from __future__ import annotations

from datetime import datetime
from math import sqrt
from statistics import median
from typing import Any

from django.utils import timezone

from farm_data.context import load_farm_context
from farm_data.models import SensorData
from location_data.satellite_snapshot import build_location_satellite_snapshot
from rag.services import get_soil_anomaly_insight

from .anomaly_detection import build_anomaly_detection_card
from .health_summary import build_soil_health_summary


QUALITY_REAL = "REAL"
QUALITY_INTERPOLATED = "INTERPOLATED"
QUALITY_MISSING = "MISSING"
QUALITY_EXTRAPOLATED = "EXTRAPOLATED"

IDW_POWER = 2
MAX_GRID_STEPS = 10
FRESHNESS_HALF_LIFE_HOURS = 24.0
MAX_SENSOR_INFLUENCE_DISTANCE = 0.08


def _safe_float(value: Any) -> float | None:
    try:
        if value in (None, ""):
            return None
        return float(value)
    except (TypeError, ValueError):
        return None


def _sensor_time_series(sensor: Any) -> list[dict[str, Any]]:
    sensor_block = sensor.get_sensor_block() if hasattr(sensor, "get_sensor_block") else {}
    soil_moisture = _safe_float(getattr(sensor, "soil_moisture", None))
    measured_at = sensor_block.get("timestamp") or sensor_block.get("measured_at")
    if measured_at is None and getattr(sensor, "updated_at", None):
        measured_at = sensor.updated_at.isoformat()
    return [
        {
            "timestamp": measured_at,
            "value": soil_moisture,
            "quality_flag": QUALITY_REAL if soil_moisture is not None else QUALITY_MISSING,
        }
    ]


def _parse_timestamp(value: Any) -> datetime | None:
    if isinstance(value, datetime):
        return value
    if not value:
        return None
    if isinstance(value, str):
        try:
            parsed = datetime.fromisoformat(value.replace("Z", "+00:00"))
        except ValueError:
            return None
        if timezone.is_naive(parsed):
            return timezone.make_aware(parsed, timezone.get_current_timezone())
        return parsed
    return None


def _hours_since(timestamp: Any) -> float | None:
    parsed = _parse_timestamp(timestamp)
    if parsed is None:
        return None
    delta = timezone.now() - parsed
    return max(delta.total_seconds() / 3600.0, 0.0)


def _freshness_weight(timestamp: Any) -> float:
    age_hours = _hours_since(timestamp)
    if age_hours is None:
        return 0.65
    return 1.0 / (1.0 + (age_hours / FRESHNESS_HALF_LIFE_HOURS))


def _sensor_anomaly_penalty(value: float | None, network_values: list[float]) -> float:
    if value is None or len(network_values) < 3:
        return 1.0

    center = median(network_values)
    deviations = [abs(item - center) for item in network_values]
    typical_deviation = median(deviations) or 1.0
    normalized_distance = abs(value - center) / typical_deviation
    return max(0.45, min(1.0, 1.15 - (normalized_distance * 0.18)))


def _boundary_points(sensor: Any) -> list[tuple[float, float]]:
    boundary = getattr(sensor.center_location, "farm_boundary", None) or {}
    coordinates = []
    if isinstance(boundary, dict) and boundary.get("type") == "Polygon":
        coordinates = boundary.get("coordinates") or []
        if coordinates and isinstance(coordinates[0], list):
            return [(float(point[1]), float(point[0])) for point in coordinates[0] if len(point) >= 2]
    corners = boundary.get("corners") if isinstance(boundary, dict) else boundary if isinstance(boundary, list) else []
    points = []
    for point in corners or []:
        if isinstance(point, dict) and point.get("lat") is not None and point.get("lon") is not None:
            points.append((float(point["lat"]), float(point["lon"])))
    return points


def _point_in_polygon(lat: float, lon: float, polygon: list[tuple[float, float]]) -> bool:
    if len(polygon) < 3:
        return True

    inside = False
    for index in range(len(polygon)):
        lat1, lon1 = polygon[index]
        lat2, lon2 = polygon[(index + 1) % len(polygon)]
        intersects = ((lon1 > lon) != (lon2 > lon)) and (
            lat < ((lat2 - lat1) * (lon - lon1) / max(lon2 - lon1, 1e-12)) + lat1
        )
        if intersects:
            inside = not inside
    return inside


