import re
from functools import partial
from typing import Dict, List, Optional, Protocol, Union

from django.http import HttpRequest, HttpResponse

from zerver.decorator import webhook_view
from zerver.lib.exceptions import UnsupportedWebhookEventTypeError
from zerver.lib.request import REQ, has_request_variables
from zerver.lib.response import json_success
from zerver.lib.validator import WildValue, check_bool, check_int, check_string, to_wild_value
from zerver.lib.webhooks.common import (
    check_send_webhook_message,
    validate_extract_webhook_http_header,
)
from zerver.lib.webhooks.git import (
    EMPTY_SHA,
    TOPIC_WITH_PR_OR_ISSUE_INFO_TEMPLATE,
    get_commits_comment_action_message,
    get_issue_event_message,
    get_pull_request_event_message,
    get_push_commits_event_message,
    get_push_tag_event_message,
    get_remove_branch_event_message,
)
from zerver.models import UserProfile


def fixture_to_headers(fixture_name: str) -> Dict[str, str]:
    if fixture_name.startswith("build"):
        return {}  # Since there are 2 possible event types.

    # Map "push_hook__push_commits_more_than_limit.json" into GitLab's
    # HTTP event title "Push Hook".
    return {"HTTP_X_GITLAB_EVENT": fixture_name.split("__")[0].replace("_", " ").title()}


def get_push_event_body(payload: WildValue, include_title: bool) -> str:
    after = payload.get("after")
    if after:
        stringified_after = after.tame(check_string)
        if stringified_after == EMPTY_SHA:
            return get_remove_branch_event_body(payload)
    return get_normal_push_event_body(payload)


def get_normal_push_event_body(payload: WildValue) -> str:
    compare_url = "{}/compare/{}...{}".format(
        get_project_homepage(payload),
        payload["before"].tame(check_string),
        payload["after"].tame(check_string),
    )

    commits = [
        {
            "name": commit["author"]["name"].tame(check_string),
            "sha": commit["id"].tame(check_string),
            "message": commit["message"].tame(check_string),
            "url": commit["url"].tame(check_string),
        }
        for commit in payload["commits"]
    ]

    return get_push_commits_event_message(
        get_user_name(payload),
        compare_url,
        get_branch_name(payload),
        commits,
    )


def get_remove_branch_event_body(payload: WildValue) -> str:
    return get_remove_branch_event_message(
        get_user_name(payload),
        get_branch_name(payload),
    )


def get_tag_push_event_body(payload: WildValue, include_title: bool) -> str:
    return get_push_tag_event_message(
        get_user_name(payload),
        get_tag_name(payload),
        action="pushed" if payload.get("checkout_sha") else "removed",
    )


def get_issue_created_event_body(payload: WildValue, include_title: bool) -> str:
    description = payload["object_attributes"].get("description")
    # Filter out multiline hidden comments
    if description:
        stringified_description = description.tame(check_string)
        stringified_description = re.sub("<!--.*?-->", "", stringified_description, 0, re.DOTALL)
        stringified_description = stringified_description.rstrip()
    else:
        stringified_description = None

    return get_issue_event_message(
        user_name=get_issue_user_name(payload),
        action="created",
        url=get_object_url(payload),
        number=payload["object_attributes"]["iid"].tame(check_int),
        message=stringified_description,
        assignees=replace_assignees_username_with_name(get_assignees(payload)),
        title=payload["object_attributes"]["title"].tame(check_string) if include_title else None,
    )


def get_issue_event_body(payload: WildValue, action: str, include_title: bool) -> str:
    return get_issue_event_message(
        user_name=get_issue_user_name(payload),
        action=action,
        url=get_object_url(payload),
        number=payload["object_attributes"]["iid"].tame(check_int),
        title=payload["object_attributes"]["title"].tame(check_string) if include_title else None,
    )


def get_merge_request_updated_event_body(payload: WildValue, include_title: bool) -> str:
    if payload["object_attributes"].get("oldrev"):
        return get_merge_request_event_body(
            payload,
            "added commit(s) to",
            include_title=include_title,
        )

    return get_merge_request_open_or_updated_body(
        payload,
        "updated",
        include_title=include_title,
    )


def get_merge_request_event_body(payload: WildValue, action: str, include_title: bool) -> str:
    pull_request = payload["object_attributes"]
    target_branch = None
    base_branch = None
    if action == "merged":
        target_branch = pull_request["source_branch"].tame(check_string)
        base_branch = pull_request["target_branch"].tame(check_string)

    return get_pull_request_event_message(
        user_name=get_issue_user_name(payload),
        action=action,
        url=pull_request["url"].tame(check_string),
        number=pull_request["iid"].tame(check_int),
        target_branch=target_branch,
        base_branch=base_branch,
        type="MR",
        title=payload["object_attributes"]["title"].tame(check_string) if include_title else None,
    )


