# the backend would need to have these OBJECTS and functions:

class Download:
    sha256: str
    download_date: str
    download_url: str
    filename: str
    
   

class DownloadStore:

   def list():
      """Return an iterable of all the stored downloads"""
       
   def get(sha256_checksum: string):
      """Return a download object for this checksum or None."""

   def put(content: bytes, download_url: string, download_date: string, filename: string):
      """Store content with its metadata. Return a Download object on success. Raise an exception on error."""

   def find(download_url: [string|None], filename: [string|None], download_date: [string|None]):
      """Return a download object for this checksum or None."""


class LocalFilesystemProvider(DownloadStore):
    """Use a local storage for downloads"""
    root_path: Path # absolute path this would be a global setting for an SCIO instance


class S3LikeProvider(DownloadStore):
    """Use a an S3 bucket for download storage"""
    bucket_name: str
    aws_userid: str
    aws_apikey: str
    other_aws_creddentials: str

class SftpProvider(DownloadStore):
    """Use a an SFTP/SSH account for download storage"""
    host: str
    root_path: str
    ssh_creddentials: str

<checksum>/
    content: actual unique blob for that checksum
    <origin-hash>.json: actual unique JSON for an origin
    <origin-hash>.json: actual unique JSON for an origin
    <origin-hash>.json: actual unique JSON for an origin
    <origin-hash>.json: actual unique JSON for an origin

# Stored locally at: 

59/4c/67/807fb16238b30c44bdf74f36c02cdf22d1c8cda91ef8a0ed8dabf5620a/
   content
   origin-234682346.json # here 234682346 is a computed hash based on filename, download_date and url
    {
    "sha256": "594c67807fb16238b30c44bdf74f36c02cdf22d1c8cda91ef8a0ed8dabf5620a",
    "filename": "MarkupSafe-2.0.1.tar.gz",
    "download_date": "2025-03-12-13:10",
    "url": "https://files.pythonhosted.org/packages/bf/10/MarkupSafe-2.0.1.tar.gz"
    }
   origin-23sdsdf4682346.json
    {
    "sha256": "594c67807fb16238b30c44bdf74f36c02cdf22d1c8cda91ef8a0ed8dabf5620a",
    "filename": "MarkupSafe-2.2.1.tar.gz",
    "download_date": "2025-03-15-13:10",
    "url": "https://files.pypi.org//MarkupSafe-2.2.1.tar.gz"
    }

>>> content=b"serfsrfserwe"
>>> content_sha256=sha256(content).hexdigest()
>>> # create paths for storage
>>> # write content blob
....
>>> # write metadata
>>> dnl ={
...     "sha256": "594c67807fb16238b30c44bdf74f36c02cdf22d1c8cda91ef8a0ed8dabf5620a",
...     "filename": "MarkupSafe-2.0.1.tar.gz",
...     "download_date": "2025-03-12-13:10",
...     "url": "https://files.pythonhosted.org/packages/bf/10/MarkupSafe-2.0.1.tar.gz"
...     }
>>> to_hash= b"{dnl['filename']}{dnl['download_date']}{dnl['download_url']}"
>>> origin_filename= sha256(to_hash).hexdigest()
>>> with open(f"origin-{origin_filename}.json", "w") as output:
...   json.dump(dnl, output, indent=2)
... 
...