def _latest_sensor_measurement(sensor: Any, network_values: list[float]) -> dict[str, Any]:
    series = _sensor_time_series(sensor)
    latest = series[-1] if series else {"timestamp": None, "value": None, "quality_flag": QUALITY_MISSING}
    reliability = _sensor_anomaly_penalty(latest["value"], network_values) * _freshness_weight(latest["timestamp"])
    return {
        "sensor_id": str(sensor.farm_uuid),
        "latitude": float(sensor.center_location.latitude),
        "longitude": float(sensor.center_location.longitude),
        "depth": None,
        "timestamp": latest["timestamp"],
        "soil_moisture_value": latest["value"],
        "quality_flag": latest["quality_flag"],
        "freshness_weight": round(_freshness_weight(latest["timestamp"]), 4),
        "reliability_score": round(reliability, 4),
    }


def _spatial_weight(distance: float) -> float:
    if distance == 0:
        return 1.0
    if distance > MAX_SENSOR_INFLUENCE_DISTANCE:
        return 0.0
    return 1 / (distance**IDW_POWER)


def _interpolate_cell(
    lat: float,
    lon: float,
    sensor_points: list[dict[str, Any]],
) -> tuple[float | None, str, float]:
    weighted_sum = 0.0
    weight_total = 0.0
    min_distance = None

    for point in sensor_points:
        value = point["soil_moisture_value"]
        if value is None:
            continue
        distance = sqrt(((lat - point["latitude"]) ** 2) + ((lon - point["longitude"]) ** 2))
        min_distance = distance if min_distance is None else min(min_distance, distance)
        if distance == 0:
            return round(float(value), 2), point["quality_flag"], 1.0

        spatial_weight = _spatial_weight(distance)
        if spatial_weight == 0.0:
            continue
        composite_weight = spatial_weight * float(point.get("reliability_score", 1.0))
        weighted_sum += composite_weight * float(value)
        weight_total += composite_weight

    if weight_total == 0.0:
        return None, QUALITY_MISSING, 0.0

    uncertainty = 1.0 - min(weight_total / (weight_total + 6.0), 1.0)
    quality_flag = QUALITY_INTERPOLATED
    if min_distance is not None and min_distance > (MAX_SENSOR_INFLUENCE_DISTANCE / 2):
        quality_flag = QUALITY_EXTRAPOLATED

    return round(weighted_sum / weight_total, 2), quality_flag, round(max(0.0, min(1.0, uncertainty)), 4)


def _grid_axis(min_value: float, max_value: float) -> list[float]:
    if min_value == max_value:
        return [round(min_value, 6)]
    step_count = min(MAX_GRID_STEPS, max(int((max_value - min_value) / 0.0001) + 1, 2))
    step = (max_value - min_value) / (step_count - 1)
    return [round(min_value + (step * index), 6) for index in range(step_count)]


def _load_sensor_network(current_sensor: Any) -> list[Any]:
    plant_ids = list(
        current_sensor.plant_assignments.values_list("plant__backend_plant_id", flat=True)
    )
    queryset = SensorData.objects.select_related("center_location").prefetch_related(
        "plant_assignments__plant",
    )
    if plant_ids:
        queryset = queryset.filter(
            plant_assignments__plant__backend_plant_id__in=plant_ids
        ).distinct()
    return list(queryset)


def _soil_profile(sensor: Any) -> list[dict[str, Any]]:
    snapshot = build_location_satellite_snapshot(sensor.center_location)
    metrics = snapshot.get("resolved_metrics") or {}
    if not metrics:
        return []
    return [
        {
            "depth_label": "surface_30x30_remote_sensing",
            "field_capacity": metrics.get("ndwi"),
            "wilting_point": None,
            "saturation": None,
            "nitrogen": None,
            "ph": None,
            "sand": None,
            "silt": None,
            "clay": None,
            "ndvi": metrics.get("ndvi"),
            "soil_vv_db": metrics.get("soil_vv_db"),
            "dem_m": metrics.get("dem_m"),
            "slope_deg": metrics.get("slope_deg"),
        }
    ]


def _depth_layers(soil_profile: list[dict[str, Any]], grid_cells: list[dict[str, Any]]) -> list[dict[str, Any]]:
    layers = []
    if not soil_profile or not grid_cells:
        return layers

    for index, depth in enumerate(soil_profile):
        depth_factor = max(0.72, 1.0 - (index * 0.08))
        layer_cells = []
        for cell in grid_cells:
            if cell["moisture_value"] is None:
                moisture_value = None
            else:
                moisture_value = round(cell["moisture_value"] * depth_factor, 2)
            layer_cells.append(
                {
                    "lat": cell["lat"],
                    "lon": cell["lon"],
                    "moisture_value": moisture_value,
                    "quality_flag": cell["quality_flag"],
                    "uncertainty": cell.get("uncertainty"),
                }
            )
        layers.append(
            {
                "depth_label": depth.get("depth_label"),
                "estimated_from_surface": True,
                "cells": layer_cells,
            }
        )
    return layers


