import os
import glob
import torch
import torch.jit
import torch.nn as nn


class Model(torch.jit.ScriptModule):
    CHECKPOINT_FILENAME_PATTERN = 'model-{}.pth'

    __constants__ = [
        '_hidden1', '_hidden2', '_hidden3', '_hidden4', '_hidden5', '_hidden6',
        '_hidden7', '_hidden8', '_hidden9', '_hidden10', '_features', '_classifier',
        '_digit_length', '_digit1', '_digit2', '_digit3', '_digit4', '_digit5'
    ]

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

        self._hidden1 = nn.Sequential(
            nn.Conv2d(
                in_channels=3,
                out_channels=48,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=48),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=2, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden2 = nn.Sequential(
            nn.Conv2d(
                in_channels=48,
                out_channels=64,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=64),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=1, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden3 = nn.Sequential(
            nn.Conv2d(
                in_channels=64,
                out_channels=128,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=128),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=2, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden4 = nn.Sequential(
            nn.Conv2d(
                in_channels=128,
                out_channels=160,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=160),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=1, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden5 = nn.Sequential(
            nn.Conv2d(
                in_channels=160,
                out_channels=192,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=192),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=2, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden6 = nn.Sequential(
            nn.Conv2d(
                in_channels=192,
                out_channels=192,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=192),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=1, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden7 = nn.Sequential(
            nn.Conv2d(
                in_channels=192,
                out_channels=192,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=192),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=2, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden8 = nn.Sequential(
            nn.Conv2d(
                in_channels=192,
                out_channels=192,
                kernel_size=5,
                padding=2
            ),
            nn.BatchNorm2d(num_features=192),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=2, stride=1, padding=1),
            nn.Dropout(0.2)
        )
        self._hidden9 = nn.Sequential(
            nn.Linear(192 * 7 * 7, 3072),
            nn.ReLU()
        )
        self._hidden10 = nn.Sequential(
            nn.Linear(3072, 3072),
            nn.ReLU()
        )

        self._digit_length = nn.Sequential(nn.Linear(3072, 7))
        self._digit1 = nn.Sequential(nn.Linear(3072, 11))
        self._digit2 = nn.Sequential(nn.Linear(3072, 11))
        self._digit3 = nn.Sequential(nn.Linear(3072, 11))
        self._digit4 = nn.Sequential(nn.Linear(3072, 11))
        self._digit5 = nn.Sequential(nn.Linear(3072, 11))

    @torch.jit.script_method
    def forward(self, x):
        x = self._hidden1(x)
        x = self._hidden2(x)
        x = self._hidden3(x)
        x = self._hidden4(x)
        x = self._hidden5(x)
        x = self._hidden6(x)
        x = self._hidden7(x)
        x = self._hidden8(x)
        x = x.view(x.size(0), 192 * 7 * 7)
        x = self._hidden9(x)
        x = self._hidden10(x)

        length_logits = self._digit_length(x)
        digit1_logits = self._digit1(x)
        digit2_logits = self._digit2(x)
        digit3_logits = self._digit3(x)
        digit4_logits = self._digit4(x)
        digit5_logits = self._digit5(x)

        return length_logits, digit1_logits, digit2_logits, digit3_logits, digit4_logits, digit5_logits

    def store(self, path_to_dir, step, maximum=5):
        path_to_models = glob.glob(os.path.join(
            path_to_dir, Model.CHECKPOINT_FILENAME_PATTERN.format('*')))
        if len(path_to_models) == maximum:
            min_step = min(
                [int(path_to_model.split('\\')[-1][6:-4])
                 for path_to_model in path_to_models]
            )
            path_to_min_step_model = os.path.join(
                path_to_dir,
                Model.CHECKPOINT_FILENAME_PATTERN.format(min_step)
            )
            os.remove(path_to_min_step_model)

        path_to_checkpoint_file = os.path.join(
            path_to_dir, Model.CHECKPOINT_FILENAME_PATTERN.format(step)
        )
        torch.save(self.state_dict(), path_to_checkpoint_file)
        return path_to_checkpoint_file

    def restore(self, path_to_checkpoint_file):
        self.load_state_dict(
            torch.load(
                path_to_checkpoint_file,
                map_location=torch.device('cpu')
            )
        )
        step = int(path_to_checkpoint_file.split('\\')[-1][6:-4])
        return step