# Copyright 2022 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

r"""A binary to run unified detector."""

import json
import os
from typing import Any, Dict, Sequence, Union

from absl import app
from absl import flags
from absl import logging

import cv2
import gin
import numpy as np
import tensorflow as tf
import tqdm

from official.projects.unified_detector import external_configurables  # pylint: disable=unused-import
from official.projects.unified_detector.modeling import universal_detector
from official.projects.unified_detector.utils import utilities


# group two lines into a paragraph if affinity score higher than this
_PARA_GROUP_THR = 0.5


# MODEL spec
_GIN_FILE = flags.DEFINE_string(
    'gin_file', None, 'Path to the Gin file that defines the model.')
_CKPT_PATH = flags.DEFINE_string(
    'ckpt_path', None, 'Path to the checkpoint directory.')
_IMG_SIZE = flags.DEFINE_integer(
    'img_size', 1024, 'Size of the image fed to the model.')

# Input & Output
# Note that, all images specified by `img_file` and `img_dir` will be processed.
_IMG_FILE = flags.DEFINE_multi_string('img_file', [], 'Paths to the images.')
_IMG_DIR = flags.DEFINE_multi_string(
    'img_dir', [], 'Paths to the image directories.')
_OUTPUT_PATH = flags.DEFINE_string('output_path', None, 'Path for the output.')
_VIS_DIR = flags.DEFINE_string(
    'vis_dir', None, 'Path for the visualization output.')


def _preprocess(raw_image: np.ndarray) -> Union[np.ndarray, float]:
  """Convert a raw image to properly resized, padded, and normalized ndarray."""
  # (1) convert to tf.Tensor and float32.
  img_tensor = tf.convert_to_tensor(raw_image, dtype=tf.float32)

  # (2) pad to square.
  height, width = img_tensor.shape[:2]
  maximum_side = tf.maximum(height, width)
  height_pad = maximum_side - height
  width_pad = maximum_side - width
  img_tensor = tf.pad(
      img_tensor, [[0, height_pad], [0, width_pad], [0, 0]],
      constant_values=127)
  ratio = maximum_side / _IMG_SIZE.value
  # (3) resize long side to the maximum length.
  img_tensor = tf.image.resize(
      img_tensor, (_IMG_SIZE.value, _IMG_SIZE.value))
  img_tensor = tf.cast(img_tensor, tf.uint8)

  # (4) normalize
  img_tensor = utilities.normalize_image_to_range(img_tensor)

  # (5) Add batch dimension and return as numpy array.
  return tf.expand_dims(img_tensor, 0).numpy(), float(ratio)


def load_model() -> tf.keras.layers.Layer:
  gin.parse_config_file(_GIN_FILE.value)
  model = universal_detector.UniversalDetector()
  ckpt = tf.train.Checkpoint(model=model)
  ckpt_path = _CKPT_PATH.value
  logging.info('Load ckpt from: %s', ckpt_path)
  ckpt.restore(ckpt_path).expect_partial()
  return model


def inference(img_file: str, model: tf.keras.layers.Layer) -> Dict[str, Any]:
  """Inference step."""
  img = cv2.cvtColor(cv2.imread(img_file), cv2.COLOR_BGR2RGB)
  img_ndarray, ratio = _preprocess(img)

  output_dict = model.serve(img_ndarray)
  class_tensor = output_dict['classes'].numpy()
  mask_tensor = output_dict['masks'].numpy()
  group_tensor = output_dict['groups'].numpy()

  indices = np.where(class_tensor[0])[0].tolist()  # indices of positive slots.
  mask_list = [
      mask_tensor[0, :, :, index] for index in indices]  # List of mask ndarray.

