#!/usr/bin/env python3

#    Kosmorro - Compute The Next Ephemerides
#    Copyright (C) 2019  Jérôme Deuchnord <jerome@deuchnord.fr>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as
#    published by the Free Software Foundation, either version 3 of the
#    License, or (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.

from abc import ABC, abstractmethod
from typing import Union
from datetime import datetime

from skyfield.api import Topos, Time
from skyfield.vectorlib import VectorSum as SkfPlanet

from .core import get_skf_objects, get_timescale
from .i18n import _

MOON_PHASES = {
    'NEW_MOON': _('New Moon'),
    'WAXING_CRESCENT': _('Waxing crescent'),
    'FIRST_QUARTER': _('First Quarter'),
    'WAXING_GIBBOUS': _('Waxing gibbous'),
    'FULL_MOON': _('Full Moon'),
    'WANING_GIBBOUS': _('Waning gibbous'),
    'LAST_QUARTER': _('Last Quarter'),
    'WANING_CRESCENT': _('Waning crescent')
}

EVENTS = {
    'OPPOSITION': {'message': _('%s is in opposition')},
    'CONJUNCTION': {'message': _('%s and %s are in conjunction')},
    'MAXIMAL_ELONGATION': {'message': _("%s's largest elongation")}
}


class MoonPhase:
    def __init__(self, identifier: str, time: Union[datetime, None], next_phase_date: Union[datetime, None]):
        if identifier not in MOON_PHASES.keys():
            raise ValueError('identifier parameter must be one of %s (got %s)' % (', '.join(MOON_PHASES.keys()),
                                                                                  identifier))

        self.identifier = identifier
        self.time = time
        self.next_phase_date = next_phase_date

    def get_phase(self):
        return MOON_PHASES[self.identifier]

    def get_next_phase(self):
        if self.identifier == 'NEW_MOON' or self.identifier == 'WAXING_CRESCENT':
            next_identifier = 'FIRST_QUARTER'
        elif self.identifier == 'FIRST_QUARTER' or self.identifier == 'WAXING_GIBBOUS':
            next_identifier = 'FULL_MOON'
        elif self.identifier == 'FULL_MOON' or self.identifier == 'WANING_GIBBOUS':
            next_identifier = 'LAST_QUARTER'
        else:
            next_identifier = 'NEW_MOON'

        return MOON_PHASES[next_identifier]


class Position:
    def __init__(self, latitude: float, longitude: float):
        self.latitude = latitude
        self.longitude = longitude
        self.observation_planet = None
        self._topos = None

    def get_planet_topos(self) -> Topos:
        if self.observation_planet is None:
            raise TypeError('Observation planet must be set.')

        if self._topos is None:
            self._topos = self.observation_planet + Topos(latitude_degrees=self.latitude,
                                                          longitude_degrees=self.longitude)

        return self._topos


class AsterEphemerides:
    def __init__(self,
                 rise_time: Union[datetime, None],
                 culmination_time: Union[datetime, None],
                 set_time: Union[datetime, None]):
        self.rise_time = rise_time
        self.culmination_time = culmination_time
        self.set_time = set_time


class Object(ABC):
    """
    An astronomical object.
    """

    def __init__(self,
                 name: str,
                 skyfield_name: str,
                 ephemerides: AsterEphemerides or None = None):
        """
        Initialize an astronomical object

        :param str name: the official name of the object (may be internationalized)
        :param str skyfield_name: the internal name of the object in Skyfield library
        :param AsterEphemerides ephemerides: the ephemerides associated to the object
        """
        self.name = name
        self.skyfield_name = skyfield_name
        self.ephemerides = ephemerides

    def get_skyfield_object(self) -> SkfPlanet:
        return get_skf_objects()[self.skyfield_name]

    @abstractmethod
    def get_type(self) -> str:
        pass


class Star(Object):
    def get_type(self) -> str:
        return 'star'


class Planet(Object):
    def get_type(self) -> str:
        return 'planet'


class DwarfPlanet(Planet):
    def get_type(self) -> str:
        return 'dwarf_planet'


class Satellite(Object):
    def get_type(self) -> str:
        return 'satellite'


class Event:
    def __init__(self, event_type: str, objects: [Object], start_time: datetime,
                 end_time: Union[datetime, None] = None, details: str = None):
        if event_type not in EVENTS.keys():
            accepted_types = ', '.join(EVENTS.keys())
            raise ValueError('event_type parameter must be one of the following: %s (got %s)' % (accepted_types,
                                                                                                 event_type))

        self.event_type = event_type
        self.objects = objects
        self.start_time = start_time
        self.end_time = end_time
        self.details = details

    def get_description(self, show_details: bool = True) -> str:
        description = EVENTS[self.event_type]['message'] % self._get_objects_name()
        if show_details and self.details is not None:
            description += ' ({:s})'.format(self.details)
        return description

    def _get_objects_name(self):
        if len(self.objects) == 1:
            return self.objects[0].name

        return tuple(object.name for object in self.objects)


def skyfield_to_moon_phase(times: [Time], vals: [int], now: Time) -> Union[MoonPhase, None]:
    tomorrow = get_timescale().utc(now.utc_datetime().year, now.utc_datetime().month, now.utc_datetime().day + 1)

    phases = list(MOON_PHASES.keys())
    current_phase = None
    current_phase_time = None
    next_phase_time = None
    i = 0

    if len(times) == 0:
        return None

    for i, time in enumerate(times):
        if now.utc_iso() <= time.utc_iso():
            if vals[i] in [0, 2, 4, 6]:
                if time.utc_datetime() < tomorrow.utc_datetime():
                    current_phase_time = time
                    current_phase = phases[vals[i]]
                else:
                    i -= 1
                    current_phase_time = None
                    current_phase = phases[vals[i]]
            else:
                current_phase = phases[vals[i]]

            break

    for j in range(i + 1, len(times)):
        if vals[j] in [0, 2, 4, 6]:
            next_phase_time = times[j]
            break

    return MoonPhase(current_phase,
                     current_phase_time.utc_datetime() if current_phase_time is not None else None,
                     next_phase_time.utc_datetime() if next_phase_time is not None else None)


MONTHS = ['JAN', 'FEB', 'MAR', 'APR', 'MAY', 'JUN', 'JUL', 'AUG', 'SEP', 'OCT', 'NOV', 'DEC']

ASTERS = [Star(_('Sun'), 'SUN'),
          Satellite(_('Moon'), 'MOON'),
          Planet(_('Mercury'), 'MERCURY'),
          Planet(_('Venus'), 'VENUS'),
          Planet(_('Mars'), 'MARS'),
          Planet(_('Jupiter'), 'JUPITER BARYCENTER'),
          Planet(_('Saturn'), 'SATURN BARYCENTER'),
          Planet(_('Uranus'), 'URANUS BARYCENTER'),
          Planet(_('Neptune'), 'NEPTUNE BARYCENTER'),
          Planet(_('Pluto'), 'PLUTO BARYCENTER')]