"""
Forex Signal Intelligence Platform - Data Provider
====================================================
Retrieves and validates currency-pair OHLCV from the Twelve Data API.
Raises DataUnavailableError when the API is unreachable or credits exhausted.
No fallback data source — forex pairs only.
"""

import logging
import os
import threading
import time
from collections import deque
from datetime import datetime, timedelta, timezone
from typing import Dict, List, Optional

import pandas as pd
import requests

from config import PlatformConfig, Timeframe, SYMBOL_DISPLAY, PIP_VALUES

logger = logging.getLogger(__name__)
_no_data_warned: set = set()  # suppress duplicate "no data" warnings per symbol


class DataIntegrityError(Exception):
    """Raised when data fails validation checks."""
    pass


class DataUnavailableError(Exception):
    """Raised when live market data cannot be fetched (no key, rate limit, API error)."""
    pass


# ── Module-level shared rate limiter ───────────────────────────────
# All ForexDataProvider instances share these so concurrent scans
# don't each think they have a full 8-credit budget.
_rate_lock          = threading.Lock()
_rate_request_times: deque = deque()
_rate_daily_credits: int   = 0
_rate_daily_reset:   float = 0.0


class ForexDataProvider:
    """
    Forex data provider backed by Twelve Data API.

    Twelve Data has native 4h candles, eliminating the H1→H4 resampling
    hack needed for Yahoo Finance. Free tier: 800 credits/day, 8 req/min.
    """

    TD_BASE_URL = "https://api.twelvedata.com"

    TD_INTERVALS = {
        Timeframe.M1:  "1min",
        Timeframe.M5:  "5min",
        Timeframe.M15: "15min",
        Timeframe.M30: "30min",
        Timeframe.H1:  "1h",
        Timeframe.H4:  "4h",
        Timeframe.D1:  "1day",
        Timeframe.W1:  "1week",
    }

    # Approximate bars per day for each timeframe (used to size outputsize)
    BARS_PER_DAY = {
        Timeframe.M1:  1440,
        Timeframe.M5:  288,
        Timeframe.M15: 96,
        Timeframe.M30: 48,
        Timeframe.H1:  24,
        Timeframe.H4:  6,
        Timeframe.D1:  1,
        Timeframe.W1:  0.143,
    }

    # Free plan: 8 credits/minute, 800 credits/day
    RATE_LIMIT = 8
    RATE_WINDOW = 60.0
    DAILY_LIMIT = 800

    def __init__(self, config: PlatformConfig):
        self.config = config
        self._api_key = (
            os.environ.get("TWELVE_DATA_API_KEY")
            or config.twelve_data_api_key
        )
        self._cache: Dict[str, pd.DataFrame] = {}
        self._cache_timestamps: Dict[str, float] = {}
        self._session = requests.Session()
        self._session.headers.update({
            "User-Agent": "Mozilla/5.0 (compatible; ForexIntel/1.0)",
        })
        if self._api_key:
            self._session.headers["Authorization"] = f"apikey {self._api_key}"

    @staticmethod
    def _to_td_symbol(symbol: str) -> str:
        """Convert internal symbol (EURUSD=X) to Twelve Data format (EUR/USD)."""
        clean = symbol.replace("=X", "")
        return f"{clean[:3]}/{clean[3:]}"

    def _cache_ttl(self, timeframe: Timeframe) -> int:
        """Cache TTL for a given timeframe — falls back to refresh_interval."""
        return self.config.cache_ttl_per_tf.get(timeframe, self.config.refresh_interval)

    def fetch_ohlcv(
        self,
        symbol: str,
        timeframe: Timeframe,
        lookback_days: Optional[int] = None,
    ) -> pd.DataFrame:
        """
        Fetch OHLCV data for a Forex pair with full validation.

        Returns a DataFrame with columns: Open, High, Low, Close, Volume
        Index is a timezone-aware DatetimeIndex in UTC.
        """
        if lookback_days is None:
            lookback_days = self.config.data_lookback_days

        cache_key = f"{symbol}_{timeframe.value}"
        now = time.time()
        ttl = self._cache_ttl(timeframe)

        if (
            cache_key in self._cache_timestamps
            and (now - self._cache_timestamps[cache_key]) < ttl
            and cache_key in self._cache
        ):
            cached = self._cache.get(cache_key)
            if cached is not None and not cached.empty:
                return cached

        df = self._fetch_twelve_data(symbol, timeframe, lookback_days)
        df = self._validate_and_clean(df, symbol, timeframe)

        self._cache[cache_key] = df
        self._cache_timestamps[cache_key] = now
        return df

    def prefetch_batch(
        self,
        symbols: List[str],
        timeframes: List[Timeframe],
        lookback_days: Optional[int] = None,
    ) -> None:
        """
        Batch-fetch all symbols for each timeframe in a single API call per TF.