  # Form lines and words
  lines = []
  line_indices = []
  for index, mask in tqdm.tqdm(zip(indices, mask_list)):
    line = {
        'words': [],
        'text': '',
    }

    contours, _ = cv2.findContours(
        (mask > 0.).astype(np.uint8),
        cv2.RETR_TREE,
        cv2.CHAIN_APPROX_SIMPLE)[-2:]
    for contour in contours:
      if (isinstance(contour, np.ndarray) and
          len(contour.shape) == 3 and
          contour.shape[0] > 2 and
          contour.shape[1] == 1 and
          contour.shape[2] == 2):
        cnt_list = (contour[:, 0] * ratio).astype(np.int32).tolist()
        line['words'].append({'text': '', 'vertices': cnt_list})
      else:
        logging.error('Invalid contour: %s, discarded', str(contour))
    if line['words']:
      lines.append(line)
      line_indices.append(index)

  # Form paragraphs
  line_grouping = utilities.DisjointSet(len(line_indices))
  affinity = group_tensor[0][line_indices][:, line_indices]
  for i1, i2 in zip(*np.where(affinity > _PARA_GROUP_THR)):
    line_grouping.union(i1, i2)

  line_groups = line_grouping.to_group()
  paragraphs = []
  for line_group in line_groups:
    paragraph = {'lines': []}
    for id_ in line_group:
      paragraph['lines'].append(lines[id_])
    if paragraph:
      paragraphs.append(paragraph)

  return paragraphs


def main(argv: Sequence[str]) -> None:
  if len(argv) > 1:
    raise app.UsageError('Too many command-line arguments.')

  # Get list of images
  img_lists = []
  img_lists.extend(_IMG_FILE.value)
  for img_dir in _IMG_DIR.value:
    img_lists.extend(tf.io.gfile.glob(os.path.join(img_dir, '*')))

  logging.info('Total number of input images: %d', len(img_lists))

  model = load_model()

  vis_dis = _VIS_DIR.value

  output = {'annotations': []}
  for img_file in tqdm.tqdm(img_lists):
    output['annotations'].append({
        'image_id': img_file.split('/')[-1].split('.')[0],
        'paragraphs': inference(img_file, model),
    })

    if vis_dis:
      key = output['annotations'][-1]['image_id']
      paragraphs = output['annotations'][-1]['paragraphs']
      img = cv2.cvtColor(cv2.imread(img_file), cv2.COLOR_BGR2RGB)
      word_bnds = []
      line_bnds = []
      para_bnds = []
      for paragraph in paragraphs:
        paragraph_points_list = []
        for line in paragraph['lines']:
          line_points_list = []
          for word in line['words']:
            word_bnds.append(
                np.array(word['vertices'], np.int32).reshape((-1, 1, 2)))
            line_points_list.extend(word['vertices'])
          paragraph_points_list.extend(line_points_list)

          line_points = np.array(line_points_list, np.int32)  # (N,2)
          left = int(np.min(line_points[:, 0]))
          top = int(np.min(line_points[:, 1]))
          right = int(np.max(line_points[:, 0]))
          bottom = int(np.max(line_points[:, 1]))
          line_bnds.append(
              np.array([[[left, top]], [[right, top]], [[right, bottom]],
                        [[left, bottom]]], np.int32))
        para_points = np.array(paragraph_points_list, np.int32)  # (N,2)
        left = int(np.min(para_points[:, 0]))
        top = int(np.min(para_points[:, 1]))
        right = int(np.max(para_points[:, 0]))
        bottom = int(np.max(para_points[:, 1]))
        para_bnds.append(
            np.array([[[left, top]], [[right, top]], [[right, bottom]],
                      [[left, bottom]]], np.int32))

      for name, bnds in zip(['paragraph', 'line', 'word'],
                            [para_bnds, line_bnds, word_bnds]):
        vis = cv2.polylines(img, bnds, True, (0, 0, 255), 2)
        cv2.imwrite(os.path.join(vis_dis, f'{key}-{name}.jpg'),
                    cv2.cvtColor(vis, cv2.COLOR_RGB2BGR))

  with tf.io.gfile.GFile(_OUTPUT_PATH.value, mode='w') as f:
    f.write(json.dumps(output, ensure_ascii=False, indent=2))


if __name__ == '__main__':
  flags.mark_flags_as_required(['gin_file', 'ckpt_path', 'output_path'])
  app.run(main)
