"""
#5 On-chain + derivatives signals (free, no key).

  - Funding rates (BTC, ETH)        : Binance USD-M futures premiumIndex
  - Open interest + 24h change (BTC): Binance futures openInterest
  - Liquidation spike proxy          : Binance 24h taker buy/sell imbalance + range
  - Stablecoin inflow/outflow proxy  : 24h market-cap change of USDT+USDC (CoinGecko)

All endpoints are public. Each is wrapped so one failure (or a geo-block on
Binance) degrades gracefully and is logged to system health.
"""

import logging
import requests

logger = logging.getLogger(__name__)

_BINANCE_FAPI = "https://fapi.binance.com"
_CG = "https://api.coingecko.com/api/v3"
_HEADERS = {"accept": "application/json"}


def _get(url, params=None, timeout=12):
    r = requests.get(url, params=params, headers=_HEADERS, timeout=timeout)
    r.raise_for_status()
    return r.json()


class OnChainCollector:
    def fetch(self, prev_oi_btc: float | None = None) -> dict:
        from monitoring import monitor
        sig: dict = {}

        # Funding rates
        try:
            for sym, key in (("BTCUSDT", "funding_btc"), ("ETHUSDT", "funding_eth")):
                d = _get(f"{_BINANCE_FAPI}/fapi/v1/premiumIndex", {"symbol": sym})
                sig[key] = round(float(d.get("lastFundingRate", 0)) * 100, 5)  # %
            monitor.source_ok("Binance:funding")
        except Exception as exc:
            monitor.source_failure("Binance:funding", str(exc)[:100])

        # Open interest + change
        try:
            d = _get(f"{_BINANCE_FAPI}/fapi/v1/openInterest", {"symbol": "BTCUSDT"})
            oi = float(d.get("openInterest", 0))
            sig["oi_btc"] = oi
            if prev_oi_btc:
                sig["oi_btc_change"] = round((oi - prev_oi_btc) / prev_oi_btc * 100, 3)
            monitor.source_ok("Binance:oi")
        except Exception as exc:
            monitor.source_failure("Binance:oi", str(exc)[:100])

        # Liquidation spike proxy: 24h price range × volume imbalance
        try:
            t = _get(f"{_BINANCE_FAPI}/fapi/v1/ticker/24hr", {"symbol": "BTCUSDT"})
            high, low = float(t.get("highPrice", 0)), float(t.get("lowPrice", 0))
            last = float(t.get("lastPrice", 1)) or 1
            rng = (high - low) / last * 100 if last else 0
            pct_chg = abs(float(t.get("priceChangePercent", 0)))
            sig["liq_proxy"] = round(rng + pct_chg, 3)   # higher = more violent 24h
            monitor.source_ok("Binance:ticker")
        except Exception as exc:
            monitor.source_failure("Binance:ticker", str(exc)[:100])

        # Stablecoin flow proxy: 24h mcap change of USDT + USDC
        try:
            d = _get(f"{_CG}/coins/markets", {
                "vs_currency": "usd", "ids": "tether,usd-coin",
                "price_change_percentage": "24h",
            })
            flow = 0.0
            for c in d:
                mc = c.get("market_cap") or 0
                chg = c.get("market_cap_change_percentage_24h") or c.get("price_change_percentage_24h") or 0
                flow += mc * (chg / 100.0)
            sig["stablecoin_flow"] = round(flow / 1e9, 3)   # $B net change (proxy)
            monitor.source_ok("CoinGecko:stables")
        except Exception as exc:
            monitor.source_failure("CoinGecko:stables", str(exc)[:100])

        return sig

    @staticmethod
    def context_summary(sig: dict) -> dict:
        """Compact derivatives read used by the scorer + UI."""
        if not sig:
            return {}
        f = sig.get("funding_btc")
        oi_chg = sig.get("oi_btc_change")
        liq = sig.get("liq_proxy")
        flow = sig.get("stablecoin_flow")
        notes = []
        if f is not None:
            notes.append("funding " + ("hot/long-heavy" if f > 0.03 else "negative/short-heavy" if f < -0.01 else "neutral"))
        if oi_chg is not None:
            notes.append(f"OI {('+' if oi_chg>=0 else '')}{oi_chg:.1f}%")
        if flow is not None:
            notes.append("stablecoins " + ("inflow" if flow > 0 else "outflow"))
        return {
            "funding_btc": f, "funding_eth": sig.get("funding_eth"),
            "oi_btc_change": oi_chg, "liq_proxy": liq, "stablecoin_flow": flow,
            "summary": " · ".join(notes),
        }