#!/usr/bin/env python
"""
Find time now, in the past or future in any timezone or location.
"""

import argparse
import logging
import os

import dateparser
from pytz.exceptions import UnknownTimeZoneError

FUZZ_THRESHOLD = 70
ISO_FORMAT = '%Y-%m-%dT%H:%M:%S%z'
DEFAULT_FORMAT = '%Y-%m-%d %H:%M:%S%z'

basepath = os.path.dirname(os.path.abspath(__file__))

logging.basicConfig()
logger = logging.getLogger()


def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('query', nargs='*', default="now", help="<datetime-like> to <timezone-like or location string>")
    parser.add_argument('--format', dest='format', default=DEFAULT_FORMAT)
    parser.add_argument('--iso', dest='iso', action='store_true')
    parser.add_argument('--debug', dest='debug', action='store_true')
    args = parser.parse_args()
    return args


def setup_logging_level(debug=False):
    log_level = logging.DEBUG if debug else logging.ERROR
    logger.setLevel(log_level)
    logger.debug("Debugging enabled")


class Location:
    """
    Represents a location with name, latitude and longitude
    """

    def __init__(self, name: str, latitude: float, longitude: float):
        self.name = name
        self.latitude = latitude
        self.longitude = longitude

    def __lt__(self, other):
        return self.name < other.name

    def __str__(self):
        return "{} {} {}".format(self.name, self.latitude, self.longitude)


def normalize_words_to_number(query):
    """
    Converts queries like "in one hour" -> "in 1 hour"
    Assumes one-word numbers used
    """
    from word2number import w2n

    normal_list = []

    for word in query.split():
        try:
            normal_list.append(str(w2n.word_to_num(word)))
        except ValueError:
            normal_list.append(word)
    normal = ' '.join(normal_list)
    logger.debug("Normalized dt query: {} -> {}".format(query, normal))
    return normal


def timezone_to_normal(query):
    """
    Makes a timezone written in wrong capitalization to correct one 
    as expected by IANA. E.g.:
        america/new_york -> America/New_York
    """
    import re

    # The magic in the regex is that it splits by either / OR _ OR -
    # where the | are OR; and then the parens ( ) keep the splitting
    # entries in the list so that we can join later
    normal = ''.join(x.capitalize() for x in re.split('(/|_|-)', query))
    logger.debug("Normalized timezone: {} -> {}".format(query, normal))
    return normal


def create_if_not_exists(fname):
    try:
        fh = open(fname, 'r')
    except FileNotFoundError:
        fh = open(fname, 'w')
    fh.close()


def write_to_cache(query, location):
    import csv

    logger.debug("Writing location to cache")
    with open(os.path.join(basepath, "data", ".cache.csv"), 'a+') as wf:
        cachewriter = csv.writer(wf)
        cachewriter.writerow([query,
                              location.latitude,
                              location.longitude])


def row_to_location(row):
    """
    Row from a csv file to location class
    """
    latitude, longitude = float(row[1]), float(row[2])
    return Location(row[0], latitude, longitude)


def resolve_location_local(query):
    """
    Find a location by searching in local db of countries and cities
    """
    import csv
    from heapq import heappush, heappop
    from fuzzywuzzy import fuzz

    query = query.lower()
    create_if_not_exists(os.path.join(basepath, "data", ".cache.csv"))

    # location hypothesis heap
    heap = []

    for fname in [".cache", "countries", "cities"]:
        with open(os.path.join(basepath, "data", "{}.csv".format(fname))) as f:
            cfile = csv.reader(f)
            for row in cfile:
                entry = row[0]
                if fname == ".cache" and entry == query:
                    location = row_to_location(row)
                    logger.debug("Location (from cache): {}".format(location))
                    return location
                fuzz_ratio = fuzz.ratio(query, entry)
                if fuzz_ratio > FUZZ_THRESHOLD:
                    location = row_to_location(row)
                    logger.debug("Location hyp ({} {}): {}".format(fuzz_ratio, fname, location))
                    # need to push negative result as heapq is min heap
                    heappush(heap, (-fuzz_ratio, location))
    try:
        result = heappop(heap)
    except IndexError:
        logger.critical("Could not find location {}".format(query))
        exit(1)
    ratio, location = result
    logger.debug("Location result ({}): {}".format(-ratio, location))
    write_to_cache(query, location)
    return location


