Add a dotfile synchronization script

sync.py

@@ -0,0 +1,194 @@
+#!/usr/bin/env python
+from __future__ import annotations
+
+import hashlib
+import sys
+from collections.abc import Iterable, Iterator
+from enum import Enum, auto
+from pathlib import Path
+from typing import NamedTuple
+
+try:
+    import rich
+except ImportError:
+    print("rich not found (`pip install rich`), falling back to no colors", file=sys.stderr)
+    rich = None
+
+DOTHOMEDIR = Path("./home")
+HOMEDIR = Path("~")
+DOTROOTDIR = Path("./root")
+ROOTDIR = Path("/")
+
+
+class DiffStatus(Enum):
+    NOT_FOUND = auto()
+    PERMISSION_ERROR = auto()
+    MATCH = auto()
+    EXPECTED_SYMLINK = auto()
+    UNEXPECTED_SYMLINK = auto()
+    CONTENT_DIFFERS = auto()
+    SYMLINK_DIFFERS = auto()
+
+
+class FileDiff(NamedTuple):
+    dot_file: Path
+    sys_file: Path
+    status: DiffStatus
+
+    def __repr__(self) -> str:
+        dot_file = str(self.rel_dot_file)
+        sys_file = str(self.sys_file)
+        status = self.status.name
+        return f"FileDiff({dot_file=}, {sys_file=}, {status=})"
+
+    @property
+    def rel_dot_file(self) -> Path:
+        """Returns path to a dot_file relative to workdir."""
+        return self.dot_file.relative_to(Path.cwd())
+
+
+def iter_dir(directory: Path) -> Iterator[Path]:
+    """Recursively iterate over given directory and yield all files in it."""
+    for subpath in directory.iterdir():
+        if subpath.is_file() or subpath.is_symlink():
+            yield subpath
+        else:
+            yield from iter_dir(subpath)
+
+
+def file_sum(file: Path) -> str:
+    """Compute SHA-256 hash sum of given file."""
+    sha256_hash = hashlib.sha256()
+    with file.open("rb") as f:
+        for byte_block in iter(lambda: f.read(4096), b""):
+            sha256_hash.update(byte_block)
+    return sha256_hash.hexdigest()
+
+
+def compare_files(dot_file: Path, sys_file: Path) -> DiffStatus:
+    """Compare two files returning their diff status."""
+    try:
+        if not sys_file.exists():
+            return DiffStatus.NOT_FOUND
+    except PermissionError:
+        return DiffStatus.PERMISSION_ERROR
+
+    if dot_file.is_symlink():
+        if sys_file.is_symlink():
+            if dot_file.readlink() == sys_file.readlink():
+                return DiffStatus.MATCH
+            else:
+                # In case the sys_file link uses an absolute path, make sure
+                # it points to the same location, even if that location is a
+                # symlink.
+                dot_target = sys_file.parent.joinpath(dot_file.readlink()).absolute()
+                sys_target = sys_file.parent.joinpath(sys_file.readlink()).absolute()
+                if dot_target == sys_target:
+                    return DiffStatus.MATCH
+                return DiffStatus.SYMLINK_DIFFERS
+        return DiffStatus.EXPECTED_SYMLINK
+    elif sys_file.is_symlink():
+        return DiffStatus.UNEXPECTED_SYMLINK
+
+    try:
+        if file_sum(dot_file) == file_sum(sys_file):
+            return DiffStatus.MATCH
+    except PermissionError:
+        return DiffStatus.PERMISSION_ERROR
+
+    return DiffStatus.CONTENT_DIFFERS
+
+
+def iter_pairs() -> Iterator[tuple[Path, Path]]:
+    """Go through all files in the dotfiles directories and match them to system paths.
