from __future__ import annotations

from fastapi import APIRouter, Depends, File, HTTPException, UploadFile, status
from sqlalchemy import func, select
from sqlalchemy.orm import Session

from ..config import settings
from ..db import get_db
from ..models import KnownDog, Picture, User
from ..models.base import SubjectType
from ..schemas.common import Page
from ..schemas.dog import KnownDogCreate, KnownDogOut, KnownDogUpdate, PictureOut
from ..security import get_current_user
from ..services.images import ImageValidationError, process_and_store_picture
from .helpers import estimated_breeds_for, hydrate_picture, pictures_for

router = APIRouter(prefix="/dogs", tags=["dogs"])


def _get_owned_dog(db: Session, dog_id: int, user: User) -> KnownDog:
    dog = db.get(KnownDog, dog_id)
    if not dog:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Dog not found")
    if dog.owner_id != user.id and user.role.value != "admin":
        raise HTTPException(status.HTTP_403_FORBIDDEN, "Not your dog")
    return dog


def _to_out(db: Session, dog: KnownDog) -> KnownDogOut:
    out = KnownDogOut.model_validate(dog)
    out.pictures = pictures_for(db, SubjectType.known, dog.id)
    out.estimated_breeds = estimated_breeds_for(db, SubjectType.known, dog.id, limit=8)
    return out


@router.post("", response_model=KnownDogOut, status_code=status.HTTP_201_CREATED)
def create_dog(
    payload: KnownDogCreate,
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> KnownDogOut:
    dog = KnownDog(owner_id=user.id, **payload.model_dump())
    db.add(dog)
    db.commit()
    db.refresh(dog)
    return _to_out(db, dog)


@router.get("", response_model=Page[KnownDogOut])
def list_my_dogs(
    limit: int = 50,
    offset: int = 0,
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> Page[KnownDogOut]:
    limit = max(1, min(limit, 100))
    total = db.execute(
        select(func.count()).select_from(KnownDog).where(KnownDog.owner_id == user.id)
    ).scalar_one()
    dogs = db.execute(
        select(KnownDog)
        .where(KnownDog.owner_id == user.id)
        .order_by(KnownDog.created_at.desc())
        .limit(limit)
        .offset(offset)
    ).scalars().all()
    return Page(items=[_to_out(db, d) for d in dogs], total=total, limit=limit, offset=offset)


@router.get("/{dog_id}", response_model=KnownDogOut)
def get_dog(
    dog_id: int,
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> KnownDogOut:
    return _to_out(db, _get_owned_dog(db, dog_id, user))


@router.patch("/{dog_id}", response_model=KnownDogOut)
def update_dog(
    dog_id: int,
    payload: KnownDogUpdate,
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> KnownDogOut:
    dog = _get_owned_dog(db, dog_id, user)
    for field, value in payload.model_dump(exclude_unset=True).items():
        setattr(dog, field, value)
    db.commit()
    db.refresh(dog)
    return _to_out(db, dog)


@router.post("/{dog_id}/mark-home", response_model=KnownDogOut)
def mark_dog_home(
    dog_id: int,
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> KnownDogOut:
    """Set a dog's status back to 'home' — e.g. after a reunion, or to cancel a lost report."""
    from ..models.base import KnownDogStatus

    dog = _get_owned_dog(db, dog_id, user)
    dog.status = KnownDogStatus.home
    db.commit()
    db.refresh(dog)
    return _to_out(db, dog)


@router.post("/{dog_id}/photos", response_model=list[PictureOut], status_code=status.HTTP_201_CREATED)
def upload_photos(
    dog_id: int,
    files: list[UploadFile] = File(...),
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> list[PictureOut]:
    dog = _get_owned_dog(db, dog_id, user)
    existing = db.execute(
        select(func.count())
        .select_from(Picture)
        .where(Picture.subject_type == SubjectType.known, Picture.subject_id == dog.id)
    ).scalar_one()
    if existing + len(files) > settings.max_photos_per_dog:
        raise HTTPException(
            status.HTTP_400_BAD_REQUEST,
            f"Max {settings.max_photos_per_dog} photos per dog",
        )
    out: list[PictureOut] = []
    for i, f in enumerate(files):
        data = f.file.read()
        try:
            pic = process_and_store_picture(
                db,
                subject_type=SubjectType.known,
                subject_id=dog.id,
                data=data,
                is_primary=(existing == 0 and i == 0),
            )
        except ImageValidationError as exc:
            raise HTTPException(status.HTTP_400_BAD_REQUEST, str(exc)) from exc
        out.append(hydrate_picture(pic))

    # If this dog has an open lost case, re-run matching now that new photos exist (spec §8 step 6).
    from ..models import Case
    from ..models.base import CaseStatus, CaseType
    from ..services.matching import run_matching_for_case

    open_case = db.execute(
        select(Case)
        .where(
            Case.known_dog_id == dog.id,
            Case.type == CaseType.lost,
            Case.status.in_([CaseStatus.open, CaseStatus.matched]),
        )
        .order_by(Case.created_at.desc())
    ).scalars().first()
    if open_case:
        run_matching_for_case(db, open_case)

    db.commit()
    return out


@router.delete("/{dog_id}/photos/{img_id}", status_code=status.HTTP_204_NO_CONTENT)
def delete_photo(
    dog_id: int,
    img_id: int,
    user: User = Depends(get_current_user),
    db: Session = Depends(get_db),
) -> None:
    dog = _get_owned_dog(db, dog_id, user)
    pic = db.get(Picture, img_id)
    if not pic or pic.subject_type != SubjectType.known or pic.subject_id != dog.id:
        raise HTTPException(status.HTTP_404_NOT_FOUND, "Photo not found")
    from ..storage import get_storage

    storage = get_storage()
    storage.delete(pic.file_path)
    if pic.thumb_path:
        storage.delete(pic.thumb_path)
    db.delete(pic)
    db.commit()