def _heatmap_summary(sensor_points: list[dict[str, Any]], grid_cells: list[dict[str, Any]]) -> dict[str, Any]:
    sensor_values = [point["soil_moisture_value"] for point in sensor_points if point["soil_moisture_value"] is not None]
    uncertainties = [cell["uncertainty"] for cell in grid_cells if cell.get("uncertainty") is not None]
    return {
        "sensor_count": len(sensor_points),
        "active_sensor_count": len(sensor_values),
        "interpolation_model": "boundary_aware_weighted_idw",
        "uses_sensor_history": False,
        "uses_freshness_weighting": True,
        "uses_boundary_mask": True,
        "uses_outlier_penalty": True,
        "avg_sensor_moisture": round(sum(sensor_values) / len(sensor_values), 2) if sensor_values else None,
        "avg_uncertainty": round(sum(uncertainties) / len(uncertainties), 4) if uncertainties else None,
    }


class SoilMoistureHeatmapService:
    def get_heatmap(self, *, farm_uuid: str) -> dict[str, Any]:
        current_sensor = (
            SensorData.objects.select_related("center_location")
            .prefetch_related("plant_assignments__plant")
            .filter(farm_uuid=farm_uuid)
            .first()
        )
        if current_sensor is None:
            raise ValueError("Farm not found.")

        sensors = _load_sensor_network(current_sensor)
        raw_network_values = [
            _safe_float(getattr(sensor, "soil_moisture", None))
            for sensor in sensors
            if _safe_float(getattr(sensor, "soil_moisture", None)) is not None
        ]
        sensor_points = [_latest_sensor_measurement(sensor, raw_network_values) for sensor in sensors]
        valid_sensor_points = [point for point in sensor_points if point["soil_moisture_value"] is not None]
        soil_profile = _soil_profile(current_sensor)
        farm_polygon = _boundary_points(current_sensor)

        if not valid_sensor_points:
            return {
                "farm_uuid": str(current_sensor.farm_uuid),
                "location": {
                    "lat": float(current_sensor.center_location.latitude),
                    "lon": float(current_sensor.center_location.longitude),
                },
                "current_sensor": {
                    "soil_moisture": current_sensor.soil_moisture,
                    "soil_temperature": current_sensor.soil_temperature,
                    "soil_ph": current_sensor.soil_ph,
                    "electrical_conductivity": current_sensor.electrical_conductivity,
                },
                "soil_profile": soil_profile,
                "depth_layers": [],
                "timestamp": current_sensor.updated_at.isoformat() if getattr(current_sensor, "updated_at", None) else None,
                "grid_resolution": None,
                "grid_cells": [],
                "sensor_points": sensor_points,
                "model_metadata": {
                    "interpolation_model": "boundary_aware_weighted_idw",
                    "uses_sensor_history": False,
                    "limitations": [
                        "history واقعی سنسورها در مدل حاضر در دسترس نیست",
                        "depth layers از surface estimate مشتق می‌شوند",
                    ],
                },
                "summary": _heatmap_summary(sensor_points, []),
                "quality_legend": {
                    QUALITY_REAL: "اندازه گیری واقعی سنسور",
                    QUALITY_INTERPOLATED: "مقدار برآوردشده با وزن دهی زمانی/فضایی",
                    QUALITY_MISSING: "داده معتبر در دسترس نیست",
                    QUALITY_EXTRAPOLATED: "برآورد در ناحیه دور از سنسورها",
                },
            }

        if farm_polygon:
            min_lat = min(point[0] for point in farm_polygon)
            max_lat = max(point[0] for point in farm_polygon)
            min_lon = min(point[1] for point in farm_polygon)
            max_lon = max(point[1] for point in farm_polygon)
        else:
            min_lat = min(point["latitude"] for point in valid_sensor_points)
            max_lat = max(point["latitude"] for point in valid_sensor_points)
            min_lon = min(point["longitude"] for point in valid_sensor_points)
            max_lon = max(point["longitude"] for point in valid_sensor_points)

        lat_axis = _grid_axis(min_lat, max_lat)
        lon_axis = _grid_axis(min_lon, max_lon)

        grid_cells = []
        for lat in lat_axis:
            for lon in lon_axis:
                if farm_polygon and not _point_in_polygon(lat, lon, farm_polygon):
                    grid_cells.append(
                        {
                            "lat": lat,
                            "lon": lon,
                            "moisture_value": None,
                            "quality_flag": QUALITY_MISSING,
                            "uncertainty": None,
                            "inside_farm_boundary": False,
                        }
                    )
                    continue

