from email.headerregistry import Address
from typing import Dict, Union

from django.http import HttpRequest, HttpResponse
from typing_extensions import TypeAlias

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_int, check_none_or, check_string, to_wild_value
from zerver.lib.webhooks.common import check_send_webhook_message
from zerver.models import UserProfile

FormatDictType: TypeAlias = Dict[str, Union[str, int]]

PAGER_DUTY_EVENT_NAMES = {
    "incident.trigger": "triggered",
    "incident.acknowledge": "acknowledged",
    "incident.unacknowledge": "unacknowledged",
    "incident.resolve": "resolved",
    "incident.assign": "assigned",
    "incident.escalate": "escalated",
    "incident.delegate": "delineated",
}

PAGER_DUTY_EVENT_NAMES_V2 = {
    "incident.trigger": "triggered",
    "incident.acknowledge": "acknowledged",
    "incident.resolve": "resolved",
    "incident.assign": "assigned",
}

PAGER_DUTY_EVENT_NAMES_V3 = {
    "incident.triggered": "triggered",
    "incident.acknowledged": "acknowledged",
    "incident.unacknowledged": "unacknowledged",
    "incident.resolved": "resolved",
    "incident.reassigned": "reassigned",
}

ALL_EVENT_TYPES = [
    "resolved",
    "assigned",
    "unacknowledged",
    "acknowledged",
    "triggered",
    "reassigned",
]

AGENT_TEMPLATE = "[{username}]({url})"

INCIDENT_WITH_SERVICE_AND_ASSIGNEE = (
    "Incident [{incident_num_title}]({incident_url}) {action} by [{service_name}]"
    "({service_url}) (assigned to {assignee_info}).\n\n{trigger_message}"
)

TRIGGER_MESSAGE = "``` quote\n{message}\n```"

NUM_TITLE = "{incident_title} (#{incident_num})"

INCIDENT_WITH_ASSIGNEE = """
Incident [{incident_num_title}]({incident_url}) {action} by {assignee_info}.

{trigger_message}
""".strip()

INCIDENT_ASSIGNED = """
Incident [{incident_num_title}]({incident_url}) {action} to {assignee_info}.

{trigger_message}
""".strip()

INCIDENT_RESOLVED_WITH_AGENT = """
Incident [{incident_num_title}]({incident_url}) resolved by {agent_info}.

{trigger_message}
""".strip()

INCIDENT_RESOLVED = """
Incident [{incident_num_title}]({incident_url}) resolved.

{trigger_message}
""".strip()


def build_pagerduty_formatdict(message: WildValue) -> FormatDictType:
    format_dict: FormatDictType = {}
    format_dict["action"] = PAGER_DUTY_EVENT_NAMES[message["type"].tame(check_string)]

    format_dict["incident_id"] = message["data"]["incident"]["id"].tame(check_string)
    format_dict["incident_num_title"] = message["data"]["incident"]["incident_number"].tame(
        check_int
    )
    format_dict["incident_url"] = message["data"]["incident"]["html_url"].tame(check_string)

    format_dict["service_name"] = message["data"]["incident"]["service"]["name"].tame(check_string)
    format_dict["service_url"] = message["data"]["incident"]["service"]["html_url"].tame(
        check_string
    )

    if message["data"]["incident"].get("assigned_to_user"):
        assigned_to_user = message["data"]["incident"]["assigned_to_user"]
        format_dict["assignee_info"] = AGENT_TEMPLATE.format(
            username=Address(addr_spec=assigned_to_user["email"].tame(check_string)).username,
            url=assigned_to_user["html_url"].tame(check_string),
        )
    else:
        format_dict["assignee_info"] = "nobody"

    if message["data"]["incident"].get("resolved_by_user"):
        resolved_by_user = message["data"]["incident"]["resolved_by_user"]
        format_dict["agent_info"] = AGENT_TEMPLATE.format(
            username=Address(addr_spec=resolved_by_user["email"].tame(check_string)).username,
            url=resolved_by_user["html_url"].tame(check_string),
        )

    trigger_message = []
    trigger_summary_data = message["data"]["incident"].get("trigger_summary_data")
    if trigger_summary_data:
        trigger_subject = trigger_summary_data.get("subject", "").tame(check_string)
        if trigger_subject:
            trigger_message.append(trigger_subject)

        trigger_description = trigger_summary_data.get("description", "").tame(check_string)
        if trigger_description:
            trigger_message.append(trigger_description)

    format_dict["trigger_message"] = TRIGGER_MESSAGE.format(message="\n".join(trigger_message))
    return format_dict


def build_pagerduty_formatdict_v2(message: WildValue) -> FormatDictType:
    format_dict: FormatDictType = {}
    format_dict["action"] = PAGER_DUTY_EVENT_NAMES_V2[message["event"].tame(check_string)]

    format_dict["incident_id"] = message["incident"]["id"].tame(check_string)
    format_dict["incident_num_title"] = message["incident"]["incident_number"].tame(check_int)
    format_dict["incident_url"] = message["incident"]["html_url"].tame(check_string)

    format_dict["service_name"] = message["incident"]["service"]["name"].tame(check_string)
    format_dict["service_url"] = message["incident"]["service"]["html_url"].tame(check_string)

