import uuid
from collections import defaultdict
from datetime import UTC, datetime
from typing import Annotated

from fastapi import Depends, FastAPI, Header, HTTPException, Query, status
from sqlalchemy import func, select
from sqlalchemy.orm import Session, selectinload

from app.core import settings
from app.db import SessionLocal, create_schema, get_db
from app.models import Base, Equipment, Exercise, Workout, WorkoutItem, WorkoutSet
from app.schemas import (
    CaloriesRead,
    EquipmentCreate,
    EquipmentRead,
    ExerciseCreate,
    ExerciseRead,
    ProgressionPoint,
    ProgressionRead,
    WorkoutCreate,
    WorkoutItemCreate,
    WorkoutItemRead,
    WorkoutRead,
    WorkoutSetCreate,
    WorkoutSetRead,
    WorkoutUpdate,
)

app = FastAPI(title="Train Watcher Logic Service", version="0.1.0")


def require_service_token(x_service_token: Annotated[str | None, Header()] = None) -> None:
    if x_service_token != settings.service_token:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Invalid service token",
        )


def get_user_id(x_user_id: Annotated[str | None, Header()] = None) -> uuid.UUID:
    if not x_user_id:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Missing X-User-Id header",
        )
    try:
        return uuid.UUID(x_user_id)
    except ValueError as exc:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Invalid X-User-Id",
        ) from exc


InternalAuth = Depends(require_service_token)
Db = Annotated[Session, Depends(get_db)]
CurrentUserId = Annotated[uuid.UUID, Depends(get_user_id)]


@app.on_event("startup")
def on_startup() -> None:
    create_schema(Base.metadata)
    with SessionLocal() as db:
        seed_builtin_catalog(db)


@app.get("/health")
def health() -> dict[str, str]:
    return {"status": "ok"}


def seed_builtin_catalog(db: Session) -> None:
    exists = db.scalar(
        select(func.count()).select_from(Equipment).where(Equipment.is_builtin.is_(True))
    )
    if exists:
        return

    treadmill = Equipment(
        name="Беговая дорожка",
        description="Кардио-тренажер для ходьбы и бега.",
        is_builtin=True,
    )
    smith = Equipment(
        name="Машина Смита",
        description="Силовая рама с фиксированной траекторией грифа.",
        is_builtin=True,
    )
    db.add_all([treadmill, smith])
    db.flush()
    db.add_all(
        [
            Exercise(
                name="Жим лежа",
                description="Базовое упражнение для груди, трицепса и передней дельты.",
                is_builtin=True,
                default_calories_per_minute=6,
            ),
            Exercise(
                name="Приседания",
                description="Базовое упражнение для ног и корпуса.",
                is_builtin=True,
                default_calories_per_minute=8,
            ),
            Exercise(
                name="Бег",
                description="Кардио-нагрузка на беговой дорожке.",
                equipment_id=treadmill.id,
                is_builtin=True,
                default_calories_per_minute=10,
            ),
        ]
    )
    db.commit()


def accessible_equipment(db: Session, user_id: uuid.UUID):
    return select(Equipment).where(
        (Equipment.is_builtin.is_(True)) | (Equipment.owner_user_id == user_id)
    )


def accessible_exercises(db: Session, user_id: uuid.UUID):
    return select(Exercise).where(
        (Exercise.is_builtin.is_(True)) | (Exercise.owner_user_id == user_id)
    )


@app.get(
    "/internal/catalog/equipment",
    dependencies=[InternalAuth],
    response_model=list[EquipmentRead],
)
def list_equipment(db: Db, user_id: CurrentUserId, search: str | None = None) -> list[Equipment]:
    statement = accessible_equipment(db, user_id).order_by(
        Equipment.is_builtin.desc(), Equipment.name
    )
    if search:
        statement = statement.where(Equipment.name.ilike(f"%{search}%"))
    return list(db.scalars(statement))


@app.post(
    "/internal/catalog/equipment",
    dependencies=[InternalAuth],
    response_model=EquipmentRead,
    status_code=status.HTTP_201_CREATED,
)
def create_equipment(payload: EquipmentCreate, db: Db, user_id: CurrentUserId) -> Equipment:
    equipment = Equipment(owner_user_id=user_id, is_builtin=False, **payload.model_dump())
    db.add(equipment)
    db.commit()
    db.refresh(equipment)
    return equipment


@app.get(
    "/internal/catalog/exercises",
    dependencies=[InternalAuth],
    response_model=list[ExerciseRead],
)
def list_exercises(db: Db, user_id: CurrentUserId, search: str | None = None) -> list[Exercise]:
    statement = accessible_exercises(db, user_id).order_by(
        Exercise.is_builtin.desc(), Exercise.name
    )
    if search:
        statement = statement.where(Exercise.name.ilike(f"%{search}%"))
    return list(db.scalars(statement))


