || num <= 0) continue;

    // invert: 1 CAD = 1 / (USD->CAD)
    const cadusd = 1 / num;
    const ts = Date.parse(d + "T00:00:00Z");
    points.push(cadusd);
    sparkPoints.push({ t: ts, v: cadusd });
  }

  const p7 = normalizeTo7(points);
  const sp7 = normalizeTo7(sparkPoints.map(x => x.v)).map((v, i) => {
    const t = sparkPoints[Math.min(i, sparkPoints.length - 1)]?.t ?? nowMs();
    return { t, v };
  });

  const latest = p7.length ? p7[p7.length - 1] : (points.length ? points[points.length - 1] : null);

  return { latest, spark: p7, spark_points: sp7, source: "boc" };
}

// EUR in USD base using Frankfurter timeseries EUR->USD
async function fetchEurUsdFromFrankfurter() {
  const { start, end } = dateRange(7);
  const url = `${FRANKFURTER}/${start}..${end}?from=EUR&to=USD`;

  const j = await fetchJson(url, { timeoutMs: 15000 });
  // response: { start_date, end_date, base, rates: { "YYYY-MM-DD": { "USD": 1.09 } } }
  const rates = j?.rates && typeof j.rates === "object" ? j.rates : {};

  // Sort dates ascending
  const dates = Object.keys(rates).sort();
  const points = [];
  const sparkPoints = [];

  for (const d of dates) {
    const usd = rates?.[d]?.USD;
    const num = usd != null ? Number(usd) : NaN;
    if (!isFinite(num) || num <= 0) continue;
    const ts = Date.parse(d + "T00:00:00Z");
    points.push(num);
    sparkPoints.push({ t: ts, v: num });
  }

  const p7 = normalizeTo7(points);
  const sp7 = normalizeTo7(sparkPoints.map(x => x.v)).map((v, i) => {
    const t = sparkPoints[Math.min(i, sparkPoints.length - 1)]?.t ?? nowMs();
    return { t, v };
  });

  const latest = p7.length ? p7[p7.length - 1] : (points.length ? points[points.length - 1] : null);

  return { latest, spark: p7, spark_points: sp7, source: "frankfurter" };
}

async function updateFiatLine(line) {
  const base = (cfg?.fiat?.base || "USD").toUpperCase();

  if (line.key === "USD") {
    // fixed USD base
    return {
      value: 1,
      spark: [1, 1, 1, 1, 1, 1, 1],
      spark_points: Array.from({ length: 7 }, (_, i) => ({ t: nowMs() - (6 - i) * 86400000, v: 1 })),
      source: "fixed",
      vs: base
    };
  }

  if (line.key === "CAD") {
    const r = await fetchCadUsdFromBoC();
    return {
      value: r.latest,
      spark: r.spark,
      spark_points: r.spark_points,
      source: r.source,
      vs: base
    };
  }

  if (line.key === "EUR") {
    const r = await fetchEurUsdFromFrankfurter();
    return {
      value: r.latest,
      spark: r.spark,
      spark_points: r.spark_points,
      source: r.source,
      vs: base
    };
  }

  // Unknown fiat (not implemented)
  throw new Error(`Unsupported fiat key: ${line.key}`);
}

/* --------------------- crypto fetchers --------------------- */

let cgCache = new Map(); // coinId -> { atMs, data }
const CG_CACHE_MS = 5 * 60 * 1000; // 5 min cache to reduce calls

async function fetchCoinGeckoMarketChart(coinId, vs, days = 7) {
  const now = nowMs();
  const cached = cgCache.get(coinId);
  if (cached && (now - cached.atMs) < CG_CACHE_MS) {
    return { ...cached.data, source: "coingecko:cache" };
  }

  const url = cgMarketChartUrl(coinId, vs, days);
  const j = await fetchJson(url, { timeoutMs: 15000 });

  // j.prices = [[ts, price], ...]
  const prices = Array.isArray(j?.prices) ? j.prices : [];
  const pts = [];
  const sp = [];

  for (const p of prices) {
    const t = Array.isArray(p) ? Number(p[0]) : NaN;
    const v = Array.isArray(p) ? Number(p[1]) : NaN;
    if (!isFinite(t) || !isFinite(v)) continue;
    pts.push(v);
    sp.push({ t, v });
  }

  const p7 = normalizeTo7(pts);
  const sp7 = normalizeTo7(sp.map(x => x.v)).map((v, i) => {
    const t = sp[Math.min(i, sp.length - 1)]?.t ?? nowMs();
    return { t, v };
  });

  const out = {
    value: p7.length ? p7[p7.length - 1] : (pts.length ? pts[pts.length - 1] : null),
    spark: p7,
    spark_points: sp7,
    source: "coingecko"
  };

  cgCache.set(coinId, { atMs: now, data: out });
  return out;
}

function parseKlingexPair(pair) {
  // accept "ETHO-USDT" or "ETHO_USDT"
  if (!pair) return null;
  const p = String(pair).replace("_", "-").toUpperCase();
  const m = p.match(/^([A-Z0-9]+)-([A-Z0-9]+)$/);
  if (!m) return null;
  return { base: m[1], quote: m[2], pair: `${m[1]}-${m[2]}` };
}

async function fetchKlingexLastPrice(pairStr) {
  const parsed = parseKlingexPair(pairStr);
  if (!parsed) throw new Error(`Bad klingex_pair: ${pairStr}`);

