import re
import nltk
from nltk.tokenize import word_tokenize
from nltk.corpus import stopwords
from nltk.stem import WordNetLemmatizer
from typing import List, Optional

class TextPreprocessor:
    def __init__(self):
        nltk.download('punkt')
        nltk.download('stopwords')
        nltk.download('wordnet')
        self.stop_words = set(stopwords.words('english'))
        self.lemmatizer = WordNetLemmatizer()

    def clean_text(self, text: str) -> str:
        """Clean and normalize text"""
        # Convert to lowercase
        text = text.lower()
        
        # Remove special characters and numbers
        text = re.sub(r'[^a-zA-Z\s]', '', text)
        
        # Remove extra whitespace
        text = re.sub(r'\s+', ' ', text).strip()
        
        return text

    def tokenize(self, text: str) -> List[str]:
        """Tokenize text into words"""
        return word_tokenize(text)

    def remove_stopwords(self, tokens: List[str]) -> List[str]:
        """Remove stop words from token list"""
        return [token for token in tokens if token not in self.stop_words]

    def lemmatize(self, tokens: List[str]) -> List[str]:
        """Lemmatize tokens"""
        return [self.lemmatizer.lemmatize(token) for token in tokens]

    def process(self, text: str) -> List[str]:
        """Complete preprocessing pipeline"""
        cleaned_text = self.clean_text(text)
        tokens = self.tokenize(cleaned_text)
        tokens = self.remove_stopwords(tokens)
        tokens = self.lemmatize(tokens)
        return tokens