from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, desc, delete
from pydantic import BaseModel
from typing import Optional, List
from datetime import datetime

from app.core.database import get_db
from app.core.security import get_current_user
from app.models.user import User, Activity, ActivityDataPoint, ActivityLap

router = APIRouter()


class ActivitySummary(BaseModel):
    id: int
    name: str
    sport_type: str
    start_time: datetime
    distance_m: Optional[float]
    duration_s: Optional[float]
    elevation_gain_m: Optional[float]
    avg_heart_rate: Optional[float]
    avg_cadence: Optional[float]
    avg_speed_ms: Optional[float]
    calories: Optional[float]
    polyline: Optional[str]
    bounding_box: Optional[dict]
    hr_zones: Optional[dict]
    named_route_id: Optional[int]

    class Config:
        from_attributes = True


class ActivityDetail(ActivitySummary):
    end_time: Optional[datetime]
    elevation_loss_m: Optional[float]
    max_heart_rate: Optional[float]
    avg_power: Optional[float]
    normalized_power: Optional[float]
    max_speed_ms: Optional[float]
    avg_temperature_c: Optional[float]
    training_stress_score: Optional[float]
    vo2max_estimate: Optional[float]


class DataPointOut(BaseModel):
    timestamp: Optional[datetime]
    latitude: Optional[float]
    longitude: Optional[float]
    altitude_m: Optional[float]
    heart_rate: Optional[float]
    cadence: Optional[float]
    speed_ms: Optional[float]
    power: Optional[float]
    temperature_c: Optional[float]
    distance_m: Optional[float]

    class Config:
        from_attributes = True


class LapOut(BaseModel):
    lap_number: int
    start_time: Optional[datetime]
    duration_s: Optional[float]
    distance_m: Optional[float]
    avg_heart_rate: Optional[float]
    avg_cadence: Optional[float]
    avg_speed_ms: Optional[float]
    avg_power: Optional[float]

    class Config:
        from_attributes = True


@router.get("/", response_model=List[ActivitySummary])
async def list_activities(
    page: int = Query(1, ge=1),
    per_page: int = Query(20, ge=1, le=100),
    sport_type: Optional[str] = None,
    from_date: Optional[datetime] = None,
    to_date: Optional[datetime] = None,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    q = select(Activity).where(Activity.user_id == current_user.id)

    if sport_type:
        q = q.where(Activity.sport_type == sport_type)
    if from_date:
        q = q.where(Activity.start_time >= from_date)
    if to_date:
        q = q.where(Activity.start_time <= to_date)

    q = q.order_by(desc(Activity.start_time))
    q = q.offset((page - 1) * per_page).limit(per_page)

    result = await db.execute(q)
    return result.scalars().all()


@router.get("/{activity_id}", response_model=ActivityDetail)
async def get_activity(
    activity_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    result = await db.execute(
        select(Activity).where(
            Activity.id == activity_id,
            Activity.user_id == current_user.id,
        )
    )
    activity = result.scalar_one_or_none()
    if not activity:
        raise HTTPException(status_code=404, detail="Activity not found")
    return activity


@router.get("/{activity_id}/data-points", response_model=List[DataPointOut])
async def get_data_points(
    activity_id: int,
    downsample: int = Query(0, ge=0, description="Return every Nth point; 0 = all"),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    act = await db.execute(
        select(Activity).where(
            Activity.id == activity_id,
            Activity.user_id == current_user.id,
        )
    )
    if not act.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Activity not found")

    q = select(ActivityDataPoint).where(
        ActivityDataPoint.activity_id == activity_id
    ).order_by(ActivityDataPoint.timestamp)

    result = await db.execute(q)
    points = result.scalars().all()

    if downsample > 1:
        points = points[::downsample]

    return points


@router.get("/{activity_id}/laps", response_model=List[LapOut])
async def get_laps(
    activity_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    act = await db.execute(
        select(Activity).where(
            Activity.id == activity_id,
            Activity.user_id == current_user.id,
        )
    )
    if not act.scalar_one_or_none():
        raise HTTPException(status_code=404, detail="Activity not found")

    result = await db.execute(
        select(ActivityLap)
        .where(ActivityLap.activity_id == activity_id)
        .order_by(ActivityLap.lap_number)
    )
    return result.scalars().all()


@router.patch("/{activity_id}/name")
async def rename_activity(
    activity_id: int,
    body: dict,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    result = await db.execute(
        select(Activity).where(
            Activity.id == activity_id,
            Activity.user_id == current_user.id,
        )
    )
    activity = result.scalar_one_or_none()
    if not activity:
        raise HTTPException(status_code=404, detail="Activity not found")

    activity.name = body.get("name", activity.name)
    await db.commit()
    return {"id": activity_id, "name": activity.name}


@router.delete("/{activity_id}", status_code=204)
async def delete_activity(
    activity_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    result = await db.execute(
        select(Activity).where(
            Activity.id == activity_id,
            Activity.user_id == current_user.id,
        )
    )
    activity = result.scalar_one_or_none()
    if not activity:
        raise HTTPException(status_code=404, detail="Activity not found")
    await db.delete(activity)
    await db.commit()


@router.post("/{activity_id}/reprocess")
async def reprocess_activity(
    activity_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Re-parse the source FIT file and update polyline, data points etc."""
    import os
    result = await db.execute(
        select(Activity).where(
            Activity.id == activity_id,
            Activity.user_id == current_user.id,
        )
    )
    activity = result.scalar_one_or_none()
    if not activity:
        raise HTTPException(status_code=404, detail="Activity not found")
    if not activity.source_file:
        raise HTTPException(status_code=400, detail="No source file stored for this activity")
    if not os.path.exists(activity.source_file):
        raise HTTPException(status_code=404, detail="Source file no longer exists on disk")

    source_file = activity.source_file
    source_type = activity.source_type or "fit"

    await db.execute(delete(ActivityDataPoint).where(ActivityDataPoint.activity_id == activity_id))
    await db.execute(delete(ActivityLap).where(ActivityLap.activity_id == activity_id))
    await db.delete(activity)
    await db.commit()

    from app.workers.tasks import process_activity_file
    task = process_activity_file.delay(source_file, current_user.id, source_type)
    return {"task_id": task.id, "status": "queued"}