views.py

from django.contrib.auth.decorators import login_required
from django.core.exceptions import PermissionDenied
from django.shortcuts import render, redirect, get_object_or_404
from django.views.decorators.http import require_POST

from reader.forms import BookForm
from reader.models import Book, UserBook


def user_can_access_book(request, book) -> bool:
    has_permission = False
    if book.public or book.owner == request.user:
        has_permission = True
    elif request.user.is_authenticated:
        has_permission = (request.user.has_perm("reader.book_view_others", book)
                          or request.user.has_perm("reader.book_view_others"))
    return has_permission


def index(request):
    return render(request, "reader/index.html")

@login_required(login_url='login')
def create_book(request):
    if request.method == "POST":
        form = BookForm(data=request.POST, files=request.FILES, request=request)
        if form.is_valid():
            permission_checks = True
            permission_checks = permission_checks and (
                request.user.has_perm("reader.book_create_public")
                if form.cleaned_data["public"] else True
            )
            permission_checks = permission_checks and (
                request.user.has_perm("reader.book_create_loanable")
                if form.cleaned_data["loanable"]
                   or (form.cleaned_data["loanable_copies"] != 0) else True
            )
            permission_checks = permission_checks and (
                request.user.has_perm("reader.book_create_no_owner")
                if not form.cleaned_data["owner"] else True
            )
            permission_checks = permission_checks and (
                request.user.has_perm("reader.book_create_others_owner")
                if form.cleaned_data["owner"] != request.user else True
            )
            if permission_checks:
                obj = form.save(commit=False)
                obj.created_by = request.user
                obj.save()
                return redirect("index") # TODO change this URL
            else:
                form.add_error(None, "You do not have permission to use the options you have selected")
    else:
        form = BookForm(request=request)
    return render(request, "reader/book_form.html", {
        "title": "Create Book",
        "form": form
    })


def browse_books(request):
    books = Book.objects.filter(public=True)
    books_private = []
    if request.user.is_authenticated:
        books_private_q = Book.objects.filter(public=False)
        for book in books_private_q:
            # Filter books that the user has permission to view and hasn't read
            if ((book.owner == request.user
                    or request.user.has_perm("reader.book_view_others", book)
                    or request.user.has_perm("reader.book_view_others"))
                    and (book.userbook_set.filter(user=request.user).count() == 0)):
                books_private.append(book)
    return render(request, "reader/browse.html", {
        "page": "browse",
        "books": books,
        "books_private": books_private
    })

def view_book(request, book_id):
    # Get book
    book = get_object_or_404(Book, id=book_id)

    # Check user has permission to access this book
    if not user_can_access_book(request, book):
        raise PermissionDenied

    # Get the user's book stats for this book
    user_book_q = None
    if request.user.is_authenticated:
        user_book_q = UserBook.objects.filter(book=book, user=request.user)
    user_in_library = False if user_book_q is None else user_book_q.count() > 0

    # Render
    return render(request, "reader/view_book.html", {
        "book": book,
        "user_book": user_book_q.first(),
        "user_in_library": user_in_library
    })

@login_required(login_url='login')
def library(request):
    userbooks = UserBook.objects.filter(user=request.user)
    books = []
    for userbook in userbooks:
        ub = {
            "id": userbook.book.id,
            "userbook_id": userbook.id,
            "title": userbook.book.title,
            "author": userbook.book.author,
            "publisher": userbook.book.publisher,
            "ids": userbook.book.ids,
            "description": userbook.book.description,
            "owner": userbook.book.owner,
            "public": userbook.book.public,
            "loanable": userbook.book.loanable,
            "image": userbook.book.image,
            "loanable_copies": userbook.book.loanable_copies,
            "percentage_read": userbook.percentage_read,
            "percentage_read_whole": round(userbook.percentage_read * 100),
            "last_read": userbook.last_read,
            "last_progress_device": userbook.last_progress_device,
        }
        books.append(ub)
    return render(request, "reader/library.html", {"books": books, "page": "library"})

@require_POST
@login_required(login_url='login')
def add_to_library(request, book_id):
    book = get_object_or_404(Book, id=book_id)
    if not user_can_access_book(request, book):
        raise PermissionDenied
    userbook = UserBook(book=book, user=request.user)
    userbook.save()
    return redirect("view_book", book_id=book_id)