# based on https://github.com/isl-org/MiDaS

import cv2
import torch
import torch.nn as nn
from torchvision.transforms import Compose

from ldm.modules.midas.midas.dpt_depth import DPTDepthModel
from ldm.modules.midas.midas.midas_net import MidasNet
from ldm.modules.midas.midas.midas_net_custom import MidasNet_small
from ldm.modules.midas.midas.transforms import Resize, NormalizeImage, PrepareForNet


ISL_PATHS = {
    "dpt_large": "midas_models/dpt_large-midas-2f21e586.pt",
    "dpt_hybrid": "midas_models/dpt_hybrid-midas-501f0c75.pt",
    "midas_v21": "",
    "midas_v21_small": "",
}


def disabled_train(self, mode=True):
    """Overwrite model.train with this function to make sure train/eval mode
    does not change anymore."""
    return self


def load_midas_transform(model_type):
    # https://github.com/isl-org/MiDaS/blob/master/run.py
    # load transform only
    if model_type == "dpt_large":  # DPT-Large
        net_w, net_h = 384, 384
        resize_mode = "minimal"
        normalization = NormalizeImage(mean=[0.5, 0.5, 0.5], std=[0.5, 0.5, 0.5])

    elif model_type == "dpt_hybrid":  # DPT-Hybrid
        net_w, net_h = 384, 384
        resize_mode = "minimal"
        normalization = NormalizeImage(mean=[0.5, 0.5, 0.5], std=[0.5, 0.5, 0.5])

    elif model_type == "midas_v21":
        net_w, net_h = 384, 384
        resize_mode = "upper_bound"
        normalization = NormalizeImage(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])

    elif model_type == "midas_v21_small":
        net_w, net_h = 256, 256
        resize_mode = "upper_bound"
        normalization = NormalizeImage(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225])

    else:
        assert False, f"model_type '{model_type}' not implemented, use: --model_type large"

    transform = Compose(
        [
            Resize(
                net_w,
                net_h,
                resize_target=None,
                keep_aspect_ratio=True,
                ensure_multiple_of=32,
                resize_method=resize_mode,
                image_interpolation_method=cv2.INTER_CUBIC,
            ),
            normalization,
            PrepareForNet(),
        ]
    )

    return transform


def load_model(model_type):
    # https://github.com/isl-org/MiDaS/blob/master/run.py
    # load network
    model_path = ISL_PATHS[model_type]
    if model_type == "dpt_large":  # DPT-Large
        model = DPTDepthModel(
            path=model_path,
            backbone="vitl16_384",
            non_negative=True,
        )
        net_w, net_h = 384, 384
        resize_mode = "minimal"
        normalization = NormalizeImage(mean=[0.5, 0.5, 0.5], std=[0.5, 0.5, 0.5])

    elif model_type == "dpt_hybrid":  # DPT-Hybrid
        model = DPTDepthModel(
            path=model_path,
            backbone="vitb_rn50_384",
            non_negative=True,
        )
        net_w, net_h = 384, 384
        resize_mode = "minimal"
        normalization = NormalizeImage(mean=[0.5, 0.5, 0.5], std=[0.5, 0.5, 0.5])

    elif model_type == "midas_v21":
        model = MidasNet(model_path, non_negative=True)
        net_w, net_h = 384, 384
        resize_mode = "upper_bound"
        normalization = NormalizeImage(
            mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]
        )

    elif model_type == "midas_v21_small":
        model = MidasNet_small(model_path, features=64, backbone="efficientnet_lite3", exportable=True,
                               non_negative=True, blocks={'expand': True})
        net_w, net_h = 256, 256
        resize_mode = "upper_bound"
        normalization = NormalizeImage(
            mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]
        )

    else:
        print(f"model_type '{model_type}' not implemented, use: --model_type large")
        assert False

    transform = Compose(
        [
            Resize(
                net_w,
                net_h,
                resize_target=None,
                keep_aspect_ratio=True,
                ensure_multiple_of=32,
                resize_method=resize_mode,
                image_interpolation_method=cv2.INTER_CUBIC,
            ),
            normalization,
            PrepareForNet(),
        ]
    )

    return model.eval(), transform


class MiDaSInference(nn.Module):
    MODEL_TYPES_TORCH_HUB = [
        "DPT_Large",
        "DPT_Hybrid",
        "MiDaS_small"
    ]
    MODEL_TYPES_ISL = [
        "dpt_large",
        "dpt_hybrid",
        "midas_v21",
        "midas_v21_small",
    ]

    def __init__(self, model_type):
        super().__init__()
        assert (model_type in self.MODEL_TYPES_ISL)
        model, _ = load_model(model_type)
        self.model = model
        self.model.train = disabled_train

    def forward(self, x):
        # x in 0..1 as produced by calling self.transform on a 0..1 float64 numpy array
        # NOTE: we expect that the correct transform has been called during dataloading.
        with torch.no_grad():
            prediction = self.model(x)
            prediction = torch.nn.functional.interpolate(
                prediction.unsqueeze(1),
                size=x.shape[2:],
                mode="bicubic",
                align_corners=False,
            )
        assert prediction.shape == (x.shape[0], 1, x.shape[2], x.shape[3])
        return prediction