from datetime import date, datetime
from pathlib import Path
import logging

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

from app.core.database import get_db
from app.core.deps import get_current_user
from app.models.report import ReportTemplate, ReportTask
from app.models.user import User
from app.services.report_generator import ReportGenerator, REPORTS_DIR
from app.services.audit import log_audit

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/reports", tags=["报表管理"])


class TemplateCreate(BaseModel):
    name: str
    report_type: str
    description: str | None = None
    fields: list[dict]
    filters: dict | None = None
    aggregation: str = "sum"
    time_granularity: str = "hour"


class TaskCreate(BaseModel):
    template_id: int
    name: str | None = None
    schedule: str | None = None
    recipients: list[str] | None = None
    export_format: str = "xlsx"


class QuickReportRequest(BaseModel):
    report_type: str  # daily, monthly, device_status, alarm, carbon
    export_format: str = "xlsx"
    start_date: date | None = None
    end_date: date | None = None
    month: int | None = None
    year: int | None = None
    device_ids: list[int] | None = None


# ------------------------------------------------------------------ #
#  Templates
# ------------------------------------------------------------------ #

@router.get("/templates")
async def list_templates(db: AsyncSession = Depends(get_db), user: User = Depends(get_current_user)):
    result = await db.execute(select(ReportTemplate).order_by(ReportTemplate.id))
    return [{
        "id": t.id, "name": t.name, "report_type": t.report_type, "description": t.description,
        "fields": t.fields, "is_system": t.is_system, "aggregation": t.aggregation,
        "time_granularity": t.time_granularity,
    } for t in result.scalars().all()]


@router.post("/templates")
async def create_template(data: TemplateCreate, db: AsyncSession = Depends(get_db), user: User = Depends(get_current_user)):
    template = ReportTemplate(**data.model_dump(), created_by=user.id)
    db.add(template)
    await db.flush()
    return {"id": template.id, "name": template.name}


# ------------------------------------------------------------------ #
#  Tasks CRUD
# ------------------------------------------------------------------ #

@router.get("/tasks")
async def list_tasks(db: AsyncSession = Depends(get_db), user: User = Depends(get_current_user)):
    result = await db.execute(select(ReportTask).order_by(ReportTask.id.desc()))
    return [{
        "id": t.id, "template_id": t.template_id, "name": t.name, "schedule": t.schedule,
        "status": t.status, "export_format": t.export_format, "file_path": t.file_path,
        "last_run": str(t.last_run) if t.last_run else None,
    } for t in result.scalars().all()]


@router.post("/tasks")
async def create_task(data: TaskCreate, db: AsyncSession = Depends(get_db), user: User = Depends(get_current_user)):
    task = ReportTask(**data.model_dump(), created_by=user.id)
    db.add(task)
    await db.flush()
    return {"id": task.id}


# ------------------------------------------------------------------ #
#  Run / Status / Download
# ------------------------------------------------------------------ #

REPORT_TYPE_METHODS = {
    "daily": "generate_energy_daily_report",
    "monthly": "generate_monthly_summary",
    "device_status": "generate_device_status_report",
    "alarm": "generate_alarm_report",
    "carbon": "generate_carbon_report",
}


def _parse_date(val, default: date) -> date:
    if not val:
        return default
    if isinstance(val, date):
        return val
    try:
        return date.fromisoformat(str(val))
    except (ValueError, TypeError):
        return default


@router.post("/tasks/{task_id}/run")
async def run_task(
    task_id: int,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    result = await db.execute(select(ReportTask).where(ReportTask.id == task_id))
    task = result.scalar_one_or_none()
    if not task:
        raise HTTPException(status_code=404, detail="任务不存在")

    # Try Celery first
    try:
        from app.core.config import get_settings
        from app.tasks.report_tasks import CELERY_AVAILABLE
        if CELERY_AVAILABLE and get_settings().CELERY_ENABLED:
            task.status = "running"
            await db.flush()
            from app.tasks.report_tasks import generate_report_task
            generate_report_task.delay(task_id)
            return {"message": "报表生成任务已提交(异步)", "task_id": task.id, "mode": "async"}
    except Exception:
        pass

    # Inline async generation (avoids event loop issues with BackgroundTasks)
    task.status = "running"
    await db.flush()

    template = (await db.execute(
        select(ReportTemplate).where(ReportTemplate.id == task.template_id)
    )).scalar_one_or_none()
    if not template:
        task.status = "failed"
        await db.flush()
        raise HTTPException(status_code=400, detail=f"模板 {task.template_id} 不存在")

    filters = template.filters or {}
    today = date.today()
    start_date = _parse_date(filters.get("start_date"), default=today.replace(day=1))
    end_date = _parse_date(filters.get("end_date"), default=today)
    device_ids = filters.get("device_ids")
    export_format = task.export_format or "xlsx"
    report_type = template.report_type

