from PIL import Image
import torch
from huggingface_hub import hf_hub_download

# custom installation from this PR: https://github.com/huggingface/transformers/pull/34583
# !pip install git+https://github.com/geetu040/transformers.git@depth-pro-projects#egg=transformers
from transformers import DepthProConfig, DepthProImageProcessorFast, DepthProForDepthEstimation

# load DepthPro model, used as backbone
config = DepthProConfig(
    patch_size=32,
    patch_embeddings_size=4,
    num_hidden_layers=12,
    intermediate_hook_ids=[11, 8, 7, 5],
    intermediate_feature_dims=[256, 256, 256, 256],
    scaled_images_ratios=[0.5, 1.0],
    scaled_images_overlap_ratios=[0.5, 0.25],
    scaled_images_feature_dims=[1024, 512],
    use_fov_model=False,
)
depthpro_for_depth_estimation = DepthProForDepthEstimation(config)

# create DepthPro for super resolution
class DepthProForSuperResolution(torch.nn.Module):
    def __init__(self, depthpro_for_depth_estimation):
        super().__init__()

        self.depthpro_for_depth_estimation = depthpro_for_depth_estimation
        hidden_size = self.depthpro_for_depth_estimation.config.fusion_hidden_size

        self.image_head = torch.nn.Sequential(
            torch.nn.ConvTranspose2d(
                in_channels=config.num_channels,
                out_channels=hidden_size,
                kernel_size=4, stride=2, padding=1
            ),
            torch.nn.ReLU(),
        )

        self.head = torch.nn.Sequential(
            torch.nn.Conv2d(
                in_channels=hidden_size,
                out_channels=hidden_size,
                kernel_size=3, stride=1, padding=1
            ),
            torch.nn.ReLU(),
            torch.nn.ConvTranspose2d(
                in_channels=hidden_size,
                out_channels=hidden_size,
                kernel_size=4, stride=2, padding=1
            ),
            torch.nn.ReLU(),
            torch.nn.Conv2d(
                in_channels=hidden_size,
                out_channels=self.depthpro_for_depth_estimation.config.num_channels,
                kernel_size=3, stride=1, padding=1
            ),
        )

    def forward(self, pixel_values):
        # x is the low resolution image
        x = pixel_values
        encoder_features = self.depthpro_for_depth_estimation.depth_pro(x).features
        fused_hidden_state = self.depthpro_for_depth_estimation.fusion_stage(encoder_features)[-1]
        x = self.image_head(x)
        x = torch.nn.functional.interpolate(x, size=fused_hidden_state.shape[2:])
        x = x + fused_hidden_state
        x = self.head(x)
        return x

# initialize the model
model = DepthProForSuperResolution(depthpro_for_depth_estimation)
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
model = model.to(device)

# load weights
weights_path = hf_hub_download(repo_id="geetu040/DepthPro_SR_4x_256p", filename="model_weights.pth")
model.load_state_dict(torch.load(weights_path, map_location=torch.device('cpu')))

# load image processor
image_processor = DepthProImageProcessorFast(
    do_resize=False,
    do_rescale=True,
    do_normalize=True
)

def predict(image):
	# inference

	image.thumbnail((256, 256)) # resizes the image object to fit within a 256x256 pixel box

	# prepare image for the model
	inputs = image_processor(images=image, return_tensors="pt")
	inputs = {k: v.to(device) for k, v in inputs.items()}

	with torch.no_grad():
		outputs = model(**inputs)

	# convert tensors to PIL.Image
	output = outputs[0]                        # extract the first and only batch
	output = output.cpu()                      # unload from cuda if used
	output = torch.permute(output, (1, 2, 0))  # (C, H, W) -> (H, W, C)
	output = output * 0.5 + 0.5                # undo normalization
	output = output * 255.                     # undo scaling
	output = output.clip(0, 255.)              # fix out of range
	output = output.numpy()                    # convert to numpy
	output = output.astype('uint8')            # convert to PIL.Image compatible format
	output = Image.fromarray(output)           # create PIL.Image object

	return output