"""ClickZetta Volume file lifecycle management

This module provides file lifecycle management features including version control,
automatic cleanup, backup and restore. Supports complete lifecycle management for
knowledge base files.
"""

import json
import logging
from dataclasses import asdict, dataclass
from datetime import datetime
from enum import Enum
from typing import Any, Optional

logger = logging.getLogger(__name__)


class FileStatus(Enum):
    """File status enumeration"""

    ACTIVE = "active"  # Active status
    ARCHIVED = "archived"  # Archived
    DELETED = "deleted"  # Deleted (soft delete)
    BACKUP = "backup"  # Backup file


@dataclass
class FileMetadata:
    """File metadata"""

    filename: str
    size: int | None
    created_at: datetime
    modified_at: datetime
    version: int | None
    status: FileStatus
    checksum: Optional[str] = None
    tags: Optional[dict[str, str]] = None
    parent_version: Optional[int] = None

    def to_dict(self) -> dict:
        """Convert to dictionary format"""
        data = asdict(self)
        data["created_at"] = self.created_at.isoformat()
        data["modified_at"] = self.modified_at.isoformat()
        data["status"] = self.status.value
        return data

    @classmethod
    def from_dict(cls, data: dict) -> "FileMetadata":
        """Create instance from dictionary"""
        data = data.copy()
        data["created_at"] = datetime.fromisoformat(data["created_at"])
        data["modified_at"] = datetime.fromisoformat(data["modified_at"])
        data["status"] = FileStatus(data["status"])
        return cls(**data)


class FileLifecycleManager:
    """File lifecycle manager"""

    def __init__(self, storage, dataset_id: Optional[str] = None):
        """Initialize lifecycle manager

        Args:
            storage: ClickZetta Volume storage instance
            dataset_id: Dataset ID (for Table Volume)
        """
        self._storage = storage
        self._dataset_id = dataset_id
        self._metadata_file = ".dify_file_metadata.json"
        self._version_prefix = ".versions/"
        self._backup_prefix = ".backups/"
        self._deleted_prefix = ".deleted/"

        # Get permission manager (if exists)
        self._permission_manager: Optional[Any] = getattr(storage, "_permission_manager", None)

    def save_with_lifecycle(self, filename: str, data: bytes, tags: Optional[dict[str, str]] = None) -> FileMetadata:
        """Save file and manage lifecycle

        Args:
            filename: File name
            data: File content
            tags: File tags

        Returns:
            File metadata
        """
        # Permission check
        if not self._check_permission(filename, "save"):
            from .volume_permissions import VolumePermissionError

            raise VolumePermissionError(
                f"Permission denied for lifecycle save operation on file: {filename}",
                operation="save",
                volume_type=getattr(self._storage, "_config", {}).get("volume_type", "unknown"),
                dataset_id=self._dataset_id,
            )

        try:
            # 1. Check if old version exists
            metadata_dict = self._load_metadata()
            current_metadata = metadata_dict.get(filename)

            # 2. If old version exists, create version backup
            if current_metadata:
                self._create_version_backup(filename, current_metadata)

            # 3. Calculate file information
            now = datetime.now()
            checksum = self._calculate_checksum(data)
            new_version = (current_metadata["version"] + 1) if current_metadata else 1

            # 4. Save new file
            self._storage.save(filename, data)

            # 5. Create metadata
            created_at = now
            parent_version = None

            if current_metadata:
                # If created_at is string, convert to datetime
                if isinstance(current_metadata["created_at"], str):
                    created_at = datetime.fromisoformat(current_metadata["created_at"])
                else:
                    created_at = current_metadata["created_at"]
                parent_version = current_metadata["version"]

            file_metadata = FileMetadata(
                filename=filename,
                size=len(data),
                created_at=created_at,
                modified_at=now,
                version=new_version,
                status=FileStatus.ACTIVE,
                checksum=checksum,
                tags=tags or {},
                parent_version=parent_version,
            )

            # 6. Update metadata
            metadata_dict[filename] = file_metadata.to_dict()
            self._save_metadata(metadata_dict)

            logger.info("File %s saved with lifecycle management, version %s", filename, new_version)
            return file_metadata

        except Exception:
            logger.exception("Failed to save file with lifecycle")
            raise

    def get_file_metadata(self, filename: str) -> Optional[FileMetadata]:
        """Get file metadata

        Args:
            filename: File name

        Returns:
            File metadata, returns None if not exists
        """
        try:
            metadata_dict = self._load_metadata()
            if filename in metadata_dict:
                return FileMetadata.from_dict(metadata_dict[filename])
            return None
        except Exception:
            logger.exception("Failed to get file metadata for %s", filename)
            return None

    def list_file_versions(self, filename: str) -> list[FileMetadata]:
        """List all versions of a file

