"""AI预测引擎 API - 光伏/负荷/热泵预测 & 自发自用优化"""

from datetime import datetime, timezone, timedelta
from typing import Optional

from fastapi import APIRouter, Depends, Query, HTTPException
from pydantic import BaseModel
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, and_

from app.core.database import get_db
from app.core.deps import get_current_user, require_roles
from app.models.user import User
from app.models.prediction import PredictionTask, PredictionResult, OptimizationSchedule
from app.services.ai_prediction import (
    forecast_pv, forecast_load, forecast_heatpump_cop,
    optimize_self_consumption, get_prediction_accuracy, run_prediction,
)

router = APIRouter(prefix="/prediction", tags=["AI预测"])


# ── Schemas ────────────────────────────────────────────────────────────

class RunPredictionRequest(BaseModel):
    device_id: Optional[int] = None
    prediction_type: str  # pv, load, heatpump, optimization
    horizon_hours: int = 24
    parameters: Optional[dict] = None


# ── Endpoints ──────────────────────────────────────────────────────────

@router.get("/forecast")
async def get_forecast(
    device_id: Optional[int] = None,
    type: str = Query("pv", pattern="^(pv|load|heatpump)$"),
    horizon: int = Query(24, ge=1, le=168),
    building_type: str = Query("office", pattern="^(office|factory)$"),
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """获取预测结果 - PV发电/负荷/热泵COP"""
    if type == "pv":
        if not device_id:
            raise HTTPException(400, "光伏预测需要指定device_id")
        return await forecast_pv(db, device_id, horizon)
    elif type == "load":
        return await forecast_load(db, device_id, building_type, horizon)
    elif type == "heatpump":
        if not device_id:
            raise HTTPException(400, "热泵预测需要指定device_id")
        return await forecast_heatpump_cop(db, device_id, horizon)


@router.post("/run")
async def trigger_prediction(
    req: RunPredictionRequest,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """触发新的预测任务"""
    task = await run_prediction(
        db, req.device_id, req.prediction_type,
        req.horizon_hours, req.parameters,
    )
    return {
        "task_id": task.id,
        "status": task.status,
        "prediction_type": task.prediction_type,
        "horizon_hours": task.horizon_hours,
        "error_message": task.error_message,
    }


@router.get("/accuracy")
async def prediction_accuracy(
    type: Optional[str] = Query(None, pattern="^(pv|load|heatpump|optimization)$"),
    days: int = Query(7, ge=1, le=90),
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """获取预测精度指标 (MAE, RMSE, MAPE)"""
    return await get_prediction_accuracy(db, type, days)


@router.get("/optimization")
async def get_optimization(
    horizon: int = Query(24, ge=1, le=72),
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """获取自发自用优化建议"""
    return await optimize_self_consumption(db, horizon)


@router.post("/optimization/{schedule_id}/approve")
async def approve_optimization(
    schedule_id: int,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(require_roles("admin", "energy_manager")),
):
    """审批优化调度方案"""
    result = await db.execute(
        select(OptimizationSchedule).where(OptimizationSchedule.id == schedule_id)
    )
    schedule = result.scalar_one_or_none()
    if not schedule:
        raise HTTPException(404, "优化方案不存在")
    if schedule.status != "pending":
        raise HTTPException(400, f"方案状态为 {schedule.status}，无法审批")

    schedule.status = "approved"
    schedule.approved_by = user.id
    schedule.approved_at = datetime.now(timezone.utc)
    return {"id": schedule.id, "status": "approved"}


@router.get("/history")
async def prediction_history(
    type: Optional[str] = Query(None),
    days: int = Query(7, ge=1, le=30),
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """历史预测任务列表"""
    cutoff = datetime.now(timezone.utc) - timedelta(days=days)
    conditions = [PredictionTask.created_at >= cutoff]
    if type:
        conditions.append(PredictionTask.prediction_type == type)

    query = (
        select(PredictionTask)
        .where(and_(*conditions))
        .order_by(PredictionTask.created_at.desc())
        .offset((page - 1) * page_size)
        .limit(page_size)
    )
    result = await db.execute(query)
    tasks = result.scalars().all()

    return [{
        "id": t.id,
        "device_id": t.device_id,
        "prediction_type": t.prediction_type,
        "horizon_hours": t.horizon_hours,
        "status": t.status,
        "created_at": str(t.created_at) if t.created_at else None,
        "completed_at": str(t.completed_at) if t.completed_at else None,
        "error_message": t.error_message,
    } for t in tasks]


@router.get("/schedules")
async def list_schedules(
    status: Optional[str] = Query(None, pattern="^(pending|approved|executed|rejected)$"),
    days: int = Query(7, ge=1, le=30),
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """获取优化调度方案列表"""
    cutoff = datetime.now(timezone.utc) - timedelta(days=days)
    conditions = [OptimizationSchedule.created_at >= cutoff]
    if status:
        conditions.append(OptimizationSchedule.status == status)

    result = await db.execute(
        select(OptimizationSchedule)
        .where(and_(*conditions))
        .order_by(OptimizationSchedule.created_at.desc())
    )
    schedules = result.scalars().all()

    return [{
        "id": s.id,
        "device_id": s.device_id,
        "date": str(s.date) if s.date else None,
        "expected_savings_kwh": s.expected_savings_kwh,
        "expected_savings_yuan": s.expected_savings_yuan,
        "status": s.status,
        "schedule_data": s.schedule_data,
        "created_at": str(s.created_at) if s.created_at else None,
    } for s in schedules]