src/ingestion/distance.py

# src/ingestion/distance.py
from math import radians, sin, cos, sqrt, atan2
from typing import List, Dict, Any, Optional

EARTH_RADIUS_M = 6371000.0


def haversine_m(lat1, lon1, lat2, lon2):
    """Compute distance in meters between two lat/lon points."""
    if None in (lat1, lon1, lat2, lon2):
        return None
    phi1, phi2 = radians(lat1), radians(lat2)
    dphi = radians(lat2 - lat1)
    dlambda = radians(lon2 - lon1)
    a = sin(dphi / 2) ** 2 + cos(phi1) * cos(phi2) * sin(dlambda / 2) ** 2
    c = 2 * atan2(sqrt(a), sqrt(1 - a))
    return EARTH_RADIUS_M * c


def compute_total_distance(records: List[Dict[str, Any]]) -> Optional[float]:
    """
    Compute total distance for an activity.
    Priority:
      1) Use device-reported cumulative distance_m (TCX/FIT)
      2) Reconstruct from GPS coordinates (GPX/TCX lacking distance)
    Returns meters or None if unavailable.
    """
    if not records:
        return None

    # 1 — Device-reported cumulative distance
    dist_values = [r.get("distance_m") for r in records if r.get("distance_m") is not None]
    if len(dist_values) > 1:
        return float(dist_values[-1])

    # 2 — Reconstruct from GPS points
    total = 0.0
    prev = records[0]
    for curr in records[1:]:
        d = haversine_m(prev.get("lat"), prev.get("lon"), curr.get("lat"), curr.get("lon"))
        if d is not None:
            total += d
        prev = curr

    return total if total > 0 else None