from datetime import datetime, timedelta, timezone
from fastapi import APIRouter, Depends
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, and_, text, case, literal_column
from app.core.database import get_db
from app.core.config import get_settings
from app.core.deps import get_current_user
from app.models.device import Device
from app.models.energy import EnergyData, EnergyDailySummary
from app.models.alarm import AlarmEvent
from app.models.carbon import CarbonEmission
from app.models.user import User

router = APIRouter(prefix="/dashboard", tags=["大屏数据"])


@router.get("/overview")
async def get_overview(db: AsyncSession = Depends(get_db), user: User = Depends(get_current_user)):
    """能源总览大屏核心数据"""
    now = datetime.now(timezone.utc)
    today_start = now.replace(hour=0, minute=0, second=0, microsecond=0)

    # 设备状态统计
    device_stats_q = await db.execute(
        select(Device.status, func.count(Device.id)).where(Device.is_active == True).group_by(Device.status)
    )
    device_stats = {row[0]: row[1] for row in device_stats_q.all()}

    # 今日能耗汇总 (from daily summary table)
    daily_q = await db.execute(
        select(
            EnergyDailySummary.energy_type,
            func.sum(EnergyDailySummary.total_consumption),
            func.sum(EnergyDailySummary.total_generation),
        ).where(EnergyDailySummary.date >= today_start).group_by(EnergyDailySummary.energy_type)
    )
    energy_summary = {}
    for row in daily_q.all():
        energy_summary[row[0]] = {"consumption": row[1] or 0, "generation": row[2] or 0}

    # Fallback: if daily summary is empty, compute from raw energy_data
    if not energy_summary:
        # Get the latest daily_energy per station (avoid double-counting).
        # The collector writes station-level daily_energy to individual device rows,
        # so multiple devices from the same station share the same value.
        # Group by station prefix (first 3 chars of device name, e.g. "AP1", "AP2")
        # and take MAX per station to deduplicate.
        latest_energy_q = await db.execute(
            select(
                func.substring(Device.name, text("1"), text("3")).label("station"),
                func.max(EnergyData.value).label("max_energy"),
            ).select_from(EnergyData).join(
                Device, EnergyData.device_id == Device.id
            ).where(
                and_(
                    EnergyData.timestamp >= today_start,
                    EnergyData.data_type == "daily_energy",
                    Device.device_type.in_(["pv_inverter", "sungrow_inverter"]),
                )
            ).group_by(text("station"))
        )
        total_gen = sum(row[1] or 0 for row in latest_energy_q.all())
        if total_gen > 0:
            energy_summary["electricity"] = {"consumption": 0, "generation": round(total_gen, 2)}

    # 今日碳排放
    carbon_q = await db.execute(
        select(func.sum(CarbonEmission.emission), func.sum(CarbonEmission.reduction))
        .where(CarbonEmission.date >= today_start)
    )
    carbon_row = carbon_q.first()

    # 活跃告警数
    alarm_count_q = await db.execute(
        select(func.count(AlarmEvent.id)).where(AlarmEvent.status == "active")
    )
    active_alarms = alarm_count_q.scalar() or 0

    # 最近告警
    recent_alarms_q = await db.execute(
        select(AlarmEvent).where(AlarmEvent.status == "active").order_by(AlarmEvent.triggered_at.desc()).limit(10)
    )
    recent_alarms = [
        {"id": a.id, "title": a.title, "severity": a.severity, "device_id": a.device_id,
         "triggered_at": str(a.triggered_at)}
        for a in recent_alarms_q.scalars().all()
    ]

    return {
        "device_stats": {
            "online": device_stats.get("online", 0),
            "offline": device_stats.get("offline", 0),
            "alarm": device_stats.get("alarm", 0),
            "total": sum(device_stats.values()),
        },
        "energy_today": energy_summary,
        "carbon": {
            "emission": carbon_row[0] or 0 if carbon_row else 0,
            "reduction": carbon_row[1] or 0 if carbon_row else 0,
        },
        "active_alarms": active_alarms,
        "recent_alarms": recent_alarms,
    }


@router.get("/realtime")
async def get_realtime_data(db: AsyncSession = Depends(get_db), user: User = Depends(get_current_user)):
    """实时功率数据 - 获取最近的采集数据，按站去重防止重复计数"""
    now = datetime.now(timezone.utc)
    window_start = now - timedelta(minutes=20)

    # Get latest power per station (dedup by device name prefix)
    # Sungrow collectors report station-level power, so multiple devices
    # sharing the same station (AP1xx = Phase 1, AP2xx = Phase 2) report
    # identical values. GROUP BY station prefix and take MAX to avoid
    # double-counting.
    from sqlalchemy import text as sa_text
    pv_ids = await _get_pv_device_ids(db)
    hp_ids = await _get_hp_device_ids(db)

    # PV power: dedup by station prefix
    if pv_ids:
        pv_q = await db.execute(
            select(
                func.substring(Device.name, 1, 3).label("station"),
                func.max(EnergyData.value).label("power"),
            ).select_from(EnergyData).join(
                Device, EnergyData.device_id == Device.id
            ).where(
                and_(
                    EnergyData.timestamp >= window_start,
                    EnergyData.data_type == "power",
                    EnergyData.device_id.in_(pv_ids),
                )
            ).group_by(sa_text("1"))
        )
        pv_power = sum(row[1] or 0 for row in pv_q.all())
    else:
        pv_power = 0

    # Heat pump power: dedup by station prefix
    if hp_ids:
        hp_q = await db.execute(
            select(
                func.substring(Device.name, 1, 3).label("station"),
                func.max(EnergyData.value).label("power"),
            ).select_from(EnergyData).join(
                Device, EnergyData.device_id == Device.id
            ).where(
                and_(
                    EnergyData.timestamp >= window_start,
                    EnergyData.data_type == "power",
                    EnergyData.device_id.in_(hp_ids),
                )
            ).group_by(sa_text("1"))
        )
        heatpump_power = sum(row[1] or 0 for row in hp_q.all())
    else:
        heatpump_power = 0

    return {
        "timestamp": str(now),
        "pv_power": round(pv_power, 2),
        "heatpump_power": round(heatpump_power, 2),
        "total_load": round(pv_power + heatpump_power, 2),
        "grid_power": round(max(0, heatpump_power - pv_power), 2),
    }


@router.get("/load-curve")
async def get_load_curve(
    hours: int = 24,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """负荷曲线数据"""
    now = datetime.now(timezone.utc)
    start = now - timedelta(hours=hours)

    settings = get_settings()
    if settings.is_sqlite:
        hour_expr = func.strftime('%Y-%m-%d %H:00:00', EnergyData.timestamp).label('hour')
    else:
        hour_expr = func.date_trunc('hour', EnergyData.timestamp).label('hour')

    result = await db.execute(
        select(
            hour_expr,
            func.avg(EnergyData.value).label('avg_power'),
        ).where(
            and_(EnergyData.timestamp >= start, EnergyData.data_type == "power")
        ).group_by(text('hour')).order_by(text('hour'))
    )
    return [{"time": str(row[0]), "power": round(row[1], 2)} for row in result.all()]


async def _get_pv_device_ids(db: AsyncSession):
    result = await db.execute(
        select(Device.id).where(
            Device.device_type.in_(["pv_inverter", "sungrow_inverter"]),
            Device.is_active == True,
        )
    )
    return [r[0] for r in result.fetchall()]


async def _get_hp_device_ids(db: AsyncSession):
    result = await db.execute(
        select(Device.id).where(Device.device_type == "heat_pump", Device.is_active == True)
    )
    return [r[0] for r in result.fetchall()]