  // Your smoketest showed these work:
  //   client.markets.tickers() returns array of { ticker_id: 'ETHO_USDT', last_price: '...' }
  // We'll use the provider fetchPair() which already encapsulates the SDK usage.
  const r = await fetchPair(parsed.pair); // expects "ETHO-USDT"
  // r should be: { price, source, ... }
  return r;
}

async function updateCryptoLine(line) {
  const vs = (cfg?.crypto?.vs_currency || "usd").toLowerCase();

  // KlingEx override for specific coins
  if ((line.source || "").toLowerCase() === "klingex") {
    const kp = line.klingex_pair;
    const r = await fetchKlingexLastPrice(kp);

    const price = Number(r.price);
    if (!isFinite(price)) throw new Error(`KlingEx returned non-numeric price for ${line.key}`);

    // KlingEx currently gives spot only (no OHLCV from your tests),
    // so we keep a flat 7-point spark for now using the current price.
    const spark = Array(7).fill(price);
    const spark_points = Array.from({ length: 7 }, (_, i) => ({ t: nowMs() - (6 - i) * 86400000, v: price }));

    return { value: price, spark, spark_points, source: r.source || "klingex", vs: "USD" };
  }

  // Default: CoinGecko
  const coinId = line.coingecko_id;
  if (!coinId) throw new Error(`missing coingecko_id`);
  const r = await fetchCoinGeckoMarketChart(coinId, vs, 7);
  return { ...r, vs: vs.toUpperCase() };
}

/* --------------------- rotating updater --------------------- */
async function doOneUpdate() {
  loadConfig();

  if (!queue.length) return;

  const now = nowMs();
  if (now < backoffUntilMs) return;

  // rotate pointer using cycle+done
  const idx = state.progress.done % queue.length;
  const item = queue[idx];

  setProgress(`${item.group}:${item.key}`);

  const started = nowMs();
  try {
    if (item.group === "fiat") {
      const stLine = findLineInState("fiat", item.key);
      const r = await updateFiatLine(item);

      if (stLine) {
        stLine.value = r.value;
        stLine.display = formatDisplay(r.value);
        stLine.vs = r.vs || (cfg?.fiat?.base || "USD");
        stLine.spark = r.spark || [];
        stLine.spark_points = r.spark_points || [];
        stLine.source = r.source || "fiat";
      }
    } else {
      const stLine = findLineInState("crypto", item.key);
      const r = await updateCryptoLine(item);

      if (stLine) {
        stLine.value = r.value;
        stLine.display = formatDisplay(r.value);
        stLine.vs = r.vs || "USD";
        stLine.spark = r.spark || [];
        stLine.spark_points = r.spark_points || [];
        stLine.source = r.source || "crypto";
      }
    }

    const took = nowMs() - started;
    state.progress.done += 1;
    setProgress(null);

    // reset 429 tracking on success
    consecutive429 = 0;

    console.log(`[monitor] updated ${item.group}:${item.key} ok took=${took}ms (${state.progress.done}/${queue.length} cycle=${state.progress.cycle})`);
    if (state.progress.done >= queue.length) nextCycle();
  } catch (e) {
    const took = nowMs() - started;
    const msg = String(e?.message || e);

    // If we hit 429 (CoinGecko), backoff for 60 seconds
    if (String(e?.status) === "429" || msg.includes("HTTP 429")) {
      consecutive429 += 1;
      backoffUntilMs = nowMs() + 60_000;
      console.log(`[monitor] 429 hit. backoff 60s (consecutive=${consecutive429})`);
    }

    setError(`${item.key}: ${msg}`);
    state.progress.done += 1;
    setProgress(null);

    console.log(`[monitor] updated ${item.group}:${item.key} WARN took=${took}ms err=${msg}`);

    if (state.progress.done >= queue.length) nextCycle();
  }
}

setInterval(doOneUpdate, ROTATE_SECONDS * 1000);

/* --------------------- HTTP endpoints --------------------- */
app.get("/health", (_req, res) => {
  res.json({
    ok: true,
    ts: new Date().toISOString(),
    rotate_seconds: ROTATE_SECONDS,
    backoff_until_ms: backoffUntilMs || 0
  });
});

app.get("/api/lines", (_req, res) => {
  try {
    loadConfig();
    res.json({
      ok: true,
      ts: new Date().toISOString(),
      took_ms: 0,
      fiat: state.fiat,
      crypto: state.crypto,
      errors: state.errors,
      progress: state.progress
    });
  } catch (e) {
    res.status(500).json({ ok: false, error: String(e?.message || e) });
  }
});

app.listen(PORT, "127.0.0.1", () => {
  loadConfig();
  console.log(`[monitor] backend listening on 127.0.0.1:${PORT} rotate=${ROTATE_SECONDS}s`);
});