"""LangGraph Agent (patched for robustness)"""
import os
import traceback
from dotenv import load_dotenv
from langgraph.graph import START, StateGraph, MessagesState
from langgraph.prebuilt import tools_condition
from langgraph.prebuilt import ToolNode
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_groq import ChatGroq
from langchain_huggingface import ChatHuggingFace, HuggingFaceEndpoint, HuggingFaceEmbeddings
from langchain_community.tools.tavily_search import TavilySearchResults
from langchain_community.document_loaders import WikipediaLoader
from langchain_community.document_loaders import ArxivLoader
from langchain_community.vectorstores import SupabaseVectorStore
from langchain_core.messages import SystemMessage, HumanMessage
from langchain_core.tools import tool
from supabase.client import Client, create_client

# --- Safe import + fallback for langchain.tools.retriever.create_retriever_tool ---
try:
    # Try to import the real helper (if the installed langchain provides it)
    from langchain.tools.retriever import create_retriever_tool  # type: ignore
    HAS_CREATE_RETRIEVER_TOOL = True
except Exception:
    HAS_CREATE_RETRIEVER_TOOL = False
    print("Warning: langchain.tools.retriever.create_retriever_tool not found. Using local fallback.")
    print(traceback.format_exc())

    class _SimpleRetrieverTool:
        """
        Minimal tool-like wrapper providing a `.run(query)` method.
        Most templates call tool.run(query) — adapt if your code uses a different interface.
        """
        def __init__(self, retriever, name="retriever", description=""):
            self.name = name
            self.description = description
            self._retriever = retriever

        def run(self, query: str):
            # Try common retriever methods in order
            docs = []
            try:
                if hasattr(self._retriever, "get_relevant_documents"):
                    docs = self._retriever.get_relevant_documents(query)
                elif hasattr(self._retriever, "retrieve"):
                    docs = self._retriever.retrieve(query)
                else:
                    # try calling the retriever directly (some callables return results)
                    docs = self._retriever(query)
            except Exception as e:
                return f"[retriever-fallback-error] {e}"

            # Normalize docs into strings
            out_texts = []
            for d in docs or []:
                text = getattr(d, "page_content", None)
                if text is None:
                    if isinstance(d, dict):
                        text = d.get("page_content") or d.get("text") or str(d)
                    else:
                        text = str(d)
                if text:
                    out_texts.append(text.strip())
            # return compact result
            return "\n\n".join(t for t in out_texts if t)

    def create_retriever_tool(retriever, name: str = "retriever", description: str = ""):
        """
        Minimal drop-in fallback returning an object with .run(query).
        Replace with the real langchain helper later once you pin the package.
        """
        return _SimpleRetrieverTool(retriever, name=name, description=description)


load_dotenv()

@tool
def multiply(a: int, b: int) -> int:
    """Multiply two numbers.
    Args:
        a: first int
        b: second int
    """
    return a * b

@tool
def add(a: int, b: int) -> int:
    """Add two numbers.
    
    Args:
        a: first int
        b: second int
    """
    return a + b

@tool
def subtract(a: int, b: int) -> int:
    """Subtract two numbers.
    
    Args:
        a: first int
        b: second int
    """
    return a - b

@tool
def divide(a: int, b: int) -> int:
    """Divide two numbers.
    
    Args:
        a: first int
        b: second int
    """
    if b == 0:
        raise ValueError("Cannot divide by zero.")
    return a / b

@tool
def modulus(a: int, b: int) -> int:
    """Get the modulus of two numbers.
    
    Args:
        a: first int
        b: second int
    """
    return a % b

@tool
def wiki_search(query: str) -> str:
    """Search Wikipedia for a query and return maximum 2 results.
    
    Args:
        query: The search query."""
    try:
        search_docs = WikipediaLoader(query=query, load_max_docs=2).load()
        formatted_search_docs = "\n\n---\n\n".join(
            [
                f'<Document source="{doc.metadata.get("source","")}" page="{doc.metadata.get("page", "")}"/>\n{doc.page_content}\n</Document>'
                for doc in search_docs
            ])
        return {"wiki_results": formatted_search_docs}
    except Exception as e:
        return {"wiki_results_error": str(e)}

@tool
def web_search(query: str) -> str:
    """Search Tavily for a query and return maximum 3 results.
    
    Args:
        query: The search query."""
    try:
        search_docs = TavilySearchResults(max_results=3).invoke(query=query)
        formatted_search_docs = "\n\n---\n\n".join(
            [
                f'<Document source="{doc.metadata.get("source","")}" page="{doc.metadata.get("page", "")}"/>\n{doc.page_content}\n</Document>'
                for doc in search_docs
            ])
        return {"web_results": formatted_search_docs}
    except Exception as e:
        return {"web_results_error": str(e)}

@tool
def arvix_search(query: str) -> str:
    """Search Arxiv for a query and return maximum 3 result.
    
