import json
import logging
from typing import Dict, Any, Tuple, Optional
import config
from database.db import AsyncSessionLocal
from database.models import Alpha

logger = logging.getLogger("AlphaEvaluator")


def serialize_raw_payload(raw_data: Any) -> str:
    """Preserve completed API payloads for parser and research forensics."""
    payload = json.dumps(raw_data or {}, default=str, separators=(",", ":"))
    return payload[:250_000]

# Trash reason categories for analytics
TRASH_REASON_NO_TRADES = "No Trades / Null Metrics"
TRASH_REASON_LOW_PERFORMANCE = "Low Sharpe / Fitness"
TRASH_REASON_HIGH_CORRELATION = "High Correlation"
TRASH_REASON_SYNTAX_ERROR = "Syntax / Schema Error"

def classify_trash_reason(reason: str) -> str:
    """
    Classifies a failure reason string into one of 4 canonical trash categories
    for structured analytics on the dashboard.
    """
    r = reason.lower()
    if "no trades" in r or "null" in r or "invalid stats" in r or "missing critical" in r:
        return TRASH_REASON_NO_TRADES
    if "sharpe" in r or "fitness" in r or "turnover" in r or "performance" in r:
        return TRASH_REASON_LOW_PERFORMANCE
    if "correlation" in r or "corr" in r:
        return TRASH_REASON_HIGH_CORRELATION
    # Simulation failures, schema errors, platform rejects, syntax errors
    return TRASH_REASON_SYNTAX_ERROR


class AlphaEvaluator:
    """
    Evaluation Engine for QuantForge v2.0.
    Applies strict Consultant-tier acceptance thresholds on simulated Alphas.
    """
    def __init__(self) -> None:
        # Ordinary consultant submission thresholds. Pure Power Pool uses a
        # distinct campaign and is disabled until that engine exists.
        self.min_fitness_d1 = 1.0
        self.min_fitness_d0 = 1.5
        self.min_sharpe_d1 = 1.58
        self.min_sharpe_d0 = 2.69
        self.min_turnover = 0.01
        self.max_turnover = 0.70
        self.min_htvr_ratio = 0.75         # High Turnover Returns Ratio for x2 multiplier eligibility
        self.max_self_correlation = 0.70
        self.max_prod_correlation = 0.70

    def evaluate_metrics(self, sim_results: Dict[str, Any], delay: int, expression: Optional[str] = None) -> Tuple[bool, str]:
        """
        Evaluates parsed simulation results against thresholds.
        Returns:
            (is_passing, failure_reason)
        """
        # 1. Check for system or platform errors reported during simulation/polling
        if sim_results.get("status") == "FAILED":
            err_msg = sim_results.get("error_message") or "Simulation status failed."
            return False, f"Simulation failure: {err_msg}"

        # 2. Check for missing essential metrics
        sharpe = sim_results.get("sharpe")
        fitness = sim_results.get("fitness")
        turnover = sim_results.get("turnover")

        if sharpe is None or fitness is None or turnover is None:
            msg = "Simulation produced no trades / Invalid Stats"
            logger.warning(msg)
            return False, msg

        # 3. Sharpe cutoff — match the ordinary consultant IS thresholds.
        # D0: 2.69 | D1: 1.58.  Do not spend submit quota on predictable rejects.
        min_sharpe = self.min_sharpe_d0 if delay == 0 else self.min_sharpe_d1
        
        # Pure Power Pool is opt-in only; it has its own themed campaign rules.
        if expression:
            try:
                import re
                # Calculate complexity
                operators = re.findall(r'\b[a-zA-Z_][a-zA-Z0-9_]*\b(?=\s*\()', expression)
                filtered_ops = [op for op in operators if op.lower() not in {"ts_backfill", "group_backfill"}]
                num_ops = len(filtered_ops)
                
                words = re.findall(r'\b[a-zA-Z_][a-zA-Z0-9_]*\b', expression)
                grouping_fields = {"country", "industry", "subindustry", "currency", "market", "sector", "exchange"}
                reserved = {"ts_corr", "ts_covariance", "ts_mean", "ts_std_dev", "ts_decay_linear", "ts_delta", "ts_rank", "ts_zscore", 
                            "rank", "zscore", "group_rank", "group_zscore", "group_neutralize", "signed_power", "if_else", "log", 
                            "abs", "sqrt", "power", "min", "max", "sign", "exp", "ts_backfill", "group_backfill"}
                