                direct_sensor = next(
                    (
                        point
                        for point in valid_sensor_points
                        if point["latitude"] == lat and point["longitude"] == lon
                    ),
                    None,
                )
                if direct_sensor is not None:
                    moisture_value = direct_sensor["soil_moisture_value"]
                    quality_flag = direct_sensor["quality_flag"]
                    uncertainty = round(1.0 - float(direct_sensor.get("reliability_score", 1.0)), 4)
                else:
                    moisture_value, quality_flag, uncertainty = _interpolate_cell(lat, lon, valid_sensor_points)

                grid_cells.append(
                    {
                        "lat": lat,
                        "lon": lon,
                        "moisture_value": moisture_value,
                        "quality_flag": quality_flag,
                        "uncertainty": uncertainty if moisture_value is not None else None,
                        "inside_farm_boundary": True,
                    }
                )

        lat_step = round(abs(lat_axis[1] - lat_axis[0]), 6) if len(lat_axis) > 1 else 0.0
        lon_step = round(abs(lon_axis[1] - lon_axis[0]), 6) if len(lon_axis) > 1 else 0.0
        timestamps = [point["timestamp"] for point in sensor_points if point["timestamp"]]
        depth_layers = _depth_layers(soil_profile, [cell for cell in grid_cells if cell["inside_farm_boundary"]])

        return {
            "farm_uuid": str(current_sensor.farm_uuid),
            "location": {
                "lat": float(current_sensor.center_location.latitude),
                "lon": float(current_sensor.center_location.longitude),
            },
            "current_sensor": {
                "soil_moisture": current_sensor.soil_moisture,
                "soil_temperature": current_sensor.soil_temperature,
                "soil_ph": current_sensor.soil_ph,
                "electrical_conductivity": current_sensor.electrical_conductivity,
                "nitrogen": current_sensor.nitrogen,
                "phosphorus": current_sensor.phosphorus,
                "potassium": current_sensor.potassium,
            },
            "soil_profile": soil_profile,
            "depth_layers": depth_layers,
            "timestamp": max(timestamps) if timestamps else None,
            "grid_resolution": {
                "lat_step": lat_step,
                "lon_step": lon_step,
                "rows": len(lat_axis),
                "cols": len(lon_axis),
            },
            "grid_cells": grid_cells,
            "sensor_points": sensor_points,
            "model_metadata": {
                "interpolation_model": "boundary_aware_weighted_idw",
                "uses_sensor_history": False,
                "uses_freshness_weighting": True,
                "uses_outlier_penalty": True,
                "uses_depth_estimation": True,
                "uses_boundary_mask": bool(farm_polygon),
                "limitations": [
                    "history واقعی سنسورها در مدل حاضر ذخیره نشده است",
                    "depth layers از داده سطحی و پروفایل خاک مشتق شده‌اند",
                    "uncertainty به صورت heuristic برآورد می‌شود",
                ],
            },
            "summary": _heatmap_summary(sensor_points, [cell for cell in grid_cells if cell["inside_farm_boundary"]]),
            "quality_legend": {
                QUALITY_REAL: "اندازه گیری واقعی سنسور",
                QUALITY_INTERPOLATED: "مقدار برآوردشده با وزن دهی زمانی/فضایی",
                QUALITY_MISSING: "داده معتبر در دسترس نیست",
                QUALITY_EXTRAPOLATED: "برآورد در ناحیه دور از سنسورها",
            },
        }


class SoilHealthService:
    def get_health_summary(self, *, farm_uuid: str) -> dict[str, Any]:
        sensor = (
            SensorData.objects.select_related("center_location")
            .prefetch_related("plant_assignments__plant")
            .filter(farm_uuid=farm_uuid)
            .first()
        )
        if sensor is None:
            raise ValueError("Farm not found.")
        return {
            "farm_uuid": str(sensor.farm_uuid),
            **build_soil_health_summary(
                sensor,
                list(sensor.plant_snapshots),
            ),
        }


class SoilAnomalyDetectionService:
    def get_anomaly_detection(self, *, farm_uuid: str) -> dict[str, Any]:
        context = load_farm_context(farm_uuid)
        if context is None:
            raise ValueError("Farm not found.")

        anomaly_payload = build_anomaly_detection_card(
            sensor_id=farm_uuid,
            context=context,
            ai_bundle=None,
        )
        rag_payload = get_soil_anomaly_insight(
            farm_uuid=farm_uuid,
            anomaly_payload=anomaly_payload,
        )
        return {
            "farm_uuid": farm_uuid,
            **anomaly_payload,
            **rag_payload,
        }