"""Campaign draft/send helpers for email and SMS."""

from __future__ import annotations

import re
from typing import TYPE_CHECKING

from django.urls import reverse
from django.utils import timezone

from contacts.consent import (  # noqa: F401 — re-export for tests + providers
    channel_preferences,
    contact_may_receive,
    make_unsubscribe_token,
    one_click_unsubscribe_url,
    opted_in_contacts,
    parse_unsubscribe_token,
    preferences_url,
    process_unsubscribe_token,
    record_sms_stop,
    set_channel_consent,
    set_channel_preferences,
    unsubscribe_all,
)
from contacts.models import Channel, Contact
from core.campaign_utm import ensure_campaign_utm_link
from core.scheduling import parse_scheduled_for
from email_sms.models import Campaign, Message, MessageTemplate

if TYPE_CHECKING:
    from django.contrib.auth.models import AbstractBaseUser

AUDIENCE_CHANNEL = {
    Campaign.Audience.EMAIL_OPT_IN: Channel.EMAIL,
    Campaign.Audience.SMS_OPT_IN: Channel.SMS,
}

# {{first_name}} preferred; {first_name} also accepted (composer hint legacy).
_MERGE_TAG_RE = re.compile(
    r"\{\{\s*(first_name|last_name|email|phone|full_name)\s*\}\}"
    r"|\{\s*(first_name|last_name|email|phone|full_name)\s*\}",
    re.IGNORECASE,
)

REMOVABLE_MESSAGE_STATUSES = frozenset(
    {
        Message.Status.DRAFT,
        Message.Status.SCHEDULED,
        Message.Status.FAILED,
    }
)


def render_merge_tags(text: str, contact: Contact | None) -> str:
    """Replace personalization tags with contact field values."""
    if not text:
        return text or ""
    first = (getattr(contact, "first_name", None) or "").strip() if contact else ""
    last = (getattr(contact, "last_name", None) or "").strip() if contact else ""
    email = (getattr(contact, "email", None) or "").strip() if contact else ""
    phone = (getattr(contact, "phone", None) or "").strip() if contact else ""
    full = f"{first} {last}".strip()
    values = {
        "first_name": first,
        "last_name": last,
        "email": email,
        "phone": phone,
        "full_name": full,
    }

    def _replace(match: re.Match[str]) -> str:
        key = (match.group(1) or match.group(2) or "").lower()
        return values.get(key, "")

    return _MERGE_TAG_RE.sub(_replace, text)


def message_is_removable(message: Message) -> bool:
    return message.status in REMOVABLE_MESSAGE_STATUSES


def channel_for_audience(audience: str) -> str:
    try:
        return AUDIENCE_CHANNEL[audience]
    except KeyError as exc:
        raise ValueError(f"Unknown audience: {audience}") from exc


def create_campaign_draft(
    *,
    name: str,
    audience: str,
    subject: str = "",
    body: str = "",
    scheduled_for=None,
    created_by: AbstractBaseUser | None = None,
    template: MessageTemplate | None = None,
) -> Campaign:
    """Persist a draft campaign and per-recipient Message stubs."""
    channel = channel_for_audience(audience)
    campaign = Campaign.objects.create(
        name=name,
        channel=channel,
        audience=audience,
        status=Campaign.Status.DRAFT,
        scheduled_for=scheduled_for,
        subject_override=subject,
        body_override=body,
        created_by=created_by,
        template=template,
    )
    if channel in (Channel.EMAIL, Channel.SMS):
        body = ensure_campaign_utm_link(
            body,
            name=name,
            medium=channel,
            html=(channel == Channel.EMAIL),
            campaign_id=campaign.pk,
        )
        if body != campaign.body_override:
            campaign.body_override = body
            campaign.save(update_fields=["body_override", "updated_at"])
    contacts = list(opted_in_contacts(channel))
    Message.objects.bulk_create(
        [
            Message(
                campaign=campaign,
                contact=contact,
                channel=channel,
                status=Message.Status.DRAFT,
                scheduled_for=scheduled_for,
                body_snapshot=body,
            )
            for contact in contacts
        ]
    )
    return campaign


def campaign_notify_recipient(campaign: Campaign) -> str:
    """Email address for the realtor summary (created_by, else CONTACT_EMAIL)."""
    from django.conf import settings

    user = campaign.created_by
    if user is not None:
        email = (getattr(user, "email", None) or "").strip()
        if email:
            return email
    return (settings.CONTACT_EMAIL or "").strip()


def send_campaign_completion_notify(campaign: Campaign) -> bool:
    """
    One-shot summary email when a campaign finishes sending.

    Returns True if mail was sent (or already sent earlier).
    """
    from django.conf import settings
    from django.core.mail import EmailMultiAlternatives
    from django.db.models import Count, Q
    from django.template.loader import get_template
    from django.urls import reverse

    from public.email_branding import email_brand_context

    campaign.refresh_from_db()
    if campaign.notify_sent_at:
        return True
    if campaign.status != Campaign.Status.COMPLETED:
        return False

    to_email = campaign_notify_recipient(campaign)
    if not to_email:
        return False