                fields = set()
                for w in words:
                    w_lower = w.lower()
                    if w_lower in grouping_fields or w_lower in reserved:
                        continue
                    if w_lower in {"nan", "nil", "null", "true", "false"}:
                        continue
                    fields.add(w_lower)
                num_fields = len(fields)
                
                if config.ENABLE_PURE_POWER_POOL_SUBMISSIONS and num_fields <= 3 and num_ops <= 8:
                    logger.info(f"Alpha complexity qualifies for Power Pool (fields={num_fields}, ops={num_ops}). Setting min_sharpe = 1.0.")
                    min_sharpe = 1.0
            except Exception as e:
                logger.error(f"Error checking Power Pool complexity: {e}")

        if sharpe <= min_sharpe:
            return False, f"Sharpe {sharpe:.4f} below pre-filter threshold of {min_sharpe} (Delay {delay})"

        # 4. Fitness Cutoff
        min_fitness = self.min_fitness_d0 if delay == 0 else self.min_fitness_d1
        if fitness <= min_fitness:
            return False, f"Fitness {fitness:.4f} below threshold of {min_fitness}"

        # 5. Turnover band for regular consultant alphas.
        if turnover <= self.min_turnover:
            return False, f"Turnover {turnover:.4f} below floor of {self.min_turnover}"
        if turnover >= self.max_turnover:
            return False, f"Turnover {turnover:.4f} above cap of {self.max_turnover}"

        # 5b. HTVR ratio check — log eligibility for x2/x3 multiplier campaign
        # HTVR ratio = returns / turnover (platform definition)
        returns_val = sim_results.get("returns") or sim_results.get("ann_ret")
        if returns_val is not None and turnover and turnover > 0:
            htvr_ratio = abs(returns_val) / turnover
            if turnover > 0.20 and htvr_ratio >= self.min_htvr_ratio:
                logger.info(
                    f"HTVR ELIGIBLE: Turnover={turnover:.2%}, Returns={returns_val:.2%}, "
                    f"HTVR_ratio={htvr_ratio:.2f} — qualifies for x2 High Turnover Multiplier"
                )

        # 6. Parse and check checks list for Correlation and Sub-Universe NaN failures
        raw_data = sim_results.get("raw_data") or {}

        # Extract checks from raw JSON payload
        checks = []
        alpha_data = raw_data.get("alpha", {})
        if isinstance(alpha_data, dict):
            checks = alpha_data.get("is", {}).get("checks", [])
        if not checks and isinstance(raw_data, dict):
            checks = raw_data.get("is", {}).get("checks", []) or raw_data.get("checks", [])

        if not isinstance(checks, list):
            checks = []

        self_corr = None
        prod_corr = None
        sub_universe_nan_fail = False

        for c in checks:
            if not isinstance(c, dict):
                continue

            name = str(c.get("name", "")).lower()
            val = c.get("value")
            passed = c.get("passed")
            result = str(c.get("result", "")).upper()
            msg = str(c.get("message", "")).lower()

            # Self-correlation check
            if "selfcorrelation" in name or "self_correlation" in name:
                try:
                    self_corr = float(val) if val is not None else None
                except (ValueError, TypeError):
                    pass
                if passed is False or result == "FAIL":
                    return False, f"Self-correlation check failed: {msg or 'Exceeded platform limits'}"

            # Product-correlation check
            elif "prodcorrelation" in name or "prod_correlation" in name or "productioncorrelation" in name:
                try:
                    prod_corr = float(val) if val is not None else None
                except (ValueError, TypeError):
                    pass
                if passed is False or result == "FAIL":
                    return False, f"Production-correlation check failed: {msg or 'Exceeded platform limits'}"

            # Sub-universe Sharpe NaN is not above cutoff check
            elif "sub-universe" in name or "subuniverse" in name or "sub-universe" in msg or "subuniverse" in msg:
                if passed is False or result == "FAIL" or "nan" in msg:
                    sub_universe_nan_fail = True

