feat(ai): catalogue d'outils lecture & recherche (#79 phase C)

backend/services/backups.py

@@ -0,0 +1,195 @@
+"""Backup inspection services shared by REST routes and the AI tool layer.
+
+Single source of truth for locating, listing and diffing the timestamped
+backups created before each file mutation. The write-side (creating a backup)
+stays in the route layer; only the read/inspection logic lives here so both
+``/api/file/{vault}/backups``, ``/api/file/{vault}/diff`` and the tools
+``list_backups`` / ``diff_backup`` behave identically.
+"""
+
+from __future__ import annotations
+
+import difflib
+import logging
+import os
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Any
+
+from backend.services.errors import ServiceError
+from backend.services.paths import resolve_safe_path
+from backend.services.vaults import get_vault_root
+
+logger = logging.getLogger("obsigate.services.backups")
+
+
+def get_backup_dir(vault_name: str, relative_path: str) -> Path:
+    """Return the directory where backups for a specific file are stored.
+
+    Resolves relative backup paths against the SPECIFIC vault's directory,
+    matching the backup-creation logic exactly.
+    """
+    from backend.indexer import get_vault_data
+
+    backup_root = Path(os.environ.get("OBSIGATE_BACKUP_DIR", ".obsigate-backup"))
+    if not backup_root.is_absolute():
+        vault_data = get_vault_data(vault_name)
+        if vault_data:
+            backup_root = Path(vault_data["path"]) / backup_root
+    return backup_root / vault_name / Path(relative_path).parent
+
+
+def list_backup_files(vault_name: str, relative_path: str) -> list[dict[str, Any]]:
+    """List all backup files for a vault file, sorted newest first.
+
+    Backup filename format: ``{original_filename}.{timestamp}.bak``.
+
+    Returns a list of dicts with ``timestamp``, ``datetime``, ``size`` and
+    ``filename``. Missing or unreadable backup directories yield an empty list.
+    """
+    backup_dir = get_backup_dir(vault_name, relative_path)
+    if not backup_dir.exists():
+        return []
+
+    original_name = Path(relative_path).name
+    prefix = original_name + "."
+    backups: list[dict[str, Any]] = []
+
+    try:
+        dir_entries = list(backup_dir.iterdir())
+    except PermissionError:
+        logger.warning(f"Permission denied reading backup dir: {backup_dir}")
+        return []
+    except OSError as e:
+        logger.error(f"Error reading backup dir {backup_dir}: {e}")
+        return []
+
+    for f in dir_entries:
+        try:
+            if not f.is_file():
+                continue
+            name = f.name
+            if not name.startswith(prefix) or not name.endswith(".bak"):
+                continue
+            ts_part = name[len(prefix):-len(".bak")]
+            try:
+                ts = int(ts_part)
+            except (ValueError, TypeError):
+                continue
+            try:
+                dt = datetime.fromtimestamp(ts, tz=timezone.utc).isoformat()
+            except (OSError, OverflowError, ValueError) as ts_err:
+                logger.warning(f"Skipping backup with invalid timestamp {ts}: {ts_err}")
+                continue
+            st = f.stat()
+            backups.append({
+                "timestamp": ts,
+                "datetime": dt,
+                "size": st.st_size,
+                "filename": name,
+            })
+        except Exception as entry_err:
+            logger.warning(f"Skipping unreadable backup entry {f}: {entry_err}")
+            continue
+
+    backups.sort(key=lambda b: b["timestamp"], reverse=True)
+    return backups
+
+
+def diff_backup(
+    vault_name: str,
+    path: str,
+    version: int,
+    compare_with: int | None = None,
+) -> dict[str, Any]:
+    """Generate a unified diff between a backup version and another version or the current file.
+
+    Args:
+        vault_name: Name of the vault.
+        path: Relative path of the file within the vault.
+        version: Timestamp of the backup used as the old/left side.
+        compare_with: Optional timestamp of another backup as the new/right
+            side. If omitted, the current file on disk is used.
+
+    Returns:
+        Dict with ``vault``, ``path``, ``version``, ``compare_with``, ``diff``,
+        ``left_content`` and ``right_content``.
+
+    Raises:
+        ServiceError: ``not_found`` (404) when the file or a backup is missing,
+            ``read_error`` (500) when a file cannot be read.
+    """
+    root = get_vault_root(vault_name)
+    file_path = resolve_safe_path(root, path)
+
+    if not file_path.exists() or not file_path.is_file():
+        raise ServiceError(
+            f"File not found: {path}",
+            code="not_found",
+            status=404,
+            details={"vault": vault_name, "path": path},
+        )
+
+    original_name = Path(path).name
+
+    def _read_backup(ts: int) -> tuple[str, str]:
+        backup_dir = get_backup_dir(vault_name, path)
+        backup_path = backup_dir / f"{original_name}.{ts}.bak"
+        if not backup_path.exists():
+            raise ServiceError(
+                f"Backup version {ts} not found for {path}",
+                code="not_found",
+                status=404,
+                details={"vault": vault_name, "path": path, "version": ts},
+            )
+        try:
+            content = backup_path.read_text(encoding="utf-8", errors="replace")
+        except Exception as e:
+            raise ServiceError(
+                f"Failed to read backup {ts}: {e}",
+                code="read_error",
+                status=500,
+                details={"vault": vault_name, "path": path, "version": ts},
+            ) from e
+        dt = datetime.fromtimestamp(ts, tz=timezone.utc).strftime("%Y-%m-%d %H:%M:%S UTC")
+        return content, f"{path}@{dt}"
+
+    try:
+        left_content, left_label = _read_backup(version)
+
+        if compare_with is not None:
+            right_content, right_label = _read_backup(compare_with)
+        else:
+            try:
+                right_content = file_path.read_text(encoding="utf-8", errors="replace")
+            except Exception as e:
+                raise ServiceError(
+                    f"Failed to read current file: {e}",
+                    code="read_error",
+                    status=500,
+                    details={"vault": vault_name, "path": path},
+                ) from e
+            right_label = f"{path} (current)"
+
+        left_lines = left_content.splitlines(keepends=True)
+        right_lines = right_content.splitlines(keepends=True)
+
+        diff_lines = list(difflib.unified_diff(
+            left_lines, right_lines,
+            fromfile=left_label, tofile=right_label,
+        ))
+
+        return {
+            "vault": vault_name,
+            "path": path,
+            "version": version,
+            "compare_with": compare_with,
+            "diff": "".join(diff_lines),
+            "left_content": left_content,
+            "right_content": right_content,
+        }
+    except ServiceError:
+        raise
+    except Exception as e:
+        logger.error(f"Error generating diff for {vault_name}/{path}: {type(e).__name__}: {e}", exc_info=True)
+        raise ServiceError(f"Erreur lors de la génération du diff: {e!s}", code="read_error", status=500) from e