"""
Dynamic Configuration - rider-api

Replaces all hardcoded hyperparameters with DB-backed values.
The ML hypertuner writes optimal values here; services read from here.

Fallback: If DB is unavailable or no tuned values exist, defaults are used.
This means zero risk - the system works day 1 with no data.
"""

import contextvars
import json
import logging
import os
import sqlite3
from datetime import datetime
from typing import Any, Dict, Optional

logger = logging.getLogger(__name__)

# --- DB Path ------------------------------------------------------------------
_DB_PATH = os.getenv("ML_DB_PATH", "ml_data/ml_store.db")

# ---------------------------------------------------------------------------
# Per-request strategy override (async-safe via contextvars).
# Each FastAPI request/asyncio task gets its own copy — no cross-request leaks.
# Usage:
#   set_request_strategy("fuel_saver")   → override active for this request
#   clear_request_strategy()             → restore to DB value
# ---------------------------------------------------------------------------
_strategy_override: contextvars.ContextVar[Optional[str]] = contextvars.ContextVar(
    "strategy_override", default=None
)


def set_request_strategy(strategy: Optional[str]) -> None:
    """Override ml_strategy for the current async task only (thread-safe)."""
    _strategy_override.set(strategy)


def clear_request_strategy() -> None:
    """Remove the per-request strategy override for the current async task."""
    _strategy_override.set(None)


# --- Hard Defaults (What the system used before ML) ---------------------------
DEFAULTS: Dict[str, Any] = {
    # System Strategy / Prompt
    "ml_strategy": "balanced",
    # AssignmentService
    "max_pickup_distance_km": 10.0,
    "max_kitchen_distance_km": 3.0,
    "max_orders_per_rider": 12,
    "ideal_load": 6,
    "workload_balance_threshold": 0.7,
    "workload_penalty_weight": 100.0,
    "distance_penalty_weight": 2.0,
    "preference_bonus": -15.0,
    "home_zone_bonus_4km": -3.0,
    "home_zone_bonus_2km": -5.0,
    "emergency_load_penalty": 3.0,  # km penalty per order in emergency assign
    # RouteOptimizer
    "search_time_limit_seconds": 5,
    "avg_speed_kmh": 18.0,
    "road_factor": 1.3,
    # ClusteringService
    "cluster_radius_km": 3.0,
    # KalmanFilter
    "kalman_process_noise": 1e-4,
    "kalman_measurement_noise": 0.01,
    # RealisticETACalculator
    "eta_pickup_time_min": 3.0,
    "eta_delivery_time_min": 4.0,
    "eta_navigation_buffer_min": 1.5,
    "eta_short_trip_factor": 0.8,  # speed multiplier for dist < 2km
    "eta_long_trip_factor": 1.1,  # speed multiplier for dist > 8km
    # EmpiricalETACalculator (learned ETAs from actual delivery times)
    "eta_empirical_enabled": True,  # False -> instantly revert to the formula
    "eta_min_samples": 10,          # min history samples a key needs before trust
                                    # (backtest on live 14d data: 10 -> MAE 4.85 vs
                                    #  formula 5.73; 20 -> 5.64. 10 wins on held-out.)
    "eta_history_days": 14,         # rolling window pulled from nearledb
    "eta_stat": "median",           # "median" or "p75" (p75 = more conservative)
    "eta_sync_interval_hours": 6,   # autonomous background sync cadence
    # Road-aware sequencing (Phase 2). OFF by default: enabling adds a Google
    # Directions call (cost + latency) to the route hot path. Results are cached.
    # Only the *visiting order* changes; step/ETA metrics stay aerial-based.
    "routing_use_road_distance": False,       # AGENT-MANAGED (see routing_auto_manage)
    "routing_road_cache_ttl_seconds": 86400,  # road geometry is stable; cache 24h
    "routing_road_max_stops": 25,             # Google distance-matrix practical cap
    # Autonomous road-sequencing decision agent: measures road-vs-aerial travel
    # time on real batches and flips routing_use_road_distance on its own.
    "routing_auto_manage": True,              # False -> humans own the flag
    "routing_auto_enable_gain_pct": 3.0,      # enable when mean gain >= this
    "routing_auto_disable_gain_pct": 1.0,     # disable when mean gain < this (hysteresis)
    "routing_eval_sample_batches": 8,         # batches measured per cycle (cost bound)
    "routing_eval_min_batches": 3,            # need >= this evaluated to decide
    "routing_eval_interval_hours": 24,        # decision cadence
    "routing_eval_days": 14,                  # window sampled from the local mirror
    # Learned rider->kitchen affinity (soft steering only; union with curated config).
    "rider_affinity_enabled": True,           # False -> pure curated config
    "rider_affinity_min_deliveries": 10,      # learned owner needs >= this many deliveries
    "rider_affinity_refresh_hours": 6,        # recompute cadence (piggybacks the agent)
}


class DynamicConfig:
    """
    Thread-safe, DB-backed configuration store.

