"""
File handling utilities for SkillSync
"""

import os
import shutil
from datetime import datetime

class FileHandler:
    """Handles file operations for submissions"""
    
    def __init__(self, upload_dir="data/user_data/submissions", max_size_mb=100):
        self.upload_dir = upload_dir
        self.max_size = max_size_mb * 1024 * 1024  # Convert to bytes
        self.allowed_extensions = [".zip", ".pdf", ".ipynb", ".py", ".txt", ".md"]
    
    def ensure_upload_dir(self):
        """Ensure upload directory exists"""
        os.makedirs(self.upload_dir, exist_ok=True)
    
    def validate_file(self, file):
        """Validate uploaded file"""
        if file is None:
            return False, "No file provided"
        
        # Get file name
        file_name = getattr(file, 'name', 'unknown')
        
        # Check file extension
        file_ext = os.path.splitext(file_name)[1].lower()
        if file_ext not in self.allowed_extensions:
            return False, f"File type {file_ext} not allowed. Allowed types: {', '.join(self.allowed_extensions)}"
        
        # Check file size if available
        if hasattr(file, 'size') and file.size > self.max_size:
            return False, f"File too large. Maximum size: {self.max_size // (1024*1024)}MB"
        
        return True, "File validated successfully"
    
    def save_file(self, file, user_id, assignment_type):
        """Save uploaded file"""
        try:
            self.ensure_upload_dir()
            
            # Get original filename
            original_name = getattr(file, 'name', 'uploaded_file')
            original_name = os.path.basename(original_name)
            
            # Create unique filename
            timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
            new_name = f"{user_id}_{assignment_type}_{timestamp}_{original_name}"
            
            # Save file
            destination = os.path.join(self.upload_dir, new_name)
            
            # Copy file to destination
            if hasattr(file, 'name'):
                shutil.copy2(file.name, destination)
            
            return True, destination
        except Exception as e:
            return False, str(e)
    
    def get_file_info(self, filepath):
        """Get information about a file"""
        if not os.path.exists(filepath):
            return None
        
        stat = os.stat(filepath)
        return {
            "path": filepath,
            "size": stat.st_size,
            "size_mb": round(stat.st_size / (1024 * 1024), 2),
            "created": datetime.fromtimestamp(stat.st_ctime).strftime("%Y-%m-%d %H:%M:%S"),
            "modified": datetime.fromtimestamp(stat.st_mtime).strftime("%Y-%m-%d %H:%M:%S")
        }
    
    def list_submissions(self, user_id=None):
        """List all submissions"""
        try:
            if not os.path.exists(self.upload_dir):
                return []
            
            files = os.listdir(self.upload_dir)
            
            if user_id:
                files = [f for f in files if f.startswith(str(user_id))]
            
            submissions = []
            for filename in files:
                filepath = os.path.join(self.upload_dir, filename)
                info = self.get_file_info(filepath)
                if info:
                    submissions.append({
                        "filename": filename,
                        **info
                    })
            
            return submissions
        except Exception as e:
            print(f"Error listing submissions: {e}")
            return []
    
    def delete_file(self, filepath):
        """Delete a file"""
        try:
            if os.path.exists(filepath):
                os.remove(filepath)
                return True, "File deleted successfully"
            return False, "File not found"
        except Exception as e:
            return False, str(e)
    
    def get_storage_usage(self):
        """Get total storage usage"""
        try:
            if not os.path.exists(self.upload_dir):
                return 0
            
            total_size = 0
            for filename in os.listdir(self.upload_dir):
                filepath = os.path.join(self.upload_dir, filename)
                if os.path.isfile(filepath):
                    total_size += os.path.getsize(filepath)
            
            return total_size
        except Exception as e:
            print(f"Error calculating storage: {e}")
            return 0