import filecmp import os import random import shutil import string from contextlib import contextmanager from dataclasses import dataclass from datetime import datetime from enum import Enum from pathlib import Path, PurePath from typing import BinaryIO, Iterator, Optional, Tuple from rich.markup import escape from .logging import log from .report import Report from .utils import ReusableAsyncContextManager, fmt_path, fmt_real_path, prompt_yes_no SUFFIX_CHARS = string.ascii_lowercase + string.digits SUFFIX_LENGTH = 6 TRIES = 5 class OutputDirError(Exception): pass class Redownload(Enum): NEVER = "never" NEVER_SMART = "never-smart" ALWAYS = "always" ALWAYS_SMART = "always-smart" @staticmethod def from_string(string: str) -> "Redownload": try: return Redownload(string) except ValueError: raise ValueError("must be one of 'never', 'never-smart'," " 'always', 'always-smart'") class OnConflict(Enum): PROMPT = "prompt" LOCAL_FIRST = "local-first" REMOTE_FIRST = "remote-first" NO_DELETE = "no-delete" @staticmethod def from_string(string: str) -> "OnConflict": try: return OnConflict(string) except ValueError: raise ValueError("must be one of 'prompt', 'local-first'," " 'remote-first', 'no-delete'") @dataclass class Heuristics: mtime: Optional[datetime] class FileSink: def __init__(self, file: BinaryIO): self._file = file self._done = False @property def file(self) -> BinaryIO: return self._file def done(self) -> None: self._done = True def is_done(self) -> bool: return self._done @dataclass class DownloadInfo: remote_path: PurePath path: PurePath local_path: Path tmp_path: Path heuristics: Heuristics on_conflict: OnConflict success: bool = False class FileSinkToken(ReusableAsyncContextManager[FileSink]): # Whenever this class is entered, it creates a new temporary file and # returns a corresponding FileSink. # # When it is exited again, the file is closed and information about the # download handed back to the OutputDirectory. def __init__( self, output_dir: "OutputDirectory", remote_path: PurePath, path: PurePath, local_path: Path, heuristics: Heuristics, on_conflict: OnConflict, ): super().__init__() self._output_dir = output_dir self._remote_path = remote_path self._path = path self._local_path = local_path self._heuristics = heuristics self._on_conflict = on_conflict async def _on_aenter(self) -> FileSink: tmp_path, file = await self._output_dir._create_tmp_file(self._local_path) sink = FileSink(file) async def after_download() -> None: await self._output_dir._after_download(DownloadInfo( self._remote_path, self._path, self._local_path, tmp_path, self._heuristics, self._on_conflict, sink.is_done(), )) self._stack.push_async_callback(after_download) self._stack.enter_context(file) return sink class OutputDirectory: def __init__( self, root: Path, redownload: Redownload, on_conflict: OnConflict, ): self._root = root self._redownload = redownload self._on_conflict = on_conflict self._report = Report() def prepare(self) -> None: log.explain_topic(f"Creating base directory at {fmt_real_path(self._root)}") try: self._root.mkdir(parents=True, exist_ok=True) except OSError: raise OutputDirError("Failed to create base directory") def register_reserved(self, path: PurePath) -> None: self._report.mark_reserved(path) def resolve(self, path: PurePath) -> Path: """ May throw an OutputDirError. """ if ".." in path.parts: raise OutputDirError(f"Forbidden segment '..' in path {fmt_path(path)}") if "." in path.parts: raise OutputDirError(f"Forbidden segment '.' in path {fmt_path(path)}") return self._root / path def _should_download( self, local_path: Path, heuristics: Heuristics, redownload: Redownload, ) -> bool: # If we don't have a *file* at the local path, we'll always redownload # since we know that the remote is different from the local files. This # includes the case where no local file exists. if not