import os
import mimetypes
from pathlib import Path
from typing import Dict, Any, Optional
from fastapi import UploadFile

def validate_file(file: UploadFile) -> Dict[str, Any]:
    """Validate uploaded file and return file info"""
    if not file.filename:
        raise ValueError("No filename provided")
    
    # Get file extension
    file_path = Path(file.filename)
    extension = file_path.suffix.lower()
    
    # Get MIME type
    mime_type, _ = mimetypes.guess_type(file.filename)
    
    # Validate MIME type
    allowed_mime_types = {
        'application/pdf',
        'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
        'application/msword',
        'text/plain',
        'text/csv',
        'application/json',
        'text/html',
        'text/markdown',
        'application/rtf'
    }
    
    if mime_type not in allowed_mime_types:
        raise ValueError(f"MIME type {mime_type} not supported")
    
    return {
        'filename': file.filename,
        'extension': extension,
        'mime_type': mime_type,
        'size': file.size
    }

def get_file_info(file_path: Path) -> Dict[str, Any]:
    """Get information about a file"""
    if not file_path.exists():
        raise FileNotFoundError(f"File {file_path} not found")
    
    stat = file_path.stat()
    mime_type, _ = mimetypes.guess_type(str(file_path))
    
    return {
        'filename': file_path.name,
        'extension': file_path.suffix.lower(),
        'mime_type': mime_type,
        'size': stat.st_size,
        'created_at': stat.st_ctime,
        'modified_at': stat.st_mtime
    }

def ensure_directory(directory: Path) -> None:
    """Ensure directory exists"""
    directory.mkdir(parents=True, exist_ok=True)

def clean_filename(filename: str) -> str:
    """Clean filename to be filesystem-safe"""
    # Remove or replace problematic characters
    invalid_chars = '<>:"/\\|?*'
    cleaned = filename
    
    for char in invalid_chars:
        cleaned = cleaned.replace(char, '_')
    
    # Remove leading/trailing dots and spaces
    cleaned = cleaned.strip('. ')
    
    # Ensure it's not empty
    if not cleaned:
        cleaned = "unnamed_file"
    
    return cleaned

def get_upload_path(index_id: str, filename: str, base_dir: str) -> Path:
    """Generate upload path for a file"""
    base_path = Path(base_dir)
    index_path = base_path / index_id
    ensure_directory(index_path)
    
    return index_path / clean_filename(filename)