import argparse
import logging
import os

import numpy as np
import torch
import torch.nn.functional as F
from PIL import Image
from torchvision import transforms

from utils.data_loading import BasicDataset
from unet import UNet
from utils.utils import plot_img_and_mask


def predict_img(net, full_img, device, scale_factor=1, out_threshold=0.5):
    net.eval()
    img = torch.from_numpy(BasicDataset.preprocess(full_img, scale_factor, is_mask=False))
    img = img.unsqueeze(0)
    img = img.to(device=device, dtype=torch.float32)

    with torch.no_grad():
        output = net(img)

        if net.n_classes > 1:
            probs = F.softmax(output, dim=1)[0]
        else:
            probs = torch.sigmoid(output)[0]

        tf = transforms.Compose(
            [transforms.ToPILImage(), transforms.Resize((full_img.size[1], full_img.size[0])), transforms.ToTensor()]
        )

        full_mask = tf(probs.cpu()).squeeze()

    if net.n_classes == 1:
        return (full_mask > out_threshold).numpy()
    else:
        return F.one_hot(full_mask.argmax(dim=0), net.n_classes).permute(2, 0, 1).numpy()


def get_args():
    parser = argparse.ArgumentParser(
        description="Predict masks from input images",
    )
    parser.add_argument(
        "--model",
        "-m",
        default="MODEL.pth",
        metavar="FILE",
        help="Specify the file in which the model is stored",
    )
    parser.add_argument(
        "--input",
        "-i",
        metavar="INPUT",
        nargs="+",
        help="Filenames of input images",
        required=True,
    )
    parser.add_argument(
        "--output",
        "-o",
        metavar="OUTPUT",
        nargs="+",
        help="Filenames of output images",
    )
    parser.add_argument(
        "--viz",
        "-v",
        action="store_true",
        help="Visualize the images as they are processed",
    )
    parser.add_argument(
        "--no-save",
        "-n",
        action="store_true",
        help="Do not save the output masks",
    )
    parser.add_argument(
        "--mask-threshold",
        "-t",
        type=float,
        default=0.5,
        help="Minimum probability value to consider a mask pixel white",
    )
    parser.add_argument(
        "--scale",
        "-s",
        type=float,
        default=0.5,
        help="Scale factor for the input images",
    )
    parser.add_argument(
        "--bilinear",
        action="store_true",
        default=False,
        help="Use bilinear upsampling",
    )

    return parser.parse_args()


def get_output_filenames(args):
    def _generate_name(fn):
        split = os.path.splitext(fn)
        return f"{split[0]}_OUT{split[1]}"

    return args.output or list(map(_generate_name, args.input))


def mask_to_image(mask: np.ndarray):
    if mask.ndim == 2:
        return Image.fromarray((mask * 255).astype(np.uint8))
    elif mask.ndim == 3:
        return Image.fromarray((np.argmax(mask, axis=0) * 255 / mask.shape[0]).astype(np.uint8))


if __name__ == "__main__":
    args = get_args()
    in_files = args.input
    out_files = get_output_filenames(args)

    net = UNet(n_channels=3, n_classes=2, bilinear=args.bilinear)

    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
    logging.info(f"Loading model {args.model}")
    logging.info(f"Using device {device}")

    net.to(device=device)
    net.load_state_dict(torch.load(args.model, map_location=device))

    logging.info("Model loaded!")

    for i, filename in enumerate(in_files):
        logging.info(f"\nPredicting image {filename} ...")
        img = Image.open(filename)

        mask = predict_img(
            net=net, full_img=img, scale_factor=args.scale, out_threshold=args.mask_threshold, device=device
        )

        if not args.no_save:
            out_filename = out_files[i]
            result = mask_to_image(mask)
            result.save(out_filename)
            logging.info(f"Mask saved to {out_filename}")

        if args.viz:
            logging.info(f"Visualizing results for image {filename}, close to continue...")
            plot_img_and_mask(img, mask)