import shelve
from pathlib import Path
from typing import Union

import torch
from torch.utils.data import Dataset, ConcatDataset

from datasets.utils import DatasetMapping
from lib.modules.model_parts import Generator
from lib.objects.map import Map


class TrajPairDataset(Dataset):
    @property
    def map_shape(self):
        return self.map.as_array.shape

    def __init__(self, data):
        super(TrajPairDataset, self).__init__()
        self.alternatives = data['alternatives']
        self.trajectory = data['trajectory']
        self.labels = data['labels']
        self.mapname = data['map']['name'][4:] if data['map']['name'].startswith('map_') else data['map']['name']
        self.map = data['map']['map']

    def __len__(self):
        return len(self.alternatives)

    def __getitem__(self, item):
        return self.trajectory.vertices, self.alternatives[item].vertices, self.labels[item], self.mapname


class TrajPairData(object):
    @property
    def map_shapes(self):
        return [dataset.map_shape for dataset in self._dataset.datasets]

    @property
    def map_shapes_max(self):
        shapes = self.map_shapes
        return map(max, zip(*shapes))

    @property
    def name(self):
        return self.__class__.__name__

    def __init__(self, data_root, map_root: Union[Path, str] = '', mapname='tate_sw', trajectories=1000, alternatives=10,
                 train_val_test_split=(0.6, 0.2, 0.2), rebuild=False, equal_samples=True, **_):

        self.rebuild = rebuild
        self.equal_samples = equal_samples
        self._alternatives = alternatives
        self._trajectories = trajectories
        self.mapname = mapname
        self.train_split, self.val_split, self.test_split = train_val_test_split
        self.data_root = Path(data_root)
        self.maps_root = Path(map_root) if map_root else Path() / 'res' / 'maps'
        self._dataset, self._train_map, self._val_map, self._test_map = self._load_dataset()

    def _build_data_on_demand(self):
        map_object = Map(self.mapname).from_image(self.maps_root / f'{self.mapname}.bmp')
        assert self.maps_root.exists()
        dataset_file = Path(self.data_root) / f'{self.mapname}.pik'
        if dataset_file.exists() and self.rebuild:
            dataset_file.unlink()
        if not dataset_file.exists():
            generator = Generator(self.data_root, map_object)
            generator.generate_n_trajectories_m_alternatives(self._trajectories, self._alternatives,
                                                             self.mapname, equal_samples=self.equal_samples)
        return True

    def _load_dataset(self):
        assert self._build_data_on_demand()
        with shelve.open(str(self.data_root / f'{self.mapname}.pik')) as d:
            dataset = ConcatDataset([TrajPairDataset(d[key]) for key in d.keys() if key != 'map'])
            indices = torch.randperm(len(dataset))

            train_size = int(len(dataset) * self.train_split)
            val_size = int(len(dataset) * self.val_split)
            test_size = int(len(dataset) * self.test_split)

            train_map = indices[:train_size]
            val_map = indices[train_size:val_size]
            test_map = indices[test_size:]
        return dataset, train_map, val_map, test_map

    @property
    def train_dataset(self):
        return DatasetMapping(self._dataset, self._train_map)

    @property
    def val_dataset(self):
        return DatasetMapping(self._dataset, self._val_map)

    @property
    def test_dataset(self):
        return DatasetMapping(self._dataset, self._test_map)

    def get_datasets(self):
        return self.train_dataset, self.val_dataset, self.test_dataset