# Copyright 2020 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.
# ==============================================================================
"""Benchmark for Keras text vectorization preprocessing layer's adapt method."""

import tensorflow as tf

import os
import random
import string
import time

import numpy as np

import keras
from keras.layers.preprocessing import index_lookup

tf.compat.v1.enable_v2_behavior()


# word_gen creates random sequences of ASCII letters (both lowercase and upper).
# The number of unique strings is ~2,700.
def tensor_gen(batch, num_elements):
  data = []
  for _ in range(batch):
    batch_element = []
    for _ in range(num_elements - 1):
      tok = "".join(random.choice(string.ascii_letters) for i in range(2))
      batch_element.append(tok)
    batch_element.append("")  # Explicitly test the empty string.
    data.append(batch_element)
  return tf.constant(data)


def get_vocab():
  vocab = list(
      set([a + b for a in string.ascii_letters for b in string.ascii_letters]))  # pylint:disable=g-complex-comprehension
  vocab.sort()
  return vocab


# This class uses TestCase for get_temp_dir().
class BenchmarkLookup(tf.test.Benchmark):
  """Benchmark the index lookup layer's forward pass."""

  def _write_to_temp_file(self, file_name, vocab_list):
    vocab_path = os.path.join(self.get_temp_dir(), file_name + ".txt")
    with tf.io.gfile.GFile(vocab_path, "w") as writer:
      for vocab in vocab_list:
        writer.write(vocab + "\n")
      writer.flush()
      writer.close()
    return vocab_path

  def run_numpy_implementation(self, data, vocab):
    """Test the python implementation."""
    input_t = keras.Input(shape=(), dtype=tf.string)
    layer = index_lookup.IndexLookup(
        vocabulary=vocab,
        max_tokens=None,
        num_oov_indices=1,
        mask_token="",
        oov_token="OOV",
        dtype=tf.string)
    out_t = layer(input_t)
    model = keras.Model(input_t, out_t)
    num_repeats = 5
    starts = []
    ends = []
    _ = model(data)
    for _ in range(num_repeats):
      starts.append(time.time())
      out = model(data)
      ends.append(time.time())
    avg_time = np.mean(np.array(ends) - np.array(starts))
    return avg_time, out

  def bm_adapt_implementation(self, num_elements, batch_size):
    """Test the KPL adapt implementation."""
    vocab = get_vocab()
    vocab_file = self._write_to_temp_file("vocab", vocab)
    vocabulary_initializer = tf.lookup.TextFileInitializer(
        filename=vocab_file,
        key_dtype=tf.string,
        key_index=tf.lookup.TextFileIndex.WHOLE_LINE,
        value_dtype=tf.int64,
        value_index=tf.lookup.TextFileIndex.LINE_NUMBER,
        value_index_offset=2)
    input_t = keras.Input(shape=(), dtype=tf.string)
    layer = index_lookup.IndexLookup(
        vocabulary=vocabulary_initializer,
        max_tokens=None,
        num_oov_indices=1,
        mask_token="",
        oov_token="OOV",
        dtype=tf.string)
    out_t = layer(input_t)
    model = keras.Model(input_t, out_t)
    num_repeats = 5
    starts = []
    ends = []
    data = tensor_gen(batch_size, num_elements)
    _ = model(data)
    for _ in range(num_repeats):
      starts.append(time.time())
      _ = model(data)
      ends.append(time.time())
    avg_time = np.mean(np.array(ends) - np.array(starts))
    baseline, _ = self.run_numpy_implementation(data, vocab)
    extras = {
        "numpy implementation baseline": baseline,
        "delta seconds": (baseline - avg_time),
        "delta percent": ((baseline - avg_time) / baseline) * 100
    }
    name = "index_lookup_forward|%s_elements|batch_%s" % (num_elements,
                                                          batch_size)
    self.report_benchmark(
        iters=num_repeats, wall_time=avg_time, extras=extras, name=name)

  def benchmark_vocab_size_by_batch(self):
    for tensor_size in [100, 1000, 10000]:
      for batch in [1, 16, 2048]:
        self.bm_adapt_implementation(tensor_size, batch)


if __name__ == "__main__":
  tf.test.main()