local_path.is_file(): log.explain("No corresponding file present locally") # TODO Don't download if on_conflict is LOCAL_FIRST or NO_DELETE return True log.explain(f"Redownload policy is {redownload.value}") if redownload == Redownload.NEVER: return False elif redownload == Redownload.ALWAYS: return True stat = local_path.stat() remote_newer = None if mtime := heuristics.mtime: remote_newer = mtime.timestamp() > stat.st_mtime if remote_newer: log.explain("Remote file seems to be newer") else: log.explain("Local file seems to be newer") if redownload == Redownload.NEVER_SMART: if remote_newer is None: return False else: return remote_newer elif redownload == Redownload.ALWAYS_SMART: if remote_newer is None: return True else: return not remote_newer # This should never be reached raise ValueError(f"{redownload!r} is not a valid redownload policy") # The following conflict resolution functions all return False if the local # file(s) should be kept and True if they should be replaced by the remote # files. async def _conflict_lfrf( self, on_conflict: OnConflict, path: PurePath, ) -> bool: if on_conflict == OnConflict.PROMPT: async with log.exclusive_output(): prompt = f"Replace {fmt_path(path)} with remote file?" return await prompt_yes_no(prompt, default=False) elif on_conflict == OnConflict.LOCAL_FIRST: return False elif on_conflict == OnConflict.REMOTE_FIRST: return True elif on_conflict == OnConflict.NO_DELETE: return True # This should never be reached raise ValueError(f"{on_conflict!r} is not a valid conflict policy") async def _conflict_ldrf( self, on_conflict: OnConflict, path: PurePath, ) -> bool: if on_conflict == OnConflict.PROMPT: async with log.exclusive_output(): prompt = f"Recursively delete {fmt_path(path)} and replace with remote file?" return await prompt_yes_no(prompt, default=False) elif on_conflict == OnConflict.LOCAL_FIRST: return False elif on_conflict == OnConflict.REMOTE_FIRST: return True elif on_conflict == OnConflict.NO_DELETE: return False # This should never be reached raise ValueError(f"{on_conflict!r} is not a valid conflict policy") async def _conflict_lfrd( self, on_conflict: OnConflict, path: PurePath, parent: PurePath, ) -> bool: if on_conflict == OnConflict.PROMPT: async with log.exclusive_output(): prompt = f"Delete {fmt_path(parent)} so remote file {fmt_path(path)} can be downloaded?" return await prompt_yes_no(prompt, default=False) elif on_conflict == OnConflict.LOCAL_FIRST: return False elif on_conflict == OnConflict.REMOTE_FIRST: return True elif on_conflict == OnConflict.NO_DELETE: return False # This should never be reached raise ValueError(f"{on_conflict!r} is not a valid conflict policy") async def _conflict_delete_lf( self, on_conflict: OnConflict, path: PurePath, ) -> bool: if on_conflict == OnConflict.PROMPT: async with log.exclusive_output(): prompt = f"Delete {fmt_path(path)}?" return await prompt_yes_no(prompt, default=False) elif on_conflict == OnConflict.LOCAL_FIRST: return False elif on_conflict == OnConflict.REMOTE_FIRST: return True elif on_conflict == OnConflict.NO_DELETE: return False # This should never be reached raise ValueError(f"{on_conflict!r} is not a valid conflict policy") def _tmp_path(self, base: Path, suffix_length: int) -> Path: prefix = "" if base.name.startswith(".") else "." suffix = "".join(random.choices(SUFFIX_CHARS, k=suffix_length)) name = f"{prefix}{base.name}.tmp.