"""
Statistical calculation functions for deal data.

This module provides pure mathematical functions for analyzing real estate deal data.
"""

from collections import Counter
from typing import List
from datetime import datetime

from .models import Deal, DealStatistics


def calculate_deal_statistics(deals: List[Deal]) -> DealStatistics:
    """
    Calculate statistical aggregations on deal data.

    Args:
        deals: List of Deal model instances

    Returns:
        DealStatistics model with comprehensive metrics

    Raises:
        ValueError: If deals is not a valid list
    """
    if not isinstance(deals, list):
        raise ValueError("deals must be a list")

    if not deals:
        return DealStatistics(
            total_deals=0,
            price_statistics={},
            area_statistics={},
            price_per_sqm_statistics={},
            property_type_distribution={},
            date_range=None,
        )

    # Extract numeric values
    prices = []
    areas = []
    price_per_sqm_values = []
    property_types = []
    deal_dates = []

    for deal in deals:
        # Prices
        if deal.deal_amount and deal.deal_amount > 0:
            prices.append(deal.deal_amount)

        # Areas
        if deal.asset_area and deal.asset_area > 0:
            areas.append(deal.asset_area)

        # Price per sqm (use computed field)
        if deal.price_per_sqm:
            price_per_sqm_values.append(deal.price_per_sqm)

        # Property types
        if deal.property_type_description:
            property_types.append(deal.property_type_description)

        # Deal dates
        if deal.deal_date:
            deal_dates.append(deal.deal_date)

    # Calculate statistics
    price_stats = {}
    area_stats = {}
    price_per_sqm_stats = {}

    # Price statistics
    if prices:
        sorted_prices = sorted(prices)
        price_stats = {
            "mean": round(sum(prices) / len(prices), 2),
            "median": (sorted_prices[len(sorted_prices) // 2] + sorted_prices[(len(sorted_prices) - 1) // 2]) / 2,
            "min": min(prices),
            "max": max(prices),
            "p25": sorted_prices[len(sorted_prices) // 4],
            "p75": sorted_prices[(3 * len(sorted_prices)) // 4],
            "std_dev": round(calculate_std_dev(prices), 2) if len(prices) > 1 else 0,
            "total": sum(prices),
        }

    # Area statistics
    if areas:
        sorted_areas = sorted(areas)
        area_stats = {
            "mean": round(sum(areas) / len(areas), 2),
            "median": sorted_areas[len(sorted_areas) // 2],
            "min": min(areas),
            "max": max(areas),
            "p25": sorted_areas[len(sorted_areas) // 4],
            "p75": sorted_areas[(3 * len(sorted_areas)) // 4],
        }

    # Price per sqm statistics
    if price_per_sqm_values:
        sorted_pps = sorted(price_per_sqm_values)
        price_per_sqm_stats = {
            "mean": round(sum(price_per_sqm_values) / len(price_per_sqm_values), 2),
            "median": round(sorted_pps[len(sorted_pps) // 2], 2),
            "min": round(min(price_per_sqm_values), 2),
            "max": round(max(price_per_sqm_values), 2),
            "p25": round(sorted_pps[len(sorted_pps) // 4], 2),
            "p75": round(sorted_pps[(3 * len(sorted_pps)) // 4], 2),
        }

    # Property type distribution
    property_type_dist = {}
    if property_types:
        type_counts = Counter(property_types)
        property_type_dist = dict(sorted(type_counts.items()))

    # Date range
    date_range_dict = None
    if deal_dates:
        try:
            # Parse ISO date strings to get earliest and latest
            parsed_dates = []
            for date_str in deal_dates:
                try:
                    # Handle ISO format with timezone (e.g., "2025-01-01T00:00:00.000Z")
                    if 'T' in date_str:
                        date_str = date_str.split('T')[0]
                    parsed_dates.append(date_str)
                except:
                    continue

            if parsed_dates:
                sorted_dates = sorted(parsed_dates)
                date_range_dict = {
                    "earliest": sorted_dates[0],
                    "latest": sorted_dates[-1],
                }
        except:
            pass

    return DealStatistics(
        total_deals=len(deals),
        price_statistics=price_stats,
        area_statistics=area_stats,
        price_per_sqm_statistics=price_per_sqm_stats,
        property_type_distribution=property_type_dist,
        date_range=date_range_dict,
    )


def calculate_std_dev(values: List[float]) -> float:
    """
    Calculate standard deviation of a list of values.

    Args:
        values: List of numeric values

    Returns:
        Standard deviation
    """
    if len(values) < 2:
        return 0.0
    mean = sum(values) / len(values)
    variance = sum((x - mean) ** 2 for x in values) / (len(values) - 1)
    return variance**0.5