def get_merge_request_open_or_updated_body(
    payload: WildValue, action: str, include_title: bool
) -> str:
    pull_request = payload["object_attributes"]
    return get_pull_request_event_message(
        user_name=get_issue_user_name(payload),
        action=action,
        url=pull_request["url"].tame(check_string),
        number=pull_request["iid"].tame(check_int),
        target_branch=pull_request["source_branch"].tame(check_string)
        if action == "created"
        else None,
        base_branch=pull_request["target_branch"].tame(check_string)
        if action == "created"
        else None,
        message=pull_request["description"].tame(check_string),
        assignees=replace_assignees_username_with_name(get_assignees(payload)),
        type="MR",
        title=payload["object_attributes"]["title"].tame(check_string) if include_title else None,
    )


def get_assignees(payload: WildValue) -> Union[List[WildValue], WildValue]:
    assignee_details = payload.get("assignees")
    if not assignee_details:
        single_assignee_details = payload.get("assignee")
        if not single_assignee_details:
            transformed_assignee_details = []
        else:
            transformed_assignee_details = [single_assignee_details]
        return transformed_assignee_details
    return assignee_details


def replace_assignees_username_with_name(
    assignees: Union[List[WildValue], WildValue]
) -> List[Dict[str, str]]:
    """Replace the username of each assignee with their (full) name.

    This is a hack-like adaptor so that when assignees are passed to
    `get_pull_request_event_message` we can use the assignee's name
    and not their username (for more consistency).
    """
    formatted_assignees = []
    for assignee in assignees:
        formatted_assignee = {}
        formatted_assignee["username"] = assignee["name"].tame(check_string)
        formatted_assignees.append(formatted_assignee)
    return formatted_assignees


def get_commented_commit_event_body(payload: WildValue, include_title: bool) -> str:
    comment = payload["object_attributes"]
    action = "[commented]({})".format(comment["url"].tame(check_string))
    return get_commits_comment_action_message(
        get_issue_user_name(payload),
        action,
        payload["commit"]["url"].tame(check_string),
        payload["commit"]["id"].tame(check_string),
        comment["note"].tame(check_string),
    )


def get_commented_merge_request_event_body(payload: WildValue, include_title: bool) -> str:
    comment = payload["object_attributes"]
    action = "[commented]({}) on".format(comment["url"].tame(check_string))
    url = "{}/merge_requests/{}".format(
        payload["project"]["web_url"].tame(check_string),
        payload["merge_request"]["iid"].tame(check_int),
    )

    return get_pull_request_event_message(
        user_name=get_issue_user_name(payload),
        action=action,
        url=url,
        number=payload["merge_request"]["iid"].tame(check_int),
        message=comment["note"].tame(check_string),
        type="MR",
        title=payload["merge_request"]["title"].tame(check_string) if include_title else None,
    )


def get_commented_issue_event_body(payload: WildValue, include_title: bool) -> str:
    comment = payload["object_attributes"]
    action = "[commented]({}) on".format(comment["url"].tame(check_string))
    url = "{}/issues/{}".format(
        payload["project"]["web_url"].tame(check_string),
        payload["issue"]["iid"].tame(check_int),
    )

    return get_pull_request_event_message(
        user_name=get_issue_user_name(payload),
        action=action,
        url=url,
        number=payload["issue"]["iid"].tame(check_int),
        message=comment["note"].tame(check_string),
        type="issue",
        title=payload["issue"]["title"].tame(check_string) if include_title else None,
    )


def get_commented_snippet_event_body(payload: WildValue, include_title: bool) -> str:
    comment = payload["object_attributes"]
    action = "[commented]({}) on".format(comment["url"].tame(check_string))
    url = "{}/snippets/{}".format(
        payload["project"]["web_url"].tame(check_string),
        payload["snippet"]["id"].tame(check_int),
    )

    return get_pull_request_event_message(
        user_name=get_issue_user_name(payload),
        action=action,
        url=url,
        number=payload["snippet"]["id"].tame(check_int),
        message=comment["note"].tame(check_string),
        type="snippet",
        title=payload["snippet"]["title"].tame(check_string) if include_title else None,
    )


def get_wiki_page_event_body(payload: WildValue, action: str, include_title: bool) -> str:
    return '{} {} [wiki page "{}"]({}).'.format(
        get_issue_user_name(payload),
        action,
        payload["object_attributes"]["title"].tame(check_string),
        payload["object_attributes"]["url"].tame(check_string),
    )


