from enum import Enum

from django.conf import settings
from django.utils.translation import gettext as _

from zerver.lib.display_recipient import get_display_recipient
from zerver.lib.exceptions import JsonableError, ResourceNotFoundError
from zerver.lib.markdown.fenced_code import get_unused_fence
from zerver.lib.mention import silent_mention_syntax_for_user
from zerver.lib.message import get_user_mentions_for_display, truncate_content
from zerver.lib.message_cache import MessageDict
from zerver.lib.topic_link_util import (
    TOPIC_LINK_SYNTAX_FOR_DISPLAY,
    escape_invalid_stream_topic_characters,
)
from zerver.lib.types import UserDisplayRecipient
from zerver.lib.url_encoding import message_link_url, stream_message_url
from zerver.models import Message, Stream, UserProfile
from zerver.models.scheduled_jobs import ScheduledMessage
from zerver.tornado.django_api import send_event_on_commit


def normalize_note_text(body: str) -> str:
    # Similar to zerver.lib.message.normalize_body
    body = body.rstrip().lstrip("\n")

    if len(body) > settings.MAX_REMINDER_NOTE_LENGTH:
        raise JsonableError(
            _("Maximum reminder note length: {max_length} characters").format(
                max_length=settings.MAX_REMINDER_NOTE_LENGTH
            )
        )

    return body


class ReminderRecipientType(Enum):
    CHANNEL = "channel"
    PRIVATE = "private"
    NOTE_TO_SELF = "note to self"


def get_reminder_formatted_content(
    message: Message, current_user: UserProfile, note: str | None = None
) -> str:
    if note:
        note = normalize_note_text(note)

    format_recipient_type_key: ReminderRecipientType
    user_silent_mention = silent_mention_syntax_for_user(message.sender)
    conversation_url = message_link_url(current_user.realm, MessageDict.wide_dict(message))

    if message.is_channel_message:
        # We don't need to check access here since we already have the message
        # whose access has already been checked by the caller.
        stream = Stream.objects.get(
            id=message.recipient.type_id,
            realm=current_user.realm,
        )
        url = stream_message_url(
            realm=None,
            message={
                "id": message.id,
                "stream_id": stream.id,
                "display_recipient": stream.name,
                "topic": message.topic_name(),
            },
            conversation_link=True,
            include_base_url=False,
        )
        escape = escape_invalid_stream_topic_characters
        topic_pretty_link = TOPIC_LINK_SYNTAX_FOR_DISPLAY.format(
            channel_name=escape(stream.name),
            topic_name=escape(message.topic_name()),
        )
        if note:
            content = _(
                "You requested a reminder for the following message. Note:\n > {note}"
            ).format(
                note=note,
            )
        else:
            content = _("You requested a reminder for the following message.")

        format_recipient_type_key = ReminderRecipientType.CHANNEL
        context = dict(
            user_silent_mention=user_silent_mention,
            conversation_url=conversation_url,
            topic_pretty_link=f"[{topic_pretty_link}]({url})",
        )
    else:
        if note:
            content = _(
                "You requested a reminder for the following direct message. Note:\n > {note}"
            ).format(
                note=note,
            )
        else:
            content = _("You requested a reminder for the following direct message.")
        recipients: list[UserProfile | UserDisplayRecipient] = [
            user
            for user in get_display_recipient(message.recipient)
            if user["id"] != message.sender.id
        ]

        if not recipients:
            format_recipient_type_key = ReminderRecipientType.NOTE_TO_SELF
            context = dict(
                conversation_url=conversation_url,
            )
        else:
            format_recipient_type_key = ReminderRecipientType.PRIVATE
            list_of_recipient_mentions = get_user_mentions_for_display(recipients)
            context = dict(
                user_silent_mention=user_silent_mention,
                conversation_url=conversation_url,
                list_of_recipient_mentions=list_of_recipient_mentions,
            )

    # Format the message content as a quote.
    content += "\n\n"

    REMINDER_FORMAT = {
        ReminderRecipientType.CHANNEL: {
            "widget": _(
                "{user_silent_mention} [sent]({conversation_url}) a {widget} in {topic_pretty_link}."
            ),
            "text": _("{user_silent_mention} [said]({conversation_url}) in {topic_pretty_link}:"),
        },
        ReminderRecipientType.PRIVATE: {
            "widget": _(
                "{user_silent_mention} [sent]({conversation_url}) a {widget} to {list_of_recipient_mentions}."
            ),
            "text": _(
                "{user_silent_mention} [said]({conversation_url}) to {list_of_recipient_mentions}:"
            ),
        },
        ReminderRecipientType.NOTE_TO_SELF: {
            "widget": _("You [sent]({conversation_url}) yourself a {widget}."),
            "text": _("You [sent]({conversation_url}) a note to yourself:"),
        },
    }

    if message.content.startswith("/poll"):
        context.update(widget="poll")
        content += REMINDER_FORMAT[format_recipient_type_key]["widget"].format_map(context)
    elif message.content.startswith("/todo"):
        context.update(widget="todo list")
        content += REMINDER_FORMAT[format_recipient_type_key]["widget"].format_map(context)
    else:
        content += REMINDER_FORMAT[format_recipient_type_key]["text"].format_map(context)
        content += "\n"
        fence = get_unused_fence(content)
        quoted_message = "{fence}quote\n{msg_content}\n{fence}"
        length_without_message_content = len(
            content + quoted_message.format(fence=fence, msg_content="")
        )
        max_length = settings.MAX_MESSAGE_LENGTH - length_without_message_content
        msg_content = truncate_content(message.content, max_length, "\n[message truncated]")
        content += quoted_message.format(
            fence=fence,
            msg_content=msg_content,
        )
    return content


def access_reminder(user_profile: UserProfile, reminder_id: int) -> ScheduledMessage:
    try:
        return ScheduledMessage.objects.get(
            id=reminder_id, sender=user_profile, delivery_type=ScheduledMessage.REMIND
        )
    except ScheduledMessage.DoesNotExist:
        raise ResourceNotFoundError(_("Reminder does not exist"))


def notify_remove_reminder(user_profile: UserProfile, reminder_id: int) -> None:
    event = {
        "type": "reminders",
        "op": "remove",
        "reminder_id": reminder_id,
    }
    send_event_on_commit(user_profile.realm, event, [user_profile.id])