# coding=utf-8
# Copyright 2023 The TensorFlow Datasets Authors.
#
# 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.

"""irc_disentanglement dataset."""

import collections
import os
from typing import List

from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow as tf
import tensorflow_datasets.public_api as tfds

_DOWNLOAD_URL = (
    "https://github.com/jkkummerfeld/irc-disentanglement/zipball/fd379e9"
)
_DOWNLOAD_ARCHIVE_SUBDIR = os.path.join(
    "jkkummerfeld-irc-disentanglement-fd379e9", "data"
)

_IRC_DAY_KEY = "day"
_MESSAGE_ID = "id"
_MESSAGE_TEXT = "text"
_MESSAGE_TIMESTAMP = "timestamp"
_MESSAGE_PARENTS_IDS = "parents"


def _get_day_to_paths(data_dir):
  """Prepares paths to files with raw chat messages and replies annotations.

  Args:
    data_dir: directory containing files with data. directory can be

  Returns:
    day_to_paths: dict formatted date -> dict with paths
      day_to_paths[day_str]["text"] - path to file with raw chat messages
      day_to_paths[day_str]["annot"] - path to file with replies annotations.
  """
  day_to_paths = collections.defaultdict(dict)
  for filename in tf.io.gfile.listdir(data_dir):
    filepath = os.path.join(data_dir, filename)
    day_str = filename[: len("YYYY-MM-DD")]  # e.g. 2004-12-25.train-c.raw.txt

    if "raw" in filename:
      day_to_paths[day_str]["text"] = filepath
    if "annotation" in filename:
      day_to_paths[day_str]["annot"] = filepath

  return day_to_paths


def _read_texts_file(path):
  with tf.io.gfile.GFile(path, "r") as f:
    return [line.strip() for line in f]


def _read_annot_file(path):
  """Reads file with replies annotation."""
  with tf.io.gfile.GFile(path, "r") as f:
    return [(int(first), int(second)) for first, second, _ in map(str.split, f)]


def _parse_out_timestamps(raw_texts, day_str):
  """Parsing timestamps from IRC chat messages.

  Similar logic is implemented here.
  https://github.com/jkkummerfeld/irc-disentanglement/blob/master/src/disentangle.py#L174

  Args:
    raw_texts: list of raw chat messages.
    day_str: formatted date string.

  Returns:
    texts: list of texts without timestamps.
    timestamps: list of formatted timestamps
  """
  prev_hours = 0
  timestamps, texts = [], []
  for raw_text in raw_texts:
    if raw_text.startswith("["):  # Regular messsages e.g. "[04:13]<xxx>: Hi!"
      hours = int(raw_text[1:3])
      mins = int(raw_text[4:6])

      # 12h format -> 24h format
      if hours < prev_hours:  # All messages belong to the same day and are
        hours += 12  # chronologically ordered, but AM/PM info is absent
      prev_hours = hours

      timestamps.append("{}_{:02}_{:02}".format(day_str, hours, mins))
      raw_text = raw_text[7:]
    else:  # System messages e.g. "=== xxx has joned #ubuntu"
      timestamps.append("")

    texts.append(raw_text)

  return texts, timestamps


def _get_msg_id(day, line_num):
  return "{}_{:05}".format(day, line_num)


def _prepare_examples(texts_file_path, annot_file_path, day_str):
  """Prepares examples for 1 day."""
  # Read raw data
  raw_texts = _read_texts_file(texts_file_path)
  annotations = _read_annot_file(annot_file_path)

  # Construct replies graph
  idx_to_parents = {idx: [] for idx in range(len(raw_texts))}
  for parent_msg_idx, msg_idx in annotations:
    idx_to_parents[msg_idx].append(parent_msg_idx)

  texts, timestamps = _parse_out_timestamps(raw_texts, day_str)

  for line_idx, parents in idx_to_parents.items():
    parents_ids = [_get_msg_id(day_str, parent) for parent in parents]
    yield {
        _MESSAGE_ID: _get_msg_id(day_str, line_idx),
        _MESSAGE_TEXT: texts[line_idx],
        _MESSAGE_TIMESTAMP: timestamps[line_idx],
        _MESSAGE_PARENTS_IDS: parents_ids,
    }


class Builder(tfds.core.GeneratorBasedBuilder):
  """IRC Disentanglement dataset."""

  VERSION = tfds.core.Version("2.0.0")

  def _info(self) -> tfds.core.DatasetInfo:
    return self.dataset_info_from_configs(
        features=tfds.features.FeaturesDict(
            {
                _IRC_DAY_KEY: tfds.features.Sequence(
                    tfds.features.FeaturesDict({
                        _MESSAGE_ID: tfds.features.Text(),
                        _MESSAGE_TEXT: tfds.features.Text(),
                        _MESSAGE_TIMESTAMP: tfds.features.Text(),
                        _MESSAGE_PARENTS_IDS: tfds.features.Sequence(
                            tfds.features.Text()
                        ),
                    })
                )
            }
        ),
        homepage="https://jkk.name/irc-disentanglement",
    )

  def _split_generators(
      self, dl_manager: tfds.download.DownloadManager
  ) -> List[tfds.core.SplitGenerator]:
    """Returns SplitGenerators."""
    base_dir = dl_manager.download_and_extract(_DOWNLOAD_URL)
    data_dir = os.path.join(base_dir, _DOWNLOAD_ARCHIVE_SUBDIR)

    return [
        tfds.core.SplitGenerator(
            name=tfds.Split.TRAIN,
            gen_kwargs={
                "day_to_paths": _get_day_to_paths(
                    os.path.join(data_dir, "train")
                )
            },
        ),
        tfds.core.SplitGenerator(
            name=tfds.Split.VALIDATION,
            gen_kwargs={
                "day_to_paths": _get_day_to_paths(os.path.join(data_dir, "dev"))
            },
        ),
        tfds.core.SplitGenerator(
            name=tfds.Split.TEST,
            gen_kwargs={
                "day_to_paths": _get_day_to_paths(
                    os.path.join(data_dir, "test")
                )
            },
        ),
    ]

  def _generate_examples(self, day_to_paths):
    """Yields examples."""
    for day, paths in day_to_paths.items():
      yield day, {
          _IRC_DAY_KEY: list(
              _prepare_examples(paths["text"], paths["annot"], day)
          )
      }
