# Copyright 2020 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import logging

from gold_inexact_matching import (
  iterative_parameter_optimizer as iterative_optimizer,
  parameter_set,
)


class BruteForceParameterOptimizer(
  iterative_optimizer.IterativeParameterOptimizer
):
  """A ParameterOptimizer for use with any number of changing parameters.

  VERY slow, but provides the most complete information when trying to
  optimize multiple parameters.
  """

  def _RunOptimizationImpl(self) -> None:
    # Look for the minimum max_delta that results in a successful comparison
    # for each possible edge_threshold/max_diff combination.
    #
    # range/xrange(x, y) returns the range in [x, y), so adjust by 1 to make the
    # range inclusive.
    # We go from max to min instead of min to max for edge_threshold, so
    # decrease the min by 1 instead of increasing the max by 1.
    for edge_threshold in range(
      self._args.max_edge_threshold,
      self._args.min_edge_threshold - 1,
      -1 * self._args.edge_threshold_step,
    ):
      should_continue = True
      for max_diff in range(
        self._args.min_max_diff,
        self._args.max_max_diff + 1,
        self._args.max_diff_step,
      ):
        for max_delta in range(
          self._args.min_delta_threshold,
          self._args.max_delta_threshold + 1,
          self._args.delta_threshold_step,
        ):
          parameters = parameter_set.ParameterSet(
            max_diff, max_delta, edge_threshold
          )
          success, _, _ = self._RunComparisonForParameters(parameters)
          if success:
            print(f'Found good parameters {parameters}')
            should_continue = False
            break
          logging.info('Found bad parameters %s', parameters)
        # Increasing the max_diff for a given edge_threshold once we've found
        # a good max_delta won't give us any new information, so go on to the
        # next edge_threshold.
        if not should_continue:
          break