from __future__ import annotations

import re
from typing import Any

from django.db.models import Q

from core.models import ExternalChatLink, PersonIdentifier


def channel_variants(service: str, channel: str) -> list[str]:
    value = str(channel or "").strip()
    if not value:
        return []
    variants = [value]
    service_key = str(service or "").strip().lower()
    if service_key == "whatsapp":
        bare = value.split("@", 1)[0].strip()
        if bare and bare not in variants:
            variants.append(bare)
        direct = f"{bare}@s.whatsapp.net" if bare else ""
        if direct and direct not in variants:
            variants.append(direct)
        group = f"{bare}@g.us" if bare else ""
        if group and group not in variants:
            variants.append(group)
    if service_key == "signal":
        digits = re.sub(r"[^0-9]", "", value)
        if digits and digits not in variants:
            variants.append(digits)
        if digits:
            plus = f"+{digits}"
            if plus not in variants:
                variants.append(plus)
    return variants


def resolve_external_chat_id(*, user, provider: str, service: str, channel: str) -> str:
    variants = channel_variants(service, channel)
    if not variants:
        return ""
    person_identifier = (
        PersonIdentifier.objects.filter(
            user=user,
            service=service,
            identifier__in=variants,
        )
        .select_related("person")
        .order_by("-id")
        .first()
    )
    if person_identifier is None:
        return ""
    link = (
        ExternalChatLink.objects.filter(
            user=user,
            provider=provider,
            enabled=True,
        )
        .filter(Q(person_identifier=person_identifier) | Q(person=person_identifier.person))
        .order_by("-updated_at", "-id")
        .first()
    )
    return str(getattr(link, "external_chat_id", "") or "").strip()


def compact_json_snippet(payload: Any, limit: int = 800) -> str:
    text = str(payload or "").strip()
    if len(text) <= limit:
        return text
    return text[:limit].rstrip() + "..."