        Twelve Data accepts comma-separated symbols, so 7 pairs × 3 timeframes
        = 3 requests instead of 21 — well within the free-tier 8 req/min limit.
        Results are stored in the local cache; subsequent fetch_ohlcv calls
        for the same symbol/TF will be served from cache.
        """
        if lookback_days is None:
            lookback_days = self.config.data_lookback_days

        td_symbols = list(symbols)
        if not td_symbols:
            return

        now = time.time()
        for tf in timeframes:
            ttl = self._cache_ttl(tf)
            cached = all(
                f"{s}_{tf.value}" in self._cache_timestamps
                and (now - self._cache_timestamps[f"{s}_{tf.value}"]) < ttl
                and not self._cache.get(f"{s}_{tf.value}", pd.DataFrame()).empty
                for s in td_symbols
            )
            if cached:
                logger.debug(f"Skipping prefetch for {tf.value} — all {len(td_symbols)} symbols cached (TTL {ttl}s)")
                continue
            try:
                self._batch_fetch_timeframe(td_symbols, tf, lookback_days)
                time.sleep(1.0)  # brief pause between TF requests
            except Exception as e:
                logger.warning(f"Batch prefetch failed for {tf.value}: {e}")

    def fetch_multiple(
        self,
        symbols: List[str],
        timeframe: Timeframe,
        lookback_days: Optional[int] = None,
    ) -> Dict[str, pd.DataFrame]:
        """Fetch data for multiple symbols, returning dict of DataFrames."""
        results = {}
        for symbol in symbols:
            try:
                df = self.fetch_ohlcv(symbol, timeframe, lookback_days)
                results[symbol] = df
            except Exception as e:
                logger.warning(f"Failed to fetch {symbol}: {e}")
        return results

    def get_latest_price(self, symbol: str) -> Optional[float]:
        """Return the most recent close price for a symbol."""
        try:
            df = self.fetch_ohlcv(symbol, Timeframe.M5, lookback_days=1)
            if df is not None and not df.empty:
                return float(df["Close"].iloc[-1])
        except Exception:
            pass
        return None

    def get_spread_estimate(self, symbol: str) -> float:
        """Estimate typical spread from recent M5 high-low ranges."""
        try:
            df = self.fetch_ohlcv(symbol, Timeframe.M5, lookback_days=1)
            if df is not None and not df.empty:
                return float((df["High"] - df["Low"]).median())
        except Exception:
            pass

        fallback_spreads = {
            "EURUSD=X": 0.00010, "GBPUSD=X": 0.00015,
            "USDJPY=X": 0.010,   "USDCHF=X": 0.00015,
            "AUDUSD=X": 0.00015, "USDCAD=X": 0.00018,
            "NZDUSD=X": 0.00020,
        }
        return fallback_spreads.get(symbol, 0.00020)

    def get_pair_info(self, symbol: str) -> Dict:
        """Return display name and pip value for a pair."""
        display = SYMBOL_DISPLAY.get(symbol, symbol)
        is_jpy = "JPY" in symbol
        # Commodity-specific pip values take priority, then JPY pairs, then standard forex
        pip_value = PIP_VALUES.get(symbol, 0.01 if is_jpy else 0.0001)
        return {
            "symbol": symbol,
            "display": display,
            "pip_value": pip_value,
            "is_jpy_pair": is_jpy,
        }

    # ── Private Methods ────────────────────────────────────────────

    def _throttle(self, credits: int = 1) -> None:
        """
        Block until `credits` per-minute API credits are available.
        Raises DataUnavailableError if the daily limit is exhausted.

        Uses module-level state so all ForexDataProvider instances (including
        those running in parallel threads) share the same credit accounting.

        Twelve Data free tier: 8 credits/minute, 800 credits/day.
        """
        global _rate_daily_credits, _rate_daily_reset

        with _rate_lock:
            now = time.time()

            # Reset daily counter after 24 hours
            if _rate_daily_reset == 0.0:
                _rate_daily_reset = now + 86400
            if now >= _rate_daily_reset:
                _rate_daily_credits = 0
                _rate_daily_reset = now + 86400

            # Daily limit check — raise immediately, no fallback
            if _rate_daily_credits + credits > self.DAILY_LIMIT:
                raise DataUnavailableError(
                    f"Twelve Data daily API limit reached "
                    f"({_rate_daily_credits}/{self.DAILY_LIMIT} credits). "
                    "Resets in 24 hours."
                )

            if _rate_daily_credits + credits > self.DAILY_LIMIT * 0.8:
                logger.warning(
                    f"Approaching daily API limit: "
                    f"{_rate_daily_credits}/{self.DAILY_LIMIT} credits used."
                )

