# Copyright 2016 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.
# ==============================================================================
"""A Context that captures profile and performs profiling/dumping.
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import contextlib
import os

from tensorflow.core.protobuf import config_pb2
from tensorflow.python import pywrap_tensorflow as print_mdl
from tensorflow.python.client import session
from tensorflow.python.framework import errors
from tensorflow.python.framework import ops
from tensorflow.python.platform import gfile
from tensorflow.python.profiler import model_analyzer
from tensorflow.python.util import compat

MAX_TRACED_STEPS = 100


def _profiled_init(self, target='', graph=None, config=None):
  """Overwrites the session.__init__."""
  self._profiler_init_internal(target, graph, config)  # pylint: disable=protected-access


def _profiled_run(self,
                  fetches,
                  feed_dict=None,
                  options=None,
                  run_metadata=None):
  """Overwrites the session.run()."""
  # pylint: disable=protected-access
  # Count the session steps.
  with self.profile_context._new_step():
    # Fast path if no need for profiling.
    if self.profile_context._is_fast_path():
      return self._profiler_run_internal(
          fetches, feed_dict, options, run_metadata)

    step = self.profile_context._step

    # Maybe trace this step.
    if self.profile_context._should_trace():
      # Enable tracing, perform auto profiling or auto dump.
      if not run_metadata:
        run_metadata = config_pb2.RunMetadata()

      if not options:
        options = config_pb2.RunOptions(
            trace_level=config_pb2.RunOptions.FULL_TRACE)
        old_trace_level = options.trace_level
      else:
        old_trace_level = options.trace_level
        options.trace_level = config_pb2.RunOptions.FULL_TRACE

      ret = self._profiler_run_internal(
          fetches, feed_dict, options, run_metadata)

      self.profile_context.profiler._graph = self.graph
      self.profile_context.profiler.add_step(step, run_metadata)
      options.trace_level = old_trace_level
    else:
      ret = self._profiler_run_internal(fetches, feed_dict, options)

    # Maybe dump profile.
    self.profile_context._maybe_dump()

    # Maybe profile:
    to_profiles = self.profile_context._profile_candidates()
    for to_prof in to_profiles:
      cmd, opts, _ = to_prof
      if cmd == 'graph':
        self.profile_context.profiler.profile_graph(opts)
      elif cmd == 'scope':
        self.profile_context.profiler.profile_name_scope(opts)
      elif cmd == 'op':
        self.profile_context.profiler.profile_operations(opts)
      elif cmd == 'code':
        self.profile_context.profiler.profile_python(opts)
      else:
        raise ValueError('Unknown cmd: %s\n' % cmd)

    return ret
  # pylint: enable=protected-access


class ProfileContext(object):
  """A Context that captures RunMetadata and performs profiling.

  ```python
    # Trace steps 10~20, profile at [15, 18, 20] and dump profile at 20.
    with tf.contrib.tfprof.ProfileContext('/tmp/train_dir',
                                          trace_steps=range(10, 20),
                                          dump_steps=[20]) as pctx:
      opts = tf.profiler.ProfileOptionBuilder.time_and_memory()
      pctx.add_auto_profiling('op', opts, [15, 18, 20])
      train_loop().

    # Tracing only.
    with tf.contrib.tfprof.ProfileContext('/tmp/train_dir') as pctx:
      # Run train/eval loop for at least few hundred steps. Profiles will be
      # dumped to train_dir. Use web UI or command line to do profiling.
      train_loop().

    # When session object is available, do explicit trace, profile and dump.
    with tf.contrib.tfprof.ProfileContext('/tmp/train_dir',
                                          trace_steps=[],
                                          dump_steps=[]) as pctx:
      opts = tf.profiler.ProfileOptionBuilder.time_and_memory()
      pctx.trace_next_step()
      _ = session.run(train_op)
      pctx.profiler.profile_operations(options=opts)
  ```