    # Claim the notify slot atomically so concurrent refresh calls only send once.
    now = timezone.now()
    claimed = Campaign.objects.filter(
        pk=campaign.pk,
        status=Campaign.Status.COMPLETED,
        notify_sent_at__isnull=True,
    ).update(notify_sent_at=now)
    if not claimed:
        return True
    campaign.notify_sent_at = now

    counts = campaign.messages.aggregate(
        sent=Count(
            "id",
            filter=Q(
                status__in=[
                    Message.Status.SENT,
                    Message.Status.DELIVERED,
                    Message.Status.OPENED,
                    Message.Status.CLICKED,
                ]
            ),
        ),
        delivered=Count(
            "id",
            filter=Q(
                status__in=[
                    Message.Status.DELIVERED,
                    Message.Status.OPENED,
                    Message.Status.CLICKED,
                ]
            ),
        ),
        failed=Count(
            "id",
            filter=Q(
                status__in=[
                    Message.Status.FAILED,
                    Message.Status.BOUNCED,
                ]
            ),
        ),
        suppressed=Count("id", filter=Q(status=Message.Status.SUPPRESSED)),
        total=Count("id"),
    )
    report_path = reverse("email_sms:campaign_detail", kwargs={"pk": campaign.pk})
    public = (settings.PUBLIC_SITE_URL or "").rstrip("/")
    report_url = f"{public}{report_path}" if public else report_path

    subject = f"Campaign sent: {campaign.name}"
    ctx = email_brand_context(
        subject=subject,
        campaign_name=campaign.name,
        channel_display=campaign.get_channel_display(),
        total=counts["total"],
        sent=counts["sent"],
        delivered=counts["delivered"],
        failed=counts["failed"],
        suppressed=counts["suppressed"],
        report_url=report_url,
    )
    text_content = get_template("emails/campaign_complete.txt").render(ctx)
    html_content = get_template("emails/campaign_complete.html").render(ctx)
    email = EmailMultiAlternatives(
        subject=subject,
        body=text_content,
        from_email=settings.DEFAULT_FROM_EMAIL,
        to=[to_email],
    )
    email.attach_alternative(html_content, "text/html")
    try:
        email.send(fail_silently=False)
    except Exception:  # noqa: BLE001 — don't block completion on mail errors
        import logging

        logging.getLogger(__name__).exception(
            "Campaign completion notify failed for %s", campaign.pk
        )
        Campaign.objects.filter(pk=campaign.pk).update(notify_sent_at=None)
        campaign.notify_sent_at = None
        return False

    return True


def refresh_campaign_status(campaign: Campaign) -> Campaign:
    """Set campaign to completed when no messages remain pending."""
    campaign.refresh_from_db()
    pending = campaign.messages.filter(
        status__in=[
            Message.Status.DRAFT,
            Message.Status.SCHEDULED,
            Message.Status.QUEUED,
        ]
    ).exists()
    if pending:
        return campaign
    if campaign.status == Campaign.Status.SENDING:
        campaign.status = Campaign.Status.COMPLETED
        campaign.save(update_fields=["status", "updated_at"])
        send_campaign_completion_notify(campaign)
    return campaign


def enqueue_campaign_send(campaign: Campaign) -> int:
    """
    Queue draft/scheduled/failed messages for send.

    Dev uses ImmediateBackend → each enqueue runs inline via SMTP/console.
    """
    from email_sms.tasks import send_campaign_message

    sendable = list(
        campaign.messages.filter(
            status__in=[
                Message.Status.DRAFT,
                Message.Status.SCHEDULED,
                Message.Status.FAILED,
            ]
        )
    )
    if not sendable:
        return 0

    campaign.status = Campaign.Status.SENDING
    campaign.save(update_fields=["status", "updated_at"])

    enqueued = 0
    for message in sendable:
        message.status = Message.Status.QUEUED
        message.save(update_fields=["status", "updated_at"])
        try:
            send_campaign_message.enqueue(message_id=str(message.pk))
        except Exception:  # noqa: BLE001 — task already persisted FAILED
            pass
        enqueued += 1

    refresh_campaign_status(campaign)
    return enqueued


def send_campaign_test_email(campaign: Campaign, to_email: str) -> None:
    """Send one preview copy to ``to_email`` without touching recipient rows."""
    from django.conf import settings
    from django.core.mail import EmailMultiAlternatives
    from django.template.loader import get_template

    from public.email_branding import (
        campaign_body_to_email_html,
        campaign_body_to_plain_text,
        email_brand_context,
    )

    if campaign.channel != Channel.EMAIL:
        raise ValueError("Test send is only available for email campaigns.")
    subject = campaign.subject_override or (
        campaign.template.subject if campaign.template_id else f"Message from {settings.SITE_NAME}"
    )
    body = campaign.body_override or (
        campaign.template.body if campaign.template_id else ""
    )
    if not subject.strip():
        raise ValueError("Campaign has no subject.")
    if not body.strip():
        raise ValueError("Campaign has no body.")

    # Preview merge tags using first recipient when available.
    sample = (
        campaign.messages.select_related("contact")
        .order_by("created_at")
        .first()
    )
    sample_contact = sample.contact if sample else None
    subject = render_merge_tags(subject, sample_contact)
    body = render_merge_tags(body, sample_contact)

    notice = (
        "This is a test send from the portal. "
        "Recipient list was not notified."
    )
    ctx = email_brand_context(
        title=f"[TEST] {subject}",
        content=f"{campaign_body_to_plain_text(body)}\n\n{notice}",
        content_html=(
            f"{campaign_body_to_email_html(body)}"
            f'<p style="margin:24px 0 0;color:#6b7280;font-size:13px;">{notice}</p>'
        ),
    )
    text_content = get_template("emails/marketing_email.txt").render(ctx)
    html_content = get_template("emails/marketing_email.html").render(ctx)
    email = EmailMultiAlternatives(
        subject=f"[TEST] {subject}",
        body=text_content,
        from_email=settings.DEFAULT_FROM_EMAIL,
        to=[to_email],
    )
    email.attach_alternative(html_content, "text/html")
    email.send(fail_silently=False)