import os # <-- Import the os module
from langchain.agents import AgentExecutor, create_tool_calling_agent
from langchain_core.prompts import ChatPromptTemplate
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_logic.tools import (
    schedule_appointment, 
    search_for_appointments, 
    delete_appointment_records, 
    update_appointment_record, 
    list_all_appointments
)
from datetime import datetime

# --- IMPORTANT ---
# This code will now work both locally (with a .env file) and on Hugging Face Spaces.
# On Hugging Face, os.getenv("GOOGLE_API_KEY") will read the secret you set.
# Locally, load_dotenv() in your main file will load it from .env for os.getenv to find.
google_api_key = os.getenv("GOOGLE_API_KEY")

if not google_api_key:
    raise ValueError("GOOGLE_API_KEY not found. Please set it as a secret in Hugging Face Spaces or in a .env file for local development.")
# ---------------


def create_agent_executor():
    """Creates the LangChain agent and executor."""
    tools = [
        schedule_appointment, 
        search_for_appointments, 
        list_all_appointments, 
        delete_appointment_records, 
        update_appointment_record
    ]

    # Explicitly pass the API key to the model
    llm = ChatGoogleGenerativeAI(
        model="gemini-2.5-flash-lite-preview-06-17",
        temperature=0,
        google_api_key=google_api_key # <-- Pass the key here
    )

    prompt = ChatPromptTemplate.from_messages([
        # ... (your prompt remains the same) ...
        ("system", """You are an advanced, helpful appointment scheduling assistant.

        Your tasks are to schedule, search, update, and delete appointments using the available tools.

        **Core Instructions:**
        1.  **Be Conversational:** Always be polite and helpful.
        2.  **Gather Information:** If you don't have enough information for a tool, ask the user for it.
        3.  **Search:** You can search for appointments by `customer_name`, `service_type` (which the user might call 'title'), or a specific `date`. If the user asks for *all* appointments, use the `list_all_appointments` tool.
        4.  **Update:** To update an appointment, you must know the customer's name and what specific information to change (e.g., 'update the phone for John Doe to 555-1111').
        5.  **CRITICAL-SAFETY-RULE for Deletion:** Deleting by name, service, or date can remove MULTIPLE appointments. Before using the `delete_appointment_records` tool, you MUST first search for the appointments to see how many will be affected. Then, you MUST ask the user for explicit confirmation. For example: "I found 3 appointments for 'Dental Checkup'. Are you sure you want to delete all of them? Please reply with 'yes' to confirm or 'no' to cancel." Only proceed with deletion if they confirm with 'yes'.
        6.  **Current Date:** Today's date is {today}.

        Begin the conversation by introducing yourself and what you can do.
        """.format(today=datetime.now().strftime('%Y-%m-%d'))),
        ("placeholder", "{chat_history}"),
        ("human", "{input}"),
        ("placeholder", "{agent_scratchpad}"),
    ])

    agent = create_tool_calling_agent(llm, tools, prompt)
    agent_executor = AgentExecutor(
        agent=agent,
        tools=tools,
        verbose=True,
        handle_parsing_errors=True
    )
    return agent_executor