    Usage:
        cfg = DynamicConfig()
        max_dist = cfg.get("max_pickup_distance_km")
        all_params = cfg.get_all()
    """

    _instance: Optional["DynamicConfig"] = None

    def __new__(cls) -> "DynamicConfig":
        """Singleton - one config per process."""
        if cls._instance is None:
            cls._instance = super().__new__(cls)
            cls._instance._initialized = False
        return cls._instance

    def __init__(self):
        if self._initialized:
            return
        self._initialized = True
        self._cache: Dict[str, Any] = {}
        self._last_loaded: Optional[datetime] = None
        self._ensure_db()
        self._load()

    # --------------------------------------------------------------------------
    # Public API
    # --------------------------------------------------------------------------

    def get(self, key: str, default: Any = None) -> Any:
        """Get a config value. Returns ML-tuned value if available, else default.

        For 'ml_strategy' specifically, a per-request ContextVar override takes
        precedence so that hypertuning_params requests don't mutate the shared
        singleton (thread-safe for concurrent FastAPI requests).
        """
        self._maybe_reload()
        # Per-request strategy override (async-safe, no cross-request leaks)
        if key == "ml_strategy":
            override = _strategy_override.get()
            if override is not None:
                return override
        val = self._cache.get(key)
        if val is not None:
            return val
        fallback = default if default is not None else DEFAULTS.get(key)
        return fallback

    def get_all(self) -> Dict[str, Any]:
        """Return all current config values (ML-tuned + defaults for missing keys)."""
        self._maybe_reload()
        result = dict(DEFAULTS)
        result.update(self._cache)
        return result

    def set(self, key: str, value: Any, source: str = "manual") -> None:
        """Write a config value to DB (used by hypertuner)."""
        try:
            os.makedirs(os.path.dirname(_DB_PATH) or ".", exist_ok=True)
            conn = sqlite3.connect(_DB_PATH)
            conn.execute(
                """
                INSERT INTO dynamic_config (key, value, source, updated_at)
                VALUES (?, ?, ?, ?)
                ON CONFLICT(key) DO UPDATE SET
                    value=excluded.value,
                    source=excluded.source,
                    updated_at=excluded.updated_at
            """,
                (key, json.dumps(value), source, datetime.utcnow().isoformat()),
            )
            conn.commit()
            conn.close()
            self._cache[key] = value
            logger.info(f"[DynamicConfig] Set {key}={value} (source={source})")
        except Exception as e:
            logger.error(f"[DynamicConfig] Failed to set {key}: {e}")

    def set_bulk(self, params: Dict[str, Any], source: str = "ml_hypertuner") -> None:
        """Write multiple config values at once (called after each Optuna study)."""
        for key, value in params.items():
            self.set(key, value, source=source)
        logger.info(f"[DynamicConfig] Bulk update: {len(params)} params from {source}")

    def reset_to_defaults(self) -> None:
        """Wipe all ML-tuned values, revert to hardcoded defaults."""
        try:
            conn = sqlite3.connect(_DB_PATH)
            conn.execute("DELETE FROM dynamic_config")
            conn.commit()
            conn.close()
            self._cache.clear()
            logger.warning("[DynamicConfig] Reset to factory defaults.")
        except Exception as e:
            logger.error(f"[DynamicConfig] Reset failed: {e}")

    # --------------------------------------------------------------------------
    # Internal
    # --------------------------------------------------------------------------

    def _ensure_db(self) -> None:
        try:
            os.makedirs(os.path.dirname(_DB_PATH) or ".", exist_ok=True)
            conn = sqlite3.connect(_DB_PATH)
            conn.execute("""
                CREATE TABLE IF NOT EXISTS dynamic_config (
                    key        TEXT PRIMARY KEY,
                    value      TEXT NOT NULL,
                    source     TEXT DEFAULT 'manual',
                    updated_at TEXT
                )
            """)
            conn.execute("""
                CREATE TABLE IF NOT EXISTS kitchen_encoding (
                    kitchen_name TEXT PRIMARY KEY,
                    label_id     INTEGER NOT NULL,
                    frequency    REAL DEFAULT 0.0,
                    avg_profit   REAL DEFAULT 0.0,
                    order_count  INTEGER DEFAULT 0,
                    updated_at   TEXT
                )
            """)
            conn.commit()
            conn.close()
        except Exception as e:
            logger.error(f"[DynamicConfig] DB init failed: {e}")

    def _load(self) -> None:
        try:
            conn = sqlite3.connect(_DB_PATH)
            rows = conn.execute("SELECT key, value FROM dynamic_config").fetchall()
            conn.close()
            self._cache = {}
            for key, raw in rows:
                try:
                    self._cache[key] = json.loads(raw)
                except Exception:
                    self._cache[key] = raw
            self._last_loaded = datetime.utcnow()
            if self._cache:
                logger.info(
                    f"[DynamicConfig] Loaded {len(self._cache)} ML-tuned params from DB"
                )
        except Exception as e:
            logger.warning(
                f"[DynamicConfig] Could not load from DB (using defaults): {e}"
            )
            self._cache = {}

    def _maybe_reload(self, interval_seconds: int = 300) -> None:
        """Reload from DB every 5 minutes - picks up new tuned params without restart."""
        if self._last_loaded is None:
            self._load()
            return
        delta = (datetime.utcnow() - self._last_loaded).total_seconds()
        if delta > interval_seconds:
            self._load()


