import uuid
from datetime import datetime
from typing import List, Optional

from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import func, or_
from sqlalchemy.orm import Session, joinedload

import auth
import database
import models
import schemas


router = APIRouter(
    prefix="/exercises",
    tags=["exercises"],
    dependencies=[Depends(auth.get_current_user)],
)


def get_current_timestamp() -> str:
    return datetime.utcnow().strftime("%Y-%m-%dT%H:%M:%fZ")


def new_sync_id() -> str:
    return uuid.uuid4().hex


def normalize_name(name: str) -> str:
    return (name or "").strip().lower()


def find_exercise_by_name(
    db: Session,
    user: models.User,
    name: str,
) -> Optional[models.Exercise]:
    n = normalize_name(name)
    if not n:
        return None

    owned = (
        db.query(models.Exercise)
        .filter(
            models.Exercise.owner_id == user.id,
            func.lower(models.Exercise.name) == n,
        )
        .first()
    )
    if owned:
        return owned

    return (
        db.query(models.Exercise)
        .filter(
            models.Exercise.owner_id.is_(None),
            func.lower(models.Exercise.name) == n,
        )
        .first()
    )


def get_owned_exercise(
    db: Session,
    exercise_id: int,
    user: models.User,
) -> models.Exercise:
    exercise = (
        db.query(models.Exercise)
        .filter(
            models.Exercise.id == exercise_id,
            models.Exercise.owner_id == user.id,
        )
        .first()
    )
    if not exercise:
        raise HTTPException(status_code=404, detail="Exercise not found")
    return exercise


@router.post("/", response_model=schemas.ExerciseOut)
def create_exercise(
    exercise: schemas.ExerciseCreate,
    current_user: models.User = Depends(auth.get_current_user),
    db: Session = Depends(database.get_db),
):
    sync_id = exercise.sync_id or new_sync_id()
    timestamp = get_current_timestamp()

    existing = db.query(models.Exercise).filter(models.Exercise.sync_id == sync_id).first()
    if existing:
        if existing.owner_id is not None and existing.owner_id != current_user.id:
            raise HTTPException(status_code=409, detail="Exercise sync_id belongs to another user")

        if existing.owner_id == current_user.id:
            existing.name = exercise.name
            existing.workout_type_id = exercise.workout_type_id
            existing.updated_at = timestamp
            db.commit()
            db.refresh(existing)
            return existing

        # Глобальное упражнение — не даём пользователю его менять, просто возвращаем
        return existing

    by_name = find_exercise_by_name(db, current_user, exercise.name)
    if by_name:
        if by_name.owner_id == current_user.id:
            by_name.sync_id = by_name.sync_id or sync_id
            by_name.workout_type_id = exercise.workout_type_id
            by_name.updated_at = timestamp
            db.commit()
            db.refresh(by_name)
            return by_name

        # Нашли глобальное с таким же именем — используем его
        return by_name

    db_exercise = models.Exercise(
        sync_id=sync_id,
        owner_id=current_user.id,
        name=exercise.name.strip(),
        workout_type_id=exercise.workout_type_id,
        created_at=timestamp,
        updated_at=timestamp,
    )

    db.add(db_exercise)
    db.commit()
    db.refresh(db_exercise)
    return db_exercise


@router.get("/", response_model=List[schemas.ExerciseOut])
def list_exercises(
    workout_type_id: Optional[int] = None,
    current_user: models.User = Depends(auth.get_current_user),
    db: Session = Depends(database.get_db),
):
    query = db.query(models.Exercise).filter(
        or_(
            models.Exercise.owner_id == current_user.id,
            models.Exercise.owner_id.is_(None),
        )
    )

    if workout_type_id:
        query = query.filter(models.Exercise.workout_type_id == workout_type_id)

    return query.order_by(models.Exercise.name).all()


