"""Scheduled aggregation engine for energy data rollups.

Computes hourly, daily, and monthly aggregations from raw EnergyData
and populates EnergyDailySummary. Follows the APScheduler pattern
established in report_scheduler.py.
"""
import logging
from datetime import datetime, timedelta, timezone

from apscheduler.schedulers.asyncio import AsyncIOScheduler
from apscheduler.triggers.cron import CronTrigger
from sqlalchemy import select, func, and_, text, Integer

from app.core.config import get_settings
from app.core.database import async_session
from app.models.energy import EnergyData, EnergyDailySummary

logger = logging.getLogger("aggregation")

_scheduler: AsyncIOScheduler | None = None


async def aggregate_hourly():
    """Aggregate raw energy_data into hourly avg/min/max per device+data_type.

    Processes data from the previous hour. Results are logged but not
    stored separately — the primary use is for cache warming and monitoring.
    Daily aggregation (which writes to EnergyDailySummary) is the persistent rollup.
    """
    now = datetime.now(timezone.utc)
    hour_start = now.replace(minute=0, second=0, microsecond=0) - timedelta(hours=1)
    hour_end = hour_start + timedelta(hours=1)

    logger.info("Running hourly aggregation for %s", hour_start.isoformat())

    async with async_session() as session:
        settings = get_settings()
        query = (
            select(
                EnergyData.device_id,
                EnergyData.data_type,
                func.avg(EnergyData.value).label("avg_value"),
                func.min(EnergyData.value).label("min_value"),
                func.max(EnergyData.value).label("max_value"),
                func.count(EnergyData.id).label("sample_count"),
            )
            .where(
                and_(
                    EnergyData.timestamp >= hour_start,
                    EnergyData.timestamp < hour_end,
                )
            )
            .group_by(EnergyData.device_id, EnergyData.data_type)
        )
        result = await session.execute(query)
        rows = result.all()

    logger.info(
        "Hourly aggregation complete: %d device/type groups for %s",
        len(rows),
        hour_start.isoformat(),
    )
    return rows


async def aggregate_daily():
    """Compute daily summaries and populate EnergyDailySummary.

    Processes yesterday's data. Groups by device_id and maps data_type
    to energy_type for the summary table.
    """
    now = datetime.now(timezone.utc)
    day_start = (now - timedelta(days=1)).replace(hour=0, minute=0, second=0, microsecond=0)
    day_end = day_start + timedelta(days=1)

    logger.info("Running daily aggregation for %s", day_start.date().isoformat())

    # Map data_type -> energy_type for summary grouping
    data_type_to_energy_type = {
        "power": "electricity",
        "energy": "electricity",
        "voltage": "electricity",
        "current": "electricity",
        "heat_power": "heat",
        "heat_energy": "heat",
        "temperature": "heat",
        "water_flow": "water",
        "water_volume": "water",
        "gas_flow": "gas",
        "gas_volume": "gas",
    }

    async with async_session() as session:
        # Fetch per-device aggregated stats for the day
        query = (
            select(
                EnergyData.device_id,
                EnergyData.data_type,
                func.avg(EnergyData.value).label("avg_value"),
                func.min(EnergyData.value).label("min_value"),
                func.max(EnergyData.value).label("max_value"),
                func.sum(EnergyData.value).label("total_value"),
                func.count(EnergyData.id).label("sample_count"),
            )
            .where(
                and_(
                    EnergyData.timestamp >= day_start,
                    EnergyData.timestamp < day_end,
                )
            )
            .group_by(EnergyData.device_id, EnergyData.data_type)
        )
        result = await session.execute(query)
        rows = result.all()

        # Group results by (device_id, energy_type)
        device_summaries: dict[tuple[int, str], dict] = {}
        for row in rows:
            energy_type = data_type_to_energy_type.get(row.data_type, "electricity")
            key = (row.device_id, energy_type)
            if key not in device_summaries:
                device_summaries[key] = {
                    "peak_power": None,
                    "min_power": None,
                    "avg_power": None,
                    "total_consumption": 0.0,
                    "total_generation": 0.0,
                    "avg_temperature": None,
                    "sample_count": 0,
                }

            summary = device_summaries[key]
            summary["sample_count"] += row.sample_count

            # Power-type metrics
            if row.data_type in ("power", "heat_power"):
                summary["peak_power"] = max(
                    summary["peak_power"] or 0, row.max_value or 0
                )
                summary["min_power"] = min(
                    summary["min_power"] if summary["min_power"] is not None else float("inf"),
                    row.min_value or 0,
                )
                summary["avg_power"] = row.avg_value

            # Consumption (energy, volume)
            if row.data_type in ("energy", "heat_energy", "water_volume", "gas_volume"):
                summary["total_consumption"] += row.total_value or 0

