"""Same-filesystem staging for plugin skill writes."""

from __future__ import annotations

import filecmp
import os
from pathlib import Path
import shutil
from uuid import uuid4


class PluginSkillTransaction:
    def __init__(self, workspace: str | Path) -> None:
        self.workspace = Path(workspace)
        self.transaction_id = uuid4().hex
        self.root = self.workspace / ".beaver" / "staging" / "plugin-skills" / self.transaction_id
        self.root.mkdir(parents=True, exist_ok=True)

    def stage_upstream_snapshot(self, skill_name: str, source_id: str, tree_hash: str) -> Path:
        path = self.root / "upstreams" / skill_name / source_id / tree_hash
        path.mkdir(parents=True, exist_ok=True)
        return path

    def stage_skill_version(self, skill_name: str, version: str) -> Path:
        path = self.root / "versions" / skill_name / version
        path.mkdir(parents=True, exist_ok=True)
        return path

    def promote_directory(self, staged: Path, final: Path) -> None:
        if final.exists():
            if _directories_identical(staged, final):
                return
            raise ValueError(f"Immutable directory already exists with different content: {final}")
        final.parent.mkdir(parents=True, exist_ok=True)
        os.replace(staged, final)

    def cleanup(self) -> None:
        shutil.rmtree(self.root, ignore_errors=True)


def _directories_identical(left: Path, right: Path) -> bool:
    comparison = filecmp.dircmp(left, right)
    if comparison.left_only or comparison.right_only or comparison.funny_files:
        return False
    for filename in comparison.common_files:
        if not filecmp.cmp(left / filename, right / filename, shallow=False):
            return False
    return all(_directories_identical(left / name, right / name) for name in comparison.common_dirs)