import logging
from datetime import datetime

from lxml import etree

from .loader import Loader

log = logging.getLogger(__name__)

NS = {'gpx':"http://www.topografix.com/GPX/1/1"}

class NeoCartLoader(Loader):
	def load(self, file: str):
		src = open(file, "r")
		parser = etree.XMLParser(recover=True)
		tree = etree.parse(src, parser=parser)
		self.entries = []
		for point in tree.xpath("//gpx:trkpt", namespaces=NS):
			try: 
				self.entries.append(self.parse_point(point))
			except ValueError as e:
				print(e, etree.tostring(point, pretty_print=True).decode())
				log.exception(e)
	
	def parse_point(self, point):
		raw_lat = point.xpath("@lat")[0]
		if raw_lat.count(".") > 1:
			log.warning(f"recreate lat/lon from: {raw_lat}")
			log.warn(etree.tostring(point, pretty_print=True).decode())
			start_offset = 4
			x = raw_lat[start_offset:].index(".")
			offset = start_offset + x
			raw_lon = raw_lat[offset:]
			raw_lat = raw_lat[:offset]
		else:
			raw_lon = point.xpath("@lon")[0]
		lat = float(raw_lat)
		lon = float(raw_lon)
		times = point.xpath("gpx:time",namespaces=NS)
		assert len(times) == 1
		time = times[0].text
		dt = datetime.strptime(time, "%Y-%m-%dT%H:%M:%SZ")
		timestamp = int(dt.timestamp() * 1000) # python3.6 has no timestamp_ns (yet)
		events = point.xpath(".//gpx:event",namespaces=NS)
		assert 0 <= len(events) <= 1
		event = {}
		if events:
			event = dict(events[0].attrib)
			if events[0].tail and events[0].tail.strip():
				try:
					# base case: trailing 'geoid="0"/>'
					key, v = events[0].tail.strip().split("=")
					value = v.split('"')[1]
					event[key] = value
				except:
					event['__tail__'] = events[0].tail.strip()
		
		return {
			"location": {
				"type": "Point",
				"coordinates": [lon, lat]
			},
			"timestamp": timestamp,
			"event": event,
			"type": event['message'] if event else "location"
		}

	def get_entry(self) -> object:
		for i in self.entries:
			yield i