"""Live MQTT glean subscriber for Turnstone.

Reads ``type: mqtt`` entries from sources.yaml and subscribes to each broker
in the background. Incoming messages are normalized to RetrievedEntry and
written to the Turnstone SQLite database as they arrive.

This runs as an asyncio task alongside the batch glean scheduler. It is
started from the FastAPI lifespan in rest.py.

MQTT source config format in sources.yaml::

    sources:
      - id: meshtastic-home
        type: mqtt
        broker_host: 10.1.10.5
        broker_port: 1883          # optional, default 1883
        broker_username: ~         # optional
        broker_password: ~         # optional
        topics:
          - msh/#                  # one or more topic patterns
        severity: INFO             # optional default severity for all messages

      - id: iot-sensors
        type: mqtt
        broker_host: localhost
        topics:
          - home/+/temperature
          - home/+/humidity
"""
from __future__ import annotations

import asyncio
import hashlib
import json
import logging
import sqlite3
from datetime import datetime, timezone
from pathlib import Path

import yaml

from app.services.models import RetrievedEntry

logger = logging.getLogger(__name__)


def _load_mqtt_sources(sources_file: Path) -> list[dict]:
    """Return only the ``type: mqtt`` entries from sources.yaml."""
    if not sources_file.exists():
        return []
    with sources_file.open() as f:
        data = yaml.safe_load(f) or {}
    return [s for s in data.get("sources", []) if s.get("type") == "mqtt"]


def _make_entry_id(source_id: str, seq: int, text: str) -> str:
    h = hashlib.sha1(f"{source_id}:{seq}:{text}".encode()).hexdigest()[:16]
    return f"{source_id}:{seq}:{h}"


def _write_entry(db_path: Path, entry: RetrievedEntry) -> None:
    with sqlite3.connect(db_path, timeout=30.0) as conn:
        conn.execute(
            """
            INSERT OR IGNORE INTO log_entries
                (id, source_id, sequence, timestamp_raw, timestamp_iso,
                 ingest_time, severity, repeat_count, out_of_order,
                 matched_patterns, text)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
            """,
            (
                entry.entry_id,
                entry.source_id,
                entry.sequence,
                entry.timestamp_raw,
                entry.timestamp_iso,
                entry.ingest_time,
                entry.severity,
                entry.repeat_count,
                1 if entry.out_of_order else 0,
                json.dumps(entry.matched_patterns),
                entry.text,
            ),
        )


async def _run_source_subscriber(source: dict, db_path: Path) -> None:
    """Maintain a subscription to one MQTT source, reconnecting on error."""
    try:
        from circuitforge_core.mqtt import MQTTClient, MQTTConfig
    except ImportError:
        logger.error(
            "circuitforge-core[mqtt] is not installed — MQTT source %r skipped. "
            "Run: pip install circuitforge-core[mqtt]",
            source.get("id"),
        )
        return

    source_id: str = source["id"]
    host: str = source["broker_host"]
    port: int = int(source.get("broker_port", 1883))
    username: str | None = source.get("broker_username") or source.get("username")
    password: str | None = source.get("broker_password") or source.get("password")
    topics: list[str] = source.get("topics", ["#"])
    default_severity: str = source.get("severity", "INFO")

    cfg = MQTTConfig(
        host=host,
        port=port,
        username=username,
        password=password,
        client_id=f"turnstone-{source_id}",
    )
    client = MQTTClient(cfg)
    seq = 0

    for topic in topics:
        @client.on(topic)
        async def _handle(msg, _src=source_id, _sev=default_severity):
            nonlocal seq
            seq += 1
            now = datetime.now(tz=timezone.utc).isoformat()
            text = msg.text()
            entry = RetrievedEntry(
                entry_id=_make_entry_id(_src, seq, text),
                source_id=_src,
                sequence=seq,
                timestamp_raw=now,
                timestamp_iso=now,
                ingest_time=now,
                severity=_sev,
                repeat_count=1,
                out_of_order=False,
                matched_patterns=[],
                text=f"[{msg.topic}] {text}",
            )
            _write_entry(db_path, entry)
            logger.debug("MQTT[%s] %s: %s", _src, msg.topic, text[:120])

    logger.info("MQTT subscriber starting: %s → %s:%d topics=%s", source_id, host, port, topics)
    await client.run()


async def run_mqtt_subscribers(sources_file: Path, db_path: Path) -> None:
    """Start one subscriber task per MQTT source. Runs until cancelled."""
    sources = _load_mqtt_sources(sources_file)
    if not sources:
        logger.debug("No MQTT sources configured in %s", sources_file)
        return

    logger.info("Starting %d MQTT subscriber(s)", len(sources))
    tasks = [
        asyncio.create_task(
            _run_source_subscriber(src, db_path),
            name=f"mqtt-{src.get('id', i)}",
        )
        for i, src in enumerate(sources)
    ]

    try:
        await asyncio.gather(*tasks)
    except asyncio.CancelledError:
        for t in tasks:
            t.cancel()
        await asyncio.gather(*tasks, return_exceptions=True)
        raise