"""Cloud import endpoints for the ebook library.

These let the browser browse a user-configured WebDAV server and pull one book
out of it. The fetch is proxied through the server rather than done in the
browser because the WebDAV host is a different origin and will not send CORS
headers for it.

That proxy is a deliberate, narrow relaxation of the same rule the ISBN lookup
in books/views.py bends: the server sees the file's bytes in memory for the
duration of one request, but never persists them. The book is encrypted in the
browser and only then POSTed to /books/upload/ as ciphertext, exactly like a
local upload — nothing readable is ever stored server-side.
"""

from django.conf import settings
from django.http import HttpResponse, JsonResponse
from django.utils import timezone
from django.views.decorators.http import require_http_methods

from accounts.models import WebDAVSource
from accounts.webdav import WebDAVError, WebDAVInputError, list_directory, fetch_file
from .views import _require_auth


def _get_source(request, pk):
    return WebDAVSource.objects.filter(pk=pk, user=request.user).first()


@require_http_methods(['GET'])
def cloud_sources(request):
    unauthorized = _require_auth(request)
    if unauthorized:
        return unauthorized

    sources = request.user.webdav_sources.all()
    return JsonResponse({'sources': [
        {'id': s.id, 'label': s.label, 'host': s.base_url}
        for s in sources
    ]})


@require_http_methods(['GET'])
def cloud_browse(request, pk):
    unauthorized = _require_auth(request)
    if unauthorized:
        return unauthorized

    source = _get_source(request, pk)
    if not source:
        return JsonResponse({'error': 'unknown source'}, status=404)

    path = request.GET.get('path', '')
    try:
        entries = list_directory(source, path)
    except WebDAVInputError as exc:
        return JsonResponse({'error': str(exc)}, status=400)
    except WebDAVError as exc:
        return JsonResponse({'error': str(exc)}, status=502)

    source.last_used_at = timezone.now()
    source.save(update_fields=['last_used_at'])

    return JsonResponse({'ok': True, 'path': path, 'entries': entries})


@require_http_methods(['GET'])
def cloud_fetch(request, pk):
    unauthorized = _require_auth(request)
    if unauthorized:
        return unauthorized

    source = _get_source(request, pk)
    if not source:
        return JsonResponse({'error': 'unknown source'}, status=404)

    path = request.GET.get('path', '')
    try:
        payload = fetch_file(source, path, settings.EBOOK_MAX_BYTES)
    except WebDAVInputError as exc:
        return JsonResponse({'error': str(exc)}, status=400)
    except WebDAVError as exc:
        return JsonResponse({'error': str(exc)}, status=502)

    response = HttpResponse(payload, content_type='application/octet-stream')
    # These are the book's plaintext bytes, on their way to be encrypted in the
    # browser. Keeping them out of the HTTP disk cache (and any reverse proxy
    # in front) is what makes "nothing readable is stored" true end to end.
    response['Cache-Control'] = 'no-store'
    return response