    assignments = message["incident"]["assignments"]
    if assignments:
        assignee = assignments[0]["assignee"]
        format_dict["assignee_info"] = AGENT_TEMPLATE.format(
            username=assignee["summary"].tame(check_string),
            url=assignee["html_url"].tame(check_string),
        )
    else:
        format_dict["assignee_info"] = "nobody"

    last_status_change_by = message["incident"].get("last_status_change_by")
    if last_status_change_by is not None:
        format_dict["agent_info"] = AGENT_TEMPLATE.format(
            username=last_status_change_by["summary"].tame(check_string),
            url=last_status_change_by["html_url"].tame(check_string),
        )

    trigger_description = message["incident"].get("description").tame(check_none_or(check_string))
    if trigger_description is not None:
        format_dict["trigger_message"] = TRIGGER_MESSAGE.format(message=trigger_description)
    return format_dict


def build_pagerduty_formatdict_v3(event: WildValue) -> FormatDictType:
    format_dict: FormatDictType = {}
    format_dict["action"] = PAGER_DUTY_EVENT_NAMES_V3[event["event_type"].tame(check_string)]

    format_dict["incident_id"] = event["data"]["id"].tame(check_string)
    format_dict["incident_url"] = event["data"]["html_url"].tame(check_string)
    format_dict["incident_num_title"] = NUM_TITLE.format(
        incident_num=event["data"]["number"].tame(check_int),
        incident_title=event["data"]["title"].tame(check_string),
    )

    format_dict["service_name"] = event["data"]["service"]["summary"].tame(check_string)
    format_dict["service_url"] = event["data"]["service"]["html_url"].tame(check_string)

    assignees = event["data"]["assignees"]
    if assignees:
        assignee = assignees[0]
        format_dict["assignee_info"] = AGENT_TEMPLATE.format(
            username=assignee["summary"].tame(check_string),
            url=assignee["html_url"].tame(check_string),
        )
    else:
        format_dict["assignee_info"] = "nobody"

    agent = event.get("agent")
    if agent is not None:
        format_dict["agent_info"] = AGENT_TEMPLATE.format(
            username=agent["summary"].tame(check_string),
            url=agent["html_url"].tame(check_string),
        )

    # V3 doesn't have trigger_message
    format_dict["trigger_message"] = ""

    return format_dict


def send_formatted_pagerduty(
    request: HttpRequest,
    user_profile: UserProfile,
    message_type: str,
    format_dict: FormatDictType,
) -> None:
    if message_type in (
        "incident.trigger",
        "incident.triggered",
        "incident.unacknowledge",
        "incident.unacknowledged",
    ):
        template = INCIDENT_WITH_SERVICE_AND_ASSIGNEE
    elif message_type in ("incident.resolve", "incident.resolved"):
        if "agent_info" in format_dict:
            template = INCIDENT_RESOLVED_WITH_AGENT
        else:
            template = INCIDENT_RESOLVED
    elif message_type in ("incident.assign", "incident.reassigned"):
        template = INCIDENT_ASSIGNED
    else:
        template = INCIDENT_WITH_ASSIGNEE

    topic = "Incident {incident_num_title}".format(**format_dict)
    body = template.format(**format_dict)
    assert isinstance(format_dict["action"], str)
    check_send_webhook_message(request, user_profile, topic, body, format_dict["action"])


@webhook_view("PagerDuty", all_event_types=ALL_EVENT_TYPES)
@has_request_variables
def api_pagerduty_webhook(
    request: HttpRequest,
    user_profile: UserProfile,
    payload: WildValue = REQ(argument_type="body", converter=to_wild_value),
) -> HttpResponse:
    messages = payload.get("messages")
    if messages:
        for message in messages:
            message_type = message.get("type").tame(check_none_or(check_string))

            # If the message has no "type" key, then this payload came from a
            # Pagerduty Webhook V2.
            if message_type is None:
                break

            if message_type not in PAGER_DUTY_EVENT_NAMES:
                raise UnsupportedWebhookEventTypeError(message_type)

            format_dict = build_pagerduty_formatdict(message)
            send_formatted_pagerduty(request, user_profile, message_type, format_dict)

        for message in messages:
            message_event = message.get("event").tame(check_none_or(check_string))

            # If the message has no "event" key, then this payload came from a
            # Pagerduty Webhook V1.
            if message_event is None:
                break

            if message_event not in PAGER_DUTY_EVENT_NAMES_V2:
                raise UnsupportedWebhookEventTypeError(message_event)

            format_dict = build_pagerduty_formatdict_v2(message)
            send_formatted_pagerduty(request, user_profile, message_event, format_dict)
    else:
        if "event" in payload:
            # V3 has no "messages" field, and it has key "event" instead
            event = payload["event"]
            event_type = event.get("event_type").tame(check_none_or(check_string))

            if event_type not in PAGER_DUTY_EVENT_NAMES_V3:
                raise UnsupportedWebhookEventTypeError(event_type)

            format_dict = build_pagerduty_formatdict_v3(event)
            send_formatted_pagerduty(request, user_profile, event_type, format_dict)

    return json_success(request)
