# Licensed to the Apache Software Foundation (ASF) under one
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# to you 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.
#
# Hdfs access utilities

import getpass
import httplib
import requests
from os import environ
from os.path import join as join_path
from pywebhdfs.webhdfs import PyWebHdfsClient, errors, _raise_pywebhdfs_exception
from xml.etree.ElementTree import parse

from tests.util.filesystem_base import BaseFilesystem
from tests.util.filesystem_utils import FILESYSTEM_PREFIX

class HdfsConfig(object):
  """Reads an XML configuration file (produced by a mini-cluster) into a dictionary
  accessible via get()"""
  def __init__(self, *filename):
    self.conf = {}
    for arg in filename:
      tree = parse(arg)
      for property in tree.getroot().getiterator('property'):
        self.conf[property.find('name').text] = property.find('value').text

  def get(self, key):
    return self.conf.get(key)

# Configuration object for the configuration that the minicluster will use.
CORE_CONF = HdfsConfig(join_path(environ['HADOOP_CONF_DIR'], "core-site.xml"))
# NAMENODE is the path prefix that should be used in results, since paths that come
# out of Impala have been qualified.  When running against the default filesystem,
# this will be the same as fs.defaultFS.  When running against a secondary filesystem,
# this will be the same as FILESYSTEM_PREFIX.
NAMENODE = FILESYSTEM_PREFIX or CORE_CONF.get('fs.defaultFS')

class PyWebHdfsClientWithChmod(PyWebHdfsClient, BaseFilesystem):
  def chmod(self, path, permission):
    """Set the permission of 'path' to 'permission' (specified as an octal string, e.g.
    '775'"""
    uri = self._create_uri(path, "SETPERMISSION", permission=permission)
    response = requests.put(uri, allow_redirects=True)
    if not response.status_code == httplib.OK:
      _raise_pywebhdfs_exception(response.status_code, response.text)
    return True

  def chown(self, path, user, group):
    """Sets the owner and the group of 'path to 'user' / 'group'"""
    uri = self._create_uri(path, "SETOWNER", owner=user, group=group)
    response = requests.put(uri, allow_redirects=True)
    if not response.status_code == httplib.OK:
      _raise_pywebhdfs_exception(response.status_code, response.text)
    return True

  def setacl(self, path, acls):
    uri = self._create_uri(path, "SETACL", aclspec=acls)
    response = requests.put(uri, allow_redirects=True)
    if not response.status_code == httplib.OK:
      _raise_pywebhdfs_exception(response.status_code, response.text)
    return True

  def getacl(self, path):
    uri = self._create_uri(path, "GETACLSTATUS")
    response = requests.get(uri, allow_redirects=True)
    if not response.status_code == httplib.OK:
      _raise_pywebhdfs_exception(response.status_code, response.text)
    return response.json()

  def delete_file_dir(self, path, recursive=False):
    """Deletes a file or a dir if it exists.

    Overrides the superclass's method by providing delete if exists semantics. This takes
    the burden of stat'ing the file away from the caller.
    """
    if not self.exists(path):
      return True
    return super(PyWebHdfsClientWithChmod, self).delete_file_dir(path,
        recursive=recursive)

  def get_file_dir_status(self, path):
    """Stats a file or a directoty in hdfs

    The superclass expects paths without the leading '/'. This method strips it from the
    path to make usage transparent to the caller.
    """
    path = path.lstrip('/')
    return super(PyWebHdfsClientWithChmod, self).get_file_dir_status(path)

  def get_all_file_sizes(self, path):
    """Returns a list of all file sizes in the path"""
    sizes = []
    for status in self.list_dir(path).get('FileStatuses').get('FileStatus'):
      if status['type'] == 'FILE':
        sizes += [status['length']]
    return sizes

  def copy(self, src, dest):
    """Copies a file in hdfs from src to destination

    Simulates hdfs dfs (or hadoop fs) -cp <src> <dst>. Does not resolve all the files if
    the source or destination is a directory. Files need to be explicitly copied.
    TODO: Infer whether the source or destination is a directory and do this implicitly.
    TODO: Take care of larger files by always reading/writing them in small chunks.
    """
    assert self.get_file_dir_status(src)
    # Get the data
    data = self.read_file(src)
    # Copy the data
    self.create_file(dest, data)
    assert self.get_file_dir_status(dest)
    assert self.read_file(dest) == data

  def ls(self, path):
    """Returns a list of all file and directory names in 'path'"""
    # list_dir() returns a dictionary of file statues. This function picks out the
    # file and directory names and just returns a list of the names.
    file_infos = self.list_dir(path).get('FileStatuses').get('FileStatus')
    return [info.get('pathSuffix') for info in file_infos]

  def exists(self, path):
    """Checks if a particular path exists"""
    try:
      self.get_file_dir_status(path)
    except errors.FileNotFound:
      return False
    return True

def get_hdfs_client_from_conf(conf):
  """Returns a new HTTP client for an HDFS cluster using an HdfsConfig object"""
  hostport = conf.get('dfs.namenode.http-address')
  if hostport is None:
    raise Exception("dfs.namenode.http-address not found in config")
  host, port = hostport.split(":")
  return get_hdfs_client(host=host, port=port)

def get_hdfs_client(host, port, user_name=getpass.getuser()):
  """Returns a new HTTP client for an HDFS cluster using an explict host:port pair"""
  return PyWebHdfsClientWithChmod(host=host, port=port, user_name=user_name)

def get_default_hdfs_config():
  core_site_path = join_path(environ.get('HADOOP_CONF_DIR'), 'core-site.xml')
  hdfs_site_path = join_path(environ.get('HADOOP_CONF_DIR'), 'hdfs-site.xml')
  return HdfsConfig(core_site_path, hdfs_site_path)

def create_default_hdfs_client():
  return get_hdfs_client_from_conf(get_default_hdfs_config())