import numpy as np
from math import isclose
from .base import ISDataset


class ComposeDataset(ISDataset):
    def __init__(self, datasets, **kwargs):
        super(ComposeDataset, self).__init__(**kwargs)

        self._datasets = datasets
        self.dataset_samples = []
        for dataset_indx, dataset in enumerate(self._datasets):
            self.dataset_samples.extend([(dataset_indx, i) for i in range(len(dataset))])

    def get_sample(self, index):
        dataset_indx, sample_indx = self.dataset_samples[index]
        return self._datasets[dataset_indx].get_sample(sample_indx)


class ProportionalComposeDataset(ISDataset):
    def __init__(self, datasets, ratios, **kwargs):
        super().__init__(**kwargs)

        assert len(ratios) == len(datasets),\
            "The number of datasets must match the number of ratios"
        assert isclose(sum(ratios), 1.0),\
            "The sum of ratios must be equal to 1"

        self._ratios = ratios
        self._datasets = datasets
        self.dataset_samples = []
        for dataset_indx, dataset in enumerate(self._datasets):
            self.dataset_samples.extend([(dataset_indx, i) for i in range(len(dataset))])

    def get_sample(self, index):
        dataset_indx = np.random.choice(len(self._datasets), p=self._ratios)
        sample_indx = np.random.choice(len(self._datasets[dataset_indx]))

        return self._datasets[dataset_indx].get_sample(sample_indx)
