"""Tools used by the RAG agent.

This module defines two LangChain tools:

1. `search_local_kb` – semantic search in the Chroma vector store.
2. `web_search` – web search using Tavily.

Both tools are decorated with `@tool` so that they can be used by the agent.
"""

from typing import List

from langchain_core.tools import tool
from langchain_ollama import ChatOllama
from langchain_tavily import TavilySearchResults
from langchain_chroma import Chroma

# Global LLM instance for tool responses (can be reused)
_llm = ChatOllama(model="llama3")

# ---------------------------------------------------------------------------
# Local KB search tool
# ---------------------------------------------------------------------------

@tool("search_local_kb")

def search_local_kb(query: str, top_k: int = 3, vectorstore: Chroma = None) -> str:
    """Search the local Chroma vector store for relevant chunks.

    Parameters
    ----------
    query: str
        The user's query.
    top_k: int, optional
        Number of top results to return.
    vectorstore: Chroma
        The Chroma vector store instance.

    Returns
    -------
    str
        A formatted string containing the retrieved chunks.
    """
    if vectorstore is None:
        raise ValueError("Vectorstore must be provided to search_local_kb tool.")
    retriever = vectorstore.as_retriever(search_kwargs={"k": top_k})
    docs = retriever.invoke(query)
    # docs is a list of Document objects
    if not docs:
        return "No relevant information found in the local knowledge base."
    # Concatenate the content of the top documents
    snippets = [f"{i+1}. {doc.page_content[:200]}..." for i, doc in enumerate(docs)]
    return "\n".join(snippets)

# ---------------------------------------------------------------------------
# Web search tool
# ---------------------------------------------------------------------------

@tool("web_search")

def web_search(query: str, top_k: int = 3) -> str:
    """Perform a web search using Tavily.

    Parameters
    ----------
    query: str
        The user's query.
    top_k: int, optional
        Number of results to return.

    Returns
    -------
    str
        A formatted string containing the search results.
    """
    tavily = TavilySearchResults(tavily_api_key=None, max_results=top_k)
    results = tavily.invoke(query)
    if not results:
        return "No results found on the web."
    snippets = [f"{i+1}. {res['title']} – {res['url']}" for i, res in enumerate(results)]
    return "\n".join(snippets)

# ---------------------------------------------------------------------------
# Exported tool names for agent
# ---------------------------------------------------------------------------

TOOLS = [search_local_kb, web_search]
""