import uuid
from pathlib import Path

from fastapi import APIRouter, Depends, UploadFile, File, HTTPException
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from backend.app.core.auth import get_current_rider
from backend.app.core.config import settings
from backend.app.core.database import get_session
from backend.app.models.activity import Activity, ActivityMetrics, DataPoint, Interval
from backend.app.models.fitness import PowerCurve
from backend.app.models.rider import Rider
from backend.app.schemas.activity import (
    ActivityResponse,
    ActivityListResponse,
    DataPointResponse,
    ZonesResponse,
    PowerCurveResponse,
)
from backend.app.models.fitness import DiaryEntry
from backend.app.services.fit_parser import parse_fit_file
from backend.app.services.metrics import calculate_metrics
from backend.app.services.zones import calculate_power_zones, calculate_hr_zones
from backend.app.services.power_curve import calculate_power_curve
from backend.app.services.intervals import detect_intervals
from backend.app.services.ai_summary import generate_summary

router = APIRouter()


@router.post("/upload", response_model=ActivityResponse)
async def upload_activity(
    file: UploadFile = File(...),
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    if not file.filename or not file.filename.lower().endswith(".fit"):
        raise HTTPException(status_code=400, detail="Only .FIT files are accepted")

    upload_dir = Path(settings.UPLOAD_DIR)
    upload_dir.mkdir(parents=True, exist_ok=True)

    file_id = uuid.uuid4()
    file_path = upload_dir / f"{file_id}.fit"

    content = await file.read()
    file_path.write_bytes(content)

    # 1. Parse FIT
    activity, data_points = parse_fit_file(content, rider.id, str(file_path))
    session.add(activity)
    await session.flush()

    # 2. Save data points
    for dp in data_points:
        dp.activity_id = activity.id
    session.add_all(data_points)

    # 3. Calculate & save metrics (with FTP if available)
    metrics = calculate_metrics(data_points, activity, ftp=rider.ftp)
    if metrics:
        session.add(metrics)

    # 4. Detect & save intervals
    intervals = detect_intervals(data_points, ftp=rider.ftp)
    for interval in intervals:
        interval.activity_id = activity.id
    session.add_all(intervals)

    # 5. Calculate & save power curve
    curve_data = calculate_power_curve(data_points)
    if curve_data:
        pc = PowerCurve(activity_id=activity.id, curve_data=curve_data)
        session.add(pc)

    await session.commit()
    await session.refresh(activity)
    return activity


@router.get("", response_model=ActivityListResponse)
async def list_activities(
    limit: int = 20,
    offset: int = 0,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    count_query = select(func.count(Activity.id)).where(Activity.rider_id == rider.id)
    total = (await session.execute(count_query)).scalar() or 0

    query = (
        select(Activity)
        .where(Activity.rider_id == rider.id)
        .order_by(Activity.date.desc())
        .limit(limit)
        .offset(offset)
    )
    result = await session.execute(query)
    activities = result.scalars().all()

    return ActivityListResponse(items=activities, total=total)


@router.get("/{activity_id}", response_model=ActivityResponse)
async def get_activity(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")
    return activity


@router.get("/{activity_id}/stream", response_model=list[DataPointResponse])
async def get_activity_stream(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    # Verify ownership
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    query = (
        select(DataPoint)
        .where(DataPoint.activity_id == activity_id)
        .order_by(DataPoint.timestamp)
    )
    result = await session.execute(query)
    return result.scalars().all()


@router.get("/{activity_id}/zones", response_model=ZonesResponse)
async def get_activity_zones(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    query = (
        select(DataPoint)
        .where(DataPoint.activity_id == activity_id)
        .order_by(DataPoint.timestamp)
    )
    result = await session.execute(query)
    data_points = list(result.scalars().all())

    power_zones = []
    hr_zones = []

    if rider.ftp:
        power_zones = calculate_power_zones(data_points, rider.ftp)
    if rider.lthr:
        hr_zones = calculate_hr_zones(data_points, rider.lthr)

    return ZonesResponse(power_zones=power_zones, hr_zones=hr_zones)


@router.get("/{activity_id}/power-curve", response_model=PowerCurveResponse)
async def get_activity_power_curve(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    # Try cached
    query = select(PowerCurve).where(PowerCurve.activity_id == activity_id)
    result = await session.execute(query)
    pc = result.scalar_one_or_none()

    if pc:
        return PowerCurveResponse(curve=pc.curve_data)

    # Calculate on the fly
    dp_query = (
        select(DataPoint)
        .where(DataPoint.activity_id == activity_id)
        .order_by(DataPoint.timestamp)
    )
    dp_result = await session.execute(dp_query)
    data_points = list(dp_result.scalars().all())
    curve = calculate_power_curve(data_points)

    return PowerCurveResponse(curve=curve)


@router.post("/{activity_id}/ai-summary")
async def generate_ai_summary(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    # Check for existing diary entry with summary
    query = select(DiaryEntry).where(DiaryEntry.activity_id == activity_id)
    result = await session.execute(query)
    diary = result.scalar_one_or_none()

    if diary and diary.ai_summary:
        return {"summary": diary.ai_summary}

    # Generate new summary
    summary = await generate_summary(activity, rider_ftp=rider.ftp)

    if diary:
        diary.ai_summary = summary
    else:
        diary = DiaryEntry(activity_id=activity_id, ai_summary=summary)
        session.add(diary)

    await session.commit()
    return {"summary": summary}


@router.delete("/{activity_id}")
async def delete_activity(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    # Delete related records
    for model in [DataPoint, Interval, ActivityMetrics, PowerCurve, DiaryEntry]:
        q = select(model).where(model.activity_id == activity_id)
        result = await session.execute(q)
        for row in result.scalars().all():
            await session.delete(row)

    await session.delete(activity)
    await session.commit()
    return {"ok": True}


@router.get("/{activity_id}/diary")
async def get_diary(
    activity_id: uuid.UUID,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    query = select(DiaryEntry).where(DiaryEntry.activity_id == activity_id)
    result = await session.execute(query)
    diary = result.scalar_one_or_none()

    if not diary:
        return {"rider_notes": None, "mood": None, "rpe": None, "sleep_hours": None}

    return {
        "rider_notes": diary.rider_notes,
        "mood": diary.mood,
        "rpe": diary.rpe,
        "sleep_hours": diary.sleep_hours,
    }


@router.put("/{activity_id}/diary")
async def update_diary(
    activity_id: uuid.UUID,
    data: dict,
    rider: Rider = Depends(get_current_rider),
    session: AsyncSession = Depends(get_session),
):
    activity = await session.get(Activity, activity_id)
    if not activity or activity.rider_id != rider.id:
        raise HTTPException(status_code=404, detail="Activity not found")

    query = select(DiaryEntry).where(DiaryEntry.activity_id == activity_id)
    result = await session.execute(query)
    diary = result.scalar_one_or_none()

    if not diary:
        diary = DiaryEntry(activity_id=activity_id)
        session.add(diary)

    for field in ["rider_notes", "mood", "rpe", "sleep_hours"]:
        if field in data:
            setattr(diary, field, data[field])

    await session.commit()
    return {
        "rider_notes": diary.rider_notes,
        "mood": diary.mood,
        "rpe": diary.rpe,
        "sleep_hours": diary.sleep_hours,
    }