from __future__ import absolute_import
from functools import partial
from zerver.lib.actions import check_send_message
from zerver.lib.response import json_success
from zerver.decorator import api_key_only_webhook_view, REQ, has_request_variables
from zerver.models import Client, UserProfile

from django.http import HttpRequest, HttpResponse
from six import text_type
from typing import Dict, Any, Iterable, Optional


class UnknownEventType(Exception):
    pass

def get_push_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    total_commits_count = payload['total_commits_count']
    compare_url = u'{}/compare/{}...{}'.format(
        get_repository_homepage(payload),
        payload['before'],
        payload['after']
    )
    body = u"{} pushed [{} commit{}]({}) to {} branch.".format(
        get_user_name(payload),
        total_commits_count,
        u's' if total_commits_count > 1 else u'',
        compare_url,
        get_branch_name(payload)
    )
    return body

def get_tag_push_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    return u"{} {} {} tag.".format(
        get_user_name(payload),
        "pushed" if payload.get('checkout_sha') else "removed",
        get_tag_name(payload)
    )

def get_issue_created_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    body = get_issue_event_body(payload, "created")
    assignee_name = payload.get('assignee', {}).get('name')
    if assignee_name:
        body = u"{} (assigned to {}).".format(body[:-1], assignee_name)
    return body

def get_issue_event_body(payload, action):
    # type: (Dict[str, Any], text_type) -> text_type
    return "{} {} [Issue #{}]({}).".format(
        get_issue_user_name(payload),
        action,
        get_object_iid(payload),
        get_object_url(payload)
    )

def get_merge_request_created_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    body = get_merge_request_event_body(payload, "created")
    assignee_name = payload.get('assignee', {}).get('name')
    if assignee_name:
        body = u"{} (assigned to {}).".format(body[:-1], assignee_name)
    return body

def get_merge_request_updated_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    if payload.get('object_attributes').get('oldrev'):
        return get_merge_request_event_body(payload, "added commit to")
    return get_merge_request_event_body(payload, "updated")

def get_merge_request_event_body(payload, action):
    # type: (Dict[str, Any], text_type) -> text_type
    return u"{} {} [Merge Request #{}]({}).".format(
        get_issue_user_name(payload),
        action,
        get_object_iid(payload),
        get_object_url(payload)
    )

def get_commented_commit_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    return u"{} added [comment]({}) to [Commit]({}).".format(
        get_issue_user_name(payload),
        payload.get('object_attributes').get('url'),
        payload.get('commit').get('url')
    )

def get_commented_merge_request_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    return u"{} added [comment]({}) to [Merge Request #{}]({}/merge_requests/{}).".format(
        get_issue_user_name(payload),
        payload.get('object_attributes').get('url'),
        payload.get('merge_request').get('iid'),
        payload.get('project').get('web_url'),
        payload.get('merge_request').get('iid'),
    )

def get_commented_issue_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    return u"{} added [comment]({}) to [Issue #{}]({}/issues/{}).".format(
        get_issue_user_name(payload),
        payload.get('object_attributes').get('url'),
        payload.get('issue').get('iid'),
        payload.get('project').get('web_url'),
        payload.get('issue').get('iid'),
    )

def get_commented_snippet_event_body(payload):
    # type: (Dict[str, Any]) -> text_type
    return u"{} added [comment]({}) to [Snippet #{}]({}/snippets/{}).".format(
        get_issue_user_name(payload),
        payload.get('object_attributes').get('url'),
        payload.get('snippet').get('id'),
        payload.get('project').get('web_url'),
        payload.get('snippet').get('id'),
    )

def get_wiki_page_event_body(payload, action):
    # type: (Dict[str, Any], text_type) -> text_type
    return u"{} {} [Wiki Page \"{}\"]({}).".format(
        get_issue_user_name(payload),
        action,
        payload.get('object_attributes').get('title'),
        payload.get('object_attributes').get('url'),
    )

def get_repo_name(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['project']['name']

def get_user_name(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['user_name']

def get_issue_user_name(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['user']['name']

def get_repository_homepage(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['repository']['homepage']

def get_branch_name(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['ref'].lstrip('refs/heads/')

def get_tag_name(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['ref'].lstrip('refs/tags/')

def get_object_iid(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['object_attributes']['iid']

def get_object_url(payload):
    # type: (Dict[str, Any]) -> text_type
    return payload['object_attributes']['url']

EVENT_FUNCTION_MAPPER = {
    'Push Hook': get_push_event_body,
    'Tag Push Hook': get_tag_push_event_body,
    'Issue Hook open': get_issue_created_event_body,
    'Issue Hook close': partial(get_issue_event_body, action='closed'),
    'Issue Hook reopen': partial(get_issue_event_body, action='reopened'),
    'Issue Hook update': partial(get_issue_event_body, action='updated'),
    'Note Hook Commit': get_commented_commit_event_body,
    'Note Hook MergeRequest': get_commented_merge_request_event_body,
    'Note Hook Issue': get_commented_issue_event_body,
    'Note Hook Snippet': get_commented_snippet_event_body,
    'Merge Request Hook open': get_merge_request_created_event_body,
    'Merge Request Hook update': get_merge_request_updated_event_body,
    'Merge Request Hook merge': partial(get_merge_request_event_body, action='merged'),
    'Merge Request Hook close': partial(get_merge_request_event_body, action='closed'),
    'Wiki Page Hook create': partial(get_wiki_page_event_body, action='created'),
    'Wiki Page Hook update': partial(get_wiki_page_event_body, action='updated'),
}

@api_key_only_webhook_view("Gitlab")
@has_request_variables
def api_gitlab_webhook(request, user_profile, client,
                       stream=REQ(default='gitlab'),
                       payload=REQ(argument_type='body')):
    # type: (HttpRequest, UserProfile, Client, text_type, Dict[str, Any]) -> HttpResponse
    event = get_event(request, payload)
    body = get_body_based_on_event(event)(payload)
    subject = "Repository: {}".format(get_repo_name(payload))
    check_send_message(user_profile, client, 'stream', [stream], subject, body)
    return json_success()

def get_body_based_on_event(event):
    # type: (str) -> Any
    return EVENT_FUNCTION_MAPPER[event]

def get_event(request, payload):
    # type: (HttpRequest,  Dict[str, Any]) -> str
    event = request.META['HTTP_X_GITLAB_EVENT']
    if event == 'Issue Hook':
        action = payload.get('object_attributes').get('action')
        event = "{} {}".format(event, action)
    elif event == 'Note Hook':
        action = payload.get('object_attributes').get('noteable_type')
        event = "{} {}".format(event, action)
    elif event == 'Merge Request Hook':
        action = payload.get('object_attributes').get('action')
        event = "{} {}".format(event, action)
    elif event == 'Wiki Page Hook':
        action = payload.get('object_attributes').get('action')
        event = "{} {}".format(event, action)

    if event in list(EVENT_FUNCTION_MAPPER.keys()):
        return event
    raise UnknownEventType(u'Event {} is unknown and cannot be handled'.format(event))