            # General catch-all for any failed check in the simulation logs
            elif passed is False or result == "FAIL":
                return False, f"Platform check failed: {c.get('name')} - {msg}"

        # Apply custom correlation thresholds if values are parsed
        if self_corr is not None and self_corr >= self.max_self_correlation:
            return False, f"Self-correlation {self_corr:.4f} exceeds limit of {self.max_self_correlation}"

        if prod_corr is not None and prod_corr >= self.max_prod_correlation:
            return False, f"Production-correlation {prod_corr:.4f} exceeds limit of {self.max_prod_correlation}"

        if sub_universe_nan_fail:
            return False, "Sub-universe check failed: Sharpe is NaN or below cutoff in sub-universe"

        # 7. Strict Power Pool Theme Verification (only applies to Pure Power Pool candidates: Sharpe < 1.58)
        if config.ENABLE_PURE_POWER_POOL_SUBMISSIONS and config.STRICT_POWER_POOL_THEME and sharpe < 1.58:
            from datetime import datetime, date
            current_date = datetime.now().date()
            
            # Dataset restrictions: drop if contains pvl or pv1
            expr_lower = expression.lower() if expression else ""
            if "pvl" in expr_lower or "pv1" in expr_lower:
                return False, "Failed theme check: Pure Power Pool candidate contains restricted dataset 'pvl' or 'pv1'."
                
            # Late July blocks 'model110'
            if current_date >= date(2026, 7, 27) and "model110" in expr_lower:
                return False, "Failed theme check: Pure Power Pool candidate contains restricted dataset 'model110'."
                
            # July 13 to July 26 requires High Turnover returns ratio >= 0.75
            if date(2026, 7, 13) <= current_date <= date(2026, 7, 26):
                htvr_value = None
                for c in checks:
                    if not isinstance(c, dict):
                        continue
                    c_name = str(c.get("name", "")).lower()
                    if c_name == "ht_high_turnover_returns_ratio":
                        try:
                            htvr_value = float(c.get("value"))
                        except (ValueError, TypeError):
                            pass
                
                # Alternate calculation fallback (returns / turnover)
                if htvr_value is None:
                    returns_val = sim_results.get("returns") or sim_results.get("ann_ret")
                    if returns_val is not None and turnover and turnover > 0:
                        htvr_value = abs(returns_val) / turnover
                
                if htvr_value is None or htvr_value < 0.75:
                    return False, f"Failed theme check: Simulated HTVR ratio ({htvr_value if htvr_value is not None else 'N/A'}) is below 0.75 (required for Pure Power Pool July 13-26)."

        return True, "Passed all acceptance thresholds"

    async def evaluate_and_update(self, alpha_id: int, sim_results: Dict[str, Any], delay: int) -> str:
        """
        Runs evaluation on the simulation results and updates the record in SQLite database.
        Stores categorized trash_reason for analytics observability.
        Returns the new status string.
        """
        async with AsyncSessionLocal() as session:
            # Fetch the alpha record
            alpha = await session.get(Alpha, alpha_id)
            if not alpha:
                logger.error(f"Alpha record {alpha_id} not found in database for evaluation.")
                return "NOT_FOUND"

            expr = alpha.expression
            is_passing, reason = self.evaluate_metrics(sim_results, delay, expr)

            # Parse results and save metrics
            alpha.sharpe = sim_results.get("sharpe")
            alpha.fitness = sim_results.get("fitness")
            alpha.turnover = sim_results.get("turnover")
            alpha.raw_result_json = serialize_raw_payload(sim_results.get("raw_data"))

            if is_passing:
                alpha.status = "PENDING_SUBMIT"
                alpha.error_log = reason
                alpha.trash_reason = None
                logger.info(f"Alpha {alpha_id} PASSED evaluation. Queued for submission.")
            else:
                alpha.status = "TRASHED"
                alpha.error_log = reason
                alpha.trash_reason = classify_trash_reason(reason)
                logger.info(f"Alpha {alpha_id} TRASHED during evaluation: {reason}")

            await session.commit()
            return alpha.status