def get_build_hook_event_body(payload: WildValue, include_title: bool) -> str:
    build_status = payload["build_status"].tame(check_string)
    if build_status == "created":
        action = "was created"
    elif build_status == "running":
        action = "started"
    else:
        action = f"changed status to {build_status}"
    return "Build {} from {} stage {}.".format(
        payload["build_name"].tame(check_string),
        payload["build_stage"].tame(check_string),
        action,
    )


def get_test_event_body(payload: WildValue, include_title: bool) -> str:
    return f"Webhook for **{get_repo_name(payload)}** has been configured successfully! :tada:"


def get_pipeline_event_body(payload: WildValue, include_title: bool) -> str:
    pipeline_status = payload["object_attributes"]["status"].tame(check_string)
    if pipeline_status == "pending":
        action = "was created"
    elif pipeline_status == "running":
        action = "started"
    else:
        action = f"changed status to {pipeline_status}"

    project_homepage = get_project_homepage(payload)
    pipeline_url = "{}/pipelines/{}".format(
        project_homepage,
        payload["object_attributes"]["id"].tame(check_int),
    )

    builds_status = ""
    for build in payload["builds"]:
        build_url = "{}/-/jobs/{}".format(
            project_homepage,
            build["id"].tame(check_int),
        )
        artifact_filename = build.get("artifacts_file", {}).get("filename", None)
        if artifact_filename:
            artifact_download_url = f"{build_url}/artifacts/download"
            artifact_browse_url = f"{build_url}/artifacts/browse"
            artifact_string = f"  * built artifact: *{artifact_filename.tame(check_string)}* [[Browse]({artifact_browse_url})|[Download]({artifact_download_url})]\n"
        else:
            artifact_string = ""
        builds_status += "* [{}]({}) - {}\n{}".format(
            build["name"].tame(check_string),
            build_url,
            build["status"].tame(check_string),
            artifact_string,
        )
    return "[Pipeline ({})]({}) {} with build(s):\n{}.".format(
        payload["object_attributes"]["id"].tame(check_int),
        pipeline_url,
        action,
        builds_status[:-1],
    )


def get_repo_name(payload: WildValue) -> str:
    if "project" in payload:
        return payload["project"]["name"].tame(check_string)

    # Apparently, Job Hook payloads don't have a `project` section,
    # but the repository name is accessible from the `repository`
    # section.
    return payload["repository"]["name"].tame(check_string)


def get_user_name(payload: WildValue) -> str:
    return payload["user_name"].tame(check_string)


def get_issue_user_name(payload: WildValue) -> str:
    return payload["user"]["name"].tame(check_string)


def get_project_homepage(payload: WildValue) -> str:
    if "project" in payload:
        return payload["project"]["web_url"].tame(check_string)
    return payload["repository"]["homepage"].tame(check_string)


def get_branch_name(payload: WildValue) -> str:
    return payload["ref"].tame(check_string).replace("refs/heads/", "")


def get_tag_name(payload: WildValue) -> str:
    return payload["ref"].tame(check_string).replace("refs/tags/", "")


def get_object_url(payload: WildValue) -> str:
    return payload["object_attributes"]["url"].tame(check_string)


class EventFunction(Protocol):
    def __call__(self, payload: WildValue, include_title: bool) -> str:
        ...


EVENT_FUNCTION_MAPPER: Dict[str, EventFunction] = {
    "Push Hook": get_push_event_body,
    "Tag Push Hook": get_tag_push_event_body,
    "Test Hook": get_test_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"),
    "Confidential Issue Hook open": get_issue_created_event_body,
    "Confidential Issue Hook close": partial(get_issue_event_body, action="closed"),
    "Confidential Issue Hook reopen": partial(get_issue_event_body, action="reopened"),
    "Confidential 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,
    "Confidential Note Hook Issue": get_commented_issue_event_body,
    "Note Hook Snippet": get_commented_snippet_event_body,
    "Merge Request Hook approved": partial(get_merge_request_event_body, action="approved"),
    "Merge Request Hook unapproved": partial(get_merge_request_event_body, action="unapproved"),
    "Merge Request Hook open": partial(get_merge_request_open_or_updated_body, action="created"),
    "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"),
    "Merge Request Hook reopen": partial(get_merge_request_event_body, action="reopened"),
    "Wiki Page Hook create": partial(get_wiki_page_event_body, action="created"),
    "Wiki Page Hook update": partial(get_wiki_page_event_body, action="updated"),
    "Job Hook": get_build_hook_event_body,
    "Build Hook": get_build_hook_event_body,
    "Pipeline Hook": get_pipeline_event_body,
}

ALL_EVENT_TYPES = list(EVENT_FUNCTION_MAPPER.keys())