            # Per-minute rate limit — wait inside the lock so other threads
            # queue up rather than over-counting available credits.
            while True:
                now = time.time()
                while _rate_request_times and now - _rate_request_times[0] >= self.RATE_WINDOW:
                    _rate_request_times.popleft()

                available = self.RATE_LIMIT - len(_rate_request_times)
                if available >= credits:
                    ts = time.time()
                    for _ in range(credits):
                        _rate_request_times.append(ts)
                    _rate_daily_credits += credits
                    return

                wait = (_rate_request_times[0] + self.RATE_WINDOW) - now + 0.2
                logger.info(
                    f"Rate limit: {len(_rate_request_times)}/{self.RATE_LIMIT} credits used "
                    f"— waiting {wait:.1f}s for next window…"
                )
                # Release lock while sleeping so other threads can check state
                _rate_lock.release()
                time.sleep(wait)
                _rate_lock.acquire()

    def _batch_fetch_timeframe(
        self, symbols: List[str], timeframe: Timeframe, lookback_days: int
    ) -> None:
        """
        Single API call fetching all symbols for one timeframe.
        Twelve Data returns a dict keyed by symbol when multiple are requested.
        Parsed DataFrames are validated and stored in the cache.
        """
        if not self._api_key:
            return

        td_symbols = [self._to_td_symbol(s) for s in symbols]
        interval = self.TD_INTERVALS[timeframe]
        outputsize = min(
            int(lookback_days * self.BARS_PER_DAY[timeframe]) + 20, 5000
        )
        outputsize = max(outputsize, 300)

        # Each symbol in a batch request costs 1 credit — raises DataUnavailableError
        # if daily limit reached; per-minute waits are handled inside _throttle.
        self._throttle(credits=len(symbols))

        resp = self._session.get(
            f"{self.TD_BASE_URL}/time_series",
            params={
                "symbol": ",".join(td_symbols),
                "interval": interval,
                "outputsize": outputsize,
                "timezone": "UTC",
                "format": "json",
            },
            timeout=30,
        )
        resp.raise_for_status()
        data = resp.json()

        # If the whole batch request returned a top-level error, raise it
        if isinstance(data, dict) and data.get("status") == "error":
            raise DataIntegrityError(
                f"Batch API error ({timeframe.value}): {data.get('message', 'unknown')}"
            )

        # Batch response: {"EUR/USD": {...}, "GBP/USD": {...}, ...}
        now = time.time()
        for symbol, td_sym in zip(symbols, td_symbols):
            try:
                sym_data = data.get(td_sym, {})
                if sym_data.get("status") == "error":
                    logger.warning(
                        f"Batch fetch error for {td_sym}: {sym_data.get('message')}"
                    )
                    continue

                values = sym_data.get("values")
                if not values:
                    if td_sym not in _no_data_warned:
                        logger.warning(f"No data from Twelve Data for {td_sym} — symbol may require a paid plan.")
                        _no_data_warned.add(td_sym)
                    continue

                records = [
                    {
                        "Datetime": pd.Timestamp(v["datetime"], tz="UTC"),
                        "Open":   float(v["open"])   if v.get("open")   is not None else None,
                        "High":   float(v["high"])   if v.get("high")   is not None else None,
                        "Low":    float(v["low"])    if v.get("low")    is not None else None,
                        "Close":  float(v["close"])  if v.get("close")  is not None else None,
                        "Volume": float(v["volume"]) if v.get("volume") is not None else 0.0,
                    }
                    for v in reversed(values)
                    if v.get("datetime")
                ]
                df = pd.DataFrame(records).set_index("Datetime")
                df.index.name = "Datetime"
                df = self._validate_and_clean(df, symbol, timeframe)

                cache_key = f"{symbol}_{timeframe.value}"
                self._cache[cache_key] = df
                self._cache_timestamps[cache_key] = now
                logger.info(f"[live] {td_sym} {interval}: {len(df)} bars, last close={df['Close'].iloc[-1]:.5f}")

            except Exception as e:
                logger.warning(f"Failed to parse batch data for {td_sym}: {e}")

    def _fetch_twelve_data(
        self, symbol: str, timeframe: Timeframe, lookback_days: int
    ) -> pd.DataFrame:
        """
        Fetch OHLCV from Twelve Data REST API.
        Raises DataUnavailableError when data cannot be retrieved.
        """
        if not self._api_key:
            raise DataUnavailableError(
                "No Twelve Data API key — set the TWELVE_DATA_API_KEY environment variable."
            )

        td_symbol = self._to_td_symbol(symbol)
        interval = self.TD_INTERVALS[timeframe]
        outputsize = min(
            int(lookback_days * self.BARS_PER_DAY[timeframe]) + 20,
            5000,
        )
        outputsize = max(outputsize, 300)

