import requests
import logging
from urllib.parse import urlparse, parse_qs, urlencode

def expand_short_url(short_url):
    """
    Expand short URLs (like amzn.to) to their full URLs
    """
    try:
        # Follow redirects to get the final URL
        response = requests.get(short_url, allow_redirects=True, timeout=10)
        final_url = response.url
        
        logging.info(f"Expanded URL: {short_url} -> {final_url}")
        return final_url
    except Exception as e:
        logging.error(f"Error expanding URL {short_url}: {str(e)}")
        return short_url  # Return original URL if expansion fails

def add_affiliate_tag_to_amazon_url(url, affiliate_tag='anrdcomm-21'):
    """
    Add or replace affiliate tag in Amazon URLs
    """
    try:
        parsed_url = urlparse(url)
        
        # Check if it's an Amazon URL
        if 'amazon' in parsed_url.netloc:
            query_params = parse_qs(parsed_url.query)
            
            # Check if our tag is already present
            existing_tag = query_params.get('tag', [])
            if existing_tag and existing_tag[0] == affiliate_tag:
                logging.info(f"Affiliate tag '{affiliate_tag}' already present, no change needed")
                return url
            
            # Remove existing tag if present and different
            if 'tag' in query_params and existing_tag[0] != affiliate_tag:
                logging.info(f"Removing existing tag: {query_params['tag']}")
            
            # Add our affiliate tag
            query_params['tag'] = [affiliate_tag]
            
            # Rebuild the URL with the new query parameters
            new_query = urlencode(query_params, doseq=True)
            affiliate_url = parsed_url._replace(query=new_query).geturl()
            
            logging.info(f"Added affiliate tag '{affiliate_tag}' to Amazon URL")
            return affiliate_url
        
        # Return original URL if not Amazon
        return url
    except Exception as e:
        logging.error(f"Error adding affiliate tag to URL {url}: {str(e)}")
        return url

def is_amazon_short_link(url):
    """
    Check if the URL is an Amazon short link (amzn.to)
    """
    parsed_url = urlparse(url)
    return 'amzn.to' in parsed_url.netloc

def is_flipkart_short_link(url):
    """
    Check if the URL is a Flipkart short link (fkrt.it)
    """
    parsed_url = urlparse(url)
    return 'fkrt.it' in parsed_url.netloc

def is_amazon_url(url):
    """
    Check if the URL is an Amazon URL
    """
    parsed_url = urlparse(url)
    return 'amazon' in parsed_url.netloc

def expand_ecommerce_url(url, add_affiliate_tag=True, affiliate_tag='anrdcomm-21'):
    """
    Expand e-commerce short URLs and optionally add affiliate tags
    """
    expanded_url = url
    
    # Expand short URLs
    if is_amazon_short_link(url) or is_flipkart_short_link(url):
        expanded_url = expand_short_url(url)
    
    # Add affiliate tag to Amazon URLs if requested
    if add_affiliate_tag and is_amazon_url(expanded_url):
        expanded_url = add_affiliate_tag_to_amazon_url(expanded_url, affiliate_tag)
    
    return expanded_url