cloud-sync/cloud_sync/sync.py

"""pull + push entry points.

Both subprocess restic against ``rest:<scheme>://<id>:<password>@<host>/<id>/``
where the password is HTTP basic auth ONLY. Restic repos are initialised with
``--insecure-no-password`` so no encryption-at-rest password exists; protection
relies on:

  1. TLS in transit at the reverse proxy
  2. ``--private-repos`` + htpasswd per user at restic-rest-server
  3. ``--append-only`` to prevent client-side deletion
  4. Disk-level encryption (LUKS) on the host

Defense-in-depth via repo encryption was dropped because the threat model
(homelab, operator-trusted) doesn't justify the password-coordination cost.
"""

from __future__ import annotations

import sys
import urllib.parse
from pathlib import Path

from . import restic, scope as scopemod
from .cli import Args
from .creds import read_credentials
from .ui import HeadlessProgress, Progress


def pull(args: Args, progress: Progress | None = None) -> int:
    """Restore latest snapshot's files into pack_folder.

    If the repo has no snapshots yet, this is a no-op (first run on this
    machine; nothing to restore).
    """
    ui = progress or HeadlessProgress()
    ui.set_status("Reading credentials…")
    discord_id, password = read_credentials(args.token_file)

    ui.set_status("Resolving restic binary…")
    binary = restic.resolve_binary(args)
    repo = _restic_repo(args.url, discord_id, password)
    env = _restic_env()

    ui.set_status("Checking remote snapshots…")
    code, out = restic.run(
        binary,
        ["-r", repo, "--insecure-no-password", "snapshots", "--json", "--latest", "1"],
        env=env,
        cancel_check=ui.is_cancelled,
    )
    if code == -1:
        return 1
    if code != 0:
        print(
            f"cloud-sync: failed to list snapshots (restic exit {code})",
            file=sys.stderr,
        )
        return 2
    stripped = out.strip()
    if stripped in ("", "null", "[]"):
        ui.set_status("No snapshots yet — nothing to pull")
        print(
            "cloud-sync: no snapshots yet for this user "
            "(first run on this machine?); nothing to pull"
        )
        return 0

    scope = scopemod.load(args.pack_folder)
    _, exclude_from = scopemod.materialize_for_restic(args.pack_folder, scope)

    ui.set_status("Restoring files…")
    code, _ = restic.run(
        binary,
        [
            "-r", repo, "--insecure-no-password",
            "restore", "latest",
            "--target", str(args.pack_folder),
            "--exclude-file", str(exclude_from),
        ],
        env=env,
        cancel_check=ui.is_cancelled,
    )
    if code == -1:
        return 1
    if code != 0:
        print(f"cloud-sync: restic restore failed (exit {code})", file=sys.stderr)
        return 2
    ui.set_status("Pull complete")
    print("cloud-sync: pull ok")
    return 0


def push(args: Args, progress: Progress | None = None) -> int:
    """Snapshot the in-scope files into the user's repo."""
    ui = progress or HeadlessProgress()
    ui.set_status("Reading credentials…")
    discord_id, password = read_credentials(args.token_file)

    ui.set_status("Resolving restic binary…")
    binary = restic.resolve_binary(args)
    repo = _restic_repo(args.url, discord_id, password)
    env = _restic_env()

    scope = scopemod.load(args.pack_folder)
    files_from, exclude_from = scopemod.materialize_for_restic(args.pack_folder, scope)

    ui.set_status("Uploading snapshot…")
    code, _ = restic.run(
        binary,
        [
            "-r", repo, "--insecure-no-password",
            "backup",
            "--files-from", str(files_from),
            "--exclude-file", str(exclude_from),
            "--host", "cloud-sync",
            "--tag", "auto",
        ],
        env=env,
        cwd=args.pack_folder,
        cancel_check=ui.is_cancelled,
    )
    if code == -1:
        return 1
    if code != 0:
        print(f"cloud-sync: restic backup failed (exit {code})", file=sys.stderr)
        return 2
    ui.set_status("Push complete")
    print("cloud-sync: push ok")
    return 0


# ---------------------------------------------------------------------------
# helpers
# ---------------------------------------------------------------------------


def _restic_repo(base_url: str, discord_id: str, password: str) -> str:
    """Build rest:<scheme>://<id>:<pw>@<host>/<id>/

    URL-embedded basic auth is universally supported by restic; alternative
    env vars (RESTIC_REST_USERNAME, RESTIC_REST_PASSWORD) require 0.16+.
    """
    raw = base_url.strip()
    if raw.startswith("rest:"):
        raw = raw[len("rest:"):]
    raw = raw.rstrip("/")
    scheme_end = raw.find("://")
    if scheme_end <= 0:
        raise ValueError(
            f"--url must include scheme (http:// or https://): {base_url!r}"
        )
    scheme = raw[: scheme_end + 3]
    host_and_path = raw[scheme_end + 3 :]
    u = urllib.parse.quote(discord_id, safe="")
    p = urllib.parse.quote(password, safe="")
    return f"rest:{scheme}{u}:{p}@{host_and_path}/{discord_id}/"


def _restic_env() -> dict[str, str]:
    return {
        # No RESTIC_PASSWORD — repos use --insecure-no-password.
        "RESTIC_PROGRESS_FPS": "0",
    }