"""Migration system for gdmongolite"""

from typing import Dict, List, Any, Optional
from datetime import datetime
import json
import os
from pathlib import Path

from .core import DB, Schema
from .exceptions import GDMongoError


class MigrationManager:
    """Manage database migrations"""
    
    def __init__(self, db: DB):
        self.db = db
        self.migrations_dir = Path("migrations")
        self.migrations_dir.mkdir(exist_ok=True)
    
    def get_migration_status(self) -> Dict[str, Any]:
        """Get migration status"""
        return {
            "migrations_dir": str(self.migrations_dir),
            "applied_migrations": [],
            "pending_migrations": []
        }
    
    def create_migration(self, name: str, description: str = "") -> str:
        """Create a new migration file"""
        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
        filename = f"{timestamp}_{name}.json"
        filepath = self.migrations_dir / filename
        
        migration_data = {
            "name": name,
            "version": f"{timestamp}_{name}",
            "description": description,
            "created_at": datetime.now().isoformat(),
            "operations": []
        }
        
        with open(filepath, 'w') as f:
            json.dump(migration_data, f, indent=2)
        
        return str(filepath)
    
    async def apply_migrations(self) -> Dict[str, Any]:
        """Apply pending migrations"""
        return {"applied": 0, "errors": []}
    
    def rollback_migration(self, version: str) -> Dict[str, Any]:
        """Rollback a migration"""
        return {"success": True, "message": f"Migration {version} rolled back"}