"""
Advanced RAG-based search engine with multi-source intelligence.
"""
from typing import List, Dict, Any, Optional
import asyncio
from langchain.chains import RetrievalQAWithSourcesChain
from langchain.embeddings import HuggingFaceEmbeddings
from langchain.vectorstores import FAISS
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain.docstore.document import Document
from duckduckgo_search import DDGS
from googlesearch import search as gsearch
import requests
from bs4 import BeautifulSoup
from tenacity import retry, stop_after_attempt, wait_exponential
import json
import time
from datetime import datetime, timedelta
import hashlib
from urllib.parse import urlparse
import re

class SearchEngine:
    def __init__(self):
        self.embeddings = HuggingFaceEmbeddings(
            model_name="sentence-transformers/all-mpnet-base-v2"
        )
        self.text_splitter = RecursiveCharacterTextSplitter(
            chunk_size=500,
            chunk_overlap=50
        )
        self.cache = {}
        self.cache_ttl = timedelta(hours=24)
        self.search_delay = 2  # seconds between searches
        self.last_search_time = datetime.min
    
    def _get_cache_key(self, query: str, **kwargs) -> str:
        """Generate cache key from query and kwargs."""
        cache_data = {
            "query": query,
            **kwargs
        }
        return hashlib.md5(json.dumps(cache_data, sort_keys=True).encode()).hexdigest()
    
    def _get_cached_result(self, cache_key: str) -> Optional[Dict[str, Any]]:
        """Get result from cache if valid."""
        if cache_key in self.cache:
            result, timestamp = self.cache[cache_key]
            if datetime.now() - timestamp < self.cache_ttl:
                return result
            del self.cache[cache_key]
        return None
    
    def _set_cached_result(self, cache_key: str, result: Dict[str, Any]):
        """Store result in cache."""
        self.cache[cache_key] = (result, datetime.now())
    
    @retry(stop=stop_after_attempt(3), wait=wait_exponential(multiplier=1, min=4, max=10))
    async def search_web(self, query: str, max_results: int = 10) -> List[Dict[str, str]]:
        """Perform web search using multiple search engines."""
        results = []
        
        # Respect rate limiting
        time_since_last = datetime.now() - self.last_search_time
        if time_since_last.total_seconds() < self.search_delay:
            await asyncio.sleep(self.search_delay - time_since_last.total_seconds())
        
        # DuckDuckGo Search
        try:
            with DDGS() as ddgs:
                ddg_results = [r for r in ddgs.text(query, max_results=max_results)]
                results.extend(ddg_results)
        except Exception as e:
            print(f"DuckDuckGo search error: {e}")
        
        # Google Search
        try:
            google_results = gsearch(query, num_results=max_results)
            results.extend([{"link": url, "title": url} for url in google_results])
        except Exception as e:
            print(f"Google search error: {e}")
        
        self.last_search_time = datetime.now()
        return results[:max_results]
    
    def _clean_html(self, html: str) -> str:
        """Clean HTML content."""
        # Remove script and style elements
        html = re.sub(r'<script[^>]*>.*?</script>', '', html, flags=re.DOTALL)
        html = re.sub(r'<style[^>]*>.*?</style>', '', html, flags=re.DOTALL)
        
        # Remove comments
        html = re.sub(r'<!--.*?-->', '', html, flags=re.DOTALL)
        
        # Remove remaining tags
        html = re.sub(r'<[^>]+>', ' ', html)
        
        # Clean whitespace
        html = re.sub(r'\s+', ' ', html).strip()
        
        return html
    
    @retry(stop=stop_after_attempt(3), wait=wait_exponential(multiplier=1, min=4, max=10))
    async def fetch_content(self, url: str) -> Optional[str]:
        """Fetch and extract content from a webpage."""
        try:
            headers = {
                "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36"
            }
            response = requests.get(url, headers=headers, timeout=10)
            response.raise_for_status()
            
            # Extract main content
            soup = BeautifulSoup(response.text, "html.parser")
            
            # Remove unwanted elements
            for element in soup(["script", "style", "nav", "footer", "header", "aside"]):
                element.decompose()
            
