from __future__ import annotations

from asgiref.sync import sync_to_async
from django.conf import settings

from core.commands.base import CommandContext, CommandResult
from core.commands.handlers.bp import (
    BPCommandHandler,
    bp_reply_is_optional_for_trigger,
    bp_trigger_matches,
)
from core.commands.registry import get as get_handler
from core.commands.registry import register
from core.messaging.reply_sync import is_mirrored_origin
from core.models import CommandChannelBinding, CommandProfile, Message
from core.util import logs

log = logs.get_logger("command_engine")

_REGISTERED = False


def _channel_variants(service: str, channel_identifier: str) -> list[str]:
    value = str(channel_identifier or "").strip()
    if not value:
        return []
    variants = [value]
    svc = str(service or "").strip().lower()
    if svc == "whatsapp":
        bare = value.split("@", 1)[0].strip()
        if bare and bare not in variants:
            variants.append(bare)
        group = f"{bare}@g.us" if bare else ""
        if group and group not in variants:
            variants.append(group)
    return variants


def ensure_handlers_registered():
    global _REGISTERED
    if _REGISTERED:
        return
    register(BPCommandHandler())
    _REGISTERED = True


async def _eligible_profiles(ctx: CommandContext) -> list[CommandProfile]:
    def _load():
        direct_variants = _channel_variants(ctx.service, ctx.channel_identifier)
        if not direct_variants:
            return []
        direct = list(
            CommandProfile.objects.filter(
                user_id=ctx.user_id,
                enabled=True,
                channel_bindings__enabled=True,
                channel_bindings__direction="ingress",
                channel_bindings__service=ctx.service,
                channel_bindings__channel_identifier__in=direct_variants,
            ).distinct()
        )
        if direct:
            return direct
        # Compose-originated messages use `web` service even when the
        # underlying conversation is mapped to a platform identifier.
        if str(ctx.service or "").strip().lower() != "web":
            return []
        trigger = (
            Message.objects.select_related("session", "session__identifier")
            .filter(id=ctx.message_id, user_id=ctx.user_id)
            .first()
        )
        identifier = getattr(getattr(trigger, "session", None), "identifier", None)
        fallback_service = str(getattr(identifier, "service", "") or "").strip().lower()
        fallback_identifier = str(getattr(identifier, "identifier", "") or "").strip()
        fallback_variants = _channel_variants(fallback_service, fallback_identifier)
        if not fallback_service or not fallback_variants:
            return []
        return list(
            CommandProfile.objects.filter(
                user_id=ctx.user_id,
                enabled=True,
                channel_bindings__enabled=True,
                channel_bindings__direction="ingress",
                channel_bindings__service=fallback_service,
                channel_bindings__channel_identifier__in=fallback_variants,
            ).distinct()
        )

    return await sync_to_async(_load)()


def _matches_trigger(profile: CommandProfile, text: str) -> bool:
    if profile.slug == "bp" and bool(getattr(settings, "BP_SUBCOMMANDS_V1", True)):
        return bp_trigger_matches(
            message_text=text,
            trigger_token=profile.trigger_token,
            exact_match_only=profile.exact_match_only,
        )
    body = str(text or "").strip()
    trigger = str(profile.trigger_token or "").strip()
    if not trigger:
        return False
    if profile.exact_match_only:
        return body == trigger
    return trigger in body


async def process_inbound_message(ctx: CommandContext) -> list[CommandResult]:
    ensure_handlers_registered()
    trigger_message = await sync_to_async(
        lambda: Message.objects.filter(id=ctx.message_id).first()
    )()
    if trigger_message is None:
        return []
    if is_mirrored_origin(trigger_message.message_meta):
        return []

    profiles = await _eligible_profiles(ctx)
    results: list[CommandResult] = []
    for profile in profiles:
        if not _matches_trigger(profile, ctx.message_text):
            continue
        if profile.reply_required and trigger_message.reply_to_id is None:
            if (
                profile.slug == "bp"
                and bool(getattr(settings, "BP_SUBCOMMANDS_V1", True))
                and bp_reply_is_optional_for_trigger(ctx.message_text)
            ):
                pass
            else:
                results.append(
                    CommandResult(
                        ok=False,
                        status="skipped",
                        error="reply_required",
                        payload={"profile": profile.slug},
                    )
                )
                continue
        handler = get_handler(profile.slug)
        if handler is None:
            results.append(
                CommandResult(
                    ok=False,
                    status="failed",
                    error=f"missing_handler:{profile.slug}",
                )
            )
            continue
        try:
            result = await handler.execute(ctx)
            results.append(result)
        except Exception as exc:
            log.exception("command execution failed for profile=%s: %s", profile.slug, exc)
            results.append(
                CommandResult(
                    ok=False,
                    status="failed",
                    error=f"handler_exception:{exc}",
                )
            )
    return results