import folium
import sys
from geopy.distance import geodesic
from xml.etree import ElementTree as ET
from math import atan, degrees

def parse_gpx(file_path):
    ns = {'default': 'http://www.topografix.com/GPX/1/1'}
    tree = ET.parse(file_path)
    root = tree.getroot()
    trkpts = root.findall('.//default:trkpt', ns)
    data = []
    for pt in trkpts:
        lat = float(pt.attrib['lat'])
        lon = float(pt.attrib['lon'])
        ele = float(pt.find('default:ele', ns).text)
        data.append((lat, lon, ele))
    return data

def calculate_gradients(data):
    segments = []
    for i in range(1, len(data)):
        segment = {
            'start': data[i-1][:2],
            'end': data[i][:2],
            'gradient': degrees(atan((data[i][2] - data[i-1][2]) / geodesic(data[i-1][:2], data[i][:2]).meters))
        }
        segments.append(segment)
    return segments

def add_segments_to_map(segments, map_obj):
    for segment in segments:
        color = 'red' if abs(segment['gradient']) > 30 else ('yellow' if abs(segment['gradient']) > 15 else 'green')
        folium.PolyLine([segment['start'], segment['end']], color=color, weight=5).add_to(map_obj)

if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("Usage: python main.py <path_to_gpx_file>")
        sys.exit(1)

    gpx_file_path = sys.argv[1]
    data = parse_gpx(gpx_file_path)
    segments = calculate_gradients(data)

    # 地図の中心を最初のポイントに設定
    map_center = data[0][:2]
    map_obj = folium.Map(location=map_center, zoom_start=14)

    add_segments_to_map(segments, map_obj)

    # 地図をHTMLファイルとして保存
    map_obj.save('map_with_gradients.html')
    print("Map with gradients saved to map_with_gradients.html")