        Args:
            filename: File name

        Returns:
            File version list, sorted by version number
        """
        try:
            versions = []

            # Get current version
            current_metadata = self.get_file_metadata(filename)
            if current_metadata:
                versions.append(current_metadata)

            # Get historical versions
            try:
                version_files = self._storage.scan(self._dataset_id or "", files=True)
                for file_path in version_files:
                    if file_path.startswith(f"{self._version_prefix}{filename}.v"):
                        # Parse version number
                        version_str = file_path.split(".v")[-1].split(".")[0]
                        try:
                            _ = int(version_str)
                            # Simplified processing here, should actually read metadata from version file
                            # Temporarily create basic metadata information
                        except ValueError:
                            continue
            except:
                # If cannot scan version files, only return current version
                pass

            return sorted(versions, key=lambda x: x.version or 0, reverse=True)

        except Exception:
            logger.exception("Failed to list file versions for %s", filename)
            return []

    def restore_version(self, filename: str, version: int) -> bool:
        """Restore file to specified version

        Args:
            filename: File name
            version: Version number to restore

        Returns:
            Whether restore succeeded
        """
        try:
            version_filename = f"{self._version_prefix}{filename}.v{version}"

            # Check if version file exists
            if not self._storage.exists(version_filename):
                logger.warning("Version %s of %s not found", version, filename)
                return False

            # Read version file content
            version_data = self._storage.load_once(version_filename)

            # Save current version as backup
            current_metadata = self.get_file_metadata(filename)
            if current_metadata:
                self._create_version_backup(filename, current_metadata.to_dict())

            # Restore file
            self.save_with_lifecycle(filename, version_data, {"restored_from": str(version)})
            return True

        except Exception:
            logger.exception("Failed to restore %s to version %s", filename, version)
            return False

    def archive_file(self, filename: str) -> bool:
        """Archive file

        Args:
            filename: File name

        Returns:
            Whether archive succeeded
        """
        # Permission check
        if not self._check_permission(filename, "archive"):
            logger.warning("Permission denied for archive operation on file: %s", filename)
            return False

        try:
            # Update file status to archived
            metadata_dict = self._load_metadata()
            if filename not in metadata_dict:
                logger.warning("File %s not found in metadata", filename)
                return False

            metadata_dict[filename]["status"] = FileStatus.ARCHIVED.value
            metadata_dict[filename]["modified_at"] = datetime.now().isoformat()

            self._save_metadata(metadata_dict)

            logger.info("File %s archived successfully", filename)
            return True

        except Exception:
            logger.exception("Failed to archive file %s", filename)
            return False

    def soft_delete_file(self, filename: str) -> bool:
        """Soft delete file (move to deleted directory)

        Args:
            filename: File name

        Returns:
            Whether delete succeeded
        """
        # Permission check
        if not self._check_permission(filename, "delete"):
            logger.warning("Permission denied for soft delete operation on file: %s", filename)
            return False

        try:
            # Check if file exists
            if not self._storage.exists(filename):
                logger.warning("File %s not found", filename)
                return False

            # Read file content
            file_data = self._storage.load_once(filename)

            # Move to deleted directory
            deleted_filename = f"{self._deleted_prefix}{filename}.{datetime.now().strftime('%Y%m%d_%H%M%S')}"
            self._storage.save(deleted_filename, file_data)

            # Delete original file
            self._storage.delete(filename)

            # Update metadata
            metadata_dict = self._load_metadata()
            if filename in metadata_dict:
                metadata_dict[filename]["status"] = FileStatus.DELETED.value
                metadata_dict[filename]["modified_at"] = datetime.now().isoformat()
                self._save_metadata(metadata_dict)

            logger.info("File %s soft deleted successfully", filename)
            return True

        except Exception:
            logger.exception("Failed to soft delete file %s", filename)
            return False

    def cleanup_old_versions(self, max_versions: int = 5, max_age_days: int = 30) -> int:
        """Cleanup old version files

        Args:
            max_versions: Maximum number of versions to keep
            max_age_days: Maximum retention days for version files

        Returns:
            Number of files cleaned
        """
        try:
            cleaned_count = 0

            # Get all version files
            try:
                all_files = self._storage.scan(self._dataset_id or "", files=True)
                version_files = [f for f in all_files if f.startswith(self._version_prefix)]

                # Group by file
                file_versions: dict[str, list[tuple[int, str]]] = {}
                for version_file in version_files:
                    # Parse filename and version
                    parts = version_file[len(self._version_prefix) :].split(".v")
                    if len(parts) >= 2:
                        base_filename = parts[0]
                        version_part = parts[1].split(".")[0]
                        try:
                            version_num = int(version_part)
                            if base_filename not in file_versions:
                                file_versions[base_filename] = []
                            file_versions[base_filename].append((version_num, version_file))
                        except ValueError:
                            continue