@app.post(
    "/internal/catalog/exercises",
    dependencies=[InternalAuth],
    response_model=ExerciseRead,
    status_code=status.HTTP_201_CREATED,
)
def create_exercise(payload: ExerciseCreate, db: Db, user_id: CurrentUserId) -> Exercise:
    if payload.equipment_id:
        equipment = db.get(Equipment, payload.equipment_id)
        if not equipment or (not equipment.is_builtin and equipment.owner_user_id != user_id):
            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Equipment not found")
    exercise = Exercise(owner_user_id=user_id, is_builtin=False, **payload.model_dump())
    db.add(exercise)
    db.commit()
    db.refresh(exercise)
    return exercise


@app.get("/internal/workouts", dependencies=[InternalAuth], response_model=list[WorkoutRead])
def list_workouts(db: Db, user_id: CurrentUserId) -> list[Workout]:
    return list(
        db.scalars(
            select(Workout)
            .where(Workout.user_id == user_id)
            .options(selectinload(Workout.items).selectinload(WorkoutItem.sets))
            .order_by(Workout.started_at.desc())
        )
    )


@app.post(
    "/internal/workouts",
    dependencies=[InternalAuth],
    response_model=WorkoutRead,
    status_code=status.HTTP_201_CREATED,
)
def create_workout(payload: WorkoutCreate, db: Db, user_id: CurrentUserId) -> Workout:
    workout = Workout(
        user_id=user_id,
        started_at=payload.started_at or datetime.now(UTC),
        notes=payload.notes,
    )
    db.add(workout)
    db.commit()
    db.refresh(workout)
    return workout


@app.get("/internal/workouts/{workout_id}", dependencies=[InternalAuth], response_model=WorkoutRead)
def get_workout(workout_id: uuid.UUID, db: Db, user_id: CurrentUserId) -> Workout:
    workout = db.scalar(
        select(Workout)
        .where(Workout.id == workout_id, Workout.user_id == user_id)
        .options(selectinload(Workout.items).selectinload(WorkoutItem.sets))
    )
    if not workout:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Workout not found")
    return workout


@app.patch(
    "/internal/workouts/{workout_id}",
    dependencies=[InternalAuth],
    response_model=WorkoutRead,
)
def update_workout(
    workout_id: uuid.UUID, payload: WorkoutUpdate, db: Db, user_id: CurrentUserId
) -> Workout:
    workout = get_workout(workout_id, db, user_id)
    if payload.finished_at is not None:
        workout.finished_at = payload.finished_at
    if payload.notes is not None:
        workout.notes = payload.notes
    recalculate_workout_calories(db, workout.id)
    db.commit()
    db.refresh(workout)
    return workout


@app.post(
    "/internal/workouts/{workout_id}/items",
    dependencies=[InternalAuth],
    response_model=WorkoutItemRead,
    status_code=status.HTTP_201_CREATED,
)
def add_workout_item(
    workout_id: uuid.UUID, payload: WorkoutItemCreate, db: Db, user_id: CurrentUserId
) -> WorkoutItem:
    workout = get_workout(workout_id, db, user_id)
    if payload.exercise_id:
        exercise = db.get(Exercise, payload.exercise_id)
        if not exercise or (not exercise.is_builtin and exercise.owner_user_id != user_id):
            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Exercise not found")
    if payload.equipment_id:
        equipment = db.get(Equipment, payload.equipment_id)
        if not equipment or (not equipment.is_builtin and equipment.owner_user_id != user_id):
            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Equipment not found")

    next_index = payload.order_index
    if next_index is None:
        next_index = len(workout.items)
    item = WorkoutItem(
        workout_id=workout.id,
        **payload.model_dump(exclude={"order_index"}),
        order_index=next_index,
    )
    db.add(item)
    db.commit()
    db.refresh(item)
    return item


@app.post(
    "/internal/workout-items/{item_id}/sets",
    dependencies=[InternalAuth],
    response_model=WorkoutSetRead,
    status_code=status.HTTP_201_CREATED,
)
def add_workout_set(
    item_id: uuid.UUID,
    payload: WorkoutSetCreate,
    db: Db,
    user_id: CurrentUserId,
) -> WorkoutSet:
    item = db.scalar(
        select(WorkoutItem)
        .join(Workout)
        .where(WorkoutItem.id == item_id, Workout.user_id == user_id)
        .options(selectinload(WorkoutItem.sets), selectinload(WorkoutItem.exercise))
    )
    if not item:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Workout item not found")

    calories = payload.calories
    if calories is None:
        calories = estimate_set_calories(item, payload)

    workout_set = WorkoutSet(
        workout_item_id=item.id,
        set_index=len(item.sets) + 1,
        weight=payload.weight,
        reps=payload.reps,
        duration_seconds=payload.duration_seconds,
        calories=calories,
        completed_at=payload.completed_at or datetime.now(UTC),
    )
    db.add(workout_set)
    db.flush()
    recalculate_workout_calories(db, item.workout_id)
    db.commit()
    db.refresh(workout_set)
    return workout_set


