# Copyright 2016 Google Inc. 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.

"""Methods for managing the static completion table."""

import compileall
import os
from pprint import pprint

from googlecloudsdk.calliope import walker
from googlecloudsdk.command_lib.static_completion import lookup
from googlecloudsdk.core import config
from googlecloudsdk.core.util import files


_HYPHEN = '-'
_UNDERSCORE = '_'
_COMPLETER_ATTR = 'completer'
_COMPLETION_RESOURCE_ATTR = 'completion_resource'


def _CompletionValueType(arg):
  if arg.choices:
    return sorted(arg.choices)
  elif (getattr(arg, _COMPLETER_ATTR, None) or
        getattr(arg, _COMPLETION_RESOURCE_ATTR, None)):
    return lookup.DYNAMIC
  elif arg.nargs == 0:
    return None
  else:
    return lookup.CANNOT_BE_COMPLETED


class CompletionTableGenerator(walker.Walker):
  """Generates a static completion table by walking the gcloud CLI tree."""

  def __init__(self, cli):
    """Constructor.

    Args:
      cli: The Cloud SDK CLI object.
    """
    super(CompletionTableGenerator, self).__init__(cli)
    self.global_flags = set()

  def _VisitFlags(self, flags, at_root):
    """Visits all the flags for a node and contructs the required dict.

    Args:
      flags: The flag args of the current command.
      at_root: bool, Whether the current command is the top level.

    Returns:
      The appropriate flags dict with required information.
    """
    flags_dict = {}
    for flag in flags:
      for flag_name in flag.option_strings:
        if not flag_name.startswith(lookup.FLAG_PREFIX):
          continue

        flag_name = flag_name.replace(_UNDERSCORE, _HYPHEN)
        if at_root:
          self.global_flags.add(flag_name)
        elif flag_name in self.global_flags:
          # Global flags are only included in the root node.
          continue

        flags_dict[flag_name] = _CompletionValueType(flag)

    return flags_dict

  def _VisitPositionals(self, positionals, at_root):
    """Visits all the positionals for a node and contructs the required dict.

    Args:
      positionals: The positional args of the current command.
      at_root: bool, Whether the current command is the top level.

    Returns:
      The appropriate positionals dict with required information.
    """
    positionals_dict = {}
    for positional in positionals:
      positional_name = positional.dest.replace(_UNDERSCORE, _HYPHEN)
      positionals_dict[positional_name] = _CompletionValueType(positional)
    return positionals_dict

  def Visit(self, node, parent, is_group):
    """Visits each node in the CLI command tree to construct the external rep.

    Args:
      node: group/command CommandCommon info.
      parent: The parent Visit() return value, None at the top level.
      is_group: True if node is a group, otherwise its is a command.

    Returns:
      The subtree parent value, used here to construct an external rep node.
    """
    command = {}

    name = node.name.replace(_UNDERSCORE, _HYPHEN)
    # Add to parent's children
    if parent:
      siblings = parent.get(lookup.COMMANDS_KEY, {})
      siblings[name] = command
      parent[lookup.COMMANDS_KEY] = siblings

    # Populate flags
    command[lookup.FLAGS_KEY] = self._VisitFlags(
        node.ai.flag_args, parent is None)

    # Populate positionals
    command[lookup.POSITIONALS_KEY] = self._VisitPositionals(
        node.ai.positional_args, parent is None)

    return command


def _TableDirPath():
  paths = config.Paths()
  # Completion table will be stored at root/.install/static_completion.
  table_dir_path = os.path.join(paths.sdk_root, paths.CLOUDSDK_STATE_DIR,
                                'static_completion')
  # Ensure directory exists.
  files.MakeDir(table_dir_path)

  return table_dir_path


def _TablePath():
  return os.path.join(_TableDirPath(), 'table.py')


def Update(cli):
  """Create or overwrite static completion table.

  Args:
    cli: Calliope CLI object for generating the completion table.
  """
  # Overwrite the completion table file with updated content
  with files.Context(open(_TablePath(), 'w')) as table_file:
    table = CompletionTableGenerator(cli).Walk(hidden=True)
    table_file.write('table=')
    pprint(table, table_file)
  # Pre-compile table source to enable fast loading
  compileall.compile_dir(_TableDirPath(), quiet=True)
