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import requests
from typing import *
__all__ = ["WebFile"]
class WebFile:
def __init__(self, url: str, session: Optional[requests.Session] = None, headers: Optional[Dict[str, str]] = None, size: Optional[int] = None):
self.url = url
self.session = session or requests.Session()
self.session.headers.update(headers or {})
self._offset = 0
self.size = size if size is not None else self._fetch_size()
def _fetch_size(self):
with self.session.get(self.url, stream=True) as response:
response.raise_for_status()
content_length = response.headers.get("Content-Length")
if content_length is None:
raise ValueError("Missing Content-Length in header")
return int(content_length)
def _fetch_data(self, offset: int, n: int) -> bytes:
headers = {"Range": f"bytes={offset}-{min(offset + n - 1, self.size)}"}
response = self.session.get(self.url, headers=headers)
response.raise_for_status()
return response.content
def seekable(self) -> bool:
return True
def tell(self) -> int:
return self._offset
def available(self) -> int:
return self.size - self._offset
def seek(self, offset: int, whence: int = 0) -> None:
if whence == 0:
new_offset = offset
elif whence == 1:
new_offset = self._offset + offset
elif whence == 2:
new_offset = self.size + offset
else:
raise ValueError("Invalid value for whence")
self._offset = max(0, min(new_offset, self.size))
def read(self, n: Optional[int] = None) -> bytes:
if n is None or n < 0:
n = self.available()
else:
n = min(n, self.available())
if n == 0:
return b''
data = self._fetch_data(self._offset, n)
self._offset += len(data)
return data
def close(self) -> None:
pass
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
pass
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