from __future__ import annotations

import json
import time

from django.core.management.base import BaseCommand, CommandError

from core.events.projection import shadow_compare_session
from core.models import ChatSession, Message


class Command(BaseCommand):
    help = (
        "Run event->message shadow projection comparison and emit mismatch counters "
        "per chat session."
    )

    def add_arguments(self, parser):
        parser.add_argument("--user-id", default="")
        parser.add_argument("--session-id", default="")
        parser.add_argument("--service", default="")
        parser.add_argument("--recent-only", action="store_true", default=False)
        parser.add_argument("--recent-minutes", type=int, default=0)
        parser.add_argument("--limit-sessions", type=int, default=50)
        parser.add_argument("--detail-limit", type=int, default=25)
        parser.add_argument("--fail-on-mismatch", action="store_true", default=False)
        parser.add_argument("--json", action="store_true", default=False)

    def handle(self, *args, **options):
        user_id = str(options.get("user_id") or "").strip()
        session_id = str(options.get("session_id") or "").strip()
        service = str(options.get("service") or "").strip().lower()
        recent_only = bool(options.get("recent_only"))
        recent_minutes = max(0, int(options.get("recent_minutes") or 0))
        if recent_only and recent_minutes <= 0:
            recent_minutes = 120
        limit_sessions = max(1, int(options.get("limit_sessions") or 50))
        detail_limit = max(0, int(options.get("detail_limit") or 25))
        as_json = bool(options.get("json"))
        fail_on_mismatch = bool(options.get("fail_on_mismatch"))

        sessions = ChatSession.objects.all().order_by("-last_interaction", "id")
        if user_id:
            sessions = sessions.filter(user_id=user_id)
        if session_id:
            sessions = sessions.filter(id=session_id)
        if service:
            sessions = sessions.filter(identifier__service=service)
        if recent_minutes > 0:
            cutoff_ts = int(time.time() * 1000) - (recent_minutes * 60 * 1000)
            recent_session_ids = (
                Message.objects.filter(ts__gte=cutoff_ts)
                .values_list("session_id", flat=True)
                .distinct()
            )
            sessions = sessions.filter(id__in=recent_session_ids)
        sessions = list(sessions.select_related("user", "identifier")[:limit_sessions])

        if not sessions:
            raise CommandError("No chat sessions matched.")

        aggregate = {
            "sessions_scanned": 0,
            "db_message_count": 0,
            "projected_message_count": 0,
            "mismatch_total": 0,
            "counters": {
                "missing_in_projection": 0,
                "missing_in_db": 0,
                "text_mismatch": 0,
                "ts_mismatch": 0,
                "delivered_ts_mismatch": 0,
                "read_ts_mismatch": 0,
                "reactions_mismatch": 0,
            },
            "cause_counts": {
                "missing_event_write": 0,
                "ambiguous_reaction_target": 0,
                "payload_normalization_gap": 0,
            },
        }
        results = []

        for session in sessions:
            compared = shadow_compare_session(session, detail_limit=detail_limit)
            aggregate["sessions_scanned"] += 1
            aggregate["db_message_count"] += int(compared.get("db_message_count") or 0)
            aggregate["projected_message_count"] += int(compared.get("projected_message_count") or 0)
            aggregate["mismatch_total"] += int(compared.get("mismatch_total") or 0)
            for key in aggregate["counters"].keys():
                aggregate["counters"][key] += int(
                    (compared.get("counters") or {}).get(key) or 0
                )
            for key in aggregate["cause_counts"].keys():
                aggregate["cause_counts"][key] += int(
                    (compared.get("cause_counts") or {}).get(key) or 0
                )
            results.append(compared)

        payload = {
            "filters": {
                "user_id": user_id,
                "session_id": session_id,
                "service": service,
                "recent_only": recent_only,
                "recent_minutes": recent_minutes,
                "limit_sessions": limit_sessions,
                "detail_limit": detail_limit,
            },
            "aggregate": aggregate,
            "sessions": results,
        }
        if as_json:
            self.stdout.write(json.dumps(payload, indent=2, sort_keys=True))
        else:
            self.stdout.write(
                "shadow compare: "
                f"sessions={aggregate['sessions_scanned']} "
                f"db={aggregate['db_message_count']} "
                f"projected={aggregate['projected_message_count']} "
                f"mismatches={aggregate['mismatch_total']}"
            )
            self.stdout.write(f"counters={aggregate['counters']}")
            self.stdout.write(f"cause_counts={aggregate['cause_counts']}")
            for row in results:
                self.stdout.write(
                    f"session={row.get('session_id')} mismatch_total={row.get('mismatch_total')} "
                    f"db={row.get('db_message_count')} projected={row.get('projected_message_count')}"
                )

        if fail_on_mismatch and int(aggregate["mismatch_total"] or 0) > 0:
            raise CommandError(
                f"Shadow projection mismatch detected: {aggregate['mismatch_total']}"
            )