def resolve_location_remote(query):
    import random
    import string

    from geopy.geocoders import Nominatim
    from geopy.exc import GeocoderTimedOut

    user_agent = ''.join(random.choices(string.ascii_uppercase + string.digits, k=20))
    geolocator = Nominatim(user_agent=user_agent)
    try:
        location = geolocator.geocode(query)
        write_to_cache(query, location)
        return location
    except GeocoderTimedOut:
        logger.critical("Timed out resolving location. Try specifying a timezone directly")
        exit(1)


def parse_query(query):
    """
    Parses the user query to the datetime, tz/loc parts
    """
    query = ' '.join(query)
    query = query.strip()
    if not query:
        logger.critical("Use a query like <datetime-like> ['to' <timezone or location>]")
        exit(1)
    to_query = query.split(" to ")
    logger.debug("to_query: {}".format(to_query))
    if len(to_query) == 1:
        # only datetime
        human_dt, human_tz_loc = to_query[0], None
    elif len(to_query) == 2:
        # datetime to timezone
        human_dt, human_tz_loc = to_query
    else:
        logger.critical("There can be only one 'to' in the query string")
        exit(1)

    logger.debug("raw human_dt: {}".format(human_dt))
    logger.debug("raw human_tz_loc: {}".format(human_tz_loc))

    human_dt = normalize_words_to_number(human_dt)

    return human_dt, human_tz_loc


def solve_query(human_dt, human_tz_loc):
    try:
        # first try parsing the timezone from user input
        result = dateparser.parse(human_dt, settings={'RETURN_AS_TIMEZONE_AWARE': True})
        logger.debug("human_dt result: {}".format(result))
        if human_tz_loc:
            # if the human_tz_loc contains /, assume it's a timezone which could be
            # incorrectly written with small letters - need Continent/City
            if "/" in human_tz_loc:
                human_tz_loc = timezone_to_normal(human_tz_loc)
            isofmt = result.isoformat()
            logger.debug("human_dt isofmt: {}".format(isofmt))
            result = dateparser.parse(isofmt, settings={'TO_TIMEZONE': human_tz_loc})
            logger.debug("human_dt to_timezone result: {}".format(result))
    except UnknownTimeZoneError:
        from timezonefinder import TimezoneFinder
        logger.debug("No timezone: {}".format(human_tz_loc))
        # if the human_tz_loc contains /, assume it's a timezone 
        # the timezone could still be guessed badly, attempt to get the city
        # e.g.america/dallas
        if "/" in human_tz_loc:
            logger.debug("Assuming wrongly guessed tz {}".format(human_tz_loc))
            human_tz_loc = human_tz_loc.split('/')[-1]
            logger.debug("Try city {}".format(human_tz_loc))
        # we don't know this timezone one, assume location
        # Try to get from local file first
        location = resolve_location_local(human_tz_loc)
        if not location:
            # finally go to remote
            location = resolve_location_remote(human_tz_loc)
        tzf = TimezoneFinder()
        loc_tz = tzf.timezone_at(lat=location.latitude, lng=location.longitude)
        logger.debug("Timezone: {}".format(loc_tz))
        result = dateparser.parse(human_dt, settings={'TO_TIMEZONE': loc_tz})
    return result


def format_result(result, fmt):
    if result is None:
        logger.critical("Could not solve query")
        exit(1)
    logger.debug("Format: {}".format(fmt))
    format_result = result.strftime(fmt)
    logger.debug("Formated result: {} -> {}".format(result, format_result))
    return format_result


def query_to_format_result(query, fmt=DEFAULT_FORMAT):
    human_dt, human_tz_loc = parse_query(query)
    result = solve_query(human_dt, human_tz_loc)
    formated_result = format_result(result, fmt)
    return formated_result


def main(args):
    fmt = ISO_FORMAT if args.iso else args.format
    formated_result = query_to_format_result(args.query, fmt)
    print(formated_result)


if __name__ == "__main__":
    args = parse_args()
    setup_logging_level(args.debug)
    main(args)