# modified from: https://colab.research.google.com/github/tensorflow/models/blob/master/research/deeplab/deeplab_demo.ipynb

import tensorflow as tf
import numpy as np
import urllib
import tarfile
import PIL.Image
import os
from matplotlib import gridspec
from matplotlib import pyplot as plt


class DeepLabModel(object):
    """Class to load deeplab model and run inference."""

    INPUT_TENSOR_NAME = 'ImageTensor:0'
    OUTPUT_TENSOR_NAME = 'SemanticPredictions:0'
    INPUT_SIZE = 513
    FROZEN_GRAPH_NAME = 'frozen_inference_graph'

    def __init__(self, tarball_path, sess):
        """Creates and loads pretrained deeplab model."""
        self.sess = sess
        self.graph = tf.get_default_graph()

        graph_def = None
        # Extract frozen graph from tar archive.
        tar_file = tarfile.open(tarball_path)
        for tar_info in tar_file.getmembers():
            if self.FROZEN_GRAPH_NAME in os.path.basename(tar_info.name):
                file_handle = tar_file.extractfile(tar_info)
                graph_def = tf.GraphDef.FromString(file_handle.read())
                break

        tar_file.close()

        if graph_def is None:
          raise RuntimeError('Cannot find inference graph in tar archive.')

        # adds to default graph
        with self.graph.as_default():
            tf.import_graph_def(graph_def, name='')


    def run(self, image):
        """Runs inference on a single image.

        Args:
          image: A PIL.Image object, raw input image.

        Returns:
          resized_image: RGB image resized from original input image.
          seg_map: Segmentation map of `resized_image`.
        """
        width, height = image.size
        resize_ratio = 1.0 * self.INPUT_SIZE / max(width, height)
        target_size = (int(resize_ratio * width), int(resize_ratio * height))
        resized_image = image.convert('RGB').resize(target_size, PIL.Image.ANTIALIAS)
        batch_seg_map = self.sess.run(
            self.OUTPUT_TENSOR_NAME,
            feed_dict={self.INPUT_TENSOR_NAME: [np.asarray(resized_image)]})
        seg_map = batch_seg_map[0]
        return resized_image, seg_map


def create_pascal_label_colormap():
    """Creates a label colormap used in PASCAL VOC segmentation benchmark.

    Returns:
      A Colormap for visualizing segmentation results.
    """
    colormap = np.zeros((256, 3), dtype=int)
    ind = np.arange(256, dtype=int)

    for shift in reversed(range(8)):
        for channel in range(3):
            colormap[:, channel] |= ((ind >> channel) & 1) << shift
        ind >>= 3

    return colormap


def label_to_color_image(label):
    """Adds color defined by the dataset colormap to the label.

    Args:
      label: A 2D array with integer type, storing the segmentation label.

    Returns:
      result: A 2D array with floating type. The element of the array
        is the color indexed by the corresponding element in the input label
        to the PASCAL color map.

    Raises:
      ValueError: If label is not of rank 2 or its value is larger than color
        map maximum entry.
    """
    if label.ndim != 2:
        raise ValueError('Expect 2-D input label')

    colormap = create_pascal_label_colormap()

    if np.max(label) >= len(colormap):
        raise ValueError('label value too large.')

    return colormap[label]


def vis_segmentation(image, seg_map):
    """Visualizes input image, segmentation map and overlay view."""
    plt.figure(figsize=(15, 5))
    grid_spec = gridspec.GridSpec(1, 4, width_ratios=[6, 6, 6, 1])

    plt.subplot(grid_spec[0])
    plt.imshow(image)
    plt.axis('off')
    plt.title('input image')

    plt.subplot(grid_spec[1])
    seg_image = label_to_color_image(seg_map).astype(np.uint8)
    plt.imshow(seg_image)
    plt.axis('off')
    plt.title('segmentation map')

    plt.subplot(grid_spec[2])
    plt.imshow(image)
    plt.imshow(seg_image, alpha=0.7)
    plt.axis('off')
    plt.title('segmentation overlay')

    unique_labels = np.unique(seg_map)
    ax = plt.subplot(grid_spec[3])
    plt.imshow(FULL_COLOR_MAP[unique_labels].astype(np.uint8), interpolation='nearest')
    ax.yaxis.tick_right()
    plt.yticks(range(len(unique_labels)), LABEL_NAMES[unique_labels])
    plt.xticks([], [])
    ax.tick_params(width=0.0)
    plt.grid('off')
    plt.show()


# pascal voc classes
LABEL_NAMES = np.asarray([
    'background', 'aeroplane', 'bicycle', 'bird', 'boat', 'bottle', 'bus',
    'car', 'cat', 'chair', 'cow', 'diningtable', 'dog', 'horse', 'motorbike',
    'person', 'pottedplant', 'sheep', 'sofa', 'train', 'tv'
])


FULL_LABEL_MAP = np.arange(len(LABEL_NAMES)).reshape(len(LABEL_NAMES), 1)
FULL_COLOR_MAP = label_to_color_image(FULL_LABEL_MAP)

MODEL_NAME = 'mobilenetv2_coco_voctrainaug'  # @param ['mobilenetv2_coco_voctrainaug', 'mobilenetv2_coco_voctrainval', 'xception_coco_voctrainaug', 'xception_coco_voctrainval']

_DOWNLOAD_URL_PREFIX = 'http://download.tensorflow.org/models/'
_MODEL_URLS = {
    'mobilenetv2_coco_voctrainaug':
        'deeplabv3_mnv2_pascal_train_aug_2018_01_29.tar.gz',
    'mobilenetv2_coco_voctrainval':
        'deeplabv3_mnv2_pascal_trainval_2018_01_29.tar.gz',
    'xception_coco_voctrainaug':
        'deeplabv3_pascal_train_aug_2018_01_04.tar.gz',
    'xception_coco_voctrainval':
        'deeplabv3_pascal_trainval_2018_01_04.tar.gz',
}
_TARBALL_NAME = 'deeplab_model.tar.gz'


def load_model(sess, model_dir=os.path.join(os.path.dirname(__file__), 'deeplab_model')):
    '''
        sess: tf.Session
        model_dir: directory to save model
    '''
    os.makedirs(model_dir, exist_ok=True)
    tf.gfile.MakeDirs(model_dir)

    download_path = os.path.join(model_dir, _TARBALL_NAME)

    if not os.path.isfile(download_path):
        print('downloading model, this might take a while...')
        urllib.request.urlretrieve(_DOWNLOAD_URL_PREFIX + _MODEL_URLS[MODEL_NAME],
                           download_path)
        print('download completed!')

    print("loading DeepLab model...")
    MODEL = DeepLabModel(download_path, sess)
    print("finished loading...")
    return MODEL