@router.get("/history/{exercise_name}")
def get_exercise_history(
    exercise_name: str,
    client_id: Optional[int] = None,
    limit: int = 10,
    current_user: models.User = Depends(auth.get_current_user),
    db: Session = Depends(database.get_db),
):
    """
    Возвращает историю упражнения для текущего пользователя.
    Если указан client_id — только тренировки этого клиента.
    """
    normalized = normalize_name(exercise_name)

    workout_query = (
        db.query(models.Workout.id)
        .join(models.WorkoutExercise, models.WorkoutExercise.workout_id == models.Workout.id)
        .filter(
            models.Workout.owner_id == current_user.id,
            models.Workout.end_time.isnot(None),
            func.lower(models.WorkoutExercise.exercise_name) == normalized,
        )
    )

    if client_id:
        client = (
            db.query(models.Client)
            .filter(
                models.Client.id == client_id,
                models.Client.owner_id == current_user.id,
            )
            .first()
        )
        if not client:
            raise HTTPException(status_code=404, detail="Client not found")
        workout_query = workout_query.filter(models.Workout.client_id == client_id)

    workout_ids = [
        row[0]
        for row in workout_query.order_by(models.Workout.start_time.desc()).limit(limit).all()
    ]

    if not workout_ids:
        return []

    workouts = (
        db.query(models.Workout)
        .options(
            joinedload(models.Workout.workout_exercises)
            .joinedload(models.WorkoutExercise.sets)
            .joinedload(models.Set.dropset_items)
        )
        .filter(models.Workout.id.in_(workout_ids))
        .order_by(models.Workout.start_time.desc())
        .all()
    )

    result = []

    for workout in workouts:
        for we in workout.workout_exercises or []:
            if normalize_name(we.exercise_name) != normalized:
                continue

            sets_payload = []
            for s in we.sets or []:
                sets_payload.append(
                    {
                        "is_dropset": bool(s.is_dropset),
                        "weight": s.weight,
                        "reps": s.reps,
                        "rating": s.rating,
                        "notes": s.notes or "",
                        "timestamp": s.timestamp,
                        "dropset_items": [
                            {
                                "weight": di.weight,
                                "reps": di.reps,
                                "sort_order": di.sort_order,
                            }
                            for di in (s.dropset_items or [])
                        ],
                    }
                )

            if sets_payload:
                result.append(
                    {
                        "workout_sync_id": workout.sync_id,
                        "date": workout.start_time,
                        "client_id": workout.client_id,
                        "exercise_name": we.exercise_name,
                        "sets": sets_payload,
                    }
                )

    return result


@router.get("/{exercise_id}", response_model=schemas.ExerciseOut)
def get_exercise(
    exercise_id: int,
    current_user: models.User = Depends(auth.get_current_user),
    db: Session = Depends(database.get_db),
):
    exercise = (
        db.query(models.Exercise)
        .filter(
            or_(
                models.Exercise.id == exercise_id,
            ),
            or_(
                models.Exercise.owner_id == current_user.id,
                models.Exercise.owner_id.is_(None),
            ),
        )
        .first()
    )
    if not exercise:
        raise HTTPException(status_code=404, detail="Exercise not found")
    return exercise


@router.put("/{exercise_id}", response_model=schemas.ExerciseOut)
def update_exercise(
    exercise_id: int,
    exercise: schemas.ExerciseUpdate,
    current_user: models.User = Depends(auth.get_current_user),
    db: Session = Depends(database.get_db),
):
    db_exercise = get_owned_exercise(db, exercise_id, current_user)

    update_data = exercise.dict(exclude_unset=True)
    for key, value in update_data.items():
        setattr(db_exercise, key, value)

    db_exercise.updated_at = get_current_timestamp()
    db.commit()
    db.refresh(db_exercise)
    return db_exercise


@router.delete("/{exercise_id}")
def delete_exercise(
    exercise_id: int,
    current_user: models.User = Depends(auth.get_current_user),
    db: Session = Depends(database.get_db),
):
    db_exercise = get_owned_exercise(db, exercise_id, current_user)
    db.delete(db_exercise)
    db.commit()
    return {"status": "deleted"}