# -*- coding: utf-8 -*-
# Copyright (c) Alibaba, Inc. and its affiliates.
"""MidashNet: Network for monocular depth estimation trained by mixing several datasets.
This file contains code that is adapted from
https://github.com/thomasjpfan/pytorch_refinenet/blob/master/pytorch_refinenet/refinenet/refinenet_4cascade.py
"""
import torch
import torch.nn as nn

from .base_model import BaseModel
from .blocks import FeatureFusionBlock_custom, Interpolate, _make_encoder


class MidasNet_small(BaseModel):
    """Network for monocular depth estimation.
    """
    def __init__(self,
                 path=None,
                 features=64,
                 backbone='efficientnet_lite3',
                 non_negative=True,
                 exportable=True,
                 channels_last=False,
                 align_corners=True,
                 blocks={'expand': True}):
        """Init.

        Args:
            path (str, optional): Path to saved model. Defaults to None.
            features (int, optional): Number of features. Defaults to 256.
            backbone (str, optional): Backbone network for encoder. Defaults to resnet50
        """
        print('Loading weights: ', path)

        super(MidasNet_small, self).__init__()

        use_pretrained = False if path else True

        self.channels_last = channels_last
        self.blocks = blocks
        self.backbone = backbone

        self.groups = 1

        features1 = features
        features2 = features
        features3 = features
        features4 = features
        self.expand = False
        if 'expand' in self.blocks and self.blocks['expand'] is True:
            self.expand = True
            features1 = features
            features2 = features * 2
            features3 = features * 4
            features4 = features * 8

        self.pretrained, self.scratch = _make_encoder(self.backbone,
                                                      features,
                                                      use_pretrained,
                                                      groups=self.groups,
                                                      expand=self.expand,
                                                      exportable=exportable)

        self.scratch.activation = nn.ReLU(False)

        self.scratch.refinenet4 = FeatureFusionBlock_custom(
            features4,
            self.scratch.activation,
            deconv=False,
            bn=False,
            expand=self.expand,
            align_corners=align_corners)
        self.scratch.refinenet3 = FeatureFusionBlock_custom(
            features3,
            self.scratch.activation,
            deconv=False,
            bn=False,
            expand=self.expand,
            align_corners=align_corners)
        self.scratch.refinenet2 = FeatureFusionBlock_custom(
            features2,
            self.scratch.activation,
            deconv=False,
            bn=False,
            expand=self.expand,
            align_corners=align_corners)
        self.scratch.refinenet1 = FeatureFusionBlock_custom(
            features1,
            self.scratch.activation,
            deconv=False,
            bn=False,
            align_corners=align_corners)

        self.scratch.output_conv = nn.Sequential(
            nn.Conv2d(features,
                      features // 2,
                      kernel_size=3,
                      stride=1,
                      padding=1,
                      groups=self.groups),
            Interpolate(scale_factor=2, mode='bilinear'),
            nn.Conv2d(features // 2, 32, kernel_size=3, stride=1, padding=1),
            self.scratch.activation,
            nn.Conv2d(32, 1, kernel_size=1, stride=1, padding=0),
            nn.ReLU(True) if non_negative else nn.Identity(),
            nn.Identity(),
        )

        if path:
            self.load(path)

    def forward(self, x):
        """Forward pass.

        Args:
            x (tensor): input data (image)

        Returns:
            tensor: depth
        """
        if self.channels_last is True:
            print('self.channels_last = ', self.channels_last)
            x.contiguous(memory_format=torch.channels_last)

        layer_1 = self.pretrained.layer1(x)
        layer_2 = self.pretrained.layer2(layer_1)
        layer_3 = self.pretrained.layer3(layer_2)
        layer_4 = self.pretrained.layer4(layer_3)

        layer_1_rn = self.scratch.layer1_rn(layer_1)
        layer_2_rn = self.scratch.layer2_rn(layer_2)
        layer_3_rn = self.scratch.layer3_rn(layer_3)
        layer_4_rn = self.scratch.layer4_rn(layer_4)

        path_4 = self.scratch.refinenet4(layer_4_rn)
        path_3 = self.scratch.refinenet3(path_4, layer_3_rn)
        path_2 = self.scratch.refinenet2(path_3, layer_2_rn)
        path_1 = self.scratch.refinenet1(path_2, layer_1_rn)

        out = self.scratch.output_conv(path_1)

        return torch.squeeze(out, dim=1)


def fuse_model(m):
    prev_previous_type = nn.Identity()
    prev_previous_name = ''
    previous_type = nn.Identity()
    previous_name = ''
    for name, module in m.named_modules():
        if prev_previous_type == nn.Conv2d and previous_type == nn.BatchNorm2d and type(
                module) == nn.ReLU:
            # print("FUSED ", prev_previous_name, previous_name, name)
            torch.quantization.fuse_modules(
                m, [prev_previous_name, previous_name, name], inplace=True)
        elif prev_previous_type == nn.Conv2d and previous_type == nn.BatchNorm2d:
            # print("FUSED ", prev_previous_name, previous_name)
            torch.quantization.fuse_modules(
                m, [prev_previous_name, previous_name], inplace=True)
        # elif previous_type == nn.Conv2d and type(module) == nn.ReLU:
        #    print("FUSED ", previous_name, name)
        #    torch.quantization.fuse_modules(m, [previous_name, name], inplace=True)

        prev_previous_type = previous_type
        prev_previous_name = previous_name
        previous_type = type(module)
        previous_name = name