  Args:
    profile_dir: Directory to store profiles.
    trace_steps: A list of session run steps to trace. If None, use
        pre-defined steps.
    dump_steps: A list of steps to dump the profile to `profile_dir`. If None,
        use pre-defined steps.
  """

  def __init__(self,
               profile_dir,
               trace_steps=None,
               dump_steps=None):
    if not profile_dir:
      raise ValueError('Must have a directory for profile.\n')
    self._profiler_dir = profile_dir

    if trace_steps is None:
      self._trace_steps = set(list(range(10, 50, 3)) +
                              list(range(100, 10000, 1000)))
    else:
      if len(trace_steps) > MAX_TRACED_STEPS:
        raise ValueError('Only support tracing up to 100 steps.\n')
      self._trace_steps = set(trace_steps[:])

    if dump_steps is None:
      self._dump_steps = set([50] + list(range(100, 10000, 2000)))
    else:
      self._dump_steps = set(dump_steps[:])

    self._slow_path_steps = self._dump_steps | self._trace_steps
    self._trace_next_step = False
    self._dump_next_step = False
    self._step = 0
    self._traced_steps = 0
    self._auto_profiles = []
    self._profiler = None

  def add_auto_profiling(self, cmd, options, profile_steps):
    """Traces and profiles at some session run steps.

    Args:
      cmd: The profiling commands. (i.e. scope, op, python, graph)
      options: The profiling options.
      profile_steps: A list/set of integers. The profiling command and options
          will be run automatically at these integer steps. Each step is
          a session.run.
    """
    self._auto_profiles.append((cmd, options, profile_steps[:]))
    self._slow_path_steps |= set(profile_steps)
    self._trace_steps |= set(profile_steps)

  @property
  def profiler(self):
    """Returns the current profiler object."""
    if not self._profiler:
      self._profiler = model_analyzer.Profiler(ops.get_default_graph())
    return self._profiler

  def trace_next_step(self):
    """Enables tracing and add traces to profiler at next step."""
    self._trace_next_step = True

  def dump_next_step(self):
    """Enable tracing and dump profiles at next step."""
    self._dump_next_step = True

  def _is_fast_path(self):
    if (self._step in self._slow_path_steps or
        self._trace_next_step or
        self._dump_next_step):
      return False
    return True

  def _should_trace(self):
    if self._traced_steps > MAX_TRACED_STEPS:
      return False
    trace = self._step in self._trace_steps or self._trace_next_step
    if trace:
      self._traced_steps += 1
    return trace

  def _maybe_dump(self):
    if not (self._step in self._dump_steps or self._dump_next_step):
      return
    if not gfile.Exists(self._profiler_dir):
      gfile.MakeDirs(self._profiler_dir)
    print_mdl.WriteProfile(
        os.path.join(compat.as_bytes(self._profiler_dir),
                     compat.as_bytes('profile_%d' % self._step)))

  @contextlib.contextmanager
  def _new_step(self):
    yield
    self._step += 1
    self._trace_next_step = False
    self._dump_next_step = False

  def _profile_candidates(self):
    to_profile = []
    for auto_prof in self._auto_profiles:
      _, _, prof_steps = auto_prof
      if self._step in prof_steps:
        to_profile.append(auto_prof)
    return to_profile

  def __enter__(self):
    self.old_run = getattr(session.BaseSession, 'run', None)
    self.old_init = getattr(session.BaseSession, '__init__', None)
    if not self.old_run:
      raise errors.InternalError(None, None, 'BaseSession misses run method.')
    elif not self.old_init:
      raise errors.InternalError(None, None,
                                 'BaseSession misses __init__ method.')
    elif getattr(session.BaseSession, '_profiler_run_internal', None):
      raise errors.InternalError(None, None,
                                 'Already in context or context not cleaned.')
    elif getattr(session.BaseSession, '_profiler_init_internal', None):
      raise errors.InternalError(None, None,
                                 'Already in context or context not cleaned.')
    else:
      setattr(session.BaseSession, 'run', _profiled_run)
      setattr(session.BaseSession, '__init__', _profiled_init)
      setattr(session.BaseSession, '_profiler_run_internal', self.old_run)
      setattr(session.BaseSession, '_profiler_init_internal', self.old_init)
      setattr(session.BaseSession, 'profile_context', self)
      return self

  def __exit__(self, exec_type, exec_value, exec_tb):
    print_mdl.DeleteProfiler()
    setattr(session.BaseSession, 'run', self.old_run)
    setattr(session.BaseSession, '__init__', self.old_init)
    setattr(session.BaseSession, '_profiler_run_internal', None)
    setattr(session.BaseSession, '_profiler_init_internal', None)
    setattr(session.BaseSession, 'profile_context', None)
