from django.db import models
from django.utils.functional import cached_property
from django.utils.translation import ugettext_lazy as _
from shapely.geometry import JOIN_STYLE
from shapely.ops import cascaded_union

from c3nav.mapdata.models.base import MapItem


class Level(MapItem):
    """
    A map level (-1, 0, 1, 2…)
    """
    name = models.SlugField(_('level name'), unique=True, max_length=50,
                            help_text=_('Usually just an integer (e.g. -1, 0, 1, 2)'))
    altitude = models.DecimalField(_('level altitude'), null=True, max_digits=6, decimal_places=2)
    intermediate = models.BooleanField(_('intermediate level'))

    class Meta:
        verbose_name = _('Level')
        verbose_name_plural = _('Levels')
        default_related_name = 'levels'

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    @cached_property
    def geometries(self):
        return LevelGeometries.by_level(self)

    def tofilename(self):
        return 'levels/%s.json' % self.name

    def lower(self):
        return Level.objects.filter(altitude__lt=self.altitude).order_by('altitude')

    def higher(self):
        return Level.objects.filter(altitude__gt=self.altitude).order_by('altitude')

    @classmethod
    def fromfile(cls, data, file_path):
        kwargs = super().fromfile(data, file_path)

        if 'altitude' not in data:
            raise ValueError('missing altitude.')

        if not isinstance(data['altitude'], (int, float)):
            raise ValueError('altitude has to be int or float.')

        kwargs['altitude'] = data['altitude']

        if 'intermediate' not in data:
            raise ValueError('missing intermediate.')

        if not isinstance(data['intermediate'], bool):
            raise ValueError('intermediate has to be boolean.')

        kwargs['intermediate'] = data['intermediate']

        return kwargs

    def tofile(self):
        result = super().tofile()
        result['altitude'] = float(self.altitude)
        result['intermediate'] = self.intermediate
        return result

    def __str__(self):
        return self.name


class LevelGeometries():
    by_level_name = {}

    @classmethod
    def by_level(cls, level):
        return cls.by_level_name.setdefault(level.name, cls(level))

    def __init__(self, level):
        self.level = level

    @cached_property
    def raw_rooms(self):
        return cascaded_union([room.geometry for room in self.level.rooms.all()])

    @cached_property
    def buildings(self):
        result = cascaded_union([building.geometry for building in self.level.buildings.all()])
        if self.level.intermediate:
            result = cascaded_union([result, self.raw_rooms])
        return result

    @cached_property
    def rooms(self):
        return self.raw_rooms.intersection(self.buildings)

    @cached_property
    def outsides(self):
        return cascaded_union([outside.geometry for outside in self.level.outsides.all()]).difference(self.buildings)

    @cached_property
    def mapped(self):
        return cascaded_union([self.buildings, self.outsides])

    @cached_property
    def obstacles(self):
        levels_by_name = {}
        obstacles_by_crop_to_level = {}
        for obstacle in self.level.obstacles.all():
            level_name = None if obstacle.crop_to_level is None else obstacle.crop_to_level.name
            levels_by_name.setdefault(level_name, obstacle.crop_to_level)
            obstacles_by_crop_to_level.setdefault(level_name, []).append(obstacle.geometry)

        all_obstacles = []
        for level_name, obstacles in obstacles_by_crop_to_level.items():
            obstacles = cascaded_union(obstacles)
            if level_name is not None:
                obstacles = obstacles.intersection(levels_by_name[level_name].geometries.mapped)
            all_obstacles.append(obstacles)

        return cascaded_union(all_obstacles).intersection(self.mapped)

    @cached_property
    def raw_doors(self):
        return cascaded_union([door.geometry for door in self.level.doors.all()]).intersection(self.mapped)

    @cached_property
    def elevatorlevels(self):
        return cascaded_union([elevatorlevel.geometry for elevatorlevel in self.level.elevatorlevels.all()])

    @cached_property
    def areas(self):
        return cascaded_union([self.rooms, self.outsides, self.elevatorlevels])

    @cached_property
    def holes(self):
        return cascaded_union([holes.geometry for holes in self.level.holes.all()]).intersection(self.areas)

    @cached_property
    def accessible(self):
        return self.areas.difference(self.holes).difference(self.obstacles)

    @cached_property
    def buildings_with_holes(self):
        return self.buildings.difference(self.holes)

    @cached_property
    def outsides_with_holes(self):
        return self.outsides.difference(self.holes)

    @cached_property
    def areas_and_doors(self):
        return cascaded_union([self.areas, self.raw_doors])

    @cached_property
    def walls(self):
        return self.buildings.difference(self.areas_and_doors)

    @cached_property
    def walls_shadow(self):
        return self.walls.buffer(0.2, join_style=JOIN_STYLE.mitre).intersection(self.buildings_with_holes)

    @cached_property
    def doors(self):
        return self.raw_doors.difference(self.areas)

    def get_levelconnectors(self, to_level=None):
        queryset = self.level.levelconnectors.prefetch_related('levels')
        if to_level is not None:
            queryset = queryset.filter(levels=to_level)
        return cascaded_union([levelconnector.geometry for levelconnector in queryset])

    @cached_property
    def levelconnectors(self):
        return cascaded_union([levelconnector.geometry for levelconnector in self.level.levelconnectors])

    @cached_property
    def intermediate_shadows(self):
        qs = self.level.levelconnectors.prefetch_related('levels').filter(levels__altitude__lt=self.level.altitude)
        connectors = cascaded_union([levelconnector.geometry for levelconnector in qs])
        shadows = self.buildings.difference(connectors.buffer(0.4, join_style=JOIN_STYLE.mitre))
        shadows = shadows.buffer(0.3)
        return shadows

    @cached_property
    def hole_shadows(self):
        holes = self.holes.buffer(0.1, join_style=JOIN_STYLE.mitre)
        shadows = holes.difference(self.holes.buffer(-0.3, join_style=JOIN_STYLE.mitre))

        qs = self.level.levelconnectors.prefetch_related('levels').filter(levels__altitude__lt=self.level.altitude)
        connectors = cascaded_union([levelconnector.geometry for levelconnector in qs])

        shadows = shadows.difference(connectors.buffer(1.0, join_style=JOIN_STYLE.mitre))
        return shadows