    Args:
        query: The search query."""
    try:
        search_docs = ArxivLoader(query=query, load_max_docs=3).load()
        formatted_search_docs = "\n\n---\n\n".join(
            [
                f'<Document source="{doc.metadata.get("source","")}" page="{doc.metadata.get("page", "")}"/>\n{doc.page_content[:1000]}\n</Document>'
                for doc in search_docs
            ])
        return {"arvix_results": formatted_search_docs}
    except Exception as e:
        return {"arvix_results_error": str(e)}


# load the system prompt from the file
with open("system_prompt.txt", "r", encoding="utf-8") as f:
    system_prompt = f.read()

# System message
sys_msg = SystemMessage(content=system_prompt)

# --- Build a retriever (defensive: don't crash if heavy deps or credentials missing) ---
retriever_tool = None
vector_store = None
embeddings = None

# Try to create HuggingFaceEmbeddings and SupabaseVectorStore if dependencies and env are present.
try:
    embeddings = HuggingFaceEmbeddings(model_name="sentence-transformers/all-mpnet-base-v2")  # dim=768
except Exception as e:
    print(f"⚠️  Could not initialize HuggingFaceEmbeddings: {e}")
    embeddings = None

SUPABASE_URL = os.environ.get("SUPABASE_URL")
SUPABASE_SERVICE_KEY = os.environ.get("SUPABASE_SERVICE_KEY")

if SUPABASE_URL and SUPABASE_SERVICE_KEY and embeddings is not None:
    try:
        supabase: Client = create_client(SUPABASE_URL, SUPABASE_SERVICE_KEY)
        vector_store = SupabaseVectorStore(
            client=supabase,
            embedding=embeddings,
            table_name="documents",
            query_name="match_documents_langchain",
        )
    except Exception as e:
        print(f"⚠️  Could not initialize SupabaseVectorStore: {e}")
        vector_store = None
else:
    if not SUPABASE_URL or not SUPABASE_SERVICE_KEY:
        print("⚠️  SUPABASE_URL or SUPABASE_SERVICE_KEY not set — skipping vector store initialization.")
    elif embeddings is None:
        print("⚠️  Embeddings not available — skipping vector store initialization.")
    vector_store = None

# Create a retriever tool only if vector_store exists
if vector_store is not None:
    try:
        retriever_tool = create_retriever_tool(
            retriever=vector_store.as_retriever(),
            name="Question Search",
            description="A tool to retrieve similar questions from a vector store.",
        )
    except Exception as e:
        print(f"⚠️  Failed to create retriever tool from vector store: {e}")
        retriever_tool = None
else:
    retriever_tool = None


tools = [
    multiply,
    add,
    subtract,
    divide,
    modulus,
    wiki_search,
    web_search,
    arvix_search,
]

# Add retriever_tool to tools if available and matches the callable interface
if retriever_tool is not None:
    try:
        if hasattr(retriever_tool, "run"):
            @tool
            def retriever_wrapper(query: str) -> str:
                return retriever_tool.run(query)
            tools.append(retriever_wrapper)
        else:
            tools.append(retriever_tool)
    except Exception as e:
        print(f"⚠️  Could not append retriever tool to tools list: {e}")


# Build graph function
def build_graph(provider: str = "google"):
    """Build the graph"""
    # Load environment variables from .env file
    if provider == "google":
        # Google Gemini
        llm = ChatGoogleGenerativeAI(model="gemini-2.0-flash", temperature=0)
    elif provider == "groq":
        # Groq https://console.groq.com/docs/models
        llm = ChatGroq(model="qwen-qwq-32b", temperature=0)  # optional : qwen-qwq-32b gemma2-9b-it
    elif provider == "huggingface":
        # TODO: Add huggingface endpoint
        llm = ChatHuggingFace(
            llm=HuggingFaceEndpoint(
                url="https://api-inference.huggingface.co/models/Meta-DeepLearning/llama-2-7b-chat-hf",
                temperature=0,
            ),
        )
    else:
        raise ValueError("Invalid provider. Choose 'google', 'groq' or 'huggingface'.")

    # Bind tools to LLM
    try:
        llm_with_tools = llm.bind_tools(tools)
    except Exception as e:
        print(f"⚠️  Could not bind tools to LLM: {e}")
        # fallback: keep LLM without tools
        llm_with_tools = llm

    # Node: assistant
    def assistant(state: MessagesState):
        """Assistant node"""
        try:
            return {"messages": [llm_with_tools.invoke(state["messages"])]}
        except Exception as e:
            print(f"⚠️  assistant node failed: {e}")
            # return empty message so graph can continue
            return {"messages": [HumanMessage(content="")]}

    from langchain_core.messages import AIMessage

    def retriever(state: MessagesState):
        query = state["messages"][-1].content
        # If vector_store not available, return empty message so assistant proceeds normally
        if vector_store is None:
            return {"messages": [AIMessage(content="")]}

        try:
            similar_docs = vector_store.similarity_search(query, k=1)
            if not similar_docs:
                return {"messages": [AIMessage(content="")]}
            similar_doc = similar_docs[0]
            content = similar_doc.page_content
            if "Final answer :" in content:
                answer = content.split("Final answer :")[-1].strip()
            else:
                answer = content.strip()
            return {"messages": [AIMessage(content=answer)]}
        except Exception as e:
            print(f"⚠️  retriever node failed: {e}")
            return {"messages": [AIMessage(content="")]}

    # Build the state graph: a simple retriever-only entry point (defensive)
    builder = StateGraph(MessagesState)
    builder.add_node("retriever", retriever)

    # Retriever is both the entry and finish point in this design
    builder.set_entry_point("retriever")
    builder.set_finish_point("retriever")

    # Compile graph
    return builder.compile()