"""Shared constants, request models, and access helpers for document routes."""
from __future__ import annotations

import uuid
from typing import Optional

from fastapi import HTTPException
from pydantic import BaseModel, Field, field_validator
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from db.models import Document, Share

_CLOUD_PROVIDERS = frozenset({"google_drive", "onedrive", "nextcloud", "webdav"})


class UploadUrlRequest(BaseModel):
    filename: str
    content_type: str


class DocumentPatch(BaseModel):
    filename: Optional[str] = Field(None, min_length=1, max_length=255)
    folder_id: Optional[uuid.UUID] = None

    @field_validator("filename")
    @classmethod
    def filename_no_path_separators(cls, v: Optional[str]) -> Optional[str]:
        if v is not None and ("/" in v or "\\" in v):
            raise ValueError("filename must not contain path separators")
        return v


def _document_not_found() -> HTTPException:
    return HTTPException(status_code=404, detail="Document not found")


def parse_document_uuid(doc_id: str) -> uuid.UUID:
    try:
        return uuid.UUID(doc_id)
    except ValueError:
        raise _document_not_found()


async def get_owned_document(
    session: AsyncSession,
    doc_id: str,
    user_id: uuid.UUID,
) -> Document:
    uid = parse_document_uuid(doc_id)
    doc = await session.get(Document, uid)
    if doc is None or doc.user_id != user_id:
        raise _document_not_found()
    return doc


async def get_accessible_document(
    session: AsyncSession,
    doc_id: str,
    user_id: uuid.UUID,
) -> tuple[Document, bool]:
    uid = parse_document_uuid(doc_id)
    doc = await session.get(Document, uid)
    if doc is None:
        raise _document_not_found()

    if doc.user_id == user_id:
        return doc, False

    result = await session.execute(
        select(Share).where(
            Share.document_id == doc.id,
            Share.recipient_id == user_id,
        )
    )
    if result.scalar_one_or_none() is None:
        raise _document_not_found()
    return doc, True