# --- Module-level convenience singleton ---------------------------------------
_cfg = DynamicConfig()


def get_config() -> DynamicConfig:
    """Get the global DynamicConfig singleton."""
    return _cfg


__all__ = [
    "DynamicConfig",
    "get_config",
    "set_request_strategy",
    "clear_request_strategy",
    "get_kitchen_label_id",
    "get_kitchen_frequency",
    "update_kitchen_stats",
    "get_kitchen_avg_profit_smoothed",
]


# --- Kitchen Encoding Persistence ---------------------------------------------
def get_kitchen_label_id(kitchen_name: str) -> int:
    """Get or create persistent label ID for a kitchen."""
    try:
        conn = sqlite3.connect(_DB_PATH)
        row = conn.execute(
            "SELECT label_id FROM kitchen_encoding WHERE kitchen_name = ?",
            (kitchen_name,),
        ).fetchone()
        if row:
            conn.close()
            return row[0]

        max_id = conn.execute(
            "SELECT COALESCE(MAX(label_id), -1) FROM kitchen_encoding"
        ).fetchone()[0]
        new_id = max_id + 1
        conn.close()
        return new_id
    except Exception as e:
        logger.warning(f"[KitchenEncoding] Failed to get label_id: {e}")
        return hash(kitchen_name.lower().strip()) % 10000


def get_kitchen_frequency(kitchen_name: str) -> float:
    """Get frequency ratio for a kitchen from DB."""
    try:
        conn = sqlite3.connect(_DB_PATH)
        row = conn.execute(
            "SELECT frequency FROM kitchen_encoding WHERE kitchen_name = ?",
            (kitchen_name,),
        ).fetchone()
        conn.close()
        return row[0] if row else 0.0
    except Exception:
        return 0.0


def update_kitchen_stats(kitchen_name: str, profit: float):
    """Update kitchen stats after order completion."""
    try:
        conn = sqlite3.connect(_DB_PATH)
        row = conn.execute(
            "SELECT order_count, avg_profit FROM kitchen_encoding WHERE kitchen_name = ?",
            (kitchen_name,),
        ).fetchone()

        if row:
            count, avg = row
            new_count = count + 1
            new_avg = ((avg * count) + profit) / new_count
            new_freq = new_count / (
                conn.execute(
                    "SELECT SUM(order_count) FROM kitchen_encoding"
                ).fetchone()[0]
                or 1
            )
            conn.execute(
                "UPDATE kitchen_encoding SET order_count = ?, avg_profit = ?, frequency = ?, updated_at = ? WHERE kitchen_name = ?",
                (
                    new_count,
                    new_avg,
                    new_freq,
                    datetime.utcnow().isoformat(),
                    kitchen_name,
                ),
            )
        else:
            conn.execute(
                "INSERT INTO kitchen_encoding (kitchen_name, label_id, frequency, avg_profit, order_count, updated_at) VALUES (?, ?, ?, ?, ?, ?)",
                (
                    kitchen_name,
                    get_kitchen_label_id(kitchen_name),
                    1.0,
                    profit,
                    1,
                    datetime.utcnow().isoformat(),
                ),
            )
        conn.commit()
        conn.close()
    except Exception as e:
        logger.warning(f"[KitchenEncoding] Failed to update stats: {e}")


def get_kitchen_avg_profit_smoothed(
    kitchen_name: str, global_avg: float = 40.0, min_samples: int = 5
) -> float:
    """
    Get smoothed average profit for a kitchen using Bayesian smoothing.
    Reduces noise for kitchens with few orders.

    Formula: smoothed = (kitchen_count * kitchen_avg + min_samples * global_avg) / (kitchen_count + min_samples)

    This means:
    - Kitchen with many samples -> uses its own avg
    - Kitchen with few samples -> pulls toward global avg
    """
    try:
        conn = sqlite3.connect(_DB_PATH)
        row = conn.execute(
            "SELECT order_count, avg_profit FROM kitchen_encoding WHERE kitchen_name = ?",
            (kitchen_name,),
        ).fetchone()
        conn.close()

        if row and row[0] > 0:
            count, avg = row
            if count >= min_samples:
                return avg
            # Bayesian smoothing
            smoothed = ((count * avg) + (min_samples * global_avg)) / (
                count + min_samples
            )
            return smoothed

        return global_avg  # Unknown kitchen defaults to global avg
    except Exception:
        return global_avg
