import cStringIO as StringIO
import os
import logging

import boto.s3.connection
import boto.s3.key

from . import Storage


logger = logging.getLogger(__name__)


class StreamReadKeyAsFile(object):
  def __init__(self, key):
    self._key = key
    self._finished = False

  def __enter__(self):
    return self

  def __exit__(self, type, value, tb):
    self._key.close(fast=True)

  def read(self, amt=None):
    if self._finished:
      return None

    resp = self._key.read(amt)
    if not resp:
      self._finished = True
    return resp


class S3Storage(Storage):

  def __init__(self, storage_path, s3_access_key, s3_secret_key, s3_bucket):
    self._s3_conn = \
      boto.s3.connection.S3Connection(s3_access_key, s3_secret_key)
    self._s3_bucket = self._s3_conn.get_bucket(s3_bucket)
    self._root_path = storage_path

  def _debug_key(self, key):
    """Used for debugging only."""
    orig_meth = key.bucket.connection.make_request

    def new_meth(*args, **kwargs):
      print '#' * 16
      print args
      print kwargs
      print '#' * 16
      return orig_meth(*args, **kwargs)
    key.bucket.connection.make_request = new_meth

  def _init_path(self, path=None):
    path = os.path.join(self._root_path, path) if path else self._root_path
    if path and path[0] == '/':
      return path[1:]
    return path

  def get_content(self, path):
    path = self._init_path(path)
    key = boto.s3.key.Key(self._s3_bucket, path)
    if not key.exists():
      raise IOError('No such key: \'{0}\''.format(path))
    return key.get_contents_as_string()

  def put_content(self, path, content):
    path = self._init_path(path)
    key = boto.s3.key.Key(self._s3_bucket, path)
    key.set_contents_from_string(content, encrypt_key=True)
    return path

  def stream_read(self, path):
    path = self._init_path(path)
    key = boto.s3.key.Key(self._s3_bucket, path)
    if not key.exists():
      raise IOError('No such key: \'{0}\''.format(path))
    while True:
      buf = key.read(self.buffer_size)
      if not buf:
        break
      yield buf

  def stream_read_file(self, path):
    path = self._init_path(path)
    key = boto.s3.key.Key(self._s3_bucket, path)
    if not key.exists():
      raise IOError('No such key: \'{0}\''.format(path))
    return StreamReadKeyAsFile(key)

  def stream_write(self, path, fp):
    # Minimum size of upload part size on S3 is 5MB
    buffer_size = 5 * 1024 * 1024
    if self.buffer_size > buffer_size:
      buffer_size = self.buffer_size
    path = self._init_path(path)
    mp = self._s3_bucket.initiate_multipart_upload(path, encrypt_key=True)
    num_part = 1
    while True:
      try:
        buf = fp.read(buffer_size)
        if not buf:
          break
        io = StringIO.StringIO(buf)
        mp.upload_part_from_file(io, num_part)
        num_part += 1
        io.close()
      except IOError:
        break
    mp.complete_upload()

  def list_directory(self, path=None):
    path = self._init_path(path)
    if not path.endswith('/'):
      path += '/'
    ln = 0
    if self._root_path != '/':
      ln = len(self._root_path)
    exists = False
    for key in self._s3_bucket.list(prefix=path, delimiter='/'):
      exists = True
      name = key.name
      if name.endswith('/'):
        yield name[ln:-1]
      else:
        yield name[ln:]
    if exists is False:
      # In order to be compliant with the LocalStorage API. Even though
      # S3 does not have a concept of folders.
      raise OSError('No such directory: \'{0}\''.format(path))

  def exists(self, path):
    path = self._init_path(path)
    key = boto.s3.key.Key(self._s3_bucket, path)
    return key.exists()

  def remove(self, path):
    path = self._init_path(path)
    key = boto.s3.key.Key(self._s3_bucket, path)
    if key.exists():
      # It's a file
      key.delete()
      return
    # We assume it's a directory
    if not path.endswith('/'):
      path += '/'
    for key in self._s3_bucket.list(prefix=path):
      key.delete()

  def get_size(self, path):
    path = self._init_path(path)
    # Lookup does a HEAD HTTP Request on the object
    key = self._s3_bucket.lookup(path)
    if not key:
      raise OSError('No such key: \'{0}\''.format(path))
    return key.size