# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

from __future__ import absolute_import, print_function, unicode_literals

from requests import HTTPError

from taskgraph.util.taskcluster import (
    find_task_id,
    get_artifact,
    status_task,
)


BACKSTOP_PUSH_INTERVAL = 20
BACKSTOP_TIME_INTERVAL = 60 * 4  # minutes
BACKSTOP_INDEX = "gecko.v2.{project}.latest.taskgraph.backstop"


def is_backstop(
    params, push_interval=BACKSTOP_PUSH_INTERVAL, time_interval=BACKSTOP_TIME_INTERVAL
):
    """Determines whether the given parameters represent a backstop push.

    Args:
        push_interval (int): Number of pushes
        time_interval (int): Minutes between forced schedules.
                             Use 0 to disable.
    Returns:
        bool: True if this is a backtop, otherwise False.
    """
    # In case this is being faked on try.
    if params.get("backstop", False):
        return True

    project = params["project"]
    pushid = int(params["pushlog_id"])
    pushdate = int(params["pushdate"])

    if project == "try":
        return False
    elif project != "autoland":
        return True

    # On every Nth push, want to run all tasks.
    if pushid % push_interval == 0:
        return True

    if time_interval <= 0:
        return False

    # We also want to ensure we run all tasks at least once per N minutes.
    index = BACKSTOP_INDEX.format(project=project)

    try:
        last_backstop_id = find_task_id(index)
    except KeyError:
        # Index wasn't found, implying there hasn't been a backstop push yet.
        return True

    if status_task(last_backstop_id) in ("failed", "exception"):
        # If the last backstop failed its decision task, make this a backstop.
        return True

    try:
        last_pushdate = get_artifact(last_backstop_id, "public/parameters.yml")[
            "pushdate"
        ]
    except HTTPError as e:
        # If the last backstop decision task exists in the index, but
        # parameters.yml isn't available yet, it means the decision task is
        # still running. If that's the case, we can be pretty sure the time
        # component will not cause a backstop, so just return False.
        if e.response.status_code == 404:
            return False
        raise

    if (pushdate - last_pushdate) / 60 >= time_interval:
        return True
    return False