from fastapi import APIRouter, Depends, HTTPException
from sqlmodel import Session, select
from typing import List, Dict

from library_service.settings import get_session
from library_service.models.db import Author, Book, Genre, AuthorBookLink, GenreBookLink
from library_service.models.dto import AuthorRead, BookRead, GenreRead

router = APIRouter(tags=["relations"])


# Add author to book
@router.post(
    "/relationships/author-book",
    response_model=AuthorBookLink,
    summary="Связать автора и книгу",
    description="Добавляет связь между автором и книгой в систему",
)
def add_author_to_book(
    author_id: int, book_id: int, session: Session = Depends(get_session)
):
    author = session.get(Author, author_id)
    if not author:
        raise HTTPException(status_code=404, detail="Author not found")

    book = session.get(Book, book_id)
    if not book:
        raise HTTPException(status_code=404, detail="Book not found")

    existing_link = session.exec(
        select(AuthorBookLink)
        .where(AuthorBookLink.author_id == author_id)
        .where(AuthorBookLink.book_id == book_id)
    ).first()

    if existing_link:
        raise HTTPException(status_code=400, detail="Relationship already exists")

    link = AuthorBookLink(author_id=author_id, book_id=book_id)
    session.add(link)
    session.commit()
    session.refresh(link)
    return link


# Remove author from book
@router.delete(
    "/relationships/author-book",
    response_model=Dict[str, str],
    summary="Разделить автора и книгу",
    description="Удаляет связь между автором и книгой в системе",
)
def remove_author_from_book(
    author_id: int, book_id: int, session: Session = Depends(get_session)
):
    link = session.exec(
        select(AuthorBookLink)
        .where(AuthorBookLink.author_id == author_id)
        .where(AuthorBookLink.book_id == book_id)
    ).first()

    if not link:
        raise HTTPException(status_code=404, detail="Relationship not found")

    session.delete(link)
    session.commit()
    return {"message": "Relationship removed successfully"}


# Get author's books
@router.get(
    "/authors/{author_id}/books/",
    response_model=List[BookRead],
    summary="Получить книги, написанные автором",
    description="Возвращает все книги в системе, написанные автором",
)
def get_books_for_author(author_id: int, session: Session = Depends(get_session)):
    author = session.get(Author, author_id)
    if not author:
        raise HTTPException(status_code=404, detail="Author not found")

    books = session.exec(
        select(Book).join(AuthorBookLink).where(AuthorBookLink.author_id == author_id)
    ).all()

    return [BookRead(**book.model_dump()) for book in books]


# Get book's authors
@router.get(
    "/books/{book_id}/authors/",
    response_model=List[AuthorRead],
    summary="Получить авторов книги",
    description="Возвращает всех авторов книги в системе",
)
def get_authors_for_book(book_id: int, session: Session = Depends(get_session)):
    book = session.get(Book, book_id)
    if not book:
        raise HTTPException(status_code=404, detail="Book not found")

    authors = session.exec(
        select(Author).join(AuthorBookLink).where(AuthorBookLink.book_id == book_id)
    ).all()

    return [AuthorRead(**author.model_dump()) for author in authors]


# Add genre to book
@router.post(
    "/relationships/genre-book",
    response_model=GenreBookLink,
    summary="Связать книгу и жанр",
    description="Добавляет связь между книгой и жанром в систему",
)
def add_genre_to_book(
    genre_id: int, book_id: int, session: Session = Depends(get_session)
):
    genre = session.get(Genre, genre_id)
    if not genre:
        raise HTTPException(status_code=404, detail="Genre not found")

    book = session.get(Book, book_id)
    if not book:
        raise HTTPException(status_code=404, detail="Book not found")

    existing_link = session.exec(
        select(GenreBookLink)
        .where(GenreBookLink.genre_id == genre_id)
        .where(GenreBookLink.book_id == book_id)
    ).first()

    if existing_link:
        raise HTTPException(status_code=400, detail="Relationship already exists")

    link = GenreBookLink(genre_id=genre_id, book_id=book_id)
    session.add(link)
    session.commit()
    session.refresh(link)
    return link


# Remove author from book
@router.delete(
    "/relationships/genre-book",
    response_model=Dict[str, str],
    summary="Разделить жанр и книгу",
    description="Удаляет связь между жанром и книгой в системе",
)
def remove_genre_from_book(
    genre_id: int, book_id: int, session: Session = Depends(get_session)
):
    link = session.exec(
        select(GenreBookLink)
        .where(GenreBookLink.genre_id == genre_id)
        .where(GenreBookLink.book_id == book_id)
    ).first()

    if not link:
        raise HTTPException(status_code=404, detail="Relationship not found")

    session.delete(link)
    session.commit()
    return {"message": "Relationship removed successfully"}


# Get genre's books
@router.get(
    "/genres/{author_id}/books/",
    response_model=List[BookRead],
    summary="Получить книги, написанные в жанре",
    description="Возвращает все книги в системе в этом жанре",
)
def get_books_for_genre(genre_id: int, session: Session = Depends(get_session)):
    genre = session.get(Genre, genre_id)
    if not genre:
        raise HTTPException(status_code=404, detail="Genre not found")

    books = session.exec(
        select(Book).join(GenreBookLink).where(GenreBookLink.author_id == genre_id)
    ).all()

    return [BookRead(**book.model_dump()) for book in books]


# Get book's genres
@router.get(
    "/books/{book_id}/genres/",
    response_model=List[GenreRead],
    summary="Получить жанры книги",
    description="Возвращает все жанры книги в системе",
)
def get_authors_for_book(book_id: int, session: Session = Depends(get_session)):
    book = session.get(Book, book_id)
    if not book:
        raise HTTPException(status_code=404, detail="Book not found")

    genres = session.exec(
        select(Genre).join(GenreBookLink).where(GenreBookLink.book_id == book_id)
    ).all()

    return [GenreRead(**author.model_dump()) for genre in genres]