                # Cleanup old versions for each file
                for base_filename, versions in file_versions.items():
                    # Sort by version number
                    versions.sort(key=lambda x: x[0], reverse=True)

                    # Keep the newest max_versions versions, delete the rest
                    if len(versions) > max_versions:
                        to_delete = versions[max_versions:]
                        for version_num, version_file in to_delete:
                            self._storage.delete(version_file)
                            cleaned_count += 1
                            logger.debug("Cleaned old version: %s", version_file)

                logger.info("Cleaned %d old version files", cleaned_count)

            except Exception as e:
                logger.warning("Could not scan for version files: %s", e)

            return cleaned_count

        except Exception:
            logger.exception("Failed to cleanup old versions")
            return 0

    def get_storage_statistics(self) -> dict[str, Any]:
        """Get storage statistics

        Returns:
            Storage statistics dictionary
        """
        try:
            metadata_dict = self._load_metadata()

            stats: dict[str, Any] = {
                "total_files": len(metadata_dict),
                "active_files": 0,
                "archived_files": 0,
                "deleted_files": 0,
                "total_size": 0,
                "versions_count": 0,
                "oldest_file": None,
                "newest_file": None,
            }

            oldest_date = None
            newest_date = None

            for filename, metadata in metadata_dict.items():
                file_meta = FileMetadata.from_dict(metadata)

                # Count file status
                if file_meta.status == FileStatus.ACTIVE:
                    stats["active_files"] = (stats["active_files"] or 0) + 1
                elif file_meta.status == FileStatus.ARCHIVED:
                    stats["archived_files"] = (stats["archived_files"] or 0) + 1
                elif file_meta.status == FileStatus.DELETED:
                    stats["deleted_files"] = (stats["deleted_files"] or 0) + 1

                # Count size
                stats["total_size"] = (stats["total_size"] or 0) + (file_meta.size or 0)

                # Count versions
                stats["versions_count"] = (stats["versions_count"] or 0) + (file_meta.version or 0)

                # Find newest and oldest files
                if oldest_date is None or file_meta.created_at < oldest_date:
                    oldest_date = file_meta.created_at
                    stats["oldest_file"] = filename

                if newest_date is None or file_meta.modified_at > newest_date:
                    newest_date = file_meta.modified_at
                    stats["newest_file"] = filename

            return stats

        except Exception:
            logger.exception("Failed to get storage statistics")
            return {}

    def _create_version_backup(self, filename: str, metadata: dict):
        """Create version backup"""
        try:
            # Read current file content
            current_data = self._storage.load_once(filename)

            # Save as version file
            version_filename = f"{self._version_prefix}{filename}.v{metadata['version']}"
            self._storage.save(version_filename, current_data)

            logger.debug("Created version backup: %s", version_filename)

        except Exception as e:
            logger.warning("Failed to create version backup for %s: %s", filename, e)

    def _load_metadata(self) -> dict[str, Any]:
        """Load metadata file"""
        try:
            if self._storage.exists(self._metadata_file):
                metadata_content = self._storage.load_once(self._metadata_file)
                result = json.loads(metadata_content.decode("utf-8"))
                return dict(result) if result else {}
            else:
                return {}
        except Exception as e:
            logger.warning("Failed to load metadata: %s", e)
            return {}

    def _save_metadata(self, metadata_dict: dict):
        """Save metadata file"""
        try:
            metadata_content = json.dumps(metadata_dict, indent=2, ensure_ascii=False)
            self._storage.save(self._metadata_file, metadata_content.encode("utf-8"))
            logger.debug("Metadata saved successfully")
        except Exception:
            logger.exception("Failed to save metadata")
            raise

    def _calculate_checksum(self, data: bytes) -> str:
        """Calculate file checksum"""
        import hashlib

        return hashlib.md5(data).hexdigest()

    def _check_permission(self, filename: str, operation: str) -> bool:
        """Check file operation permission

        Args:
            filename: File name
            operation: Operation type

        Returns:
            True if permission granted, False otherwise
        """
        # If no permission manager, allow by default
        if not self._permission_manager:
            return True

        try:
            # Map operation type to permission
            operation_mapping = {
                "save": "save",
                "load": "load_once",
                "delete": "delete",
                "archive": "delete",  # Archive requires delete permission
                "restore": "save",  # Restore requires write permission
                "cleanup": "delete",  # Cleanup requires delete permission
                "read": "load_once",
                "write": "save",
            }

            mapped_operation = operation_mapping.get(operation, operation)

            # Check permission
            result = self._permission_manager.validate_operation(mapped_operation, self._dataset_id)
            return bool(result)

        except Exception:
            logger.exception("Permission check failed for %s operation %s", filename, operation)
            # Safe default: deny access when permission check fails
            return False