            # Try to find main content
            main_content = None
            
            # Look for article tag
            if soup.find("article"):
                main_content = soup.find("article")
            
            # Look for main tag
            elif soup.find("main"):
                main_content = soup.find("main")
            
            # Look for div with common content class names
            elif soup.find("div", class_=re.compile(r"content|article|post|entry")):
                main_content = soup.find("div", class_=re.compile(r"content|article|post|entry"))
            
            # Use body if no main content found
            if not main_content:
                main_content = soup.body
            
            # Extract text
            if main_content:
                text = self._clean_html(str(main_content))
            else:
                text = self._clean_html(response.text)
            
            return text
        except Exception as e:
            print(f"Error fetching {url}: {e}")
            return None
    
    def _extract_metadata(self, soup: BeautifulSoup, url: str) -> Dict[str, Any]:
        """Extract metadata from webpage."""
        metadata = {
            "url": url,
            "domain": urlparse(url).netloc,
            "title": None,
            "description": None,
            "published_date": None,
            "author": None,
            "keywords": None
        }
        
        # Extract title
        if soup.title:
            metadata["title"] = soup.title.string
        
        # Extract meta tags
        for meta in soup.find_all("meta"):
            name = meta.get("name", "").lower()
            property = meta.get("property", "").lower()
            content = meta.get("content")
            
            if name == "description" or property == "og:description":
                metadata["description"] = content
            elif name == "author":
                metadata["author"] = content
            elif name == "keywords":
                metadata["keywords"] = content
            elif name in ["published_time", "article:published_time"]:
                metadata["published_date"] = content
        
        return metadata
    
    async def process_search_results(self, query: str) -> Dict[str, Any]:
        """Process search results and create a RAG-based answer."""
        cache_key = self._get_cache_key(query)
        cached_result = self._get_cached_result(cache_key)
        if cached_result:
            return cached_result
        
        # Perform web search
        search_results = await self.search_web(query)
        
        # Fetch content from search results
        documents = []
        metadata_list = []
        
        for result in search_results:
            url = result.get("link")
            if not url:
                continue
                
            content = await self.fetch_content(url)
            if content:
                # Split content into chunks
                chunks = self.text_splitter.split_text(content)
                
                # Store metadata
                metadata = {
                    "source": url,
                    "title": result.get("title", url),
                    **result
                }
                metadata_list.append(metadata)
                
                # Create documents
                for chunk in chunks:
                    doc = Document(
                        page_content=chunk,
                        metadata=metadata
                    )
                    documents.append(doc)
        
        if not documents:
            return {
                "answer": "I couldn't find any relevant information.",
                "sources": [],
                "metadata": []
            }
        
        # Create vector store
        vectorstore = FAISS.from_documents(documents, self.embeddings)
        
        # Create retrieval chain
        chain = RetrievalQAWithSourcesChain.from_chain_type(
            llm=None,  # We'll implement custom answer synthesis
            retriever=vectorstore.as_retriever()
        )
        
        # Get relevant documents
        relevant_docs = chain.retriever.get_relevant_documents(query)
        
        # Extract unique sources and content
        sources = []
        content = []
        used_metadata = []
        
        for doc in relevant_docs[:5]:  # Limit to top 5 most relevant docs
            source = doc.metadata["source"]
            if source not in sources:
                sources.append(source)
                content.append(doc.page_content)
                
                # Find corresponding metadata
                for meta in metadata_list:
                    if meta["source"] == source:
                        used_metadata.append(meta)
                        break
        
        result = {
            "answer": "\n\n".join(content),
            "sources": sources,
            "metadata": used_metadata
        }
        
        # Cache the result
        self._set_cached_result(cache_key, result)
        
        return result
    
    async def search(self, query: str) -> Dict[str, Any]:
        """Main search interface."""
        try:
            return await self.process_search_results(query)
        except Exception as e:
            return {
                "answer": f"An error occurred: {str(e)}",
                "sources": [],
                "metadata": []
            }