+
+    Yields tuples of (dotfile file path, matching system path)
+    """
+    for dot_file in iter_dir(DOTHOMEDIR):
+        real_file = Path(HOMEDIR, *dot_file.parts[1:])
+        yield dot_file.expanduser().absolute(), real_file.expanduser().absolute()
+
+    for dot_file in iter_dir(DOTROOTDIR):
+        real_file = Path(ROOTDIR, *dot_file.parts[1:])
+        yield dot_file.expanduser().absolute(), real_file.expanduser().absolute()
+
+
+def iter_diffs() -> Iterator[FileDiff]:
+    """Go through all files and compute their diffs."""
+    for dot_file, sys_file in iter_pairs():
+        diff_status = compare_files(dot_file, sys_file)
+        yield FileDiff(dot_file, sys_file, diff_status)
+
+
+def print_status(diffs: Iterable[FileDiff]) -> None:
+    """Pretty print the individual diff statuses."""
+    # Exhause the iterable, and ensure we work on a copy
+    diffs = list(diffs)
+
+    # Sort by DiffStatus, with MATCH entries being first
+    diffs.sort(key=lambda v: (v.status is not DiffStatus.MATCH, v.status.name))
+
+    if rich is None:
+        for diff in diffs:
+            print(f"{diff.status.name}   ->    {diff.sys_file}")
+        return
+
+    from rich.table import Table
+    table = Table()
+    table.add_column("Status")
+    table.add_column("System file", style="magenta")
+    table.add_column("Dotfile file", style="magenta")
+
+    for diff in diffs:
+        _str_status = diff.status.name.replace("_", " ")
+        if diff.status is DiffStatus.MATCH:
+            status_str = (f"[green]{_str_status}[/green]")
+        elif diff.status is DiffStatus.PERMISSION_ERROR:
+            status_str = f"[bold yellow]{_str_status}[/bold yellow]"
+        elif diff.status is DiffStatus.NOT_FOUND:
+            status_str = f"[bold orange_red1]{_str_status}[/bold orange_red1]"
+        else:
+            status_str = f"[bold red]{_str_status}[/bold red]"
+
+        try:
+            # Unexpand home (/home/xyz/foo -> ~/foo)
+            sys_file = Path("~") / diff.sys_file.relative_to(Path.home())
+        except ValueError:  # File not in home
+            sys_file = diff.sys_file
+
+        sys_file = str(sys_file)
+        dot_file = "./" + str(diff.rel_dot_file)
+        table.add_row(status_str, sys_file, dot_file)
+
+    rich.print(table)
+
+def exclude_fun(diff: FileDiff) -> bool:
+    EXCLUDE_RULES = [
+        lambda d: d.status is DiffStatus.MATCH,
+        lambda d: d.rel_dot_file.name == ".keep" and d.sys_file.parent.is_dir(),
+        lambda d: Path("root/etc/opensnitchd/rules") in d.rel_dot_file.parents,
+        lambda d: Path("home/.config/xmobar") in d.rel_dot_file.parents,
+        lambda d: Path("home/.config/xmonad") in d.rel_dot_file.parents,
+        lambda d: Path("home/.local/share/xmonad") in d.rel_dot_file.parents,
+        lambda d: Path("home/.config/topgrade.toml") == d.rel_dot_file,
+        lambda d: Path("home/.config/newsboat") in d.rel_dot_file.parents,
+        lambda d: Path("home/.cache/zsh/history") == d.rel_dot_file and d.status is DiffStatus.CONTENT_DIFFERS,
+        lambda d: Path("home/.local/scripts") in d.rel_dot_file.parents,  # Temporary
+        lambda d: Path("root") in d.rel_dot_file.parents,  # Temporary
+    ]
+
+    for exc_rule in EXCLUDE_RULES:
+        if exc_rule(diff):
+            return False
+    return True
+
+
+def main() -> None:
+    diffs = iter_diffs()
+    diffs = filter(exclude_fun, diffs)
+    print_status(diffs)
+
+
+
+if __name__ == "__main__":
+    main()