from dotenv import load_dotenv

load_dotenv()

True

import os, asyncio, json

from langchain.chat_models import init_chat_model
from langchain.agents import create_agent, AgentState
from langchain.messages import HumanMessage, AIMessage, ToolMessage
from langchain.tools import tool, ToolRuntime

from langchain_mcp_adapters.client import MultiServerMCPClient

from langchain_community.utilities import SQLDatabase
from langchain_community.document_loaders import PyPDFLoader

from langgraph.checkpoint.memory import InMemorySaver
from langgraph.types import Command

from mcp.shared.exceptions import McpError
from mcp.types import CallToolResult, TextContent

from typing import Dict, Any
from tavily import TavilyClient
from pprint import pprint
from dataclasses import dataclass
from datetime import date



DEEPSEEK_MODEL = "deepseek-chat"
DEEPSEEK_BASE_URL = "https://api.deepseek.com"

def deepseek_model(model: str = DEEPSEEK_MODEL, max_tokens=1000, **kwargs):
    return init_chat_model(
        model=model,
        # DeepSeek uses LangChain's OpenAI-compatible transport.
        model_provider="openai",
        api_key=os.environ["DEEPSEEK_API_KEY"],
        base_url=DEEPSEEK_BASE_URL,
        max_tokens=max_tokens,
        **kwargs,
    )

from langchain_community.utilities import SQLDatabase

db = SQLDatabase.from_uri("sqlite:///resources/Chinook.db")

@tool
def sql_query(query: str) -> str:
    """Obtain information from the database using SQL queries"""

    try:
        return db.run(query)
    except Exception as e:
        return f"Error: {e}"

sql_query.invoke("SELECT * FROM Artist LIMIT 10")

"[(1, 'AC/DC'), (2, 'Accept'), (3, 'Aerosmith'), (4, 'Alanis Morissette'), (5, 'Alice In Chains'), (6, 'Antônio Carlos Jobim'), (7, 'Apocalyptica'), (8, 'Audioslave'), (9, 'BackBeat'), (10, 'Billy Cobham')]"

agent = create_agent(
    model=deepseek_model(),
    tools=[sql_query]
)

question = HumanMessage(content="Who is the most popular artist beginning with 'S' in this database?")

response = agent.invoke(
    {"messages": [question]}
)

print(response["messages"][-3].tool_calls[0]['args']['query'])

SELECT a.Name, SUM(il.Quantity) as total_sold
FROM Artist a
JOIN Album al ON a.ArtistId = al.ArtistId
JOIN Track t ON al.AlbumId = t.AlbumId
JOIN InvoiceLine il ON t.TrackId = il.TrackId
WHERE a.Name LIKE 'S%'
GROUP BY a.ArtistId
ORDER BY total_sold DESC
LIMIT 10;

print(response['messages'][-1].content)

The most popular artist beginning with 'S' in this database is **Smashing Pumpkins**, with 24 total tracks sold.