"""Integration with Google Cloud Storage.

"""
import os
import requests
import urllib3

# Root URL to use for our queries.
DEFAULT_GCS = "https://www.googleapis.com/storage/v1/"

# Specify a different root URL if compilers are hosted elsewhere.
GCS = os.getenv("GCS_SERVER", DEFAULT_GCS)

DEFAULT_BUCKET = "llvm-build-artifacts"

BUCKET = os.getenv("BUCKET", DEFAULT_BUCKET)

class HttpClient(object):
    def __init__(self):
        self.session = requests.Session()
        # Retry after 0s, 0.2s, 0.4s.
        retry = urllib3.util.retry.Retry(total=3, backoff_factor=0.1)
        adapter = requests.adapters.HTTPAdapter(max_retries=retry)
        self.session.mount('https://', adapter)

    def get(self, url, **kwargs):
        if "timeout" not in kwargs:
            kwargs["timeout"] = 5  # seconds
        return self.session.get(url, **kwargs)

HTTP_CLIENT = HttpClient()


def fetch_builders():
    """Each build kind is stored as a folder in the GCS bucket.
    List all the folders in the bucket, which is our list of possible
    compilers.
    """
    params = {'delimiter': "/", 'fields': "prefixes,nextPageToken"}
    r = HTTP_CLIENT.get(GCS + "b/" + BUCKET + "/o", params=params)
    r.raise_for_status()
    reply_data = r.json()
    assert "nextPageToken" not in reply_data.keys(), "Too many builders!"
    folders = reply_data['prefixes']
    no_slashes = [x.replace("/", "") for x in folders]
    return no_slashes


def fetch_builds(project):
    """Given a builder name, get the list of all the files stored for that
    builder.
    """
    assert project is not None
    all_data = {'items':[]}
    params = {'delimiter': "/",
             "fields": "nextPageToken,kind,items(name, mediaLink)",
             'prefix': project + "/"}
    r = HTTP_CLIENT.get(GCS + "b/" + BUCKET + "/o", params=params)
    r.raise_for_status()
    reply_data = r.json()
    all_data['items'].extend(reply_data['items'])
    while reply_data.get('nextPageToken'):
        params['pageToken'] = reply_data['nextPageToken']
        r = HTTP_CLIENT.get(GCS + "b/" + BUCKET + "/o", params=params)
        r.raise_for_status()
        reply_data = r.json()
        all_data['items'].extend(reply_data['items'])
    return all_data

#  Dunno what this could be moved up to?
CHUNK_SIZE = 5124288


def get_compiler(url, filename):
    """Get the compiler at the url, and save to filename."""
    r = HTTP_CLIENT.get(url)
    r.raise_for_status()
    with open(filename, 'wb') as fd:
        for chunk in r.iter_content(CHUNK_SIZE):
            fd.write(chunk)
    return filename