    method_name = REPORT_TYPE_METHODS.get(report_type)
    if not method_name:
        task.status = "failed"
        await db.flush()
        raise HTTPException(status_code=400, detail=f"未知报表类型: {report_type}")

    try:
        gen = ReportGenerator(db)
        method = getattr(gen, method_name)
        if report_type == "monthly":
            month = filters.get("month", today.month)
            year = filters.get("year", today.year)
            filepath = await method(month=month, year=year, export_format=export_format)
        elif report_type == "device_status":
            filepath = await method(export_format=export_format)
        else:
            kwargs = {"start_date": start_date, "end_date": end_date, "export_format": export_format}
            if device_ids and report_type == "daily":
                kwargs["device_ids"] = device_ids
            filepath = await method(**kwargs)

        task.status = "completed"
        task.file_path = filepath
        task.last_run = datetime.now()
        await db.flush()
        await log_audit(db, user.id, "export", "report", detail=f"运行报表任务 #{task_id}")
        logger.info(f"Report task {task_id} completed: {filepath}")
        return {"message": "报表生成完成", "task_id": task.id, "mode": "sync", "status": "completed"}
    except Exception as e:
        logger.error(f"Report task {task_id} failed: {e}")
        task.status = "failed"
        await db.flush()
        raise HTTPException(status_code=500, detail=f"报表生成失败: {str(e)}")


@router.get("/tasks/{task_id}/status")
async def task_status(
    task_id: int,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    result = await db.execute(select(ReportTask).where(ReportTask.id == task_id))
    task = result.scalar_one_or_none()
    if not task:
        raise HTTPException(status_code=404, detail="任务不存在")
    return {
        "id": task.id,
        "status": task.status,
        "file_path": task.file_path,
        "last_run": str(task.last_run) if task.last_run else None,
    }


@router.get("/tasks/{task_id}/download")
async def download_report(
    task_id: int,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    result = await db.execute(select(ReportTask).where(ReportTask.id == task_id))
    task = result.scalar_one_or_none()
    if not task:
        raise HTTPException(status_code=404, detail="任务不存在")
    if task.status != "completed" or not task.file_path:
        raise HTTPException(status_code=400, detail="报表尚未生成完成")
    if not Path(task.file_path).exists():
        raise HTTPException(status_code=404, detail="报表文件不存在")

    filename = Path(task.file_path).name
    media_type = (
        "application/pdf" if filename.endswith(".pdf")
        else "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
    )
    return FileResponse(task.file_path, filename=filename, media_type=media_type)


# ------------------------------------------------------------------ #
#  Quick report (synchronous, no task record needed)
# ------------------------------------------------------------------ #

@router.post("/generate")
async def generate_quick_report(
    req: QuickReportRequest,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """Generate a report synchronously and return the download URL.
    Useful for demo and quick one-off reports without creating a task record.
    """
    gen = ReportGenerator(db)
    today = date.today()

    try:
        if req.report_type == "daily":
            filepath = await gen.generate_energy_daily_report(
                start_date=req.start_date or today.replace(day=1),
                end_date=req.end_date or today,
                device_ids=req.device_ids,
                export_format=req.export_format,
            )
        elif req.report_type == "monthly":
            filepath = await gen.generate_monthly_summary(
                month=req.month or today.month,
                year=req.year or today.year,
                export_format=req.export_format,
            )
        elif req.report_type == "device_status":
            filepath = await gen.generate_device_status_report(
                export_format=req.export_format,
            )
        elif req.report_type == "alarm":
            filepath = await gen.generate_alarm_report(
                start_date=req.start_date or today.replace(day=1),
                end_date=req.end_date or today,
                export_format=req.export_format,
            )
        elif req.report_type == "carbon":
            filepath = await gen.generate_carbon_report(
                start_date=req.start_date or today.replace(day=1),
                end_date=req.end_date or today,
                export_format=req.export_format,
            )
        else:
            raise HTTPException(status_code=400, detail=f"未知的报表类型: {req.report_type}")
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"报表生成失败: {str(e)}")

    filename = Path(filepath).name
    await log_audit(db, user.id, "export", "report", detail=f"生成报表: {req.report_type} ({req.export_format})")
    return {
        "message": "报表生成成功",
        "filename": filename,
        "download_url": f"/api/v1/reports/download/{filename}",
    }


@router.get("/download/{filename}")
async def download_by_filename(
    filename: str,
    user: User = Depends(get_current_user),
):
    """Download a generated report file by filename."""
    filepath = REPORTS_DIR / filename
    if not filepath.exists():
        raise HTTPException(status_code=404, detail="文件不存在")
    # Prevent path traversal
    if not filepath.resolve().parent == REPORTS_DIR.resolve():
        raise HTTPException(status_code=400, detail="非法文件路径")

    media_type = (
        "application/pdf" if filename.endswith(".pdf")
        else "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
    )
    return FileResponse(str(filepath), filename=filename, media_type=media_type)