@webhook_view("GitLab", all_event_types=ALL_EVENT_TYPES)
@has_request_variables
def api_gitlab_webhook(
    request: HttpRequest,
    user_profile: UserProfile,
    payload: WildValue = REQ(argument_type="body", converter=to_wild_value),
    branches: Optional[str] = REQ(default=None),
    use_merge_request_title: bool = REQ(default=True, json_validator=check_bool),
    user_specified_topic: Optional[str] = REQ("topic", default=None),
) -> HttpResponse:
    event = get_event(request, payload, branches)
    if event is not None:
        event_body_function = get_body_based_on_event(event)
        body = event_body_function(
            payload,
            include_title=user_specified_topic is not None,
        )

        # Add a link to the project if a custom topic is set
        if user_specified_topic:
            project_url = f"[{get_repo_name(payload)}]({get_project_homepage(payload)})"
            body = f"[{project_url}] {body}"

        topic = get_subject_based_on_event(event, payload, use_merge_request_title)
        check_send_webhook_message(request, user_profile, topic, body, event)
    return json_success(request)


def get_body_based_on_event(event: str) -> EventFunction:
    return EVENT_FUNCTION_MAPPER[event]


def get_subject_based_on_event(
    event: str, payload: WildValue, use_merge_request_title: bool
) -> str:
    if event == "Push Hook":
        return f"{get_repo_name(payload)} / {get_branch_name(payload)}"
    elif event == "Job Hook" or event == "Build Hook":
        return "{} / {}".format(
            payload["repository"]["name"].tame(check_string), get_branch_name(payload)
        )
    elif event == "Pipeline Hook":
        return "{} / {}".format(
            get_repo_name(payload),
            payload["object_attributes"]["ref"].tame(check_string).replace("refs/heads/", ""),
        )
    elif event.startswith("Merge Request Hook"):
        return TOPIC_WITH_PR_OR_ISSUE_INFO_TEMPLATE.format(
            repo=get_repo_name(payload),
            type="MR",
            id=payload["object_attributes"]["iid"].tame(check_int),
            title=payload["object_attributes"]["title"].tame(check_string)
            if use_merge_request_title
            else "",
        )
    elif event.startswith(("Issue Hook", "Confidential Issue Hook")):
        return TOPIC_WITH_PR_OR_ISSUE_INFO_TEMPLATE.format(
            repo=get_repo_name(payload),
            type="issue",
            id=payload["object_attributes"]["iid"].tame(check_int),
            title=payload["object_attributes"]["title"].tame(check_string),
        )
    elif event == "Note Hook Issue" or event == "Confidential Note Hook Issue":
        return TOPIC_WITH_PR_OR_ISSUE_INFO_TEMPLATE.format(
            repo=get_repo_name(payload),
            type="issue",
            id=payload["issue"]["iid"].tame(check_int),
            title=payload["issue"]["title"].tame(check_string),
        )
    elif event == "Note Hook MergeRequest":
        return TOPIC_WITH_PR_OR_ISSUE_INFO_TEMPLATE.format(
            repo=get_repo_name(payload),
            type="MR",
            id=payload["merge_request"]["iid"].tame(check_int),
            title=payload["merge_request"]["title"].tame(check_string)
            if use_merge_request_title
            else "",
        )

    elif event == "Note Hook Snippet":
        return TOPIC_WITH_PR_OR_ISSUE_INFO_TEMPLATE.format(
            repo=get_repo_name(payload),
            type="snippet",
            id=payload["snippet"]["id"].tame(check_int),
            title=payload["snippet"]["title"].tame(check_string),
        )
    return get_repo_name(payload)


def get_event(request: HttpRequest, payload: WildValue, branches: Optional[str]) -> Optional[str]:
    event = validate_extract_webhook_http_header(request, "X-GitLab-Event", "GitLab")
    if event == "System Hook":
        # Convert the event name to a GitLab event title
        if "event_name" in payload:
            event_name = payload["event_name"].tame(check_string)
        else:
            event_name = payload["object_kind"].tame(check_string)
        event = event_name.split("__")[0].replace("_", " ").title()
        event = f"{event} Hook"
    if event in ["Confidential Issue Hook", "Issue Hook", "Merge Request Hook", "Wiki Page Hook"]:
        action = payload["object_attributes"].get("action", "open").tame(check_string)
        event = f"{event} {action}"
    elif event in ["Confidential Note Hook", "Note Hook"]:
        action = payload["object_attributes"]["noteable_type"].tame(check_string)
        event = f"{event} {action}"
    elif event == "Push Hook" and branches is not None:
        branch = get_branch_name(payload)
        if branches.find(branch) == -1:
            return None

    if event in list(EVENT_FUNCTION_MAPPER.keys()):
        return event

    raise UnsupportedWebhookEventTypeError(event)