"""Per-distribution sync scope (include/exclude paths).

Each instance-sync deployment ships its own ``scope.json`` that picks
which files participate in sync. Lives at
``<pack-folder>/.cloud-sync/scope.json``. Defaults are baked in so a
fresh install with no scope.json works.
"""

from __future__ import annotations

import json
import sys
from dataclasses import dataclass, field
from pathlib import Path


DEFAULT_INCLUDE: list[str] = [
    "options.txt",
    "optionsof.txt",
    "optionsshaders.txt",
    "config/",
    "journeymap/data/",
    "screenshots/",
]

DEFAULT_EXCLUDE: list[str] = [
    ".cloud-sync/",         # never sync our own state dir
    ".cloud-token",         # legacy location (pre-jar/pre-restic era)
    "config/simple-mod-sync*",
    "config/packwiz*",
    "**/cache/",
    "**/*.log",
    "**/*.tmp",
]


@dataclass(frozen=True)
class Scope:
    include: list[str] = field(default_factory=lambda: list(DEFAULT_INCLUDE))
    exclude: list[str] = field(default_factory=lambda: list(DEFAULT_EXCLUDE))


def load(pack_folder: Path) -> Scope:
    """Read scope.json or return defaults."""
    path = pack_folder / ".cloud-sync" / "scope.json"
    if not path.exists():
        return Scope()
    try:
        data = json.loads(path.read_text(encoding="utf-8"))
    except (OSError, json.JSONDecodeError) as e:
        print(
            f"instance-sync: scope.json invalid ({e}); using defaults",
            file=sys.stderr,
        )
        return Scope()
    return Scope(
        include=list(data.get("include", DEFAULT_INCLUDE)),
        exclude=list(data.get("exclude", DEFAULT_EXCLUDE)),
    )


def materialize_for_restic(pack_folder: Path, scope: Scope) -> tuple[Path, Path]:
    """Write files-from + exclude-from text files restic can consume.

    Files include directories; restic recurses into them. Exclude patterns
    are matched against file paths during the walk.
    """
    state_dir = pack_folder / ".cloud-sync"
    state_dir.mkdir(parents=True, exist_ok=True)
    files_from = state_dir / "files-from.txt"
    exclude_from = state_dir / "exclude-from.txt"

    files_from.write_text(
        "\n".join(_trim_trailing_slash(p) for p in scope.include) + "\n",
        encoding="utf-8",
    )
    exclude_from.write_text(
        "\n".join(scope.exclude) + "\n",
        encoding="utf-8",
    )
    return files_from, exclude_from


def _trim_trailing_slash(s: str) -> str:
    return s.rstrip("/") if s.endswith("/") else s