"""
Intent Classification Service
Replaces naive direction (BULL/BEAR) with nuanced volatility and hedging intent classification
"""
import pandas as pd
import numpy as np
from typing import Optional
from enum import Enum
from utils.logger import logger
from utils.error_handler import safe_divide


class VolatilityIntent(Enum):
    """Volatility and hedging intent classification"""
    LONG_VOL = "LONG_VOL"  # Buying volatility (call/put buying, expecting large moves)
    SHORT_VOL = "SHORT_VOL"  # Selling volatility (premium collection, expecting low vol)
    DIRECTIONAL = "DIRECTIONAL"  # Directional positioning (directional bias)
    HEDGE_UNWIND = "HEDGE_UNWIND"  # Hedging or unwinding existing positions


class IntentClassifier:
    """
    Classifies options flow intent beyond simple BULL/BEAR direction.
    Identifies volatility trading, hedging, and directional positioning.
    """
    
    def __init__(self):
        # Configuration thresholds
        self.otm_threshold_pct = 5.0  # Strikes >5% OTM considered OTM
        self.long_vol_premium_threshold = 100000  # Minimum premium for long vol signal
        self.short_vol_premium_threshold = 200000  # Minimum premium for short vol signal
    
    def estimate_delta(self, row: pd.Series) -> float:
        """
        Estimate option delta from moneyness.
        Returns delta estimate (0-1 for calls, -1-0 for puts, use absolute value).
        """
        spot_num = row.get('spot_num', 0) or 0
        strike_num = row.get('strike_num', 0) or 0
        cp_norm = row.get('cp_norm', '')
        
        if pd.isna(spot_num) or spot_num == 0 or pd.isna(strike_num) or pd.isna(cp_norm):
            return 0.5  # Default to ATM
        
        moneyness_ratio = strike_num / spot_num if spot_num > 0 else 1.0
        
        if cp_norm == 'CALL':
            if strike_num <= spot_num:
                # ITM call: delta 0.5 to 1.0
                delta = 0.5 + (1.0 - moneyness_ratio) * 0.5
            else:
                # OTM call: delta 0.5 to 0.0
                delta = max(0.0, 0.5 * (1.5 - moneyness_ratio) / 0.5)
        else:  # PUT
            if strike_num >= spot_num:
                # ITM put: delta -0.5 to -1.0 (return absolute)
                delta = abs(0.5 + (moneyness_ratio - 1.0) * 0.5)
            else:
                # OTM put: delta -0.5 to 0.0 (return absolute)
                delta = max(0.0, 0.5 * (1.0 - moneyness_ratio) / 0.5)
        
        return float(delta)
    
    def estimate_gamma(self, row: pd.Series, delta: float) -> float:
        """
        Estimate option gamma (sensitivity of delta to price changes).
        Higher near ATM, lower ITM/OTM.
        Returns gamma estimate (positive value).
        """
        spot_num = row.get('spot_num', 0) or 0
        strike_num = row.get('strike_num', 0) or 0
        
        if pd.isna(spot_num) or spot_num == 0 or pd.isna(strike_num):
            return 0.0
        
        # Gamma is highest at-the-money
        moneyness_ratio = strike_num / spot_num if spot_num > 0 else 1.0
        
        # Simple approximation: gamma peaks at 1.0 (ATM) and decays away
        # Use normal distribution approximation
        distance_from_atm = abs(moneyness_ratio - 1.0)
        
        # Gamma ≈ exp(-distance^2 / (2*sigma^2)) where sigma ≈ 0.1 (10% moneyness)
        gamma = np.exp(-(distance_from_atm ** 2) / (2 * 0.01))
        
        return float(gamma)
    
    def calculate_delta_exposure(self, row: pd.Series) -> float:
        """
        Calculate delta exposure: contracts * delta * 100 * spot_price.
        Positive = long delta (bullish), Negative = short delta (bearish).
        """
        premium_num = row.get('premium_num', 0) or 0
        spot_num = row.get('spot_num', 0) or 0
        vol_num = row.get('vol_num', 0) or 0
        cp_norm = row.get('cp_norm', '')
        side_norm = row.get('side_norm', '')
        
        if pd.isna(spot_num) or spot_num == 0:
            return 0.0
        
        # Estimate delta
        delta = self.estimate_delta(row)
        
        # Determine sign based on call/put and buy/sell
        if cp_norm == 'CALL':
            if side_norm == 'BUY':
                delta_sign = 1.0  # Long calls = positive delta
            else:  # SELL
                delta_sign = -1.0  # Short calls = negative delta
        else:  # PUT
            if side_norm == 'BUY':
                delta_sign = -1.0  # Long puts = negative delta
            else:  # SELL
                delta_sign = 1.0  # Short puts = positive delta
        