        # Raises DataUnavailableError on daily limit; blocks on per-minute limit.
        self._throttle(credits=1)

        try:
            resp = self._session.get(
                f"{self.TD_BASE_URL}/time_series",
                params={
                    "symbol": td_symbol,
                    "interval": interval,
                    "outputsize": outputsize,
                    "timezone": "UTC",
                    "format": "json",
                },
                timeout=15,
            )
            resp.raise_for_status()
            data = resp.json()

            if data.get("status") == "error":
                raise DataUnavailableError(
                    f"Twelve Data API error for {td_symbol}: {data.get('message', 'unknown')}"
                )

            values = data.get("values")
            if not values:
                raise DataUnavailableError(
                    f"No data returned for {td_symbol} — symbol may require a paid plan."
                )

            records = [
                {
                    "Datetime": pd.Timestamp(v["datetime"], tz="UTC"),
                    "Open":   float(v["open"])   if v.get("open")   is not None else None,
                    "High":   float(v["high"])   if v.get("high")   is not None else None,
                    "Low":    float(v["low"])    if v.get("low")    is not None else None,
                    "Close":  float(v["close"])  if v.get("close")  is not None else None,
                    "Volume": float(v["volume"]) if v.get("volume") is not None else 0.0,
                }
                for v in reversed(values)
                if v.get("datetime")
            ]

            df = pd.DataFrame(records).set_index("Datetime")
            df.index.name = "Datetime"
            logger.info(f"[live] {td_symbol} {interval}: {len(df)} bars, last close={df['Close'].iloc[-1]:.5f}")
            return df

        except (DataUnavailableError, DataIntegrityError):
            raise
        except Exception as e:
            raise DataUnavailableError(
                f"Failed to fetch {td_symbol}: {e}"
            ) from e

    def _validate_and_clean(
        self, df: pd.DataFrame, symbol: str, timeframe: Timeframe
    ) -> pd.DataFrame:
        """
        Validate and clean OHLCV data.

        Steps: drop all-NaN rows → ffill small gaps → remove future timestamps
        → fix OHLC inconsistencies → remove >10-sigma outliers → sort & deduplicate.
        """
        if df is None or df.empty:
            raise DataIntegrityError(f"Empty dataset for {symbol}")

        original_len = len(df)

        df = df.dropna(subset=["Open", "High", "Low", "Close"], how="all")
        df = df.ffill(limit=3)
        df = df.dropna(subset=["Close"])

        now = pd.Timestamp.utcnow()
        future_mask = df.index > now + pd.Timedelta(minutes=5)
        if future_mask.any():
            logger.warning(f"{symbol}: Dropping {future_mask.sum()} future timestamps")
            df = df[~future_mask]

        invalid_ohlc = (
            (df["High"] < df["Low"]) |
            (df["High"] < df["Open"]) |
            (df["High"] < df["Close"]) |
            (df["Low"] > df["Open"]) |
            (df["Low"] > df["Close"])
        )
        if invalid_ohlc.any():
            logger.warning(f"{symbol}: Fixing {invalid_ohlc.sum()} OHLC-inconsistent bars")
            for idx in df[invalid_ohlc].index:
                vals = [df.loc[idx, "Open"], df.loc[idx, "Close"]]
                df.loc[idx, "High"] = max(vals + [df.loc[idx, "High"]])
                df.loc[idx, "Low"]  = min(vals + [df.loc[idx, "Low"]])

        returns = df["Close"].pct_change()
        std_ret = returns.std()
        if std_ret > 0:
            outlier_mask = (returns - returns.mean()).abs() > 10 * std_ret
            if outlier_mask.any():
                logger.debug(f"{symbol}: Removing {outlier_mask.sum()} extreme outlier bars")
                df = df[~outlier_mask]

        min_required = max(
            self.config.technical.ema_trend,
            self.config.technical.ichimoku_senkou_b,
            200,
        ) + 10

        if len(df) < min_required:
            logger.warning(
                f"{symbol} {timeframe.value}: Only {len(df)} bars "
                f"(need {min_required}). Some indicators will be partial."
            )

        df = df.sort_index()
        df = df[~df.index.duplicated(keep="last")]

        cleaned = original_len - len(df)
        if cleaned > 0:
            logger.info(f"{symbol}: Cleaned {cleaned}/{original_len} bars")

        return df