@app.delete(
    "/internal/workout-items/{item_id}",
    dependencies=[InternalAuth],
    status_code=status.HTTP_204_NO_CONTENT,
)
def delete_workout_item(item_id: uuid.UUID, db: Db, user_id: CurrentUserId) -> None:
    item = db.scalar(
        select(WorkoutItem)
        .join(Workout)
        .where(WorkoutItem.id == item_id, Workout.user_id == user_id)
    )
    if not item:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Workout item not found")
    workout = db.get(Workout, item.workout_id)
    if workout and workout.finished_at:
        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Workout already finished")
    workout_id = item.workout_id
    db.delete(item)
    db.flush()
    recalculate_workout_calories(db, workout_id)
    db.commit()


@app.delete(
    "/internal/workout-items/{item_id}/sets/{set_id}",
    dependencies=[InternalAuth],
    status_code=status.HTTP_204_NO_CONTENT,
)
def delete_workout_set(
    item_id: uuid.UUID, set_id: uuid.UUID, db: Db, user_id: CurrentUserId
) -> None:
    ws = db.scalar(
        select(WorkoutSet)
        .join(WorkoutItem)
        .join(Workout)
        .where(
            WorkoutSet.id == set_id,
            WorkoutItem.id == item_id,
            Workout.user_id == user_id,
        )
    )
    if not ws:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Set not found")
    workout = db.scalar(
        select(Workout).join(WorkoutItem).where(WorkoutItem.id == item_id)
    )
    if workout and workout.finished_at:
        raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Workout already finished")
    db.delete(ws)
    db.flush()
    if workout:
        recalculate_workout_calories(db, workout.id)
    db.commit()


def estimate_set_calories(item: WorkoutItem, payload: WorkoutSetCreate) -> float:
    if item.exercise and item.exercise.default_calories_per_minute and payload.duration_seconds:
        return round(
            float(item.exercise.default_calories_per_minute) * payload.duration_seconds / 60,
            2,
        )
    return round((payload.weight * max(payload.reps, 1)) / 120, 2)


def recalculate_workout_calories(db: Session, workout_id: uuid.UUID) -> None:
    total = db.scalar(
        select(func.coalesce(func.sum(WorkoutSet.calories), 0))
        .join(WorkoutItem, WorkoutSet.workout_item_id == WorkoutItem.id)
        .where(WorkoutItem.workout_id == workout_id)
    )
    workout = db.get(Workout, workout_id)
    if workout:
        workout.estimated_calories = float(total or 0)


@app.get(
    "/internal/analytics/progression",
    dependencies=[InternalAuth],
    response_model=ProgressionRead,
)
def get_progression(
    db: Db,
    user_id: CurrentUserId,
    kind: Annotated[str, Query(pattern="^(exercise|equipment)$")],
    entity_id: Annotated[uuid.UUID | None, Query()] = None,
) -> ProgressionRead:
    statement = (
        select(Workout.started_at, WorkoutSet.weight, WorkoutSet.reps)
        .join(WorkoutItem, WorkoutSet.workout_item_id == WorkoutItem.id)
        .join(Workout, WorkoutItem.workout_id == Workout.id)
        .where(Workout.user_id == user_id)
        .order_by(Workout.started_at.asc(), WorkoutSet.completed_at.asc())
    )
    if entity_id and kind == "exercise":
        statement = statement.where(WorkoutItem.exercise_id == entity_id)
    elif entity_id and kind == "equipment":
        statement = statement.where(WorkoutItem.equipment_id == entity_id)

    rows = list(db.execute(statement))
    grouped: dict[str, dict[str, float]] = defaultdict(lambda: {"max_weight": 0, "volume": 0})
    weights: list[float] = []
    for started_at, weight, reps in rows:
        date_key = started_at.date().isoformat()
        numeric_weight = float(weight or 0)
        grouped[date_key]["max_weight"] = max(grouped[date_key]["max_weight"], numeric_weight)
        grouped[date_key]["volume"] += numeric_weight * int(reps or 0)
        weights.append(numeric_weight)

    points = [
        ProgressionPoint(date=date, max_weight=values["max_weight"], volume=values["volume"])
        for date, values in sorted(grouped.items())
    ]
    previous_delta = None
    if len(weights) >= 2:
        previous_delta = round(weights[-1] - weights[-2], 2)
    return ProgressionRead(
        last_weight=weights[-1] if weights else None,
        max_weight=max(weights) if weights else None,
        previous_delta=previous_delta,
        points=points,
    )


@app.get("/internal/analytics/calories", dependencies=[InternalAuth], response_model=CaloriesRead)
def get_calories(db: Db, user_id: CurrentUserId) -> CaloriesRead:
    workouts = list(
        db.scalars(
            select(Workout).where(Workout.user_id == user_id).order_by(Workout.started_at.desc())
        )
    )
    total = sum(float(workout.estimated_calories or 0) for workout in workouts)
    return CaloriesRead(
        total_calories=round(total, 2),
        workouts=[
            {
                "id": str(workout.id),
                "date": workout.started_at.date().isoformat(),
                "calories": float(workout.estimated_calories or 0),
            }
            for workout in workouts
        ],
    )