# Copyright 2015 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.
"""The GCI API Client.  A thin wrapper around the GCI API.

Exmple usage:

client = gciclient.GCIAPIClient(
      auth_token='xxxxxxxxxxxxxx',
      url_prefix='https://codein.withgoogle.com',
      debug=False)

client.NewTask(myTaskDict)
"""

import json
import logging
import urlparse

import requests


class GCIAPIClient(object):
  """GCIAPIClient provides a thin wrapper around the GCI Task API.

    A GCIAPIClient simplifies working with tasks by forming the HTTP requests on
    behalf of the caller.

    Attributes:
      url_prefix: A string prefix for the codin URL
      headers: A dictionary of HTTP headers
    """

  def __init__(self,
               auth_token=None,
               url_prefix='https://codein.withgoogle.com/',
               debug=False):
    self.url_prefix = urlparse.urljoin(url_prefix, 'api/program/current/')
    self.headers = {
        'Authorization': 'Bearer %s' % auth_token,
        'Content-Type': 'application/json',
    }

    if debug:
      logging.basicConfig()
      logging.getLogger().setLevel(logging.DEBUG)
      requests_log = logging.getLogger('requests.packages.urllib3')
      requests_log.setLevel(logging.DEBUG)
      requests_log.propagate = True

  def _Url(self, path):
    return urlparse.urljoin(self.url_prefix, path) + '/'

  def ListTasks(self, page_size=25, page=1):
    """Fetches a list of tasks.

        Args:
          page_size: the number of records to fetch
                     per page(Default: 25, Maximum: 100)
          page: Which page of results to return.

        Returns:
          A JSON encoded list of tasks.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
          ValueError: if page_size is less than or equal to 0
                      or greater than 100
        """
    self._CheckPageSize(page_size)
    r = requests.get(
        self._Url('tasks'),
        headers=self.headers,
        params={
            'page_size': page_size,
            'page': page
        })
    r.raise_for_status()
    return r.json()

  def GetTask(self, task_id):
    """Fetches a single task.

        Args:
          task_id: An integer id for the task.

        Returns:
            A JSON encoded task.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
        """
    r = requests.get(self._Url('tasks/%d' % task_id), headers=self.headers)
    r.raise_for_status()
    return r.json()

  def NewTask(self, task):
    """Creates a single new task.

        Args:
          task: A task object.

        Returns:
          A JSON encoded response.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
        """
    r = requests.post(
        self._Url('tasks'), headers=self.headers, data=json.dumps(task))
    r.raise_for_status()
    return r.json()

  def UpdateTask(self, task_id, task):
    """Modifies a single task.

        Args:
          task_id: An integer id for the task.
          task: A task object.

        Returns:
          A JSON encoded response.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
        """
    r = (requests.put(
        self._Url('tasks/%d' % task_id),
        data=json.dumps(task),
        headers=self.headers))
    r.raise_for_status()
    return r.json()

  def DeleteTask(self, task_id):
    """Deletes a single task.

        Args:
          task_id: An integer id for the task.

        Returns:
          A JSON encoded response, if there is content in the response.
          Otherwise None.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
        """
    r = (requests.delete(self._Url('tasks/%d' % task_id), headers=self.headers))
    r.raise_for_status()
    # DELETE returns nothing on success, don't try and parse it.
    if r.content:
      return r.json()
    return

  def ListTaskInstances(self, page_size=25, page=1):
    """Fetches a list of tasks.

        Args:
          page_size: the number of records to fetch
                     per page(Default: 25, Maximum: 100)
          page: Which page of results to return.

        Returns:
          A JSON encoded list of task instances.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
          ValueError: if page_size is less than or equal to 0
                      or greater than 100
        """

    self._CheckPageSize(page_size)
    r = requests.get(
        self._Url('instances'),
        headers=self.headers,
        params={
            'page_size': page_size,
            'page': page
        })
    r.raise_for_status()
    return r.json()

  def GetTaskInstance(self, task_instance_id):
    """Fetches a single task.

        Args:
          task_instance_id: An integer id for the task instance.

        Returns:
            A JSON encoded task instance.

        Raises:
          HTTPError: a 4XX client error or 5XX server error
                     response was returned.
        """
    r = requests.get(
        self._Url('instances/%d' % task_instance_id), headers=self.headers)
    r.raise_for_status()
    return r.json()

  def _CheckPageSize(self, page_size):
    """Helper function to check if page_size is within the range of:
       0 < page_size <= 100.

        Args:
          page_size: An integer representing page size

        Raises:
          ValueError: if page_size is less than or equal to 0
                      or greater than 100
        """
    if page_size <= 0:
      raise ValueError("page_size must be greater than 0.")
    elif page_size > 100:
      raise ValueError("page_size is limited to a maximum of 100 records.")