        # Delta exposure = contracts * delta * 100 * spot
        # Use volume as proxy for contracts
        contracts = vol_num if not pd.isna(vol_num) else 0
        delta_exposure = contracts * delta * delta_sign * 100 * spot_num
        
        return float(delta_exposure)
    
    def calculate_gamma_exposure(self, row: pd.Series) -> float:
        """
        Calculate gamma exposure: contracts * gamma * 100 * spot_price^2.
        Positive = long gamma (volatility long), Negative = short gamma (volatility short).
        """
        premium_num = row.get('premium_num', 0) or 0
        spot_num = row.get('spot_num', 0) or 0
        vol_num = row.get('vol_num', 0) or 0
        cp_norm = row.get('cp_norm', '')
        side_norm = row.get('side_norm', '')
        
        if pd.isna(spot_num) or spot_num == 0:
            return 0.0
        
        # Estimate delta and gamma
        delta = self.estimate_delta(row)
        gamma = self.estimate_gamma(row, delta)
        
        # Determine sign: buying options = long gamma, selling = short gamma
        if side_norm == 'BUY':
            gamma_sign = 1.0  # Long gamma
        else:  # SELL
            gamma_sign = -1.0  # Short gamma
        
        # Gamma exposure = contracts * gamma * 100 * spot^2
        contracts = vol_num if not pd.isna(vol_num) else 0
        gamma_exposure = contracts * gamma * gamma_sign * 100 * (spot_num ** 2)
        
        return float(gamma_exposure)
    
    def classify_volatility_intent(self, row: pd.Series) -> str:
        """
        Classify volatility intent based on trade characteristics.
        Returns VolatilityIntent enum value as string.
        """
        premium_num = row.get('premium_num', 0) or 0
        spot_num = row.get('spot_num', 0) or 0
        strike_num = row.get('strike_num', 0) or 0
        cp_norm = row.get('cp_norm', '')
        side_norm = row.get('side_norm', '')
        vol_num = row.get('vol_num', 0) or 0
        oi_num = row.get('oi_num', 0) or 0
        
        # Calculate moneyness
        if pd.isna(spot_num) or spot_num == 0 or pd.isna(strike_num):
            mny_pct = 0.0
        else:
            if cp_norm == 'CALL':
                mny_pct = ((strike_num - spot_num) / spot_num * 100.0) if spot_num > 0 else 0
            else:  # PUT
                mny_pct = ((spot_num - strike_num) / spot_num * 100.0) if spot_num > 0 else 0
        
        is_otm = abs(mny_pct) > self.otm_threshold_pct
        
        # Long volatility: buying OTM options (calls or puts)
        # High premium, OTM strikes, buying side
        if (side_norm == 'BUY' and 
            is_otm and 
            premium_num >= self.long_vol_premium_threshold):
            return VolatilityIntent.LONG_VOL.value
        
        # Short volatility: selling options, collecting premium
        # High premium, selling side, vol > OI (opening new short positions)
        if (side_norm == 'SELL' and 
            premium_num >= self.short_vol_premium_threshold and
            vol_num > oi_num):
            return VolatilityIntent.SHORT_VOL.value
        
        # Directional: ITM options, buying side, strong directional flow
        if (side_norm == 'BUY' and 
            not is_otm and 
            premium_num >= 50000):
            return VolatilityIntent.DIRECTIONAL.value
        
        # Hedge/Unwind: Selling existing positions (vol < OI)
        # Or buying protective puts/calls
        if (side_norm == 'SELL' and vol_num < oi_num) or \
           (side_norm == 'BUY' and is_otm and premium_num < self.long_vol_premium_threshold):
            return VolatilityIntent.HEDGE_UNWIND.value
        
        # Default: directional (fallback)
        return VolatilityIntent.DIRECTIONAL.value
    
    def enrich_with_intent_classification(self, df: pd.DataFrame) -> pd.DataFrame:
        """
        Add intent classification metrics to DataFrame.
        Adds: delta_exposure, gamma_exposure, volatility_intent
        """
        if df.empty:
            return df
        
        df = df.copy()
        
        # Initialize columns
        df['delta_exposure'] = 0.0
        df['gamma_exposure'] = 0.0
        df['volatility_intent'] = VolatilityIntent.DIRECTIONAL.value
        
        # Calculate metrics
        df['delta_exposure'] = df.apply(self.calculate_delta_exposure, axis=1)
        df['gamma_exposure'] = df.apply(self.calculate_gamma_exposure, axis=1)
        df['volatility_intent'] = df.apply(self.classify_volatility_intent, axis=1)
        
        # Log distribution
        intent_counts = df['volatility_intent'].value_counts()
        logger.info(f"Intent classification complete. Distribution: {intent_counts.to_dict()}")
        
        return df