{suffix}" return base.parent / name async def _create_tmp_file( self, local_path: Path, ) -> Tuple[Path, BinaryIO]: """ May raise an OutputDirError. """ # Create tmp file for attempt in range(TRIES): suffix_length = SUFFIX_LENGTH + 2 * attempt tmp_path = self._tmp_path(local_path, suffix_length) try: return tmp_path, open(tmp_path, "xb") except FileExistsError: pass # Try again raise OutputDirError("Failed to create temporary file") async def download( self, remote_path: PurePath, path: PurePath, mtime: Optional[datetime] = None, redownload: Optional[Redownload] = None, on_conflict: Optional[OnConflict] = None, ) -> Optional[FileSinkToken]: """ May throw an OutputDirError, a MarkDuplicateError or a MarkConflictError. """ heuristics = Heuristics(mtime) redownload = self._redownload if redownload is None else redownload on_conflict = self._on_conflict if on_conflict is None else on_conflict local_path = self.resolve(path) self._report.mark(path) if not self._should_download(local_path, heuristics, redownload): return None # Detect and solve local-dir-remote-file conflict if local_path.is_dir(): log.explain("Conflict: There's a dir in place of the local file") if await self._conflict_ldrf(on_conflict, path): log.explain("Result: Delete the dir") shutil.rmtree(local_path) else: log.explain("Result: Keep the dir") return None # Detect and solve local-file-remote-dir conflict for parent in path.parents: local_parent = self.resolve(parent) if local_parent.exists() and not local_parent.is_dir(): log.explain("Conflict: One of the local file's parents is a file") if await self._conflict_lfrd(on_conflict, path, parent): log.explain("Result: Delete the obstructing file") local_parent.unlink() break else: log.explain("Result: Keep the obstructing file") return None # Ensure parent directory exists local_path.parent.mkdir(parents=True, exist_ok=True) return FileSinkToken(self, remote_path, path, local_path, heuristics, on_conflict) def _update_metadata(self, info: DownloadInfo) -> None: if mtime := info.heuristics.mtime: mtimestamp = mtime.timestamp() os.utime(info.local_path, times=(mtimestamp, mtimestamp)) @contextmanager def _ensure_deleted(self, path: Path) -> Iterator[None]: try: yield finally: path.unlink(missing_ok=True) async def _after_download(self, info: DownloadInfo) -> None: with self._ensure_deleted(info.tmp_path): log.action(f"[bold bright_cyan]Downloaded[/] {fmt_path(info.remote_path)}") log.explain_topic(f"Processing downloaded file for {fmt_path(info.path)}") changed = False if not info.success: log.explain("Download unsuccessful, aborting") return # Solve conflicts arising from existing local file if info.local_path.exists(): changed = True if filecmp.cmp(info.local_path, info.tmp_path): log.explain("Contents identical with existing file") log.explain("Updating metadata on existing file instead") self._update_metadata(info) return log.explain("Conflict: The local and remote versions differ") if await self._conflict_lfrf(info.on_conflict, info.path): log.explain("Result: Keeping the remote version") else: log.explain("Result: Keeping the local version") return log.explain("Replacing local file with temporary file") info.tmp_path.replace(info.local_path) log.explain("Updating metadata on local file") self._update_metadata(info) if changed: log.action(f"[bold bright_yellow]Changed[/] {escape(fmt_path(info.path))}") self._report.change_file(info.path) else: log.action(f"[bold bright_green]Added[/] {escape(fmt_path(info.path))}") self._report.add_file(info.path) async def cleanup(self) -> None: await self._cleanup_dir(self._root, PurePath(), delete_self=False) async def _cleanup(self, path: Path, pure: PurePath) -> None: if path.is_dir(): await self._cleanup_dir(path, pure) elif path.is_file(): await self._cleanup_file(path, pure) async def _cleanup_dir(self, path: Path, pure: PurePath, delete_self: bool = True) -> None: for child in path.iterdir(): pure_child = pure / child.name await self._cleanup(child, pure_child) if delete_self: try: path.rmdir() except OSError: pass async def _cleanup_file(self, path: Path, pure: PurePath) -> None: if self._report.is_marked(pure): return if await self._conflict_delete_lf(self._on_conflict, pure): try: path.unlink() log.action(f"[bold bright_magenta]Deleted[/] {escape(fmt_path(pure))}") self._report.delete_file(pure) except OSError: pass