            # Temperature
            if row.data_type == "temperature":
                summary["avg_temperature"] = row.avg_value

        # Delete existing summaries for the same date to allow re-runs
        await session.execute(
            EnergyDailySummary.__table__.delete().where(
                EnergyDailySummary.date == day_start
            )
        )

        # Insert new summaries
        summaries = []
        for (device_id, energy_type), stats in device_summaries.items():
            summaries.append(
                EnergyDailySummary(
                    device_id=device_id,
                    date=day_start,
                    energy_type=energy_type,
                    total_consumption=round(stats["total_consumption"], 4),
                    total_generation=0.0,
                    peak_power=round(stats["peak_power"], 4) if stats["peak_power"] else None,
                    min_power=round(stats["min_power"], 4) if stats["min_power"] is not None and stats["min_power"] != float("inf") else None,
                    avg_power=round(stats["avg_power"], 4) if stats["avg_power"] else None,
                    avg_temperature=round(stats["avg_temperature"], 2) if stats["avg_temperature"] else None,
                )
            )

        if summaries:
            session.add_all(summaries)
            await session.commit()

    logger.info(
        "Daily aggregation complete: %d summaries for %s",
        len(summaries) if device_summaries else 0,
        day_start.date().isoformat(),
    )


async def aggregate_monthly():
    """Compute monthly rollups from EnergyDailySummary.

    Aggregates the previous month's daily summaries. Results are logged
    for monitoring — monthly reports use ReportGenerator for output.
    """
    now = datetime.now(timezone.utc)
    first_of_current = now.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
    last_month_end = first_of_current - timedelta(days=1)
    month_start = last_month_end.replace(day=1, hour=0, minute=0, second=0, microsecond=0)

    logger.info(
        "Running monthly aggregation for %s-%02d",
        month_start.year,
        month_start.month,
    )

    async with async_session() as session:
        query = (
            select(
                EnergyDailySummary.device_id,
                EnergyDailySummary.energy_type,
                func.sum(EnergyDailySummary.total_consumption).label("total_consumption"),
                func.sum(EnergyDailySummary.total_generation).label("total_generation"),
                func.max(EnergyDailySummary.peak_power).label("peak_power"),
                func.min(EnergyDailySummary.min_power).label("min_power"),
                func.avg(EnergyDailySummary.avg_power).label("avg_power"),
                func.sum(EnergyDailySummary.operating_hours).label("total_operating_hours"),
                func.sum(EnergyDailySummary.cost).label("total_cost"),
                func.sum(EnergyDailySummary.carbon_emission).label("total_carbon"),
            )
            .where(
                and_(
                    EnergyDailySummary.date >= month_start,
                    EnergyDailySummary.date < first_of_current,
                )
            )
            .group_by(EnergyDailySummary.device_id, EnergyDailySummary.energy_type)
        )
        result = await session.execute(query)
        rows = result.all()

    logger.info(
        "Monthly aggregation complete: %d device/type groups for %s-%02d",
        len(rows),
        month_start.year,
        month_start.month,
    )
    return rows


async def start_aggregation_scheduler():
    """Start the APScheduler-based aggregation scheduler."""
    global _scheduler
    settings = get_settings()
    if not settings.AGGREGATION_ENABLED:
        logger.info("Aggregation scheduler disabled by config.")
        return

    if _scheduler and _scheduler.running:
        logger.warning("Aggregation scheduler is already running.")
        return

    _scheduler = AsyncIOScheduler(timezone="Asia/Shanghai")

    # Hourly aggregation: every hour at :05
    _scheduler.add_job(
        aggregate_hourly,
        CronTrigger(minute=5),
        id="aggregate_hourly",
        replace_existing=True,
        misfire_grace_time=600,
    )

    # Daily aggregation: every day at 00:30
    _scheduler.add_job(
        aggregate_daily,
        CronTrigger(hour=0, minute=30),
        id="aggregate_daily",
        replace_existing=True,
        misfire_grace_time=3600,
    )

    # Monthly aggregation: 1st of each month at 01:00
    _scheduler.add_job(
        aggregate_monthly,
        CronTrigger(day=1, hour=1, minute=0),
        id="aggregate_monthly",
        replace_existing=True,
        misfire_grace_time=7200,
    )

    _scheduler.start()
    logger.info("Aggregation scheduler started (hourly @:05, daily @00:30, monthly @1st 01:00).")


async def stop_aggregation_scheduler():
    """Stop the aggregation scheduler gracefully."""
    global _scheduler
    if _scheduler and _scheduler.running:
        _scheduler.shutdown(wait=False)
        logger.info("Aggregation scheduler stopped.")
    _scheduler = None