from abc import ABC
from pathlib import Path

import torch
from torch import nn
from torch import functional as F
from torch.utils.data import DataLoader

from lib.objects.map import MapStorage

import pytorch_lightning as pl


# Utility - Modules
###################


class Flatten(nn.Module):

    @property
    def shape(self):
        try:
            x = torch.randn(self.in_shape).unsqueeze(0)
            output = self(x)
            return output.shape[1:]
        except Exception as e:
            print(e)
            return -1

    def __init__(self, in_shape, to=(-1, )):
        super(Flatten, self).__init__()
        self.in_shape = in_shape
        self.to = to

    def forward(self, x):
        return x.view(x.size(0), *self.to)


class Interpolate(nn.Module):
    def __init__(self,  size=None, scale_factor=None, mode='nearest', align_corners=None):
        super(Interpolate, self).__init__()
        self.interp = nn.functional.interpolate
        self.size = size
        self.scale_factor = scale_factor
        self.align_corners = align_corners
        self.mode = mode

    def forward(self, x):
        x = self.interp(x, size=self.size, scale_factor=self.scale_factor,
                        mode=self.mode, align_corners=self.align_corners)
        return x


class AutoPad(nn.Module):

    def __init__(self, interpolations=3, base=2):
        super(AutoPad, self).__init__()
        self.fct = base ** interpolations

    def forward(self, x):
        # noinspection PyUnresolvedReferences
        x = F.pad(x,
                  [0,
                   (x.shape[-1] // self.fct + 1) * self.fct - x.shape[-1] if x.shape[-1] % self.fct != 0 else 0,
                   (x.shape[-2] // self.fct + 1) * self.fct - x.shape[-2] if x.shape[-2] % self.fct != 0 else 0,
                   0])
        return x


class LightningBaseModule(pl.LightningModule, ABC):

    @classmethod
    def name(cls):
        raise NotImplementedError('Give your model a name!')

    @property
    def shape(self):
        try:
            x = torch.randn(self.in_shape).unsqueeze(0)
            output = self(x)
            return output.shape[1:]
        except Exception as e:
            print(e)
            return -1

    def __init__(self, params):
        super(LightningBaseModule, self).__init__()
        self.hparams = params

        # Data loading
        # =============================================================================
        # Map Object
        self.map_storage = MapStorage(self.hparams.data_param.map_root)

    def size(self):
        return self.shape

    def _move_to_model_device(self, x):
        return x.cuda() if next(self.parameters()).is_cuda else x.cpu()

    def save_to_disk(self, model_path):
        Path(model_path, exist_ok=True).mkdir(parents=True, exist_ok=True)
        if not (model_path / 'model_class.obj').exists():
            with (model_path / 'model_class.obj').open('wb') as f:
                torch.save(self.__class__, f)
        return True

    @pl.data_loader
    def train_dataloader(self):
        return DataLoader(dataset=self.dataset.train_dataset, shuffle=True,
                          batch_size=self.hparams.data_param.batchsize,
                          num_workers=self.hparams.data_param.worker)

    @pl.data_loader
    def test_dataloader(self):
        return DataLoader(dataset=self.dataset.test_dataset, shuffle=True,
                          batch_size=self.hparams.data_param.batchsize,
                          num_workers=self.hparams.data_param.worker)

    @pl.data_loader
    def val_dataloader(self):
        return DataLoader(dataset=self.dataset.val_dataset, shuffle=True,
                          batch_size=self.hparams.data_param.batchsize,
                          num_workers=self.hparams.data_param.worker)

    def configure_optimizers(self):
        raise NotImplementedError

    def forward(self, *args, **kwargs):
        raise NotImplementedError

    def validation_step(self, *args, **kwargs):
        raise NotImplementedError

    def validation_end(self, outputs):
        raise NotImplementedError

    def training_step(self, batch_xy, batch_nb, *args, **kwargs):
        raise NotImplementedError

    def test_step(self, *args, **kwargs):
        raise NotImplementedError

    def test_end(self, outputs):
        from sklearn.metrics import roc_auc_score

        y_scores, y_true = [], []
        for output in outputs:
            y_scores.append(output['y_pred'])
            y_true.append(output['y_true'])

        y_true = torch.cat(y_true, dim=0)
        # FIXME: What did this do do i need it?
        # y_true = (y_true != V.HOMOTOPIC).long()
        y_scores = torch.cat(y_scores, dim=0)

        roc_auc_scores = roc_auc_score(y_true.cpu().numpy(), y_scores.cpu().numpy())
        print(f'AUC Score: {roc_auc_scores}')
        return {'roc_auc_scores': roc_auc_scores}

    def init_weights(self):
        def _weight_init(m):
            if hasattr(m, 'weight'):
                if isinstance(m.weight, torch.Tensor):
                    torch.nn.init.xavier_uniform_(m.weight)
            if hasattr(m, 'bias'):
                if isinstance(m.bias, torch.Tensor):
                    m.bias.data.fill_(0.01)
        self.apply(_weight_init)


class FilterLayer(nn.Module):

    def __init__(self):
        super(FilterLayer, self).__init__()

    def forward(self, x):
        tensor = x[:, -1]
        return tensor


class MergingLayer(nn.Module):

    def __init__(self):
        super(MergingLayer, self).__init__()

    def forward(self, x):
        # ToDo: Which ones to combine?
        return


class FlipTensor(nn.Module):
    def __init__(self, dim=-2):
        super(FlipTensor, self).__init__()
        self.dim = dim

    def forward(self, x):
        idx = [i for i in range(x.size(self.dim) - 1, -1, -1)]
        idx = torch.as_tensor(idx).long()
        inverted_tensor = x.index_select(self.dim, idx)
        return inverted_tensor